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Biomedical subjects

J W Lister

Publications and source records attributed to J W Lister.

At least 19 recordsLinked to original sources
PubMed1989

Efficacy of procainamide on ventricular tachycardia: relation to prolongation of refractoriness and slowing of conduction.

The effect of procainamide on intraventricular conduction and refractoriness, and the prevention of induction of ventricular tachycardia (VT) were studied in 29 patients who had remote myocardial infarction and inducible sustained monomorphic VT. AFter intravenous administration of 15 mg/kg procainamide, induction of VT was suppressed in seven (24%) patients (responders), while in 22 (76%) VT was still inducible (nonresponders). The percent change in paced QRS duration at a cycle length (CL) of 400 msec produced by procainamide was significantly less in responders than in nonresponders: 29.8 +/- 3.9% versus 38.9 +/- 10.8% (p = 0.0020). The percent change in the right ventricular effective refractory period (ERP) at CLs of 600 and 400 msec was significantly greater in responders than in nonresponders: 14.6 +/- 6.9% versus 7.9 +/- 7.3% (p = 0.0414) for ERP at a CL of 600 msec and 15.1 +/- 7.0% versus 8.0 +/- 7.4% (p = 0.0386) for ERP at a CL of 400 msec. Stepwise discriminant analysis showed that greater percent increase in ERP at a CL of 400 msec and lesser percent increase in paced QRS duration at a CL of 400 msec were significantly independent markers for the responders. These findings suggest that lesser slowing of conduction and greater prolongation of refractoriness by procainamide tend to abolish reentry within the reentrant circuit. Greater slowing of conduction and lesser prolongation of refractoriness tend to stabilize a reentrant circuit, and promote the continued induction of VT.

Electrocardiography↗
PubMed1989

Predictors of sustained ventricular tachycardia inducibility in patients with nonsustained ventricular tachycardia and chronic coronary artery disease.

To assess the likelihood of inducing sustained ventricular tachycardia, we analyzed a cohort of 58 retrospective and 18 prospective patients with chronic coronary artery disease who underwent electrophysiologic study because of spontaneous nonsustained ventricular tachycardia (three or more beats, lasting less than 30 seconds, at a rate greater than 100/min). In 24 of the 58 retrospective patients (41%) sustained ventricular tachycardia was inducible. Stepwise logistic regression identified two "major" variables--left ventricular aneurysm/dyskinesis/akinesis (p = 0.0001; relative risk = 11.88) and ejection fraction less than 40% (p = 0.0002; relative risk = 9.69)--and one "minor" variable--nonsustained ventricular tachycardia longer than 10 beats (p = 0.0151; relative risk = 4.21)--as significant predictors of inducibility. Nineteen patients with both major variables had a high probability of inducibility (greater than 90%). Nineteen patients with neither major variable had a low probability of inducibility (less than 5%). The remaining 20 patients with only one of the major variables had an intermediate probability of inducibility (14% to 75%). The significance of the third minor factor, nonsustained ventricular tachycardia longer than 10 beats, was confined to this intermediate group, in which it could be used to segregate relatively high (65% to 75%) and relatively low (14% to 20%) probability of inducibility. Prospective application of the predictor function stratified 18 additional patients into three groups with high (six patients), intermediate (seven patients), and low (five patients) probability of inducibility. The observed rate of inducibility in each group was 5 of 6 (83%), 2 of 7 (29%), and 0 of 5 (0%), respectively. These data suggest that patients with nonsustained ventricular tachycardia and chronic coronary artery disease can be stratified into subgroups with high, intermediate, and low probability of inducibility of sustained ventricular tachycardia on the basis of ejection fraction and regional ventricular wall motion defects alone.

Aged↗
PubMed1989

Rapid assessment of rate and antiarrhythmic drug effect on the myocardium using asymmetric biphasic pulse stimulation.

An asymmetric biphasic pulse which stimulates the heart and neutralizes the poststimulation polarization at the electrode-myocardial interface permitting the recording of the evoked endocardial response (EER) up to approximately 1 ms poststimulation with the same electrode used for stimulation is described. Using this mode of cardiac stimulation in 20 dogs the effects on the EER of increasing heart rate and antiarrhythmic drugs, procainamide (PA) and N-acetylprocainamide (NAPA), were studied. EERs were recorded during bipolar and unipolar pacing rates of 120, 150, and 200/min before and during a five step PA or NAPA infusion which resulted in progressively increasing PA and NAPA plasma concentrations (Cps), 1.7-32.5 mg/l for PA and 8.1-116.1 mg/l for NAPA. The effects of progressively increasing heart rates were: The T wave amplitude and QS area increased with increases in rate; during pacing at 120, 150, and 200/min, the T wave amplitudes were 7.6 +/- 2.3, 8.2 +/- 2.1, and 9.8 +/- 2.5 mV and the QS areas were 905 +/- 204, 995 +/- 199, and 1101 +/- 231 mVms. The QT interval and QST area decreased with increases in rate; during pacing at 120, 150, and 200/min, the QT intervals were 265 +/- 61, 249 +/- 57, and 226 +/- 52 ms and the QST areas were 288 +/- 198, 221 +/- 154, and 154 +/- 52 mVms. The effects of the antiarrhythmic drugs, PA and NAPA, on the EER were: PA prolonged both the QS duration and QT interval at low Cp (type Ia antiarrhythmic drug property); at a therapeutic PA Cp of 15.0 +/- 0.2 mg/l and a heart rate of 120/min the percent increase of the QS duration was 12 +/- 4% (P = 0.001) and that of the QT interval was 20 +/- 6% (P less than 0.001). The prolongation of the QS duration by PA was rate dependent, the faster the rate the greater the prolongation. NAPA prolonged the QT interval at low Cp, while the QS duration was not significantly effected at low or therapeutic Cps (type III antiarrhythmic drug property); at a therapeutic NAPA Cp of 15.9 +/- 1.6 mg/l and a heart rate of 120/min the percent increase of the QS duration was 1 +/- 1% (NS) and that of the QT interval was 13 +/- 9% (P = 0.018). Our results show that the use of an asymmetric biphasic pulse allows for pacing and recording of an EER, QS and T waves, with a single electrode.(ABSTRACT TRUNCATED AT 400 WORDS)

Acecainide↗
PubMed1989

Time-dependent risk of and predictors for cardiac arrest recurrence in survivors of out-of-hospital cardiac arrest with chronic coronary artery disease.

One hundred one consecutive patients with chronic coronary artery disease who had survived out-of-hospital cardiac arrest in the absence of acute myocardial infarction underwent electrophysiologic evaluation and were followed prospectively. Ventricular tachyarrhythmias were inducible in 76 patients (75%) in the control state and were suppressed by antiarrhythmic drugs or surgery in 32 of the 76 patients (42%). During a mean follow-up of 27 months, cardiac arrest recurred in 21 patients: in two of the 25 patients in whom ventricular tachyarrhythmias were not inducible in the control state, three of the 32 in whom inducible ventricular tachyarrhythmias were suppressed after treatment, and 16 of the 44 in whom inducible ventricular tachyarrhythmias could not be suppressed after treatment. Actuarial rate of cardiac arrest recurrence was 11.2% during the first 6 months of follow-up ("high-risk early phase") and then decreased to less than 4% in each subsequent 6-month period. Multivariate Cox proportional hazards analysis identified an ejection fraction less than 35% (p = 0.0013) and persistent inducibility of ventricular tachyarrhythmias (p = 0.0025) as independent predictors of cardiac arrest recurrence for the entire follow-up period. Separate analysis of variables within and after the first 6 months showed that an ejection fraction less than 35% was the strongest predictor for early phase recurrence (p = 0.0078) but had only marginally significant predictive value for late phase recurrence (p = 0.0516). Persistent inducibility of ventricular tachyarrhythmias had no significant predictive value for early phase recurrence (p = 0.1382) but was the strongest predictor for late phase recurrence (p = 0.0061). These data suggest that, in patients with chronic coronary artery disease who survive out-of-hospital cardiac arrest, poor ejection fraction and persistent inducibility of ventricular tachyarrhythmias have a different predictive influence on early and late phase recurrence. Time-dependent risk factor analysis may have great clinical relevance in assessing an individual's changing risk over time.

Aged↗
PubMed1989

Triphasic time dependence of prognostic markers in patients with sustained ventricular tachyarrhythmias and coronary artery disease.

To characterize the time dependence of prognostic markers for arrhythmia recurrence and arrhythmic death, 81 consecutive patients with documented sustained ventricular tachycardia (VT) or fibrillation (VF) and coronary artery disease (CAD) were analyzed. During follow-up, 28 patients had arrhythmia recurrence and 15 patients had sudden or arrhythmic death. Three different hazard phases were identified by fitting piece-wise exponential function curves to the distribution of both arrhythmia recurrence and sudden/arrhythmic death. An initial phase (0 to 6 months) had an arrhythmia recurrence rate of 2.1% per month; a second low-risk phase (6 to 38 months) had a rate of 0.88%; and a late high-risk phase (greater than 38 months) had a rate of 2.2%. Sudden/arrhythmic death rates in each phase were 1.1%, 0.41%, and 1.7% per month, respectively. Separate Cox regression analyses within each phase identified the following independent predictors of arrhythmia recurrence: in the early phase, ejection fraction (EF) (p = 0.033) and VT inducibility rank (p = 0.048); and in the late phase, VT inducibility rank only (p = 0.003). Likewise, independent predictors of sudden/arrhythmic death were: in the early phase, EF (p = 0.049); and in the late phase, VT inducibility rank (p = 0.008) and previous history of congestive heart failure (p = 0.032). In CAD patients with documented sustained VT/VF, the probabilities of arrhythmia recurrence and sudden/arrhythmic death each followed a similar triphasic hazard function. Highest risk occurred in the late phase and the VT inducibility rank was predictive of late phase events, while EF was a predictor of early phase events.

Adult↗
PubMed1986

Cardiac syncope: a case exhibiting dichotomy between clinical impression and electrophysiologic evaluation.

This case report illustrates the value of electrophysiologic study in patients presenting with graphically unmonitored syncope and/or sudden cardiac death, and who have clinical markers of both bradycardia and ventricular tachycardia. In our patient, a wide QRS on the electrocardiogram and Holter monitor documented high grade ventricular ectopic activity. In this case, had therapy been solely guided by the clinical impression that the patient had ventricular tachycardia, the treatment would have resulted in increasing the risk of recurrence of syncope and/or sudden cardiac death.

Cardiac Pacing, Artificial↗
PubMed1985

Externally activated antitachycardia pacemaker with noninvasive electrophysiologic re-testing capability.

An Omni Orthocor 234A special device pacemaker was implanted in nine patients for treatment of drug-resistant supraventricular tachycardia (three patients) or ventricular tachycardia (six patients). This device is activated using a special external unit, which delivers from six to 15 stimuli at preselected coupling intervals ranging from 195 to 500 ms. Serial noninvasive electrophysiology studies were performed either in the hospital or on an outpatient basis using the triggered mode, which can respond to programmed chest wall stimulation. Three patients with reciprocating supraventricular tachycardia were treated effectively by this device during an average follow-up of 2.2 years. Of the six patients with stable ventricular tachycardia amenable to pacemaker termination, only four remained successful during an average follow-up of 1.9 years. Such devices may find important use in serial noninvasive electrophysiologic testing during long-term clinical follow-up. The present form of this device is inadequate for widespread application, but may be useful for highly selected individuals.

Aged↗
PubMed1984

Lymphocytic myocarditis presenting as unexplained ventricular arrhythmias: diagnosis with endomyocardial biopsy and response to immunosuppression.

During a period of 18 months beginning in January 1982, a total of 65 patients were referred to the Miami Heart Institute for evaluation of either aborted out of hospital sudden death, ventricular tachycardia resistant to standard clinically directed antiarrhythmic medication programs or high grade ventricular arrhythmia (Lown class greater than or equal to IV B) with or without syncope. After complete evaluation including cardiac catheterization in all but 1 patient, 17 patients were identified in whom no obvious cardiac disease could be found. Twelve of the 17 underwent right ventricular endomyocardial biopsy. Six of the 12 biopsies demonstrated clinically unsuspected lymphocytic myocarditis (Group A). Findings in three of the remaining six biopsies were consistent with an early cardiomyopathy and in three were completely normal (Group B). Retrospective review of the clinical, laboratory, electrophysiologic, hemodynamic and angiographic data failed to identify a marker that reliably separated Group A from Group B patients. In addition to antiarrhythmic therapy guided by laboratory electrophysiologic study, all Group A patients were treated with prednisone and azathioprine. After 6 months of immunosuppression, all patients with myocarditis were reevaluated in the hospital without antiarrhythmic medication. Ventricular tachycardia/fibrillation could not be provoked in the laboratory during repeat electrophysiologic testing in five of the six patients. Repeat myocardial biopsy after all immunosuppressive therapy had been discontinued revealed absence of inflammation associated with varying degrees of residual interstitial fibrosis. There were no deaths. It was concluded that a patient with an otherwise clinically silent lymphocytic myocarditis can present with potentially life-threatening ventricular arrhythmias.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1984

Pacemaker alternans.

A 52-year-old man was implanted with a Gemini pacemaker for complete heart block which developed suddenly three months after coronary reconstruction and endocardial resection to treat chronic recurrent ventricular tachycardia. Pacemaker alternans, which is a rare phenomenon, occurred two days after pacemaker implantation and then disappeared 24 hours later. The patient was followed for a two-month period during which the pacemaker system functioned normally. Many of the possible mechanisms which may produce pacemaker alternans were explored. Our findings are presented in this report.

Arrhythmias, Cardiac↗
PubMed1983

Macroreentry as a mechanism of atrial-induced ventricular ectopic beats: a laboratory curiosity?

During electrophysiologic study in a patient, programmed stimulation of the atrium induced fixed coupled ventricular premature beats on the basis of intraventricular macroreentry. This type of macroreentry, which was reproducible, appears to have been merely a "laboratory curiosity" and never played a clinical role in this patient with chronic recurrent ventricular tachycardia.

Cardiac Complexes, Premature↗
PubMed1983

A permanently implanted endocardial electrode complicating ventricular tachycardia with a second VT.

A VVI pacemaker was permanently implanted for the purpose of suppressing recurrent ventricular tachycardia (VT). Not only did the device fail to suppress the VT, but also the permanent endocardial electrode caused a second VT which was more rapid and clinically more severe. When a new VT occurs in the presence of a permanently implanted ventricular pacing system, the implanted electrode should be considered as one of the possible etiologic causes for the VT.

Aneurysm↗
PubMed1982

Intrahisian functional bundle branch block.

A patient with functional complete left bundle branch block is presented. The site of block was localized to the area of the His bundle. This case demonstrates that functional complete left bundle branch block may be due to longitudinal dissociation in the His bundle.

Adult↗
PubMed1981

Should this patient be paced? An indication for His bundle study: syncope, a normal P-R interval and a narrow QRS.

This report describes a patient who presented with transient central nervous system symptoms of unknown etiology with an electro-cardiogram exhibiting a narrow QRS complex and normal. P-R interval. The decision to implant a permanent VII pacemaker was made on the basis of a His bundle study that revealed significant prolongation of the HV interval. The successful clinical outcome re-emphasizes the clinical usefulness of electrophysiological investigation in patients with syncope of undetermined etiology.

Aged↗
PubMed1978

Obscure syncope and the sick sinus syndrome.

This report describes a 25-year-old vigorous young man who had a history of eight years of near syncope and syncope of unknown etiology. Repeat in-hospital observation and laboratory electrophysiologic functional testing did not elucidate the origin of the symptoms. Prolonged Holter monitoring finally showed that the syncopal attacks were caused by a sick sinus syndrome (SSS). On electrophysiologic study, a concealed rate-dependent unidirectional antegrade accessory A-V pathway (AP) was found to be present. The AP was an incidental finding and was unrelated to the patient's symptoms. The symptomatic SSS may occur in the young as well as in the elderly. Sinoatrial dysfunction may be intermittent and difficult to detect, may cause severe symptoms, and may even be life-threatening. Prior to definitive therapy (such as the permanent implantation of a pacemaker), the importance of relating symptoms to a rhythm disturbance has been stressed. In cases where the cause of the symptoms is not obvious, this is best accomplished by continuous Holter monitoring.

Adult↗
PubMed1978

An unusual form of the bradycardia-tachycardia syndrome: paroxysmal A-V block and ventricular tachycardia.

An unusual case of alternating bradycardia-tachycardia, paroxysmal Mobitz II A-V block and ventricular tachycardia is described. The patient presented with a normal resting (control) electrocardiogram and intracardiac conduction times (A-H and H-V intervals). The clinical evaluation, electrophysiology, and importance of defining the cause of serious rhythm disturbances prior to therapy are discussed.

Bradycardia↗