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Conduction Delay (conduction + delay)

Distribution by Scientific Domains

Medical Sciences	95%

Selected Abstracts

Phytanic Acid Accumulation Is Associated with Conduction Delay and Sudden Cardiac Death in Sterol Carrier Protein-2/Sterol Carrier Protein-x Deficient Mice

JOURNAL OF CARDIOVASCULAR ELECTROPHYSIOLOGY, Issue 11 2004
GEROLD MÖNNIG M.D.
Introduction: The sterol carrier protein-2 gene encodes two functionally distinct proteins: sterol carrier protein-2 (SCP2, a peroxisomal lipid carrier) and sterol carrier protein-x (SCPx, a peroxisomal thiolase known as peroxisomal thiolase-2), which is involved in peroxisomal metabolism of bile acids and branched-chain fatty acids. We show in this study that mice deficient in SCP2 and SCPx (SCP2null) develop a cardiac phenotype leading to a high sudden cardiac death rate if mice are maintained on diets enriched for phytol (a metabolic precursor of branched-chain fatty acids). Methods and Results: In 210 surface and 305 telemetric ECGs recorded in wild-type (C57BL/6; wt; n = 40) and SCP2 null mice (n = 40), no difference was observed at baseline. However, on diet, cycle lengths were prolonged in SCP2 null mice (262.9 ± 190 vs 146.3 ± 43 msec), AV conduction was prolonged (58.3 ± 17 vs 42.6 ± 4 ms), and QRS complexes were wider (19.1 ± 5 vs 14.0 ± 4 ms). In 11 gene-targeted Langendorff-perfused hearts isolated from SCP2 null mice after dietary challenge, complete AV blocks (n = 5/11) or impaired AV conduction (Wenckebach point 132 ± 27 vs 92 ± 10 msec; P < 0.05) could be confirmed. Monophasic action potentials were not different between the two genotypes. Left ventricular function studied by echocardiography was similar in both strains. Phytanic acid but not pristanic acid accumulated in the phospholipid fraction of myocardial membranes isolated from SCP2 null mice. Conclusion: Accumulation of phytanic acid in myocardial phospholipid membranes is associated with bradycardia and impaired AV nodal and intraventricular impulse conduction, which could provide an explanation for sudden cardiac death in this model. [source]

Relatively Benign Clinical Course in Asymptomatic Patients with Brugada-Type Electrocardiogram Without Family History of Sudden Death

JOURNAL OF CARDIOVASCULAR ELECTROPHYSIOLOGY, Issue 1 2001
SHIHO TAKENAKA M.D.
Asymptomatic Brugada-Type ECG.Introduction: The incidence of sudden death or ventricular fibrillation (VF) in asymptomatic Brugada syndrome patients with a family history of sudden death is reported to be very high. However, there are few reports on the prognosis of asymptomatic Brugada syndrome patients without a family history of sudden death. Methods and Results: Eleven patients (all male; mean age 40.5 ± 9.6 years, range 26 to 56) with asymptomatic Brugada-type ECG who had no family history of sudden death were evaluated. The degrees of ST segment elevation and conduction delay on signal-averaged ECG (SAECG) before and after pilsicainide were evaluated in all 11 patients. VF inducibility by ventricular electrical stimulation also was evaluated in 8 of 11 patients. Patients were followed for a period of 9 to 84 months (mean 42.5 ± 21.6). The J point level was increased (V1 :0.19 ± 0.09 mV to 0.36 ± 0.23 mV; V2: 0.31 ± 0.12 mV to 0.67 ± 0.35 mV) by pilsicainide. Conduction delay was increased (total QRS: 112.2 ± 6.3 msec to 131 7 ± 6.3 msec; under 40 , V: 42.0 ± 8.5 msec to 52.7 ± 12.7 msec; last 40 msec: 17.4 ± 5.9 , V to 10.4 ± 6.1 , V) on SAECG by pilsicainide. VF was induced in only 1 of 8 patients. None of the patients had syncope or sudden death during a mean follow-up of 42.5 ± 21.6 months. Conclusion: This study suggests that asymptomatic patients with Brugada-type ECG who have no family history of sudden death have a relatively benign clinical course. [source]

Is the Presence of Mitral Annular Calcification Associated with Poor Left Atrial Function?

ECHOCARDIOGRAPHY, Issue 8 2009
Vignendra Ariyarajah M.D.
Introduction: Mitral annular calcification (MAC) is characterized by calcium and lipid deposition in the annular fibrosa of the mitral valve. MAC is associated with cardiovascular events but little is known of its association with left atrial (LA) function. Methods: We prospectively obtained 12-lead electrocardiograms (ECGs) and transthoracic echocardiograms (TTE) on patients scheduled for nonemergent echocardiographic assessment at a tertiary care hospital. MAC was graded as 0 = none, 1 = mild, 2 = moderate, 3 = severe. LA linear and volume measurements (stroke volume, LA passive emptying fraction, LA active emptying fraction and LA kinetic energy) were done specifically in addition to commonly measured TTE parameters. Results: From the 124 considered for the study, 72 patients remained (aged 68±18 years; 44% male) after excluding those with poor ECG tracings and/or poor TTE images. Eighteen patients had MAC; mild MAC = 14, moderate MAC = 3, severe MAC = 1. When patients with MAC were compared to those without MAC, no significant difference was noted, except for LA linear dimension index (2.1±0.4 vs. 1.9±0.3 cm/m2; P = 0.03). For those with mild and moderate MAC, a trend was noted toward lower LA function with increasing MAC severity. In addition, significant differences were noted between those with and without interatrial conduction delay, where those with such delay had significantly impaired LA stroke volume (9.8±3 vs. 19.93±4 ml; P < 0.0001), LA active emptying fraction (18.83±8 vs. 65.71±9%; P < 0.0001) and LA total/reservoir fraction (39.54±6 vs. 75.1±6%; P < 0.0001). Conclusions: MAC is associated with increase in LA linear dimension on TTE and may be equally represented with lower overall LA function. Further study in a much larger cohort is warranted to delineate these and other potential associations of MAC. [source]

Persistence of Pulmonary Vein Isolation After Robotic Remote-Navigated Ablation for Atrial Fibrillation and its Relation to Clinical Outcome

JOURNAL OF CARDIOVASCULAR ELECTROPHYSIOLOGY, Issue 10 2010
STEPHAN WILLEMS M.D.
Robotic Remote Ablation for AF. Aims: A robotic navigation system (RNS, HansenÔ) has been developed as an alternative method of performing ablation for atrial fibrillation (AF). Despite the growing application of RNS-guided pulmonary vein isolation (PVI), its consequences and mechanisms of subsequent AF recurrences are unknown. We investigated the acute procedural success and persistence of PVI over time after robotic PVI and its relation to clinical outcome. Methods and Results: Sixty-four patients (60.7 ± 9.8 years, 53 male) with paroxysmal AF underwent robotic circumferential PVI with 3-dimensional left atrial reconstruction (NavXÔ). A voluntary repeat invasive electrophysiological study was performed 3 months after ablation irrespective of clinical course. Robotic PVI was successful in all patients without complication (fluoroscopy time: 23.5 [12,34], procedure time: 180 [150,225] minutes). Fluoroscopy time demonstrated a gradual decline but was significantly reduced after the 30th patient following the introduction of additional navigation software (34 [29,45] vs 12 [9,17] minutes; P < 0.001). A repeat study at 3 months was performed in 63% of patients and revealed electrical conduction recovery in 43% of all PVs. Restudied patients without AF recurrence (n = 28) showed a significantly lower number of recovered PVs (1 (0,2) vs 2 (2,3); P = 0.006) and a longer LA-PV conduction delay than patients with AF recurrences (n = 12). Persistent block of all PVs was associated with freedom from AF in all patients. At 3 months, 67% of patients were free of AF, while reablation of recovered PVs led to an overall freedom from AF in 81% of patients after 1 year. Conclusion: Robotic PVI for PAF is safe, effective, and requires limited fluoroscopy while yielding comparable success rates to conventional ablation approaches with PV reconduction as a common phenomenon associated with AF recurrences. (J Cardiovasc Electrophysiol, Vol. 21, pp. 1079-1084) [source]

Relatively Benign Clinical Course in Asymptomatic Patients with Brugada-Type Electrocardiogram Without Family History of Sudden Death

Correction of protein kinase C activity and macrophage migration in peripheral nerve by pioglitazone, peroxisome proliferator activated-,-ligand, in insulin-deficient diabetic rats

JOURNAL OF NEUROCHEMISTRY, Issue 2 2008
Shin-Ichiro Yamagishi
Abstract Pioglitazone, one of thiazolidinediones, a peroxisome proliferator-activated receptor (PPAR)-, ligand, is known to have beneficial effects on macrovascular complications in diabetes, but the effect on diabetic neuropathy is not well addressed. We demonstrated the expression of PPAR-, in Schwann cells and vascular walls in peripheral nerve and then evaluated the effect of pioglitazone treatment for 12 weeks (10 mg/kg/day, orally) on neuropathy in streptozotocin-diabetic rats. At end, pioglitazone treatment improved nerve conduction delay in diabetic rats without affecting the expression of PPAR-,. Diabetic rats showed suppressed protein kinase C (PKC) activity of endoneurial membrane fraction with decreased expression of PKC-,. These alterations were normalized in the treated group. Enhanced expression of phosphorylated extracellular signal-regulated kinase detected in diabetic rats was inhibited by the treatment. Increased numbers of macrophages positive for ED-1 and 8-hydroxydeoxyguanosine-positive Schwann cells in diabetic rats were also corrected by the treatment. Pioglitazone lowered blood lipid levels of diabetic rats, but blood glucose and nerve sorbitol levels were not affected by the treatment. In conclusion, our study showed that pioglitazone was beneficial for experimental diabetic neuropathy via correction of impaired PKC pathway and proinflammatory process, independent of polyol pathway. [source]

Simplified orthodromic inching test in mild carpal tunnel syndrome

MUSCLE AND NERVE, Issue 12 2001
Paul Seror MD
Abstract This prospective study was undertaken to determine the clinical relevance, reliability, sensitivity, and specificity of the orthodromic inching test with 2-cm incremental study of the median nerve over the four intracarpal centimeters in 50 control and 50 successive (unselected) patient wrists with mild carpal tunnel syndrome (CTS). In controls, the mean maximum conduction delay per 2 cm (CD/2cm) was 0.445 ± 0.04 ms, and abnormality was defined as at least one CD/2cm exceeding the mean + 2.5 SD of the normal CD/2cm. This yielded a specificity of 98%. In patients with mild unselected CTS, this simplified orthodromic inching test (SOIT) detected the median nerve lesion at the wrist in 47 cases (sensitivity = 94%). The SOIT detected 15 more CTS cases than did the orthodromic median-ulnar latency difference of the 4th digit (Chi square = 13; P = .002). Thus, the SOIT was as effective as an incremental study every centimeter over 10 cm, and the time required for the test allows its routine use when other electrodiagnostic tests fail to reveal any median nerve impairment. © 2001 John Wiley & Sons, Inc. Muscle Nerve 24: 1595,1600, 2001 [source]

Cardiac Resynchronization Therapy in Non-Left Bundle Branch Block Morphologies

PACING AND CLINICAL ELECTROPHYSIOLOGY, Issue 5 2010
JOHN RICKARD M.D.
Introduction: In select patients with systolic heart failure, cardiac resynchronization therapy (CRT) has been shown to improve quality of life, exercise capacity, ejection fraction (EF), and survival. Little is known about the response to CRT in patients with right bundle branch block (RBBB) or non-specific intraventricular conduction delay (IVCD) compared with traditionally studied patients with left bundle branch block (LBBB). Methods: We assessed 542 consecutive patients presenting for the new implantation of a CRT device. Patients were placed into one of three groups based on the preimplantation electrocardiogram morphology: LBBB, RBBB, or IVCD. Patients with a narrow QRS or paced ventricular rhythm were excluded. The primary endpoint was long-term survival. Secondary endpoints were changes in EF, left ventricular end-diastolic and systolic diameter, mitral regurgitation, and New York Heart Association (NYHA) functional class. Results: Three hundred and thirty-five patients met inclusion criteria of which 204 had LBBB, 38 RBBB, and 93 IVCD. There were 32 deaths in the LBBB group, 10 in the RBBB, and 27 in the IVCD group over a mean follow up of 3.4 ± 1.2 years. In multivariate analysis, no mortality difference amongst the three groups was noted. Patients with LBBB had greater improvements in most echocardiographic endpoints and NYHA functional class than those with IVCD and RBBB. Conclusion: There is no difference in 3-year survival in patients undergoing CRT based on baseline native QRS morphology. Patients with RBBB and IVCD derive less reverse cardiac remodeling and symptomatic benefit from CRT compared with those with a native LBBB. (PACE 2010; 590,595) [source]

Cavotricuspid Isthmus: Anatomy, Electrophysiology, and Long-Term Outcome of Radiofrequency Ablation

PACING AND CLINICAL ELECTROPHYSIOLOGY, Issue 12 2009
Ching-Tai Tai M.D.
The cavotricuspid isthmus (CTI) had a complex architecture with an anisotropic conduction property. An incremental pacing from the low right atrial isthmus produced a conduction delay and block, and initiated atrial flutter. Radiofrequency catheter ablation of the CTI was very effective in eliminating the typical atrial flutter. However, atrial fibrillation often occurred after ablation of the isthmus and needs further treatment. [source]

Electroanatomical Mapping in Partial Atrial Standstill for Visualization of Atrial Viability and a Suitable Pacing Site

PACING AND CLINICAL ELECTROPHYSIOLOGY, Issue 4 2008
TAKANORI ARIMOTO M.D.
Partial atrial standstill is characterized by the failure of atrial activity either spontaneously or in response to electrical stimulation in restricted site of atria. In this case with bradycardia, atrial standstill was restricted to the lateral and posterior right atrium. The markedly prolonged intraatrial conduction delay was observed in the superior to septal region of the right atrium. The electroanatomical mapping was successfully utilized to estimate atrial activity and to find a suitable site for atrial lead placement. The electroanatomical mapping may become an innovated strategy to estimate atrial electrical status in partial atrial standstill. [source]

Intrahisian Conduction Disease and Junctional Ectopic Tachycardia

PACING AND CLINICAL ELECTROPHYSIOLOGY, Issue 3 2008
VALENTINO DUCCESCHI M.D.
Junctional ectopic tachycardia (JET) is an uncommon arrhythmia that mainly affects pediatric patients. However, its clinical presentation may rarely occur in adulthood. Owing to its incessant nature, limited responsiveness to antiarrhythmic agents and poor prognosis, catheter ablation of the junctional focus is often required, even though this may be accompanied by the occurrence of complete atrioventricular block. We report the case of a 68-year-old man with episodes of sustained ventricular tachycardia and repetitive JET whose initiation was often anticipated by a sudden intrahisian conduction delay in the immediately preceding sinus beats. [source]

Evidence for Electrical Remodeling of the Native Conduction System with Cardiac Resynchronization Therapy

PACING AND CLINICAL ELECTROPHYSIOLOGY, Issue 5 2007
CHARLES A. HENRIKSON M.D.
Background:Cardiac resynchronization therapy (CRT) improves hemodynamics and decreases heart failure symptoms. However, the potential of CRT to bring about electrical remodeling of the heart has not been investigated. Methods and Results:We studied 25 patients, of whom 17 had a nonischemic cardiomyopathy, and 8 had an ischemic cardiomyopathy; 16 had left bundle branch block (LBBB), 1 right bundle branch block (RBBB), and 8 nonspecific intraventricular conduction delay. During routine device clinic visits, patients with chronic biventricular pacing (>6 months) were reprogrammed to VVI 40 to allow for native conduction to resume. After 5 minutes of native rhythm, a surface electrocardiogram (ECG) was recorded, and then the previous device settings were restored. This ECG was compared to the preimplant ECG. Preimplant mean ejection fraction was 19% (range, 10%,35%), and follow-up mean ejection fraction was 35% (12.5%,65%). Mean time from implant to follow-up ECG was 14 months (range, 6,31). The QRS interval prior to CRT was 155 ± 29 ms, and shortened to 144 ± 31 ms (P = 0.0006), and the QRS axis shifted from ,1 ± 59 to ,26 ± 53 (P = 0.03). There was no significant change in PR or QTc interval, or in heart rate. Conclusion:CRT leads to a decrease in the surface QRS duration, without affecting other surface ECG parameters. The reduced electrical activation time may reflect changes in the specialized conduction system or in intramyocardial impulse transmission. [source]

Improvement of Congestive Heart Failure by Upgrading of Conventional to Resynchronization Pacemakers

PACING AND CLINICAL ELECTROPHYSIOLOGY, Issue 8 2006
IBRAHIM MARAI
Aims: To compare the clinical response of patients with right ventricular apical pacing (RVAP) upgraded to cardiac resynchronization therapy (CRT) to that of previously nonpaced heart failure (HF) patients who had de novo CRT implantation. Background: The role of CRT in patients with wide QRS and HF due to RVAP is less well established than in other CRT candidates. Methods: Ninety-eight consecutive patients with CRT were studied (mean age 70, mean ejection fraction 0.23). Group A: patients having RVAP prior to CRT implantation (n = 25), group B: patients without prior RVAP (n = 73). Clinical and echocardiographic parameters were recorded prior to, and 3 months after, CRT implantation. Results: Group A patients had a wider QRS at baseline compared to group B (203 ± 32 ms vs 163 ± 30 ms respectively, P < 0.001), and a shorter 6-minute walking distance (222 ± 118 m vs 362 ± 119 m, respectively, P < 0.005). Otherwise, clinical and echocardiographic parameters were not different. At follow up, group A patients had an average 0.7 ± 0.5 decrease in their NYHA functional class, compared to 0.3 ± 0.7 in group B patients (P < 0.05). Six-minute walking distance increased by 93 ± 113 m in group A, versus 36 ± 120 m in group B (P = 0.22). There was no difference in echocardiographic response to CRT between the groups. Conclusions: HF patients with prior RVAP demonstrate clinical improvement after upgrading to CRT that is comparable, and in some aspects, even better than that observed in HF patients with native conduction delay who undergo de novo CRT implantation. [source]

Which Patients with Congestive Heart Failure May Benefit from Biventricular Pacing?

PACING AND CLINICAL ELECTROPHYSIOLOGY, Issue 1p2 2003
NESTOR O. GALIZIO
GALIZIO, N.O., et al.: Which Patients with Congestive Heart Failure May Benefit from Biventricular Pacing?Background: Biventricular pacing improves the clinical status and ventricular function in patients with congestive heart failure (CHF) and intraventricular conduction delay. However, patient selection criteria including NYHA functional class, rhythm, PR interval, QRS duration (QRSd), left ventricular ejection fraction (LVEF), left ventricular diastolic diameter (LVDD), and other variables are not clearly defined. Objective: To determine which and how many patients referred for an initial cardiac transplantation evaluation may be eligible for biventricular pacing (BP) according to the criteria of recently completed trials of cardiac resynchronization therapy (CRT). Methods: This was a retrospective review of 200 patients, whose mean age was51 ± 13years (173 men). Sinus rhythm was present in 88% of the patients, 107 had a QRSd >120 ms, and 38% had left bundle branch block. LVDD was72.5 ± 12 mmand LVEF21.7 ± 9.3%; 54% had mitral regurgitation. Results: When NYHA class, electrocardiographic, and ventricular function criteria were considered separately, a high proportion of patients appeared to be candidates for CRT: 70.5% were in NYHA functional class III/IV, 34% had QRSd ,150 ms, 60% had LVDD ,60 mm and 53.5% LVEF ,35%. However, the proportions of patients eligible for CRT were different according to the selection criteria of recently completed trials: 18% of the patients with InSync criteria, 13% of the patients with MUSTIC SR criteria, 0.5% with MUSTIC AF criteria, 27% of patients with MIRACLE criteria, and 35% of the patients with CONTAK CD criteria (without considering indications for implantable cardioverter defibrillator). Conclusion: In this population-based study, a wide range of patients (13% to 35%) would have been candidates for CRT, according to the selection criteria of different completed trials.(PACE 2003; 26[Pt. II]:158,161) [source]

Biventricular Pacing Using Two Pacemakers and the Triggered VVT Mode

PACING AND CLINICAL ELECTROPHYSIOLOGY, Issue 8 2001
BRENDAN O'COCHLAIN
O'COCHLAIN, B., et al.: Biventricular Pacing Using Two Pacemakers and the Triggered VVT Mode. Pacemaker dependent patients exhibit interventricular conduction delay due to right ventricular lead placement. The addition of a transvenous coronary sinus lead for biventricular pacing has been shown to be effective. Venous stenosis and thrombosis postpacemaker implantation can occur in up to 35% of patients. This report describes a patient with a preexisting left-sided dual chamber pacemaker and chronic left subclavian vein occlusion that was upgraded to a biventricular system by placing a coronary sinus lead and single chamber ventricular triggered pacemaker on the opposite side. [source]

Clinical Significance of the Atrial Fibrillation Threshold in Patients with Paroxysmal Atrial Fibrillation

PACING AND CLINICAL ELECTROPHYSIOLOGY, Issue 5 2001
KEIJI INOUE
INOUE, K., et al.: Clinical Significance of the Atrial Fibrillation Threshold in Patients with Paroxysmal Atrial Fibrillation. AF threshold and the other electrophysiological parameters were measured to quantify atrial vulnerability in patients with paroxysmal atrial fibrillation (PAF, n = 47), and those without AF (non-PAF, n = 25). Stimulations were delivered at the right atrial appendage with a basic cycle length of 500 ms. The PAF group had a significantly larger percentage of maximum atrial fragmentation (%MAF, non-PAF: mean ± SD = 149 ± 19%, PAF: 166 ± 26%, P = 0.009), fragmented atrial activity zone (FAZ, non-PAF: median 0 ms, interquartile range 0,20 ms, PAF: 20 ms, 10,40 ms, P = 0.008). Atrial fibrillation threshold (AF threshold, non-PAF: median 11 mA, interquartile range 6,21 mA, PAF: 5 mA, 3,6 mA, P < 0.001) was smaller in the PAF group than in the non-PAF group. Sensitivity, specificity, and positive predictive value of electrophysiological parameters were as follows, respectively: %MAF (cut off at 150%, 78%, 52%, 76%), FAZ (cut off at 20 ms, 47%, 84%, 85%), AF threshold (cut off at 10 mA, 94%, 60%, 81%). There were no statistically significant differences between the non-PAF and PAF groups in the other parameters (effective refractory period, interatrial conduction time, maximum conduction delay, conduction delay zone, repetitive atrial firing zone, wavelength index), that were not specific for PAF. In conclusion, the AF threshold could be a useful indicator to evaluate atrial vulnerability in patients with AF. [source]

Prevention of the Initiation of Atrial Fibrillation: Mechanism and Efficacy of Different Atrial Pacing Modes

PACING AND CLINICAL ELECTROPHYSIOLOGY, Issue 3 2000
WEN-CHUNG YU
Several atrial pacing modes have been reported to be effective in the prevention of atrial fibrillation (AF); they included biatrial pacing, dual site right atrial pacing, Bachmann's bundle (BB) pacing, and coronary sinus pacing. However, the relative efficacy and electrophysiological mechanisms of these pacing modes in the prevention of AF are not clear. In 15 patients (age 54 ± 14 years) with paroxysmal AF, P wave duration, effective refractory period, and atrial conduction time were determined with six different atrial drive pacings, that were right atrial appendage (RAA), BB, right posterior interatrial septum (RPS), distal coronary sinus (DCS), RAA plus RPS simultaneously (DSA), and RAA plus DCS simultaneously (BiA). All these patients consistently had AF induced with early RAA extrastimulation coupling to RAA drive pacing. No patient had AF induced with RAA extrastimulation coupled to BB, RPS, or DCS drive pacing, but seven and eight patients had AF induced with RAA extrastimulation coupled to DSA and BiA drive pacing, respectively. The P wave duration was longest during RAA pacing, and became shorter during other atrial pacing modes. Analysis of electrophysiological change showed that early RAA extrastimulation coupled to RAA drive pacing caused the longest atrial conduction delay among these atrial pacing modes; BB, RPS, and DCS drive pacing caused a greater reduction of this conduction delay than DSA and BiA drive pacing. In addition, the effective refractory periods of RAA determined with BB, RPS, and DCS drive pacing were similar and longer than that determined with DSA and BiA drive pacing. In patients with paroxysmal AF, this arrhythmia was readily induced with RAA extrastimuli coupled to RAA drive pacing. BB, RPS, and DCS pacing were similar and more effective than DSA and BiA pacing in preventing AF. [source]

Effects of Presentation and Electrocardiogram on Time to Treatment of Hyperkalemia

ACADEMIC EMERGENCY MEDICINE, Issue 3 2008
Kalev Freeman MD
Abstract Objectives:, To assess the time to treatment for emergency department (ED) patients with critical hyperkalemia and to determine whether the timing of treatment was associated with clinical characteristics or electrocardiographic abnormalities. Methods:, The authors performed a retrospective chart review of ED patients with the laboratory diagnosis of hyperkalemia (potassium level > 6.0 mmol/L). Patients presenting in cardiac arrest or who were referred for hyperkalemia or dialysis were excluded. Patient charts were reviewed to find whether patients received specific treatment for hyperkalemia and, if so, what clinical attributes were associated with the time to initiation of treatment. Results:, Of 175 ED visits that occurred over a 1-year time period, 168 (96%) received specific treatment for hyperkalemia. The median time from triage to initiation of treatment was 117 minutes (interquartile range [IQR] = 59 to 196 minutes). The 7 cases in which hyperkalemia was not treated include 4 cases in which the patient was discharged home, with a missed diagnosis of hyperkalemia. Despite initiation of specific therapy for hyperkalemia in 168 cases, 2 patients died of cardiac arrhythmias. Among the patients who received treatment, 15% had a documented systolic blood pressure (sBP) < 90 mmHg, and 30% of treated patients were admitted to intensive care units. The median potassium value was 6.5 mmol/L (IQR = 6.3 to 7.1 mmol/L). The predominant complaints were dyspnea (20%) and weakness (19%). Thirty-six percent of patients were taking angiotensin-converting enzyme (ACE) inhibitors. Initial electrocardiograms (ECGs) were abnormal in 83% of patient visits, including 24% of ECGs with nonspecific ST abnormalities. Findings of peaked T-wave morphology (34%), first-degree atrioventricular block (17%), and interventricular conduction delay (12%) did not lead to early treatment. Vital sign abnormalities, including hypotension (sBP < 90 mmHg), were not associated with early treatment. The chief complaint of "unresponsive" was most likely to lead to early treatment; treatment delays occurred in patients not transported by ambulance, those with a chief complaint of syncope and those with a history of hypertension. Conclusions:, Recognition of patients with severe hyperkalemia is challenging, and the initiation of appropriate therapy for this disorder is frequently delayed. [source]

"Sensing alternans" in a patient with a newly implanted pacemaker

CLINICAL CARDIOLOGY, Issue 3 2006
Amgad N. Makaryus M.D.
Abstract This report describes the case of an 80-year-old man with a history of coronary artery disease who presented with acute pericarditis secondary to pacemaker lead perforation of the ventricular wall 2 days after undergoing dual lead pacemaker implantation. The electrocardiogram revealed sinus rhythm with an intra-atrial conduction delay and intermittent failure of atrial sensing as evidenced by alternating atrial spikes in every other P wave. The noted pericardial effusion and the likely shifting of the atrial lead with each alternate beat caused the "sensing alternans" that was seen on the admission electrocardiogram. [source]

Hypertonic Saline Treatment of Severe Hyperkalemia in Nonnephrectomized Dogs

ACADEMIC EMERGENCY MEDICINE, Issue 9 2000
Justin L. Kaplan MD
Abstract. Objectives: To determine whether a hypertonic saline bolus improves cardiac conduction or plasma potassium levels more than normal saline infusion within 15 minutes of treatment for severe hyperkalemia. Previously with this model, 8.4% sodium chloride (NaCl) and 8.4% sodium bicarbonate (NaHCO3) lowered plasma potassium equally effectively. Methods: This was a crossover study using ten conditioned dogs (14-20 kg) that received, in random order, each of three intravenous (IV) treatments in separate experiments at least one week apart: 1) 2 mmol/kg of 8.4% NaCl over 5 minutes (bolus); 2) 2 mmol/kg of 0.9% NaCl over one hour (infusion); or 3) no treatment (control). Using isoflurane anesthesia and ventilation (pCO2= 35-40 torr), 2 mmol/kg/hr of IV potassium chloride (KCl) was infused until conduction delays (both absent p-waves and ,20% decrease in ventricular rate in ,5 minutes) were sustained for 15 minutes. The KCl was then decreased to 1 mmol/kg/hr (maintenance) for 2 hours and 45 minutes. Treatment (0 minutes) began after 45 minutes of maintenance KCl. Results: From 0 to 15 minutes, mean heart rate increased 29.6 (95% CI = 12.2 to 46; p < 0.005) beats/min more with bolus than infusion and 23.4 (95% CI = 2.6 to 43.5; p < 0.03) beats/min more with bolus than control. No clinically or statistically significant difference was seen in heart rate changes from 0 to 30 minutes. Decreases in potassium from 0 to 15 minutes were similar with bolus, infusion, and control. Conclusions: In this model, 8.4% NaCl bolus reversed cardiac conduction abnormalities within the first 15 minutes after treatment, more rapidly than did the 0.9% NaCl infusion or control. This reversal occurred despite similar reductions in potassium levels. [source]

Coronary Sinus Lead Fragmentation 2 Years After Implantation with a Retained Guidewire

PACING AND CLINICAL ELECTROPHYSIOLOGY, Issue 3 2007
HERBERT NÄGELE M.D.
Cardiac Resynchronization therapy (CRT) using coronary sinus (CS) leads is an established method for the therapy of congestive heart failure (CHF) in the case of inter- and intraventricular conduction delays. However implantation of CS leads is somewhat challenging due to a high number of peri- or postoperative dislocations at a rate of about 10%. The retained guidewire technique has been proposed for the implantation of coronary sinus leads for stabilization in case of repetitive intraoperative dislocations. This report describes CS lead and guidewire fracture 2 years after such an implant. [source]

The Resting Electrocardiogram in the Management of Patients with Congestive Heart Failure: Established Applications and New Insights

PACING AND CLINICAL ELECTROPHYSIOLOGY, Issue 1 2007
JOHN E. MADIAS M.D.
The resting electrocardiogram (ECG) furnishes essential information for the diagnosis, management, and prognostic evaluation of patients with congestive heart failure (CHF). Almost any ECG diagnostic entity may turn out to be useful in the care of patients with CHF, revealing the non-specificity of the ECG in CHF. Nevertheless a number of CHF/ECG correlates have been proposed and found to be indispensable in clinical practice; they include, among others, the ECG diagnoses of myocardial ischemia and infarction, atrial fibrillation, left ventricular hypertrophy/dilatation, left bundle branch block and intraventricular conduction delays, left atrial abnormality, and QT-interval prolongation. In addition to the above well-known applications of the ECG for patients with CHF, a recently described association of peripheral edema (PERED), sometimes even imperceptible by physical examination, with attenuated ECG potentials, could extend further the diagnostic range of the clinician. These ECG voltage attenuations are of extracardiac mechanism, and impact the amplitude of QRS complexes, P-waves, and T-waves, occasionally resulting also in shortening of the QRS complex and QT interval duration. PERED alleviation, in response to therapy of CHF, reverses all above alterations. These fresh diagnostic insights have potential application in the follow-up of patients with CHF, and in their selection for implantation of cardioverter/defibrillator and/or cardiac resynchronization systems. If sought, PERED-induced ECG changes are abundantly present in the hospital and clinic environments; if their detection and monitoring are incorporated in the clinician's "routine," considerable improvements in the care of patients with CHF may be realized. [source]