Morning increase in the time of onset of sustained ventricular tachycardia.
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Aged↗
Biomedical subjects
W F Heddle
Publications and source records attributed to W F Heddle.
Clinical implications of electrophysiology study findings in patients with chronic bifascicular block and syncope.
Electrophysiology study was performed in 93 patients with bifascicular block and unexplained syncope. Clinical evidence of organic heart disease was present in 33 (35%). Electrophysiological abnormalities were detected in 45 patients (48%). Of these, 36 had distal conduction disease, including 28 with an HV interval greater than 55 ms (mean 76.4 ms), and eight who developed infraHisian block following either intravenous procainamide (four) or atrial pacing (four). Sick sinus syndrome was evident in six patients and a further two had carotid sinus hypersensitivity. Sustained monomorphic ventricular tachycardia (VT) was induced in only three patients, two of whom also had prolonged HV interval. Among the 93 patients, 45 had therapy which was guided by positive findings at electrophysiology study (Group 1). Of these, 42 received permanent pacemakers, two were treated with combined permanent pacing and antiarrhythmic drug therapy, and one was treated with antiarrhythmic drug alone. In addition, eight patients without electrophysiologic abnormalities were treated empirically by pacing (Group 2). Finally, 40 patients without electrophysiologic abnormalities received no specific therapy (group 3). At a mean follow-up of 39 months (range two-125 months), recurrence of syncope had occurred in 4% of Group 1 patients, and 25% of Group 3 patients (p less than 0.05). No patient in Group 2 had had recurrence. Total mortality was 40%, including 47% of patients in Group 1, 25% of Group 2, and 35% of Group 3. Death was sudden in seven patients. We concluded that among patients with bifascicular block and syncope, therapy directed by findings at electrophysiology study was associated with symptomatic improvement, but mortality was not significantly influenced.(ABSTRACT TRUNCATED AT 250 WORDS)
Aged↗
Procainamide administration during electrophysiology study--utility as a provocative test for intermittent atrioventricular block.
The utility of procainamide, up to 10 mg/kg IV, as a provocative test for intermittent high degree atrioventricular (AV) block was evaluated in a total of 89 patients. Forty two patients had resting 1:1 AV conduction but had bifascicular block and a history of syncope. High degree AV block had not been documented in anyone. Before procainamide, the HV interval was greater than 60 ms in 17 of the 42 patients but no patient developed infra-Hisian block with fixed rate atrial pacing or following programmed atrial extrastimuli. Procainamide administration lengthened the mean HV interval by 11.9 ms and in seven (14%) the HV increment was marked, 15-75 ms. Furthermore, four (9.5%) of these 42 patients developed second or third degree infra-Hisian block and in two of these four patients, the HV prior to procainamide administration was normal or only mildly prolonged (less than 60 ms). The findings were compared to those in three "control" groups. Among four patients with bifascicular block, previously documented transient AV block but 1:1 AV conduction at the time of study, three developed high degree AV block following procainamide. Among five patients with bifascicular block but without syncope nor documented high degree AV block, the mean HV interval lengthened by 18.8 ms and in three the HV increment was 24-30 ms. In another 38 patients with neither syncope nor an intraventricular conduction defect, the mean HV interval lengthened by 5.3 ms and in two cases by 20-25 ms. Most importantly, high degree AV block was never observed in the latter two groups. During follow-up of up to 10 years (mean 46 months), three of the seven patients in whom procainamide provoked high degree AV block have subsequently progressed to fixed complete AV block. Although the incidence of provocation of AV block was relatively low, it was concluded that, among patients with possible intermittent AV block, administration of procainamide as a test of distal conduction has limited value but is still useful, and may provide information additional to that obtained from mere assessment of the HV interval.
Adolescent↗
Fast algorithms for the analysis of sino-atrial node function.
The calculations of parameters of the sino-atrial node function have previously required the application of a non-linear least squares curve-fitting algorithm. We have compared five algorithms, three of which eliminate the need for direct non-linear least squares routines. The fast algorithms can provide greater accuracy while using less than 10% of the computing time. They make it feasible to provide real-time analysis during clinical electrophysiological studies.
Arrhythmias, Cardiac↗
Sinus node sequences after atrial stimulation: similarities of effects of different methods.
Sinoatrial conduction is commonly assessed from features of the initial cycle after a single atrial extrastimulus or eight beats atrial pacing. In contrast, sinus node automaticity is assessed by the duration of the first interval after prolonged atrial pacing. The return cycle and initial sequences after these different methods were compared in 10 subjects with normal sinus node function and 30 patients with sick sinus syndrome. Typically, sequences after all three methods showed a maximally prolonged first interval with a progressive decrease over five or more cycles. A model of recovery from overdrive suppression was used to compute the elements of conduction time and automaticity in the first interval. The sequences which followed a single extrastimulus and pacing were similar, the only index which increased significantly with prolonged pacing was associated with the degree of suppression of automaticity. The computed component of sinoatrial conduction in the return cycle was similar for all three methods. Thus all three conventional methods which consider only the initial post-stimulation interval measure both sinoatrial conduction and sinus node automaticity. The separate components of automaticity and conduction may be assessed by analysis of the total sequence.
Adolescent↗
Arrhythmias and antiarrhythmic agents.
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Anti-Arrhythmia Agents↗
Electrophysiological testing of sinus node function.
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Cardiac Pacing, Artificial↗
Ventricular standstill despite normal electrophysiology study: a further possible indication for pacing.
Permanent pacing has usually been indicated for the treatment of organic disease of the sinus node or specific cardiac conducting tissue. We report three patients in whom profound syncope was apparently related to intense, transient autonomic dysfunction. Although ventricular standstill was documented in all three, detailed electrophysiology study, responses to graded Valsalva manoeuvres and carotid sinus massage, and repeated observations after cardiac autonomic blockade by IV atropine (0.03 mg/Kg) and propranolol (0.15 mg/Kg) were essentially normal. Permanent ventricular (VVI) pacing has controlled symptoms in all three, over follow-up period of 20 to 26 months. These observations suggest that transient autonomic imbalance may be a cause of undiagnosed cardiac syncope. This is neither excluded by normal electrophysiology study nor by normal responses to usual provocative autonomic interventions.
Adolescent↗
[Investigation of the preexcitation syndromes].
Assessment of the localization and function of accessory atrioventricular pathways may be undertaken with noninvasive and invasive examination techniques. Noninvasive methods, however, such as electrocardiography, vectorcardiography, precordial mapping, echocardiography and scintigraphy do not enable exact delineation of the site of the accessory pathway since, in general, their use requires maximal preexcitation; moreover, they are of less value in the presence of septal bundles, multiple accessory pathways or intraventricular conduction disturbances. Accordingly, localization of accessory atrioventricular pathways is based on data obtained from intracardiac electrography such as the interval between stimulus and delta wave during atrial pacing, retrograde atrial sequence, VA conduction time at onset of right or left bundle branch block as well as responses to programmed ventricular stimulation during orthodromic reciprocating tachycardia. The most exact method for determination of the localization of the Kent bundle employs intraoperative endocardial and epicardial mapping with analysis of VA and AV conduction times during reciprocating tachycardia, ventricular stimulation and atrial pacing. The conduction properties of the accessory atrioventricular bundle may be estimated noninvasively based on the persistence of a delta wave as a function of the heart rate, the influence of antiarrhythmic agents on the anterograde conduction via the normal pathway as well as the shortest interval between two consecutive QRS complexes with delta waves during atrial fibrillation. Functional assessment is carried out invasively through recording the anterograde and retrograde refractory periods of the Kent bundle as well as observations during programmed atrial and ventricular stimulation or induced atrial fibrillation.
Anti-Arrhythmia Agents↗
Atrial and His bundle stimulation with an accessory nodo-ventricular connection.
A 39-year-old man with a history of frequent paroxysmal tachycardias for 27 years was referred for electrophysiology study. His resting electrocardiogram showed left bundle branch block, which persisted during paroxysmal tachycardia. Electrophysiology study demonstrated the presence of a right-sided accessory nodo-ventricular connection. The case is of particular importance as it illustrates the diagnostic value of QRS normalization with left atrial pacing and the therapeutic use of rapid His bundle pacing to terminate the tachycardia.
Adult↗
Atrial pacing in ventricular tachycardia and supraventricular tachycardia with aberrant intraventricular conduction: diagnostic and therapeutic implications.
The diagnostic and potential therapeutic value of rapid right atrial pacing in ventricular tachycardia and supraventricular tachycardia with aberrant intraventricular conduction, was examined. The effect of right atrial pacing at incremental rates beginning 10 bpm above the rate of the tachycardia was studied in five patients with ventricular tachycardia, and in four patients with supraventricular tachycardia with rate-related bundle branch block aberration, the mechanism of tachycardia having been demonstrated at electrophysiology study. Atrial pacing resulted in persistent (four) or occasional (one) normalisation of the QRS complexes to that seen in sinus rhythm in those five patients with ventricular tachycardia. The intraventricular conduction pattern persisted with atrial pacing in those patients with supraventricular tachycardia and aberrant intraventricular conduction. This confirms that atrial pacing is a useful and simple diagnostic test in wide QRS tachycardia, which does not require sophisticated electrophysiological facilities. In three of the patients with ventricular tachycardia, atrial pacing terminated the arrhythmia, suggesting potential therapeutic use of rapid atrial pacing in such patients.
Adult↗
Association of sick sinus and Lown-Ganong-Levine syndromes.
A 38-year-old woman presented with syncopal attacks for 27 years. The electrophysiology techniques which enabled the diagnosis of both sinus node dysfunction (sick sinus syndrome) and presence of an atrionodal bypass tract (Lown-Ganong-Levine syndrome) are illustrated.
Adult↗
Intermittent atrioventricular block: procainamide administration as a provocative test.
Twelve patients with clinical features suggesting possible intermittent high degree atrioventricular block were studied. All 12 patients had basic 1:1 atrioventricular conduction but nine had an electrocardiographic pattern of bifascicular distal conduction disease (right bundle branch block with left anterior or posterior hemiblock, or left bundle branch block). Intracardiac conduction was assessed by recording of the His bundle electrocardiogram and atrial pacing techniques, before and 20 minutes after intravenous administration of procainamide, in a dose of up to 10 mg/kg. Before procainamide administration, seven of the 12 patients had a prolonged H-V interval (greater than 55 ms). Procainamide administration lengthened the H-V interval in all 12 patients by 5--40 ms. In five patients, procainamide induced second or third degree AV block below the level of the bundle of His. It was concluded that the administration of procainamide may be a useful provocative test of distal conduction in patients with possible intermittent AV block.
Aged↗
Verapamil in prophylaxis of paroxysmal atrioventricular nodal reentrant tachycardia.
We examined by electrophysiologic study and clinical follow-up the use of verapamil as a prophylactic agent in 13 patients with refractory paroxysmal supraventricular tachycardia due to atrioventricular (AV) node reentry. Electrophysiologic variables and initiation and maintenance of AV nodal reentry were studied by programmed electrical stimulation. Observations were made before and after intravenous administration of verapamil, 0.15 mg/kg. Twelve of the 13 patients had previously not been controlled by other antiarrhythmic agents. Before verapamil, AV nodal reentry was induced in all 13 patients. Verapamil increased AV nodal transmission time (AH interval), as well as the effective and functional refractory periods of the AV node. Reentry could not be initiated in 5 of the 13 patients after verapamil and was nonsustained in a further 3. The echo zone for atrial premature beats which initiated tachycardia decreased in 2 of the remaining 5 patients. The rate of tachycardia was also significantly decreased. Over a mean follow-up period of 16 months, 11 of the 13 patients had definite symptomatic improvement, with decrease in frequency, duration, and/or associated symptoms of their arrhythmia. Only 1 patient had side effects which necessitated withdrawal of the drug. It was concluded that verapamil is a useful agent in the management of such patients.
Adult↗