CONGESTIVE HEART FAILURE, Issue 2006
Sanjiv J. Shah MD
Bedside diagnostic tools remain important in the care of patients with heart failure. Over the past two centuries, cardiac auscultation and phonocardiography have been essential in understanding cardiac pathophysiology and caring for patients with heart disease. Diastolic heart sounds (S3 and S4) and systolic time intervals have been particularly useful in this regard. Unfortunately, auscultation skills have declined considerably, and systolic time intervals have traditionally required carotid pulse tracings. Newer technology allows the automated detection of heart sounds and measurement of systolic time intervals in a simple, inexpensive, noninvasive system. Using the newer system, the authors present data on the hemodynamic correlates of the S3 and abnormal systolic time intervals. These data serve as the foundation for using the system to better understand the test characteristics and pathophysiology of the S3 and systolic time intervals, and help to define their use in improving the bedside diagnosis and management of patients with heart failure. [source]

Hemodynamic and Volume Changes during Hemodialysis

HEMODIALYSIS INTERNATIONAL, Issue 3 2003
Robert M. Lindsay
Background:,Volume overload is a factor in the hypertension of hemodialysis (HD) patients. Fluid removal is therefore integral to the hemodialysis treatment. Fluid removal by hemodialysis ultrafiltration (UF) may cause intradialytic hypotension and leg cramps. Understanding blood pressure (BP) and volume changes during UF may eliminate intradialytic hypotension and cramps. Studies (S1, S2, and S3) were carried out to determine the amount and direction of changes in body fluid compartments following UF and to determine the relationships between BP, changes in blood volume (,BV), central blood volume (CBV), cardiac output (CO), peripheral vascular resistance (PVR) plus total body water (TBW), and intra- and extracellular fluid volumes (ICF, ECF) in both the whole body and body segments (arms, legs, trunk). Methods:,Indicator dilution technology (Transonic) was used for CBV, CO, and PVR; hematocrit monitoring (Crit-Line) was used for ,BV segmental bioimpedance (Xitron) for TBW, ICF, and ECF. Results:,S1 (n = 21) showed UF sufficient to cause ,BV of ,7% and lead to minor changes (same direction) in CBV and CO, and with cessation of UF, vascular refilling was preferential to CBV. S2 (n = 20) showed that predialysis HD patients are ECF-expanded (ECF/ICF ratio = 0.96, controls = 0.74 [P < 0.0001]) and BP correlates with ECF (r = 0.47, P = 0.35). UF to cause ,BV of ,7% was associated with a decrease in ECF (P < 0.0001) and BP directly (r = 0.46, P = 0.04) plus ,BV indirectly (r = ,0.5, P = 0.024) correlated with PVR, while CBV and CO were maintained. S3 (n = 11) showed that following UF, total-body ECF changes were correlated with leg ECF (r = 0.94) and arm ECF (r = 0.72) but not trunk ECF. Absolute ECF reduction was greatest from the legs. Conclusions:,Predialysis ECF influences BP and UF reduces ,BV and ECF, but CBV and BP are conserved by increasing PVR. ECF reduction is mainly from the legs, hence may cause cramps. Intradialytic hypotension is caused by failure of PVR response. [source]

Assessment of a New Experimental Model of Isolated Right Ventricular Failure

ARTIFICIAL ORGANS, Issue 3 2009
Petronio G. Thomaz
Abstract We assessed a new experimental model of isolated right ventricular (RV) failure, achieved by means of intramyocardial injection of ethanol. RV dysfunction was induced in 13 mongrel dogs via multiple injections of 96% ethanol (total dose 1 mL/kg), all over the inlet and trabecular RV free walls. Hemodynamic and metabolic parameters were evaluated at baseline, after ethanol injection, and on the 14th postoperative day (POD). Echocardiographic parameters were evaluated at baseline, on the sixth POD, and on the 13th POD. The animals were then euthanized for histopathological analysis of the hearts. There was a 15.4% mortality rate. We noticed a decrease in pulmonary blood flow right after RV failure (P = 0.0018), as well as during reoperation on the 14th POD (P = 0.002). The induced RV dysfunction caused an increase in venous lactate levels immediately after ethanol injection and on the 14th POD (P < 0.0003). The echocardiogram revealed a decrease in the RV ejection fraction on the sixth and 13th PODs (P = 0.0001). There was an increased RV end-diastolic volume on the sixth (P = 0.0001) and 13th PODs (P = 0.0084). The right ventricle showed a 74% ± 0.06% transmural infarction area, with necrotic lesions aged 14 days. Intramyocardial ethanol injection has allowed the creation of a reproducible and inexpensive model of RV failure. The hemodynamic, metabolic, and echocardiographic parameters assessed at different protocol times are compatible with severe RV failure. This model may be useful in understanding the pathophysiology of isolated right-sided heart failure, as well as in the assessment of ventricular assist devices. [source]

A Risk Adjusted Method for Comparing Adverse Outcomes among Practitioners in Pediatric and Congenital Cardiac Catheterization

CONGENITAL HEART DISEASE, Issue 4 2008
Lisa Bergersen MD
ABSTRACT Objective., We sought to develop a method to adjust for case mix diversity and allow comparison of adverse outcome rates among practitioners in pediatric and congenital cardiac catheterization. Patients and Methods., A single institutional database that captured demographic and procedural data was used to identify patient and procedural characteristics associated with adverse events (AE) and any high severity event classified as preventable or possibly preventable (P/PP). Diagnostic and procedural risk groups were created and indicators of hemodynamic vulnerability were defined. Expected event rates by the practitioners adjusting for case mix were calculated. Standardized adverse event ratios (SAER), defined as the observed rate divided by the expected rate for each practitioner were calculated with 95% confidence intervals. Results., The database included 1727 hemodynamic (30%) and interventional (70%) cases performed by seven practitioners in 18 months. During 147 cases, at least one P/PP AE occurred; among the seven practitioners observed, event rates ranged from 3.2 to 14.2%. In multivariable analysis, risk factors for all P/PP events included highest procedure risk group (odds ratio [OR] 2.1 for group 2, and 2.8 for group 3, relative to group 1, P = .001 and P < .001, respectively) and weight less than 4 kg (OR 2.8, P < .001). High severity P/PP events occurred in 67 cases with rates ranging from 2.0 to 6.6% by the practitioners. For these events, risk factors included: highest procedure risk group (OR 4.5 for group 2, and 4.9 for group 3, both P < .001) and an indicator of hemodynamic vulnerability (OR 1.8, P = .026). For the seven practitioners, the SAER ranged from 0.41 to 1.32 for any P/PP AE and from 0.69 to 1.44 for P/PP high severity events. In this cohort, we did not identify any statistically significant performance differences. Conclusion., Despite wide variations in case mix complexity in pediatric and congenital cardiac catheterization, this study demonstrates a method for risk adjustment which allows equitable comparisons among practitioners at a single institution. [source]

Hemodynamic Correlates of the Third Heart Sound and Systolic Time Intervals

Influence of lipophilicity and stereochemistry at the C7 position on the cardioprotective and antioxidant effect of ginkgolides during rat heart ischemia and reperfusion,

DRUG DEVELOPMENT RESEARCH, Issue 3 2005
Ludovic Billottet
Abstract The extent to which the cardioprotective effect of ginkgolides is related to their lipophilicity rather than to their anti-platelet activating factor (PAF) effect was addressed in isolated rat hearts submitted to ischemia and reperfusion. A new derivative of ginkgolide C (1), the 7-,- O -(4-methylphenyl) ginkgolide C (4) was synthesized and compared to 7- O -(4-methylphenyl) ginkgolide C (2) that had the same absolute configuration at C7 as 1 for its lipophilicity, anti-PAF activity, and cardioprotective and antioxidant effects. Using reversed-phase high-performance liquid chromatography HPLC, 4 and 2 were found to be significantly more lipophilic (i.e., log kw of 3.42±0.05 and 3.64±0.07, respectively) than 1 (1.15±0.03) and the strong PAF inhibitor ginkgolide B (GkB; 1.65±0.03). The anti-PAF activities (IC50 values in ,M) were 8.2, 17.1, and 2.2 for 4, 1, and GkB, respectively, while 2 was inactive. In preischemic and/or reperfused hearts perfused with ginkgolides at 0.7 ,M: (i) 2 and 4 were more efficient in improving postischemic hemodynamic and metabolic recovery than 1, (ii) a key-step in cardioprotection occurred during ischemia where 2 and 4 limited myocardial ATP depletion and contracture development, (iii) a strong anti-lipoperoxidant effect was observed with 2 and 4, but not 1. In vivo administration of 2 to rats (4 mg/kg/day for 20 days) was more effective than that of 1 regarding ischemic heart protection, suggesting a positive role for lipophilicity. It was concluded that a high lipophilicity is not an absolute prerequisite for a strong anti-PAF effect for ginkgolides, whereas it appears essential for cardioprotection. Drug Dev. Res. 64:157,171, 2005. © 2005 Wiley-Liss, Inc. [source]

Stress-Induced Wall Motion Abnormalities with Low-Dose Dobutamine Infusion Indicate the Presence of Severe Disease and Vulnerable Myocardium

ECHOCARDIOGRAPHY, Issue 7 2007
Stephen G. Sawada M.D.
Background: Patients with left ventricular (LV) systolic dysfunction due to coronary artery disease (CAD) may develop stress-induced wall motion abnormalities (SWMA) with low-dose (10 ,g/kg/min) dobutamine infusion. The clinical significance of low-dose SWMA is unknown. Objective: We investigated the clinical, hemodynamic and angiographic correlates of low-dose SWMA in patients with chronic ischemic LV systolic dysfunction. Methods: Seventy patients with chronic ischemic LV systolic dysfunction who had dobutamine stress echocardiography were studied. Clinical, hemodynamic, and angiographic parameters at rest and low-dose were compared between 38 patients (mean ejection fraction (EF) of 30 ± 8%) with low-dose SWMA and 32 patients (EF 30 ± 11%) without low-dose SWMA. Results: Multivariate analysis showed that the number of coronary territories with severe disease (stenosis ,70%)(P = 0.001, RR = 6.3) was an independent predictor of low-dose SWMA. An increasing number of collateral vessels protected patients from low-dose SWMA (P = 0.011, RR = 0.25). A higher resting heart rate was a negative predictor of low-dose SWMA (P = 0.015, RR = 0.92) but no other hemodynamic variables were predictors. In the patients with low-dose SMA, regions with low-dose SWMA were more likely to be supplied by vessels with severe disease than regions without low-dose SWMA (92% vs 58%, P < 0.001). Conclusion: In patients with ischemic LV systolic dysfunction, the extent of severe disease and a lower numbers of collaterals predict the occurrence of low-dose SWMA. Low-dose SWMA is a highly specific marker for severe disease. [source]

Adenosine A1 Antagonism Attenuates Atropine-resistant Hypoxic Bradycardia in Rats

ACADEMIC EMERGENCY MEDICINE, Issue 9 2003
Justin L. Kaplan MD
Abstract Objectives: To test the following hypotheses: Hypoxia induces bradycardia and hemodynamic compromise that are resistant to atropine but responsive to selective antagonism of the adenosine A1 receptor (A1AdoR). The mechanism for such attenuation is independent of the vagus nerve. Methods: Ten minutes after sham or actual bilateral cervical vagotomy, paralyzed ventilated rats were made hypoxic (5% fractional inspired oxygen, continued until death). Five minutes after beginning hypoxia, intravenous treatment with BG-9719, a selective A1AdoR antagonist (0.1 mg/kg); atropine (0.1 mg/kg); BG-9719 vehicle; or saline was initiated. These drug doses were based on pilot studies. Of the eight treatment groups (eight possible combinations of vagotomy status and drug/vehicle treatment), n= 8 in all except nonvagotomized, vehicle-treated rats (where n= 7). Results: Heart rate and left ventricular contractility decreased rapidly with hypoxia. Atropine had minimal effects in prolonging survival (from mean ± SEM of 15.5 ± 2.1 minutes to 20.2 ± 2.5 minutes, p = 0.94) and attenuating posthypoxic decreases in heart rate (p = 0.89) and contractility (p = 0.83) compared with saline. BG-9719 prolonged survival, however, from 14.4 ± 1.9 minutes (with vehicle treatment) to 37.2 ± 6.8 minutes (p < 0.001). Survival, heart rate, and contractility were preserved with BG-9719 compared with atropine and vehicle (p < 0.05, all comparisons). Vagotomy prevented the effects of BG-9719 on survival prolongation (p = 0.003), heart rate (p = 0.01), and contractility (p < 0.001) but did not affect those outcomes in saline-treated rats. Conclusions: Survival, heart rate, and contractility were better preserved with BG-9719 than atropine. A1AdoR selective antagonism, possibly because of its multiple mechanisms for attenuating hypoxic cardiac insufficiency, resulted in better hemodynamic and clinical outcomes. That attenuation seems to have a component of vagal mediation. [source]

Undulating toe movements in brain death,

EUROPEAN JOURNAL OF NEUROLOGY, Issue 11 2004
G. Saposnik
For many years, death implied immobility. Nevertheless, there are anecdotal reports of spontaneous or reflex movements (SRMs) in patients with Brain death (BD). The presence of some movements can preclude the diagnosis of BD, and consequently, the possibility of organ donation for transplantation. McNair and Meador [(1992), Mov Dord7: 345,347] described the presence of undulating toe flexion movements (UTF) in BD patients. UTF consists in a sequential brief plantar flexion of the toes. Our aim was to determine the frequency, characteristics and predisposing factors of UTF movements in a prospective multicenter cohort study of patients with BD. Patients with confirmed diagnosis of BD were assessed to evaluate the presence of UTF using a standardized protocol. All patients had a routine laboratory evaluation, CT scan of the head, and EEG. Demographic, clinical, hemodynamic and blood gas concentration factors were analyzed. amongst 107 BD patients who fulfilled the AAN requirements, 47 patients (44%) had abnormal movements. UTF was observed in 25 (23%) being the most common movement (53%). Early evaluation (OR 4.3, CI95% 1.5,11.9) was a predictor of UTF in a multivariate regression model. The somato-sensory evoked potential (SSEPs) as well as brainstem auditory evoked potentials (BAEPs) did not elicit a cortical response in studied patients with UTF. This spinal reflex is probably integrated in the L5 and S1 segments of the spinal cord. Abnormal movements are common in BD, being present in more than 40% of individuals. UTF was the most common spinal reflex. In our sample, early evaluation was a predictor of UTF. Health care professionals, especially those involved in organ procurement for transplantation, must be aware of this sign. The presence of this motor phenomenon does not preclude the diagnosis of BD. [source]

Iron chelation prevents lung injury after major hepatectomy

HEPATOLOGY RESEARCH, Issue 8 2010
Konstantinos Kalimeris
Aim:, Oxidative stress has been implicated in lung injury following ischemia/reperfusion and resection of the liver. We tested whether alleviating oxidative stress with iron chelation could improve lung injury after extended hepatectomy. Methods:, Twelve adult female pigs subjected to liver ischemia for 150 min, 65,70% hepatectomy and reperfusion of the remnant liver for 24 h were randomized to a desferrioxamine (DF) group (n = 6) which received i.v. desferrioxamine to a total dose of 100 mg/kg during both ischemia and reperfusion, and a control (C) group (n = 6). We recorded hemodynamic and respiratory parameters, plasma interleukin-6 and malondialdehyde levels, as well as liver malondialdehyde and protein carbonyls content. Total non-heme iron was measured in lung and liver. Pulmonary tissue was evaluated histologically for its nitrotyrosine and protein carbonyls content and for superoxide dismutase (SOD) and platelet-activating factor acetylhydrolase (PAF-AcH) activities. Results:, Reperfusion of the remnant liver resulted in gradual deterioration of gas-exchange and pulmonary vascular abnormalities. Iron chelation significantly decreased the oxidative markers in plasma, liver and the lung and lowered activities of pulmonary SOD and PAF-AcH. The improved liver function was followed by improved arterial oxygenation and pulmonary vascular resistance. DF also improved alveolar collapse and inflammatory cell infiltration, while serum interleukin-6 increased. Conclusion:, In an experimental pig model that combines liver resection with prolonged ischemia, iron chelation during reperfusion of the remnant liver is associated with improvement of several parameters of oxidative stress, lung injury and arterial oxygenation. [source]

Noninvasive dynamic imaging of seizures in epileptic patients

HUMAN BRAIN MAPPING, Issue 12 2009
Louise Tyvaert
Abstract Epileptic seizures are due to abnormal synchronized neuronal discharges. Techniques measuring electrical changes are commonly used to analyze seizures. Neuronal activity can be also defined by concomitant hemodynamic and metabolic changes. Simultaneous electroencephalogram (EEG)-functional MRI (fMRI) measures noninvasively with a high-spatial resolution BOLD changes during seizures in the whole brain. Until now, only a static image representing the whole seizure was provided. We report in 10 focal epilepsy patients a new approach to dynamic imaging of seizures including the BOLD time course of seizures and the identification of brain structures involved in seizure onset and discharge propagation. The first activation was observed in agreement with the expected location of the focus based on clinical and EEG data (three intracranial recordings), thus providing validity to this approach. The BOLD signal preceded ictal EEG changes in two cases. EEG-fMRI may detect changes in smaller and deeper structures than scalp EEG, which can only record activity form superficial cortical areas. This method allowed us to demonstrate that seizure onset zone was limited to one structure, thus supporting the concept of epileptic focus, but that a complex neuronal network was involved during propagation. Deactivations were also found during seizures, usually appearing after the first activation in areas close or distant to the activated regions. Deactivations may correspond to actively inhibited regions or to functional disconnection from normally active regions. This new noninvasive approach should open the study of seizure generation and propagation mechanisms in the whole brain to groups of patients with focal epilepsies. Hum Brain Mapp, 2009. © 2009 Wiley-Liss, Inc. [source]

Comparing MEG and fMRI views to naming actions and objects

HUMAN BRAIN MAPPING, Issue 6 2009
Mia Liljeström
Abstract Most neuroimaging studies are performed using one imaging method only, either functional magnetic resonance imaging (fMRI), electroencephalography (EEG), or magnetoencephalography (MEG). Information on both location and timing has been sought by recording fMRI and EEG, simultaneously, or MEG and fMRI in separate sessions. Such approaches assume similar active areas whether detected via hemodynamic or electrophysiological signatures. Direct comparisons, after independent analysis of data from each imaging modality, have been conducted primarily on low-level sensory processing. Here, we report MEG (timing and location) and fMRI (location) results in 11 subjects when they named pictures that depicted an action or an object. The experimental design was exactly the same for the two imaging modalities. The MEG data were analyzed with two standard approaches: a set of equivalent current dipoles and a distributed minimum norm estimate. The fMRI blood-oxygen-level dependent (BOLD) data were subjected to the usual random-effect contrast analysis. At the group level, MEG and fMRI data showed fairly good convergence, with both overall activation patterns and task effects localizing to comparable cortical regions. There were some systematic discrepancies, however, and the correspondence was less compelling in the individual subjects. The present analysis should be helpful in reconciling results of fMRI and MEG studies on high-level cognitive functions. Hum Brain Mapp, 2009. © 2009 Wiley-Liss, Inc. [source]

Arterial blood gases in extraperitoneal laparoscopic urethrocystopexy

INTERNATIONAL JOURNAL OF UROLOGY, Issue 8 2002
Hasan Kocoglu
Abstract Background: The aim of this study was to investigate the effects of extraperitoneal laparoscopy and carbon dioxide insufflation on hemodynamic parameters, arterial blood gases and complications in urethrocystopexy operations. Methods: Twenty-five female patients who underwent extraperitoneal laparoscopic mesh urethrocystopexy operation for the correction of urinary incontinence were allocated to the study. Hemodynamic parameters were noted and blood gas analyzes were performed before the induction of anesthesia, 10 min after induction, 5 and 10 min after the beginning of carbon dioxide insufflation, at the end of carbon dioxide insufflation and 30 min after exsufflation. Results: There was no significant change in mean arterial pressure, peripheral oxygen saturation, arterial carbon dioxide pressure, and arterial oxygen saturation compared to preinsufflation and preinduction values. End-tidal carbon dioxide pressure did not increase above 45 mm/Hg during carbon dioxide insufflation. Arterial oxygen saturation and partial oxygen pressure did not decrease. Subcutaneous emphysema, pneumothorax, pneumomediastinum and pleural effusion were not noted in any patient. Conclusion: We conclude that, extraperitoneal laparoscopic urethrocystopexy is not associated with hemodynamic and respiratory impairment. [source]

Infusion of hypertonic saline/starch during cardiopulmonary bypass reduces fluid overload and may impact cardiac function

ACTA ANAESTHESIOLOGICA SCANDINAVICA, Issue 4 2010
V. L. KVALHEIM
Objective: Peri-operative fluid accumulation resulting in myocardial and pulmonary tissue edema is one possible mechanism behind post-operative cardiopulmonary dysfunction. This study aimed to confirm an improvement of cardiopulmonary function by reducing fluid loading during an open-heart surgery. Materials and methods: Forty-nine elective CABG patients were randomized to an intraoperative infusion of hypertonic saline/hydroxyethyl starch (HSH group) or Ringer's solution (CT group). Both groups received 1 ml/kg/h of the study solution for 4 h after baseline values were obtained (PICCO® transpulmonary thermodilution technique). Net fluid balance (NFB), hemodynamic and laboratory parameters were measured. Results: NFB was four times higher in the CT group compared with the HSH group during the first 6 h post-operatively. The total fluid gain until the next morning was lower in the HSH group, 2993.9 (938.6) ml, compared with the CT group, 4298.7 (1059.3) ml (P<0.001). Normalized values (i.e., %-changes from the baseline) of the cardiac index and the global end diastolic volume index increased post-operatively in both groups. Both parameters were significantly higher at 6 h in the HSH group compared with CT group (P=0.002 and 0.005, respectively). Normalized values of the intrathoracic blood volume index were lower in the HSH group at 6 h post-operatively when compared with the CT group. The PaO2/FiO2 ratio decreased similarly in both groups early post-operatively, but recovery tended to be more rapid in the HSH group. Although serum-sodium and serum-chloride levels were significantly higher in the HSH group, the acid,base parameters remained similar and within the normal range. Conclusions: An intraoperative infusion of HSH during cardiac surgery contributes to reduced fluid loading and an improvement in the post-operative cardiac performance. No adverse effects of the HSH infusion were observed. [source]

Early Hemodynamic Results of the Shelhigh SuperStentless Aortic Bioprostheses

JOURNAL OF CARDIAC SURGERY, Issue 5 2007
Paolo Cattaneo M.D.
The aim of the study was to evaluate the early hemodynamic performance of the Shelhigh SuperStentless aortic valve (AV). Methods: Between July 2003 and June 2005, 35 patients (18 females; age 70.8 ± 11.7 years, range: 22-85) underwent AV replacement with the Shelhigh SuperStentless bioprostheses. Most recurrent etiology was senile degeneration in 25 (71%) patients and 24 (69%) were in New York Heart Association (NYHA) functional class III or IV. Concomitant coronary artery bypass grafting was performed in nine patients (25.7%) and mitral valve surgery in two patients (5.7%). Doppler echocardiography was performed before surgery, at six-month and one-year follow-up. Results: There were no hospital deaths and no valve-related perioperative complications. During one-year follow-up, no endocarditis or thromboembolic events were registered, no cases of structural dysfunction or valve thrombosis were noted. Mean and peak transvalvular gradients significantly decrease after AV replacement, with an evident reduction to approximately 50% of the preoperative values at six months. A 20% reduction was also observed for left ventricular mass (LVM) index at six months, with a further regression at one year. Correspondingly, significant increases in effective orifice area (EOA) and indexed EOA were determined after surgery (0.87 ± 0.14 versus 1.84 ± 0.29 cm2 and 0.54 ± 0.19 versus 1.05 ± 0.20 cm2/m2, respectively). Valve prosthesis-patient mismatch was moderate in five patients and severe in one case. Conclusions: Shelhigh SuperStentless AV provided good and encouraging hemodynamic results. Long-term follow-up is necessary to evaluate late hemodynamic performance and durability of this stentless bioprosthesis. [source]

Low Systemic Vascular Resistance After Cardiopulmonary Bypass: Incidence, Etiology, and Clinical Importance

JOURNAL OF CARDIAC SURGERY, Issue 5 2000
T. Carrel M.D.
The etiology is not completely elucidated and the clinical importance remains speculative. Methods: In this prospective clinical trial, we assessed the incidence of postoperative low systemic vascular resistance in 800 consecutive patients undergoing elective coronary artery bypass grafting and/or valve replacement. We have attempted to identify the predictive factors responsible for the presence of low systemic vascular resistance and we have examined the subsequent postoperative outcome of those patients who developed early postoperative vasoplegia. The severity of vasoplegia was divided into three groups according either to the value of systemic resistance and/or the dose of vasoconstrictive agents necessary to correct the hemodynamic. Results: Six hundred twenty-five patients (78.1%) did not develop vasoplegia, 115 patients (14.4%) developed a mild vasoplegia, and 60 patients (7.5%) suffered from severe vasoplegia. Low systemic vascular resistance did not affect hospital mortality but was the cause for delayed extubation and prolonged stay on the intensive care unit IICU). Logistic regression analysis identified temperature and duration of cardiopulmonary bypass, total cardioplegic volume infused, reduced left ventricular function, and preoperative treatment with angiotensin-converting enzyme (ACE)-inhibitors, out of 25 parameters, as predictive factors for early postoperative vasoplegia. Conclusion. The occurrence of low systemic vascular resistance following cardiopulmonary bypass is as high as 21.8%. The etiology of this clinical condition is most probably multifactorial. Mortality is not affected by vasoplegia, but there is a trend to higher morbidity and prolonged stay in the ICU. [source]

Left Ventricular Lead Proximity to an Akinetic Segment and Impact on Outcome of Cardiac Resynchronization Therapy

JOURNAL OF CARDIOVASCULAR ELECTROPHYSIOLOGY, Issue 6 2006
DANIEL ARZOLA-CASTANER M.D.
Background: Previous studies report that the optimal pacing site for cardiac resynchronization therapy (CRT) is along the left ventricular (LV) lateral and postero-lateral (PL) wall. However, little is known regarding whether pacing over an akinetic site impacts the contractile response and long-term outcome from CRT. Methods and Results: A total of 38 patients with ischemic cardiomyopathy were studied for their acute hemodynamic and 12-month clinical response to CRT. The intraindividual percentage change in dP/dt (%,dP/dt), over baseline, was derived from the mitral regurgitation (MR) Doppler profile with CRT on versus off. Two-dimensional echocardiography was used for myocardial segmentation and determinination of akinetic sites. LV lead implant site was determined using angiographic and radiographic data and categorized as being "on" (group 1) or "off" (group 2) an akinetic site. Long-term response was measured as a combined endpoint of hospitalization for heart failure and/or all cause mortality at 12 months. Time to primary endpoint was estimated by the Kaplan-Meier method. Clinical characteristics and acute hemodynamic response was similar in both (group 1 [n = 14]; %,dP/dt 48.8 ± 67.4% vs group 2 [n = 24]; %,dP/dt 32.2 ± 40.1%, P = 0.92). No difference in long-term outcome was observed (P = 0.59). In contrast, lead placement in PL or mid-lateral (ML) positions was associated with a better acute hemodynamic response when compared to antero-lateral (AL) positions (PL, %,dP/dt 45.7 ± 50.7% and ML, %,dP/dt 45.1 ± 58.8% vs AL, %,dP/dt 2.9 ± 30.9%, respectively, P = 0.014). Conclusion: LV lead proximity to an akinetic segment does not impact acute hemodynamic or 12-month clinical response to CRT. [source]

Biventricular Pacing and Left Ventricular Pacing in Heart Failure:

JOURNAL OF CARDIOVASCULAR ELECTROPHYSIOLOGY, Issue 12 2004
Similar Hemodynamic Improvement Despite Marked Electromechanical Differences
Introduction: We conducted an acute echocardiographic study comparing hemodynamic and ventricular dyssynchrony parameters during left ventricular pacing (LVP) and biventricular pacing (BVP). We sought to clarify the mechanisms responsible for similar hemodynamic improvement despite differences in electrical activation. Methods and Results: Thirty-three patients underwent echocardiography prior to implantation with a multisite pacing device (spontaneous rhythm [SR]) and 2 days after implantation (BVP and LVP). Interventricular dyssynchrony (pulsed-wave Doppler), extent of myocardium displaying delayed longitudinal contraction (%DLC; tissue tracking), and index of LV dyssynchrony (pulsed-wave tissue Doppler imaging) were assessed. Compared to SR, BVP and LVP caused similar significant improvement of cardiac output (LVP: 3.2 ± 0.5, BVP: 3.1 ± 0.7, SR: 2.3 ± 0.6 L/min; P < 0.01) and mitral regurgitation (LVP: 25.1 ± 10, BVP: 24.7 ± 11, baseline: 37.9 ± 14% jet area/left atria area; P < 0.01). LVP resulted in a smaller index of LV dyssynchrony than BVP (29 ± 10 vs 34 ± 14; P < 0.05). However, LVP exhibited a longer aortic preejection delay (220 ± 34 vs 186 ± 28 msec; P < 0.01), longer LV electromechanical delays (244.5 ± 39 vs 209.5 ± 47 msec; P < 0.05), greater interventricular dyssynchrony (56.6 ± 18 vs 31.4 ± 18; P < 0.01), and higher%DLC (40.1 ± 08 vs 30.3 ± 09; P < 0.05), leading to shorter LV filling time (387 ± 54 vs 348 ± 44 msec; P < 0.05) compared to BVP. Conclusion: Although LVP and BVP provide similar hemodynamic improvement, LVP results in more homogeneous but substantially delayed LV contraction, leading to shortened filling time and less reduction in postsystolic contraction. These data may influence the choice of individual optimal pacing configuration. [source]

Underlying mechanism of portal hypertensive gastropathy in cirrhosis: A hemodynamic and morphological approach

JOURNAL OF GASTROENTEROLOGY AND HEPATOLOGY, Issue 9 2009
Lílian Amorim Curvêlo
Abstract Background and Aim:, Portal hypertensive gastropathy (PHG) is an important cause of bleeding in patients with cirrhosis associated with portal hypertension. Histologically, the condition is characterized by dilation of the mucosal and submucosal vessels of the stomach; however, its mechanisms remain unclear. The aim of the present cross-sectional study was to evaluate the role of portal and systemic hemodynamic features, humoral factors and hepatocellular function in the development and severity of PHG in patients with cirrhosis. Methods:, Forty-six patients with cirrhosis of different etiologies underwent endoscopy. Portal hypertension was evaluated by hepatic venous pressure gradient (HVPG). The gastric mucosa was analyzed using two diagnostic methods: endoscopy according to the McCormack criteria and histological by histomorphometric analysis. Results:, The prevalence of PHG according to the endoscopic and histomorphometric methods was 93.4% and 76.1%, respectively. There were no statistically significant differences in HVPG measurements between the patients with mild (16.0 ± 5.9 mmHg) and severe PHG (16.9 ± 6.5 mmHg; P = 0.80) or between patients who did not have (15.2 ± 8.0 mmHg) and those who had PHG (16.3 ± 5.7 mmHg). No correlation was found between the presence or severity of PHG and systemic vascular resistance index (P = 0.53 and 0.34, respectively), Child,Pugh classification (P = 0.73 and 0.78, respectively) or glucagon levels (P = 0.59 and 0.62, respectively). Conclusions:, The present data show no correlation between the presence or the severity of PHG and portal pressure, Child,Pugh classification or systemic hemodynamics, suggesting that other factors may be involved in the physiopathology of PHG, such as local gastric mucosal factors or other underlying factors. [source]

Role of neuroimaging in promoting long-term recovery from ischemic stroke

JOURNAL OF MAGNETIC RESONANCE IMAGING, Issue 4 2010
Rüdiger J. Seitz MD
Abstract Human ischemic stroke is an acute disorder followed by a recovery period which may be of varying duration and mechanism. Imaging has created a means to explore the stroke process in vivo, particularly its underlying pathophysiology and recovery mechanisms. Evidence from multicenter studies has shown that, in the acute phase, arterial recanalization and reperfusion of ischemic brain tissue are the most important determinants of recovery. This is followed by functional and structural changes in the perilesional tissue and in large-scale bihemispheric networks that continue with different dynamics for weeks to months. Proof-of-principle studies have revealed that the behavioral gains induced by rehabilitation are paralleled by changes in functional representations. This is supported by data from neuroimaging and electrophysiological studies early after stroke which have shown that dedicated training can induce changes in cerebral functional representations. Accordingly, there is clear evidence that neuroimaging has a significant potential for monitoring the hemodynamic, functional, and structural factors determining recovery from stroke. New imaging methods may provide relevant biomarkers for treatment decisions and therapeutic monitoring. By combining neuroimaging with electrophysiological measures, opportunities exist to develop neuroscience-based strategies in rehabilitation. J. Magn. Reson. Imaging 2010;32:756,772. © 2010 Wiley-Liss, Inc. [source]

The use of desflurane or propofol in combination with remifentanil in myasthenic patients undergoing a video-assisted thoracoscopic-extended thymectomy

ACTA ANAESTHESIOLOGICA SCANDINAVICA, Issue 3 2009
P. GRITTI
Background: Although several studies of the use of desflurane in anesthesia have revealed many desirable qualities, there are no data on the use and effects especially on the neuromuscular function of desflurane on myasthenia gravis (MG) patients. The purpose of this study was to evaluate the use of either desflurane or propofol, both combined with remifentanil, in patients with MG undergoing a video-assisted thoracoscopic-extended thymectomy (VATET). Methods: Thirty-six MG patients who underwent VATET were enrolled. Nineteen patients were anesthetized with remifentanil and propofol infused with a target-controlled infusion plasma model, and 17 patients with desflurane and remifentanil. No muscle relaxant was used. The intubating conditions, hemodynamic and respiratory changes, neuromuscular transmission and post-operative complications were evaluated. Results: Neuromuscular transmission was significantly decreased in the desflurane group (6.7%, from 3% to 9% during anesthesia P=<0.05). The intubating conditions were good in all 36 patients and 35 patients were successfully extubated in the operating room. The time-to-awakening, post-operatory pH and base excess were significantly different in the two groups, with a decreasing mean arterial pressure in the group administered with desflurane. No patients required reintubation due to myasthenic or cholinergic crisis, or respiratory failure. No other significant differences between the two groups studied were observed. Conclusion: Our experience indicates that anesthesia with desflurane plus remifentanil in patients with MG could determine a reversible muscle relaxation effect, but with no clinical implication, allowing a faster recovery with no difference in extubation time and post-operative complications in the two groups. [source]

Facilitation of Myocardial PI3K/Akt/nNOS Signaling Contributes to Ethanol-Evoked Hypotension in Female Rats

ALCOHOLISM, Issue 7 2009
Mahmoud M. El-Mas
Background:, The mechanism by which ethanol reduces cardiac output (CO) and blood pressure (BP) in female rats remains unclear. We tested the hypothesis that enhancement of myocardial phosphatidylinositol 3-kinase (PI3K)/Akt signaling and related neuronal nitric oxide synthase (nNOS) and/or endothelial nitric oxide synthase (eNOS) activity constitutes a cellular mechanism for the hemodynamic effects of ethanol. Methods:, We measured the level of phosphorylated eNOS (p-eNOS) and p-nNOS in the myocardium of ethanol (1 g/kg intragastric, i.g.) treated female rats along with hemodynamic responses [BP, CO, stroke volume, (SV), total peripheral resistance, (TPR)], and myocardial nitrate/nitrite levels (NOx) levels. Further, we investigated the effect of selective pharmacological inhibition of nNOS with N, -propyl- l -arginine (NPLA) or eNOS with N5 -(1-iminoethyl)- l -ornithine (l -NIO) on cellular, hemodynamic, and biochemical effects of ethanol. The effects of PI3K inhibition by wortmannin on the cardiovascular actions of ethanol and myocardial Akt phosphorylation were also investigated. Results:, The hemodynamic effects of ethanol (reductions in BP, CO, and SV) were associated with significant increases in myocardial NOx and myocardial p-nNOS and p-Akt expressions while myocardial p-eNOS remained unchanged. Prior nNOS inhibition by NPLA (2.5 or 12.5 ,g/kg) attenuated hemodynamic effects of ethanol and abrogated associated increases in myocardial NOx and cardiac p-nNOS contents. The hemodynamic effects of ethanol and increases in myocardial p-Akt phosphorylation were reduced by wortmannin (15 ,g/kg). On the other hand, although eNOS inhibition by l -NIO (4 or 20 mg/kg) in a dose-dependent manner attenuated ethanol-evoked hypotension, the concomitant reductions in CO and SV remained unaltered. Also, selective eNOS inhibition uncovered dramatic increases in TPR in response to ethanol, which appeared to have offset the reduction in CO. Neither NPLA nor l -NIO altered plasma ethanol levels. Conclusions:, These findings implicate the myocardial PI3K/Akt/nNOS signaling in the reductions in BP and CO produced by ethanol in female rats. [source]

Role of Myocardial Contractility and Autonomic Control in the Hypotensive Response to a Limited Access Ethanol Paradigm in SHRs

ALCOHOLISM, Issue 6 2007
Mahmoud M. El-Mas
Background: Previous experimental studies that evaluated the chronic hemodynamic effect of ethanol employed the continuous exposure protocol of ethanol, which does not mimic the pattern of alcohol consumption in humans. This study dealt with the long-term hemodynamic and cardiovascular autonomic effects of ethanol, in a limited-access regimen in telemetered spontaneously hypertensive rats (SHRs). Methods: Changes in blood pressure (BP), heart rate (HR), myocardial contractility (dP/dtmax), and spectral cardiovascular autonomic profiles during the ethanol exposure period (2.5 or 5% w/v, 8 h/d, 8:30 am till 4:30 pm) were followed for 12 weeks. Results: Compared with control pair-fed SHRs, body weight and urine output, osmolality, and potassium levels were decreased in SHRs receiving 5% but not 2.5% ethanol. Blood pressure showed progressive falls during ethanol-feeding periods with a maximum effect observed at week 5. The peak hypotensive effect was maintained thereafter in SHRs receiving 5% ethanol in contrast to steady rises in BP in the 2.5% ethanol group to near-control levels by the conclusion of the study. Heart rate was slightly but significantly increased by ethanol 5% whereas dP/dtmax showed persistent reductions. Power spectral analysis showed that ethanol attenuated the baroreflex gain of HR as suggested by the reductions in index ,, the spectral index of spontaneous baroreflex sensitivity (BRS). Conclusions: It is concluded that limited access ethanol drinking in SHRs elicited hypotension that was concentration dependent and mediated, at least partly, through reductions in myocardial contractility. Baroreflex sensitivity attenuation by ethanol appeared to have limited the tachycardic response to ethanol and perhaps its capacity to offset the evoked hypotension. [source]

Acute Alcohol Intoxication During Hemorrhagic Shock: Impact on Host Defense From Infection

ALCOHOLISM, Issue 4 2004
K. L. Zambell
Abstract: Background: Acute alcohol intoxication is a frequent underlying condition associated with traumatic injury. Our studies have demonstrated that acute alcohol intoxication significantly impairs the immediate hemodynamic, metabolic, and inflammatory responses to hemorrhagic shock. This study investigated whether acute alcohol intoxication during hemorrhagic shock would alter the outcome from an infectious challenge during the initial 24 hr recovery period. Methods: Chronically catheterized male Sprague Dawley® rats were randomized to acute alcohol intoxication (EtOH; 1.75 g/kg bolus followed by a constant 15 hr infusion at 250,300 mg/kg/hr) or isocaloric isovolemic dextrose infusion (dex; 3 ml + 0.375 ml/hr). EtOH and dex were assigned to either fixed-volume (50%) hemorrhagic shock followed by fluid resuscitation with Ringer's lactate (EtOH/hem, dex/hem) or sham hemorrhagic shock (EtOH/sham, dex/sham). Indexes of circulating neutrophil function (apoptosis, phagocytosis, oxidative burst) were obtained at baseline, at completion of hemorrhagic shock, and at the end of fluid resuscitation. Bacterial clearance, lung cytokine expression, and myeloperoxidase activity were determined at 6 and 18 hr after an intratracheal challenge with Klebsiella pneumoniae (107 colony-forming units). Results: Mean arterial blood pressure was significantly lower in acute alcohol intoxication-hemorrhagic shock animals throughout the hemorrhagic shock. In sham animals, acute alcohol intoxication alone did not produce significant changes in neutrophil apoptosis or phagocytic activity but significantly suppressed phorbol myristic acid (PMA)-stimulated oxidative burst. Hemorrhagic shock produced a modest increase in neutrophil apoptosis and suppression of neutrophil phagocytic capacity but significantly suppressed PMA-stimulated oxidative burst. Acute alcohol intoxication exacerbated the hemorrhagic shock-induced neutrophil apoptosis and the hemorrhagic shock-induced suppression of phagocytosis without further affecting PMA-stimulated oxidative burst. Fluid resuscitation did not restore neutrophil phagocytosis or oxidative burst. Acute alcohol intoxication decreased (,40%) 3-day survival from K. pneumoniae in hemorrhagic shock animals, impaired bacterial clearance during the first 18 hr postinfection, and prolonged lung proinflammatory cytokine expression. Conclusions: These results demonstrate that the early alterations in metabolic and inflammatory responses to hemorrhagic shock produced by acute alcohol intoxication are associated with neutrophil dysfunction and impaired host response to a secondary infectious challenge leading to increased morbidity and mortality. [source]

Effects of Lidocaine Infusion during Experimental Endotoxemia in Horses

JOURNAL OF VETERINARY INTERNAL MEDICINE, Issue 4 2010
J.R. Peiró
Background: The clinical efficacy of IV infusion of lidocaine for treatment of equine endotoxemia has not been studied. Hypothesis: Lidocaine infusion after exposure to lipopolysaccharide (LPS) will inhibit the inflammatory response and have inhibitory effects on the hemodynamic and cytokine responses to endotoxemia. Animals: Twelve horses. Methods: Two equal groups (n = 6): saline (GI) and lidocaine (GII). In all animals, endotoxin (500 ng/kg body weight [BW]) was injected intraperitoneally over 5 minutes. Twenty minutes later, animals received a bolus of GI or GII (1.3 mg/kg BW) over 5 minutes, followed by a 6-hour continuous rate infusion of GI or GII (0.05 mg/kg BW/min). Treatment efficacy was judged from change in arterial blood pressure, peripheral blood and peritoneal fluid (PF) variables (total and differential cell counts, enzyme activities, and cytokine concentrations), and clinical scores (CS) for behavioral evidence of abdominal pain or discomfort during the study. Results: Compared with the control group, horses treated with lidocaine had significantly lower CS and serum and PF tumor necrosis factor-, (TNF-,) activity. At several time points in both groups, total and differential cell counts, glucose, total protein and fibrinogen concentrations, and alkaline phosphatase, creatine kinase, and TNF-, activities were significantly different from baseline values both in peripheral blood and in PF. Conclusions and Clinical Importance: Lidocaine significantly decreased severity of CS and inhibited TNF-, activity in PF. [source]

Left ventricular dysfunction: A hidden risk in patients undergoing liver transplantation

LIVER TRANSPLANTATION, Issue 1 2007
James D. Perkins M.D. Special Editor
With improved survival after liver transplantation (LT), the referral of older candidates has increased. The increasing demand for, and the decreased supply of, liver donors makes careful preoperative cardiac risk assessment imperative. There is a paucity of information regarding the cardiac characteristics of patients being referred for LT in the current era. This study aimed to describe the cardiac hemodynamic and coronary angiographic characteristics of a cohort of patients with end-stage liver disease without known coronary artery disease (CAD) being evaluated for LT. One hundred sixty-one consecutive patients aged ,45 years with end-stage liver disease who were referred for right- and left-sided cardiac catheterization as part of a liver transplant evaluation were identified. There was a high prevalence of atherosclerotic risk factors; half had hypertension or diabetes, and more than half had ,2 coronary risk factors other than age. There was a high prevalence of CAD, with 26% having unknown moderate to severe coronary narrowing. Patients with moderate to severe CAD were older, were more likely to be men, and were more likely to have hypertension or diabetes mellitus. Right- and left-sided filling pressures were elevated, suggesting abnormalities in left ventricular diastolic compliance. In conclusion, this study showed a high prevalence of coronary risk factors and unknown moderate to severe CAD in patients with end-stage liver disease being referred for LT. [source]

Hemodynamic profile and tissular oxygenation in orthotopic liver transplantation: Influence of hepatic artery or portal vein revascularization of the graft

LIVER TRANSPLANTATION, Issue 11 2006
Carlos Moreno
We performed a prospective, randomized study of adult patients undergoing orthotopic liver transplantation, comparing hemodynamic and tissular oxygenation during reperfusion of the graft. In 30 patients, revascularization was started through the hepatic artery (i.e., initial arterial revascularization) and 10 minutes later the portal vein was unclamped; in 30 others, revascularization was started through the portal vein (i.e., initial portal revascularization) and 10 minutes later the hepatic artery was unclamped. The primary endpoints of the study were mean systemic arterial pressure and the gastric-end-tidal carbon dioxide partial pressure (PCO2) difference. The secondary endpoints were other hemodynamic and metabolic data. The pattern of the hemodynamic parameters and tissue oxygenation values during the dissection and anhepatic stages were similar in both groups At the first unclamping, initial portal revascularization produced higher values of mean pulmonary pressure (25 ± 7 mm of Hg vs. 17 ± 4 mm of Hg; P < 0.05) and wedge and central venous pressures. At the second unclamping, initial portal revascularization produced higher values of cardiac output and mean arterial pressure (87 ± 15 mm of Hg vs. 79 ± 15 mm of Hg; P < 0.05) and pulmonary blood pressure. Postreperfusion syndrome was present in 13 patients (42.5%) in the arterial group and in 11 patients (36%) in the portal group. During revascularization, the values of gastric and arterial pH decreased in both groups and recovered at the end of the procedure, but were more accentuated in the initial arterial revascularization group. In conclusion, we found that initial arterial revascularization of the graft increases pulmonary pressure less markedly, so it may be indicated for those patients with poor pulmonary and cardiac reserve. Nevertheless, for the remaining patients, initial portal revascularization offers more favorable hemodynamic and metabolic behavior, less inotropic drug use, and earlier normalization of lactate and pH values. Liver Transpl, 2006. © 2006 AASLD. [source]

Venous hemodynamics in living donor right lobe liver transplantation

LIVER TRANSPLANTATION, Issue 9 2002
Gabriel E. Gondolesi MD
We evaluated the influence of portal and hepatic venous hemodynamics on the immediate and 3-month postoperative function of living donor right lobe grafts. Portal velocity was measured prospectively by ultrasound in 14 consecutive donor/recipient pairs. Velocity was converted to flow with the Moriyasu formula. Measurements were taken in donors in the operating room and in recipients at 1 hour after reperfusion and 3 months after transplant. Recipient liver function tests were measured postoperatively. Prereperfusion and postreperfusion liver biopsies were evaluated and correlated with the hemodynamic and biochemical results. There were 11 male (78.6%) and 3 female donors (mean age, 38.9 ± 9.8 years) for 10 male (71.4%) and 4 female recipients (mean age, 49.3 ± 14 years). The mean graft/recipient weight ratio was 1.22 ± 0.3. The mean right portal vein pressure was 8 ± 1.8 mm Hg in donors versus 13 ± 4.7 mm Hg in recipients (P < .05). The mean peak flow velocity (Vmax) in the portal vein in donors was 47.6 ± 12.8 cm/sec (normal, 44 cm/sec). One hour after graft reperfusion in the recipient, the mean portal Vmax was significantly higher at 94.7 ± 28.4 cm/sec (P = .004), but by 3 months follow-up, mean portal Vmax had fallen to 58.8 ± 37.8 (P = .01). Recipient portal vein Vmax highly correlated with portal flow (r = 0.7, P = .01). Increased recipient total bilirubin on postoperative day 2 correlated highly with higher recipient portal flow one hour after transplant (r = 0.6; P = .03). Portal vein velocity/flow dramatically increases after reperfusion, returning to baseline about 3 months after transplant. Evaluation of hepatic and portal venous flow is a relatively easy skill to acquire. Intraoperative ultrasound may enable the surgeon to predict graft dysfunction and possibly, may be used to implement pre-emptive therapies. [source]

Mixed venous oxygen desaturation during early mobilization after coronary artery bypass surgery

ACTA ANAESTHESIOLOGICA SCANDINAVICA, Issue 6 2005
I. Kirkeby-Garstad
Background:, Early postoperative mobilization induces a marked reduction in mixed venous oxygen saturation (SvO2) after aortic valve replacement. We investigated whether a similar desaturation occurs among coronary artery bypass grafting (CABG) patients, and if the desaturation was related to the preoperative ejection fraction (EF). Methods:, Thirty-one CABG patients with a wide range in EF were included in an open observational study. We recorded hemodynamic and oxygenation variables during mobilization on postoperative day 1 and day 2 using a pulmonary artery catheter. Results:, Patients with an EF ranging from 24 to 87% were mobilized without clinical problems. SvO2 at rest was 65.4 ± 4.9% (mean ± SD) on day 1 and 64.3 ± 5.8% on day 2 (NS). During mobilization, cardiac index and oxygen delivery were reduced while oxygen consumption was increased (P -values: 0.000, 0.007 and 0.000, respectively). Consequently, oxygen extraction increased, resulting in a marked reduction in SvO2,42.9 ± 8.3% on day 1 and 47.4 ± 8.5% on day 2 (P = 0.025 between days). Several pre-, intra- and postoperative factors were tested as possible predictors for SvO2 during mobilization. No factor contributed substantially. Conclusion:, Patients with CABG exhibit a marked desaturation during early postoperative mobilization. Preoperative ejection fraction did not affect SvO2 during exercise. The clinical consequences and underlying mechanism require further investigation. [source]

EPR oximetry in the beating heart: Myocardial oxygen consumption rate as an index of postischemic recovery

MAGNETIC RESONANCE IN MEDICINE, Issue 4 2004
Govindasamy Ilangovan
Abstract Oxygen plays a critical role in the pathophysiology of myocardial injury during both ischemia and subsequent reperfusion (I/R). Thus, oxygen concentration is an important variable to measure during I/R. In the present work, electron paramagnetic resonance (EPR)-based oximetry was used to measure the oxygen concentration during a series of I/R episodes and oxygenation levels were correlated with the contractile and hemodynamic functions of the heart. A custom-developed electronically tunable surface coil resonator working at 1.1 GHz was used to determine tissue pO2 in the beating heart. Microcrystalline particulate of lithium phthalocyanine was used as an EPR oximetry probe. Isolated and perfused rat hearts were subjected to 1 or 3 hr durations of preischemic perfusion, followed by 15-min I/R cycles. In hearts perfused for 3 hr prior to 15-min I/R cycles, the myocardial pO2 decreased gradually on subsequent reperfusions of three successive I/R cycles. However, in hearts perfused for 1 hr there was almost 100% recovery of myocardial pO2 in all three I/R cycles. The extent of oxygenation recovered in each reperfusion cycle correlated with the recovery of hemodynamic and contractile function. The results also showed that the oxygen consumption rate of the heart at the end of each I/R episode decreased in direct proportion to the functional recovery. In summary, it was observed that the amount of myocardial oxygen consumption during I/R could provide a reliable index of functional impairment in the heart. Magn Reson Med 51:835,842, 2004. © 2004 Wiley-Liss, Inc. [source]