Home About us Contact
|
Home About us Contact | ||
|
|
||
Normal Hearts (normal + heart)
Selected AbstractsMechanism of Wide Complex Tachycardia in a Structurally Normal HeartJOURNAL OF CARDIOVASCULAR ELECTROPHYSIOLOGY, Issue 9 2009ZIAD F. ISSA M.D. [source] Cardiac function during mild hypothermia in pigs: increased inotropy at the expense of diastolic dysfunctionACTA PHYSIOLOGICA, Issue 1 2010H. Post Abstract Aim:, The induction of mild hypothermia (MH; 33 °C) has become the guideline therapy to attenuate hypoxic brain injury after out-of-hospital cardiopulmonary resuscitation. While MH exerts a positive inotropic effect in vitro, MH reduces cardiac output in vivo and is thus discussed critically when severe cardiac dysfunction is present in patients. We thus assessed the effect of MH on the function of the normal heart in an in vivo model closely mimicking the clinical setting. Methods:, Ten anaesthetized, female human-sized pigs were acutely catheterized for measurement of pressure,volume loops (conductance catheter), cardiac output (Swan-Ganz catheter) and for vena cava inferior occlusion. Controlled MH (from 37 to 33 °C) was induced by a vena cava inferior cooling catheter. Results:, With MH, heart rate (HR) and whole body oxygen consumption decreased, while lactate levels remained normal. Cardiac output, left ventricular (LV) volumes, peak systolic and end-diastolic pressure and dP/dtmax did not change significantly. Changes in dP/dtmin and the time constant of isovolumetric relaxation demonstrated impaired active relaxation. In addition, MH prolonged the systolic and shortened the diastolic time interval. Pressure,volume analysis revealed increased end-systolic and end-diastolic stiffness, indicating positive inotropy and reduced end-diastolic distensibility. Positive inotropy was preserved during pacing, while LV end-diastolic pressure increased and diastolic filling was substantially impaired due to delayed LV relaxation. Conclusion:, MH negatively affects diastolic function, which, however, is compensated for by decreased spontaneous HR. Positive inotropy and a decrease in whole body oxygen consumption warrant further studies addressing the potential benefit of MH on the acutely failing heart. [source] Ventricular Asynchrony of Time-to-Peak Systolic Velocity in Structurally Normal Heart by Tissue Doppler ImagingECHOCARDIOGRAPHY, Issue 7 2010Hakimeh Sadeghian M.D. Background: Echocardiographic measurements of time-to-peak systolic velocities (Ts) are helpful for assessing the degree of cardiac asynchrony. We assessed the degree of ventricular asynchrony in structurally normal heart according to Ts by tissue Doppler imaging. Methods: We performed conventional echocardiography and tissue velocity imaging for 65 healthy adult volunteers to measure the Ts of 12 left ventricular segments in the mid and basal levels delay of Ts and standard deviation (SD) of Ts in all and basal segments. Six frequently used markers of dyssynchrony were measured and were also compared between men and women. Data are presented as median (25th and 75th percentile). Results: Septal-lateral and anteroseptal-posterior delays were 50 (20, 90) and 20 (0, 55) ms. The delay between the longest and the shortest Ts in basal and all segments were 100 (80, 120) and 110 (83, 128) ms, respectively. SD of Ts was 39 (24, 52) ms for basal and 41 (28, 51) ms for all segments. Overall, 76.9% of cases had at least one marker of dyssynchrony. Frequencies of dyssynchrony markers were almost significantly higher in women compared to men. The most frequently observed dyssynchrony marker was SD of Ts of all segments (70.8%) and the lowest was anteroseptal-posterior delay (21.5%). Conclusions: Normal population almost had dyssynchrony by previously described markers and many of these markers were more frequent in women. Conducting more studies on normal population by other tissue Doppler modalities may give better description of cardiac synchronicity. (Echocardiography 2010;27:823-830) [source] Regional sympathetic denervation affects the relation between canine local myocardial blood flow and oxygen consumptionEXPERIMENTAL PHYSIOLOGY, Issue 3 2007David J. C. Alders Myocardial blood flow and oxygen consumption are heterogeneously distributed. Perfusion and myocardial oxygen consumption are closely correlated in the normal heart. It is unknown how this metabolism,perfusion relation is influenced by sympathetic denervation. We investigated this question in seven chloralose-anaesthetized dogs, 3,4 weeks after regional sympathetic denervation of the left circumflex coronary artery area of supply of the left ventricle. Measurements were made of local myocardial blood flow (MBF, in ml min,1 (g dry wt),1), measured with microspheres, and myocardial oxygen consumption (, in ,mol min,1 (g dry wt),1) in the same location, calculated from the 13C spectrum of tissue extracts after intracoronary infusion of 3,13C-lactate. Since both innervated and denervated regions are subject to the same arterial pressure, lower blood flow indicates higher resistance. Mean MBF was 5.56 ml min,1 (g dry wt),1 (heterogeneity of 3.47 ml min,1 (g dry wt),1) innervated, 7.48 ml min,1 (g dry wt),1 (heterogeneity of 3.62 ml min,1 (g dry wt),1) denervated (n.s.). Significant linear relations were found between MBF and of individual samples within the innervated and denervated regions. The slopes of these relations were not significantly different, but the adjusted mean was significantly higher in the denervated regions (+1.92 ml min,1 (g dry wt),1, an increase of 38% of the mean MBF at the pooled mean , P= 0.028, ANCOVA). The ratio (in ml ,mol,1) was significantly higher, being 0.296 ± 0.167 ml ,mol,1 in the denervated region compared with the innervated region, 0.216 ± 0.126 ml ,mol,1, P= 0.0182, Mann,Whitney U test. These results indicate that sympathetic tone under chloralose anaesthesia imposes a moderate vasoconstrictive effect in the myocardium that is not detected by comparison of the mean blood flow or resistance. [source] Inhibition of Neuronal Nitric Oxide Reduces Heart Rate Variability in the Anaesthetised DogEXPERIMENTAL PHYSIOLOGY, Issue 5 2001F. Markos In the vagally intact anaesthetised dog, we have investigated the role of nitric oxide (NO) on a normal sinus arrhythmia using an inhibitor of neuronally released NO, 1-(2-trifluoromethylphenyl) imidazole (TRIM). The mean and S.D. of the R-R interval was used to describe mean heart rate and heart rate variability, respectively. TRIM (0.8 mg I.C.) injected into the sinus node artery increased the mean heart rate slightly but reduced heart rate variability 3-fold from a control of 790 ± 124 ms (mean ± S.D.; n = 5) to 666 ± 36 ms (P < 0.01 Student's paired t test, n = 5). These results suggest that neuronally released NO may have a vagal facilitatory role in the maintenance of sinus arrhythmia in the normal heart. [source] Electrophysiological Basis and Genetics of Brugada SyndromeJOURNAL OF CARDIOVASCULAR ELECTROPHYSIOLOGY, Issue 2005AUGUSTUS O. GRANT M.B.Ch.B., Ph.D. Brugada syndrome is a primary arrhythmic syndrome arising in the structurally normal heart. Any proposed mechanism should account for the major features of the syndrome: localization of the ST segment and T-wave changes to the right precordial leads, association of conduction slowing at several levels, precipitation or aggravation of the major ECG changes by sodium channel-blocking drugs and the occurrence of ventricular fibrillation. Heterogeneity of repolarization across the ventricle wall plays a major role. Any agency that shifts the net current gradient during phase I outward would exaggerate the normal heterogeneity of repolarization and result in the ST segment and T-wave changes characteristic of the syndrome. When the outward current shift is marked, premature repolarization may occur in epicardial zone and the resulting gradient may precipitate reentry. The syndrome is inherited as an autosomal dominant. However, 75% of clinically affected individuals are males. In 20% of cases, the syndrome is associated with mutations of the cardiac sodium channel gene SCN5A. The mutations result in a loss-of-function as a result of the synthesis of a non-functional protein, altered protein trafficking, or change in gating. Agencies that reduce the sodium current may precipitate the characteristic ECG changes, for example, sodium channel blockers and membrane depolarization by hyperkalemia. Sympathetic stimulation may reverse the ECG changes and reduce arrhythmia recurrence. By its nonspecific potassium channel blocking action, quinidine may also reduce arrhythmia recurrence. We still do not know the basis for defect in the majority of patients with Brugada syndrome. [source] Supraventricular Arrhythmias in Children and Young Adults with Implantable Cardioverter DefibrillatorsJOURNAL OF CARDIOVASCULAR ELECTROPHYSIOLOGY, Issue 10 2001BARRY A. LOVE M.D. SVT in Pediatric ICD Recipients.Introduction: Rapidly conducted supraventricular tachycardias (SVTs) can lead to inappropriate device therapy in implantable cardioverter defibrillator (ICD) patients. We sought to determine the incidence of SVTs and the occurrence of inappropriate ICD therapy due to SVT in a pediatric and young adult population. Methods and Results: We undertook a retrospective review of clinical course, Holter monitoring, and ICD interrogations of patients receiving ICD follow-up at our institution between March 1992 and December 1999. Of 81 new ICD implantations, 54 eligible patients (median age 16.5 years, range 1 to 48) were identified. Implantation indications included syncope and/or spontaneous/inducible ventricular arrhythmia with congenital heart disease (30), long QT syndrome (9), structurally normal heart (ventricular tachycardia/ventricular fibrillation [VT/VF]) (7), and cardiomyopathies (7). Sixteen patients (30%) received a dual-chamber ICD. SVT was recognized in 16 patients, with 12 of 16 having inducible or spontaneous atrial tachycardias. Eighteen patients (33%) received , 1 appropriate shock(s) for VT/VF; 8 patients (15%) received inappropriate therapy for SVT. Therapies were altered after an inappropriate shock by increasing the detection time or rate and/or increasing beta-blocker dosage. No single-chamber ICD was initially programmed with detection enhancements, such as sudden onset, rate stability, or QRS discriminators. Only one dual-chamber defibrillator was programmed with an atrial discrimination algorithm. Appropriate ICD therapy was not withheld due to detection parameters or SVT discrimination programming. Conclusion: SVT in children and young adults with ICDs is common. Inappropriate shocks due to SVT can be curtailed even without dual-chamber devices or specific SVT discrimination algorithms. [source] Cardiac diffusion MRI without motion effectsMAGNETIC RESONANCE IN MEDICINE, Issue 1 2002Jiangang Dou Abstract We present a method for diffusion tensor MRI in the beating heart that is insensitive to cardiac motion and strain. Using a stimulated echo pulse sequence with two electrocardiogram (ECG) triggers, diffusion-encoding bipolar gradient pulses are applied at identical phases in consecutive cardiac cycles. In this experiment, diffusion is encoded at a single phase in the cardiac cycle of less than 30 ms in duration. This encoding produces no phase shifts for periodic motion and is independent of intervening strains. Studies in a gel phantom with cyclic deformation confirm that by using this sequence we can map the diffusion tensor free of effects of cyclic motion. In normal human subjects, myocardial diffusion eigenvalues measured with the present method showed no significant change between acquisitions encoded at maximum contractile velocity (peak) vs. at myocardial standstill (end-systole), demonstrating motion independence of in vivo diffusion measurements. Diffusion tensor images acquired with the present method agree with registered data acquired with a previous cardiac diffusion MRI method that was shown to be valid in the normal heart, strongly supporting the validity of MRI diffusion measurement in the beating heart. Myocardial sheet and fiber dynamics measured during systole showed that normal human myocardial sheet orientations tilt toward the radial during systole, and fiber orientations tilt toward the longitudinal, in qualitative agreement with previous invasive studies in canines. These results demonstrate the technique's ability to measure myocardial diffusion accurately at any point in the cardiac cycle free of measurable motion effect, as if the heart were frozen at the point of acquisition. Magn Reson Med 48:105,114, 2002. © 2002 Wiley-Liss, Inc. [source] Clinical implication of isolated right dominant heart in the fetusPRENATAL DIAGNOSIS, Issue 8 2007Eui Jung Abstract Objective To evaluate the clinical implication of isolated right dominant heart (RDH) in fetal echocardiography. Study design We reviewed the medical records of pregnant women diagnosed with fetal RDH at Asan Medical Center from December 1999 to December 2005. The criteria of RDH were the ratio of right-to-left atrial and ventricular width and the ratio of the diameter of pulmonary artery-to-aorta were greater than 1.5. Fetuses with congenital heart disease, including coarctation of the aorta (CoA), noncardiac anomalies or chromosomal abnormalities were excluded. Results RDH was identified in 44 fetuses. Twenty-nine (66%) were confirmed to have normal heart and 15 (34%) had cardiac anomalies by postnatal echocardiogrphy; 11 CoA, 1 interruption of aortic arch, 1 patent ductus arteriosus, and 2 ventricular septal defect. Mean gestational age at presentation with RDH was later in normal fetuses as compared to fetuses with CoA (p < 0.005). Only 26% (4/15) of fetuses presenting with RDH during the second-trimester were found to have normal heart postnatally, compared with 86% (25/29) of those diagnosed in the third-trimester. Conclusion RDH in the fetus is a risk factor for postnatal CoA particularly when diagnosed in the second-trimester, and should be an indication for neonatal echocardiography. Copyright © 2007 John Wiley & Sons, Ltd. [source] Accelerated ventricular rhythm in the neonatal period: a review and two new cases in asymptomatic infants with an apparently normal heartACTA PAEDIATRICA, Issue 10 2004M Anatoliotaki Accelerated ventricular rhythm (AVR) was observed in two newborn infants. In the first case, arrhythmia was noted during the foetal period. Both neonates were asymptomatic and had no evidence of cardiac disease. The arrhythmia eventually disappeared when the infants were 4 mo and 24 d old, respectively. AVR in the neonatal period is reviewed in this report and recent information regarding appropriate diagnostic evaluation, differentiation from ventricular tachycardia and treatment is outlined. Conclusion: Accelerated ventricular rhythm is a benign and self-limited arrhythmia in the neonatal period. However, it is important to differentiate it from other serious rhythm disorders, mainly ventricular tachycardia, in order to avoid unnecessary and potentially harmful treatment and to relieve parental anxiety. [source] Right Ventricular Function in Congenital Heart Defects Assessed by Regional Wall MotionCONGENITAL HEART DISEASE, Issue 3 2010FSCAI, Michael R. Nihill MB ABSTRACT Objectives., To develop a simple method to assess right ventricular function by angiography. Background., Conventional methods of evaluating right ventricular function are inaccurate, cumbersome, and expensive. Methods., We analyzed biplane right ventricular angiograms taken in the posterior,anterior and lateral projections using software to measure right ventricular volumes and regional wall motion in 78 patients with normal hearts (n = 29), atrial septal defects (ASD n = 13), pulmonary valve stenosis (PVS n = 21), and postoperative atrial switch patients (n = 15). We also measured the shortening fraction (SF) from the midtricuspid annulus to the septum and correlated various angiographic measurements with the right ventricular (RV) ejection fraction. Results., The volume-overloaded patients (ASD) had larger end diastolic volumes and increased SF compared with normal patients, while the pressure-loaded patients (PVS) had normal volumes and SF. The postoperative atrial switch patients had decreased systolic function and increased end diastolic volume. The SF for all of the patients correlated with the ejection fraction (r= 0.785, P, .0001). Conclusions., A simple measurement of the end diastolic and end systolic distance from the midtricuspid annulus to the septum (SF) provides a good index of RV function by angiography and correlates well with RV ejection fraction. [source] Quantitative Analysis of Cytokine mRNA Expression in Hearts from Patients with Nonischemic Dilated Cardiomyopathy (DCM)JOURNAL OF CARDIAC SURGERY, Issue 2003Akira Ukimura To evaluate the role of cytokines in nonischemic DCM, we analyzed the relative quantity of cytokine mRNA expression in the hearts from DCM patients with refractory heart failure, using the ABI PRISM7700 real-time PCR system. We used heart tissues resected from 32 DCM patients at the time of elective partial ventriculectomy (PLV), and five biopsy specimens with normal histological findings as control. Results and Discussion: Interleukin (IL)-1,, IL-10, and Tumor Necrosis Factor (TNF)-, mRNA were expressed at low levels in all normal hearts. The number of IL-10-positive DCM cases was significantly smaller than normal controls (P = 0.0036). One (10%) of 10 DCM patients with IL-10 mRNA expression died after PLV, and 10 (45%) of 22 DCM patients without IL-10 mRNA expression died. IL-1, mRNA was overexpressed (over twice the mean of control subjects) in 15 of 32, and TNF-, mRNA in 10 of 32 patients. We propose the classification of DCM patients into subgroups on the basis of cytokine mRNA expression. Anticytokine therapy or cytokine therapy may have potential in improving the condition of heart failure in certain subgroups of DCM patients. Conclusions: We suggest that DCM patients with heart failure deteriorate without IL-10 mRNA expression in the myocardium. The classification of DCM patients into subgroups on the basis of cytokine mRNA expression may have great value in considering the treatment of this heterogeneous disease state. (J CARD SURG 2003;18 (Suppl 2):S101-S108) [source] Congenital Short QT Syndrome and Implantable Cardioverter Defibrillator Treatment:JOURNAL OF CARDIOVASCULAR ELECTROPHYSIOLOGY, Issue 12 2003Inherent Risk for Inappropriate Shock Delivery Introduction: A congenital short QT interval constitutes a new primary electrical abnormality associated with syncope and/or sudden cardiac death. We report on the initial use of implantable cardioverter defibrillator (ICD) therapy in patients with inherited short QT interval and discuss sensing abnormalities and detection issues. Methods and Results: In five consecutive patients from two unrelated European families who had structurally normal hearts, excessively shortened QT intervals, and a strong positive family history of sudden cardiac death, ICDs were placed for primary and secondary prevention. Mean QT intervals were 252 ± 13 ms (QTc 287 ± 13 ms). Despite normal sensing behavior during intraoperative and postoperative device testing, 3 of 5 patients experienced inappropriate shock therapies for T wave oversensing 30 ± 26 days after implantation. Programming lower sensitivities and decay delays prevented further inappropriate discharges. Conclusion: The congenital short QT syndrome constitutes a new clinical entity with an increased risk for sudden cardiac death. Currently, ICD treatment is the only therapeutic option. In patients with short QT interval and implanted ICD, increased risk for inappropriate therapy is inherent due to the detection of short-coupled and prominent T waves. Careful testing of ICD function and adaptation of sensing levels and decay delays without sacrificing correct arrhythmia detection are essential. (J Cardiovasc Electrophysiol, Vol. 14, pp. 1273-1277, December 2003) [source] Atrial Morphology in Hearts with Congenitally Corrected Transposition of the Great Arteries: Implications for the InterventionistJOURNAL OF CARDIOVASCULAR ELECTROPHYSIOLOGY, Issue 2 2002RAJNISH JUNEJA M.D. Atrial Morphology in Congenitally Corrected Transposition.Introduction: In view of the possible need for septal puncture to ablate left-sided lesions and the occasional difficulty in coronary sinus (CS) cannulation, we investigated relevant anatomic features in the right atrium of hearts with congenitally corrected transposition of the great arteries (ccTGA). Methods and Results: Nine hearts with ccTGA and an intact atrial septum and eight weight-matched normal hearts were examined by studying the "septal" aspect of the right atrium with reference to the oval fossa (OF). The anterior margin was arbitrarily measured as the shortest distance from the OF to the superior mitral/tricuspid annulus. The posterior margin was measured from the OF to the posterior-most edge of the right atrial "septal" surface. The total "septal" surface width was measured at the middle of the OF. The stretched OF dimensions and CS isthmus length were noted. Mann-Whitney test was used to compare absolute and indexed dimensions, i.e.. normalized to total width. The posterior margin in hearts with ccTGA was shorter than in controls (6.3 ± 2.4 mm vs 11 ± 1.9 mm, P < 0.001; normalized margin P = 0.09). The CS isthmus also was significantly shorter (5.3 ± 2.7 mm vs 11.4 ± 2.2 mm, P < 0.001). In two hearts with ccTGA, the CS opening into the right atrium was on the same side of the eustachian valve as the inferior caval vein. Conclusion: The shorter posterior "septal" margin in hearts with ccTGA may increase the risk of exiting the heart while performing septal puncture when pointing the needle posteriorly. The shorter CS isthmus and the abnormal location of the CS opening in some of these hearts are important when contemplating radiofrequency ablation in this area. [source] Electroanatomic Analysis of Sinus Impulse Propagation in Normal Human AtriaJOURNAL OF CARDIOVASCULAR ELECTROPHYSIOLOGY, Issue 1 2002ROBERTO DE PONTI M.D. Sinus Impulse Propagation in Normal Human Atria.Introduction: Better understanding of atrial propagation during sinus rhythm (SR) in normal hearts under the most normal physiologic conditions may be propaedeutic to pathophysiologic studies of complex atrial arrhythmias. In this study, qualitative and quantitative analyses of sinus impulse propagation in both atria were performed by electroanatomic mapping in patients with no organic heart disease who were undergoing an electrophysiologic procedure. Methods and Results: Seven patients (5 men and 2 women; age 37 ± 11 years) undergoing ablation of a left-sided accessory pathway were considered. Associated heart disease and coexisting atrial arrhythmias were excluded. After obtaining informed consent, electroanatomic mapping of both atria was performed during SR using a nonfluoroscopic system in the postablation phase. Mapping was accomplished in all patients with no complications. Qualitative analysis showed that sinus impulse propagation gives a reproducible activation pattern with minor individual variations. During interatrial propagation, two breakthroughs (anterior and posterior) in the left atrium are observed in the majority of cases. The anterior breakthrough, which reflects conduction over Bachmann's bundle, is predominant and shows a peculiar "preexcitation-like" endocardial activation pattern. Quantitative analysis showed minimal individual variations of propagation time intervals. Atria are activated simultaneously for 65% ± 9% of the duration of the atrial systolic time interval. Conclusion: In normal humans, electroanatomic mapping of SR identifies a typical and reproducible propagation pattern during SR. Bachmann's bundle plays the most important role in interatrial propagation. Atria are activated simultaneously by sinus impulse for a relevant portion of the systolic time interval. [source] Early homing of adult mesenchymal stem cells in normal and infarcted isolated beating heartsJOURNAL OF CELLULAR AND MOLECULAR MEDICINE, Issue 2 2008Claudia Penna Abstract Little is known on the early homing features of transplanted mesenchymal stem cells (MSCs). We used the isolated rat heart model to study the homing of MSCs injected in the ventricular wall of a beating heart. In this model all types of cells and matrix elements with their interactions are represented, while external interferences by endothelial/neutrophil interaction and neurohormonal factors are excluded. We studied the morphology and marker expression of MSCs implanted in normal hearts and in the border-zone of infarcted myocardium. Early morphological adaptation of MSC homing differs between normal and infarcted hearts over the first 6 hrs after transplantation. In normal hearts, MSCs migrate very early through the interstitial milieu and begin to show morphological changes. Yet, in infarcted hearts MSCs remain in the site of injection forming clusters of round-shaped cells in the border-zone of the infarcted area. Both in normal and infarcted hearts, immuno-histochemistry and confocal imaging showed that, besides the proliferative marker proliferating cell nuclear agent (PCNA), some transplanted cells early express myoblastic maker GATA-4, and some of them show a VWF immunopositivity. Moreover, a few hours after injection connexin-43 is well evident between cardiomy-ocytes and injected cells. This study indicates for the first time that the isolated beating heart is a good model to study early features of MSC homing without external interferences. The results show (i) that MSCs start to change marker expression few hours after injection into a beating heart and (ii) that infarcted myocardium influences transplanted MSC morphology and mobility within the heart. [source] Role of Left Ventricular Scar and Purkinje-Like Potentials During Mapping and Ablation of Ventricular Fibrillation in Dilated CardiomyopathyPACING AND CLINICAL ELECTROPHYSIOLOGY, Issue 3 2009ANIL-MARTIN SINHA M.D., D.Phil. Background: Purkinje-like potentials (PLPs) have been described as important contributors to initiation of ventricular fibrillation (VF) in patients with normal hearts, ischemic cardiomyopathy, and early after-myocardial infarction. Methods: Of the 11 consecutive patients with VF storm, nonischemic cardiomyopathy (68 ± 22 years, left ventricular ejection fraction 28 ± 8%) who were given antiarrhythmic drugs and/or heart failure management, five had recurrent VF and underwent electrophysiology study (EPS) and catheter ablation. Results: At EPS, frequent monomorphic premature ventricular contractions (PVC) and/or ventricular tachycardia did not occur. With isoproterenol, VF was induced in three patients, and sustained monomorphic PVCs were induced in one patient. Three-dimensional electroanatomical mapping using CARTO (Biosense-Webster Inc., Diamond Bar, CA) revealed posterior wall scar in four of the five patients. PLP in sinus rhythm were recorded around the scar border in these four patients, and radiofrequency ablation targeting PLP was successfully performed at these sites. The patient without PLP did not undergo ablation. During follow-up (12 ± 5 months), only the patient without PLP had four VF recurrences requiring implantable cardioverter-defibrillator (ICD) shocks. Conclusion: In patients with VF and dilated cardiomyopathy, left ventricular posterior wall scar in the vicinity of the mitral annulus seems to be a common finding. Targeting PLP along the scar border zone for ablation seems to efficiently prevent VF recurrence in these patients. [source] The Most Common Site of Success and Its Predictors in Radiofrequency Catheter Ablation of the Slow Atrioventricular Nodal Pathway in ChildrenPACING AND CLINICAL ELECTROPHYSIOLOGY, Issue 10 2008HAW-KWEI HWANG M.D. Background:Locating ablation targets on the slow pathway in children as one would in adults may not accommodate the dimensional changes of Koch's triangle that occur with heart growth. We investigated the most common site of success and the effect of a variety of variables on the outcome of slow pathway ablation in children. Methods:A total of 116 patients (ages 4,16 years) with structurally normal hearts underwent radiofrequency ablation of either the antegrade or the retrograde slow pathway. Ablation sites were divided into eight regions (A1, A2, M1, M2, P1, P2, CS1, and CS2) at the septal tricuspid annulus. Results:Ablation was successful in 112 (97%) children. The most common successful ablation sites were at the P1 region. The less the patient weighed, the more posteriorly the successful site was located (P = 0.023, OR 0.970, 95% CI 0.946,0.996), and the more likely the slow pathway was eliminated rather than modified: median weight was 46.7 kg (range, 14.5,94.3 kg) in the eliminated group and 56.5 kg (range, 20,82.6 kg) in the modified group (P = 0.021, OR 1.039, 95% CI 1.006,1.073). Conclusions:The most common site of success for slow pathway ablation in children is at the P1 region of the tricuspid annulus. The successful sites in lighter children are more posteriorly located. Weight is also a predictor of whether the slow pathway is eliminated or only modified. [source] Abnormal Nocturnal Heart Rate Variability and QT Dynamics in Patients with Brugada SyndromePACING AND CLINICAL ELECTROPHYSIOLOGY, Issue 2007BERTRAND PIERRE M.D. Background: In Brugada syndrome (BSY), most of the ventricular arrhythmic events are nocturnal, suggesting an influence of the autonomic nervous system. Methods: In 46 patients (mean age = 41 ± 14 years, 43 men) with electrocardiograms (ECG) consistent with BSY and structurally normal hearts, we measured heart rate variability (HRV) and QT dynamics (QT/RR slopes) on 24-hour ambulatory ECG. Type 1 BSY-ECG was spontaneous in 23 (50%) and induced in 23 patients. Results: History of syncope was present in 23 patients (50%). Programmed ventricular stimulation induced ventricular tachyarrhythmias (VTA) in 13 patients (28%). A single patient developed ventricular tachycardia during a mean follow-up of 34 months. Compared to a control group matched for age and sex, HRV was decreased over 24 hours and during nighttime in patients with BSY (SDNN 122 ± 44 vs 93 ± 36 ms, P = 0.0008 and SDANN 88 ± 39 vs 54 ± 24 ms, P < 0.0001). QTend /RR slopes were decreased over 24 hours in patients with BSY (0.159 ± 0.05 vs 0.127 ± 0.05, P = 0.003) and particularly at night (0.123 ± 0.04 vs 0.089 ± 0.04, P = 0.0001). QTend /RR slopes were significantly decreased during nighttime in patients with spontaneous versus provoked BSY-ECG patterns. By contrast, HRV and QT/RR slopes were similar in symptomatic and asymptomatic patients, whether VTA were induced or not. Conclusions: Patients with a BSY-ECG pattern had lower HRV and QT/RR slopes than control subjects during nighttime. High-risk patients with spontaneous BSY-ECG patterns had the lowest nocturnal QTend/RR slopes. These unique repolarization dynamics might be related to the frequent nocturnal occurrence of VTA in BSY. [source] Side-to-side linking of myocardial cells in hypertrophic cardiomyopathy: Whole heart microscopic observation with tangential sectionsPATHOLOGY INTERNATIONAL, Issue 11 2005Hirotake Masuda By cross-section or longitudinal section, it is difficult to investigate longitudinal features of myocardial cells in the whole heart. Here, introducing the use of tangential sections to obtain longitudinal aspect of myocardial cells in any part of myocardium, the authors evaluated myocardium in the left ventricle in 10 normal hearts and four hearts with hypertrophic cardiomyopathy (HCM). Tangential sections were obtained by peeling the superficial layer of myocardium. After peeling the whole surface, secondary deep layer was peeled. These procedures were repeated more than five times through the wall. Intercalated discs (ICD) were observed immunohistochemically with anti-N-cadherin and antidesmoplakin. In normal hearts, myocardial cells were cut longitudinally and ran parallel in tangential sections. They linked end-to-end with simple and regular ICD with average lengths of 120,130 µm and average sarcomere numbers of 56,65. In HCM hearts, many myocardial cells were cut almost longitudinally running approximately parallel in tangential sections. Myocardial cells frequently showed side-to-side linking characterized by skewed ICD, indistinct ICD counterparts, and longitudinally arranged ICD. Two young HCM hearts had circle-shaped ICD and vacuole-like structures highlighted by immunostaining for N-cadherin, which were actually extracellular structures comparable with irregular side-to-side linking. It is considered that side-to-side linking of myocardial cells is a characteristic microscopic feature in HCM rather than myocardial disarray. [source] Sodium Channel Blockers Enhance the Temporal QT Interval Variability in the Right Precordial Leads in Brugada SyndromeANNALS OF NONINVASIVE ELECTROCARDIOLOGY, Issue 1 2008Tetsuzou Kanemori M.D. Background: Temporal QT interval variability is associated with sudden cardiac death. The purpose of this study was to evaluate temporal QT interval variability in Brugada syndrome (BS). Methods: We measured QT and RR intervals in precordial leads (V1,V6) based on 12-beat resting ECG recordings from 16 BS patients (B group) with spontaneous ST elevation in right precordial leads (V1,V2) and from 10 patients with normal hearts (C group). We measured the response in B group before and after administration of pilsicainide (1 mg/kg). The standard deviation (QT-SD, RR-SD) of the time domain and total frequency power (QT-TP, RR-TP) were calculated for all precordial leads, and the latter was to analyze the frequency domain. Results: The right precordial leads in BS exhibited an additional and prominent ST elevation (coved-type) after pilsicainide administration. Both QT-SD and QT-TP values were significantly more increased in B, than in C (5.1 ± 1.2 vs 3.6 ± 0.2 and 23.4 ± 2.9 vs 12.3 ± 1.7 msec2, P < 0.01, respectively) and after pilsicainide administration in B. (5.1 ± 0.4 vs 3.9 ± 0.3, 25.8 ± 3.4 vs 16.3 ± 2.6 msec2, P < 0.01, respectively) However, QT-SD and QT-TP did not significantly change in any of other leads (V3,V6) and RR-SD and RR-TP were similar for both groups, as well as after intravenous pilsicainide administration in B. Conclusions: The temporal QT interval variability was identified in BS. Moreover, sodium channel blocker induced temporal fluctuation in QT interval and it may possibly provide a substrate for ventricular arrhythmia in BS patients. [source] Effects of Formaldehyde on Cardiovascular System in In Situ Rat HeartsBASIC AND CLINICAL PHARMACOLOGY & TOXICOLOGY, Issue 4 2009Daisuke Takeshita After 20,30 min. of intravenous infusion of 3.7% formaldehyde solution (FA) at 10 ,l (3.7 mg)/kg/min, normal and hypertrophic hearts showed significant decreases in left ventricle end-systolic pressure (ESP), heart rate and cardiac output per minute, indicating an acute pumping failure. Hypertrophic hearts showed significantly smaller ESP, stroke volumes and cardiac output than those in normal hearts. Systolic pressure,volume area at midrange left ventricular volume (PVAmLVV: a mechanical work capability index) was significantly smaller than that in normal hearts and per cent of mean PVAmLVVversus pre-infusion mean value in hypertrophic hearts was significantly decreased compared to normal hearts 30 min. after FA infusion. The marked decrease in pH, base excess and no changes in PaO2 and PaCO2 suggest metabolic acidosis. The correction of metabolic acidosis with 9% NaHCO3 did not influence on the acute pumping failure, indicating that metabolic acidosis did not cause it. Ultrastructural observations revealed marked dilation of the sarcoplasmic reticulum with intact sarcolemmal membranes and no disintegration of muscle myofibrils. Ryanodine receptors and calcium (Ca2+) pumps (SERCA2A) located in the sarcoplasmic reticulum have major roles in the cytosolic Ca2+ handling. Taken together, acute pumping failure by FA may derive from the impairment of Ca2+ handling in the cardiac excitation,contraction coupling. [source] Comparison of human and porcine aortic valvesCLINICAL ANATOMY, Issue 3 2003Eugene K.W. Sim Abstract We compared the anatomy of human and porcine aortic valves. Porcine hearts were collected from the abattoir. Human hearts from patients who had died of non-cardiac causes were examined in the mortuary; only undamaged and anatomically normal hearts were used. Silicon casts were prepared by injecting engineering silicon at 80 mm Hg into the aortic arch. Various features of the aortic valve were measured: circumference, length between the commissural end point and central point of coaptation, surface diameter, and surface area. In total, 12 porcine and 12 human aortic valves were studied. The average circumferences of the human and porcine aortic valves were 8.00 ± 0.2 (SD) cm and 7.90 ± 1.0 cm, respectively. The central point of coaptation in human valves was skewed toward the left coronary cusp, whereas in porcine valves it was skewed toward the non-coronary cusp. In human aortic valves, the non-coronary cusp had the largest surface diameter and surface area with mean measurements of 3.6 ± 0.2 cm and 1.230 ± 0.228 cm2, respectively; the left coronary cusp was smallest for the same variables with measurements of 3.1 ± 0.3 cm and 0.898 ± 0.357 cm2. In porcine valves, the right coronary cusp had the largest surface diameter and surface area with mean measurements of 3.9 ± 0.7 cm and 1.716 ± 0.81 cm2, respectively; the non-coronary cusp was the smallest for the same variables with measurements of 2.9 ± 0.5 cm and 1.023 ± 0.659 cm2. These differences suggest that when using porcine valves as transplant material (e.g., stentless valves), geometric considerations, such as commissural length, may be important. Clin. Anat. 16:193,196, 2003. © 2003 Wiley-Liss, Inc. [source] Nicorandil Improves Myocardial High-Energy Phosphates In Postinfarction Porcine HeartsCLINICAL AND EXPERIMENTAL PHARMACOLOGY AND PHYSIOLOGY, Issue 8 2002Yo Murakami SUMMARY 1.,Nicorandil is a potent vasodilator combining the effects of a nitrate with an ATP-sensitive potassium channel (KATP) opener. Because the postinfarct remodelled heart has increased vulnerability to subendocardial hypoperfusion, it is possible that the vasodilator effects of nicorandil could cause transmural redistribution of blood flow away from the subendocardium. Alternatively, the KATP channel opening effects of nicorandil could exert a beneficial effect on mitochondrial respiration. Consequently, the present study was performed to examine the effect of nicorandil on energy metabolism in the postinfarct heart. 2.,Studies were performed in swine in which myocardial infarction produced by proximal left circumflex coronary artery ligation had resulted in left ventricular remodeling. [31P] nuclear magnetic resonance spectroscopy (MRS) was used to examine the myocardial energy supply/demand relationship across the left ventricular wall while the transmural distribution of blood flow was examined with radioactive microspheres. Data were obtained during baseline conditions and during infusion of nicorandil (100 ,g, i.v., followed an infusion of 25 ,g/kg per min). 3.,Nicorandil caused coronary vasodilation with a preferential increase in subepicardial flow; however, subendocardial flow also increased significantly. Nicorandil had no significant effect on the rate,pressure product or myocardial oxygen consumption. The ratio of phosphocreatine (PCr)/ATP determined with MRS was abnormally depressed in remodelled hearts (2.01 ± 0.11, 1.85 ± 0.10 and 1.59 ± 0.11 for subepicardium, midwall and subendocardium, respectively) compared with normal (2.22 ± 0.11, 2.01 ± 0.15 and 1.80 ± 0.09, respectively). Nicorandil had no effect on the high-energy phosphate content of normal hearts. However, nicorandil increased the PCr/ATP ratio in the subendocardium of remodelled hearts from 1.59 ± 0.11 to 1.87 ± 0.10 (P < 0.05). 4.,Although nicorandil caused modest redistribution of blood flow away from the subendocardium of the postinfarct left ventricle, this was associated with an increase of the PCr/ATP ratio towards normal. These results suggest that nicorandil exerts a beneficial effect on energy metabolism in the subendocardium of the postinfarct remodelled left ventricle. [source] Screening for duct-dependent congenital heart disease with pulse oximetry: A critical evaluation of strategies to maximize sensitivityACTA PAEDIATRICA, Issue 11 2005ANNE DE-WAHL GRANELLI Abstract Aim: To evaluate the feasibility of detecting duct-dependent congenital heart disease before hospital discharge by using pulse oximetry. Design: Case-control study. Setting: A supra-regional referral centre for paediatric cardiac surgery in Sweden. Patients: 200 normal term newborns with echocardiographically normal hearts (median age 1.0 d) and 66 infants with critical congenital heart disease (CCHD; median age 3 d). Methods: Pulse oximetry was performed in the right hand and one foot using a new-generation pulse oximeter (NGoxi) and a conventional-technology oximeter (CToxi). Results: With the NGoxi, normal newborns showed a median postductal saturation of 99% (range 94,100%); intra-observer variability showed a mean difference of 0% (SD 1.3%), and inter-observer variability was 0% (SD 1.5%). The CToxi recorded a significantly greater proportion of postductal values below 95% (41% vs 1%) in the normal newborns compared with NGoxi (p < 0.0001). The CCHD group showed a median postductal saturation of 90% (45,99%) with the NGoxi. Analysis of distributions suggested a screening cut-off of < 95%; however, this still gave 7/66 false-negative patients, all with aortic arch obstruction. Best sensitivity was obtained by adding one further criterion: saturation of < 95% in both hand and foot or a difference of > ± 3% between hand and foot. These combined criteria gave a sensitivity of 98.5%, specificity of 96.0%, positive predictive value of 89.0% and negative predictive value of 99.5%. Conclusion: Systematic screening for CCHD with high accuracy requires a new-generation oximeter, and comparison of saturation values from the right hand and one foot substantially improves the detection of CCHD. [source] | |||||||||||||||||||||||||