Robert D. Patton

A Study of Heart Block in Man Using His Bundle Recordings

The technique of recording His bundle electrograms in man by a tripolar electrode catheter was applied in a study of patients with first, second, and third-degree heart block. In all patients with first-degree heart block (congenital, acquired, or induced by atrial pacing), the delay in A-V conduction occurred proximal to the His bundle as evidenced by a prolonged P-H interval. The enhancement of A-V conduction (shortening the P-H interval) due to isoproterenol was qualitatively similar in the three forms of first-degree block. In cases of Wenckebach phenomenon the P-H interval progressively increased until a dropped beat occurred. The nonconducted P wave was not followed by a His deflection, indicating block proximal to the His bundle. Cases of 2:1 and 3:1 block occurring proximal to the His bundle were also studied. The usefulness of His-bundle recordings in the diagnosis of cases of complete and incomplete bilateral bundle-branch block is also demonstrated.

A Study of Atrioventricular Conduction in Man Using Premature Atrial Stimulation and His Bundle Recordings

In 20 subjects the effects of controlled premature atrial stimulation on atrioventricular conduction was studied using an electrode catheter technic for recording electrical activity of specialized conducting fibers. The least common type of response observed was that in which A-V conduction delay was limited only to the A-V nodal region (type A). This type of response was obtained whenever the conduction delay in the A-V nodal region increased in direct proportion to the prematurity of a propagated atrial impulse. It was characterized by a progressive prolongation in the P-H interval with ultimate failure of conduction occurring proximal to the His bundle. In type B response, conduction delay occurred in both the A-V nodal and His-Purkinje systems. The recording of a characteristic A-V nodal potential permitted the localization of A-V nodal delay to the N-H interval.

The use of His bundle recordings in the analysis of unilateral and bilateral bundle branch block.

Abstract His bundle electrograms were recorded in 26 patients with bundle branch block. The interval from the His bundle electrogram to the onset of ventricular activation (H-V) was used as an approximation of conduction time in the left bundle branch in patients with right bundle branch block and of conduction time in the right bundle branch in patients with left bundle branch block. The H-V intervals of patients with right bundle branch block were within the range of those noted in patients with “normal” ventricular activation. The average H-V interval of patients with left bundle branch block was 22 msec. longer than that of patients with right bundle branch block and there was no overlap of individual values. Two patients with alternating LBBB had shorter H-V values during “normal” ventricular activation. Normalization of a bundle branch block pattern by premature atrial stimulation resulted in a shortening of the H-V interval. Two of six patients with right bundle branch block and left axis deviation had prolonged H-V intervals suggesting disease of either the most proximal portion of the left bundle branch or of the posterior-inferior division. The longest H-V values were observed in two patients with prolonged P-R intervals and left bundle branch block suggesting delayed conduction in the right bundle branch. Type I second degree A-V block induced by atrial pacing resulted in blocked impulse transmission proximal to the H potential. In Type II second degree A-V block the cardiac impulse was blocked distal to the H potential presumably in the contralateral bundle branch. Concealed conduction with blocked impulse transmission in the distal portion of the right bundle branch was observed.

A Study of Atrioventricular Conduction in Atrial Fibrillation and Flutter in Man Using His Bundle Recordings

Seven patients with atrial fibrillation and six patients with atrial flutter were studied using the technic of His bundle recordings. All 13 patients received digitalis. In atrial fibrillation each QRS complex (except for premature ventricular beats) was preceded by a single His bundle deflection. Complete block distal to the His bundle was not observed. Thus, the zone of concealment could be localized to the region proximal to the His bundle. The clinical findings were confirmed in three animal experiments. In atrial flutter the nonconducted P waves were also blocked proximal to the His bundle. In atrial fibrillation aberrant ventricular beats were distinguished from premature ventricular beats by the presence of a preceding His deflection in the former and its absence in the latter.

The effect of diphenylhydantoin on atrioventricular and intraventricular conduction in man

Abstract The effects of DPH on atrioventricular and intraventricular conduction were studied in 13 patients using an electrode catheter technique for recording His bundle activity. DPH was found to enhance A-V conduction (i.e., shorten the P-H interval) over various paced heart rates. DPH did not prolong I-V conduction as measured by the H-Q interval.

The electrically silent right atrium

Summary An electrically silent atrium unresponsive to atrial pacing has not been previously reported. Two patients with this phenomenon form the subject of this report. In one patient, return of spontaneous atrial activity was noted, while the second patient has remained unchanged after a several month follow-up.

The clinical use of diphenylhydantoin (Dilantin) in the treatment and prevention of cardiac arrhythmias

Abstract The use of intravenous diphenylhydantoin (5 mg. per kilogram) in the treatment and prevention of cardiac arrhythmias was studied. In the treatment of arrhythmias caused by digitalis, diphenylhydantoin restored 6 of 11 atrial arrhythmias to sinus rhythm and 21 of 24 ventricular arrhythmias responded. In patients whose arrhythmias were not digitalis-induced, only one of 20 patients with atrial and 5 of 16 with ventricular arrhythmias responded. Diphenylhydantoin significantly improved the cardiac rhythm in 10 of 12 patients with ventricular arrhythmias which were unresponsive to procaine amide. In 12 patients, atrial or ventricular arrhythmias developed either during digitalization or maintenance digitalis. In these patients, diphenylhydantoin was given immediately prior to DC cardioversion. In all cases, DC countershock produced sinus rhythm with no immediate postshock arrhythmias. Diphenylhydantoin was given to 11 patients prior to cyclopropane anesthesia. Ten of the 11 patients had no arrhythmias during the anesthetic, whereas only one of 9 patients in the control group was free of arrhythmias. Diphenylhydantoin restored sinus rhythm in 8 patients who developed ventricular arrhythmias during the administration of various anesthetics, but had no effect in 2 patients with atrial arrhythmias. Side effects due to diphenylhydantoin were minor and transient and no deaths occurred. It is concluded that with slow administration and careful electrocardiographic and blood pressure monitoring, diphenylhydantoin is a safe and valuable agent in both the treatment and prevention of cardiac arrhythmias.

The posterior left atrial echocardiogram of mitral regurgitation.

SUMMARYThe motion of the posterior wall of the normal left atrium has not been studied systematically. The superoposterior portion of the left atrium is adynamic throughout the cardiac cycle, whereas the inferoposterior portion is displaced posteriorly with left atrial filling during ventricular systole. In the present study, the left atrial diameter (LAD), the left atrial systolic motion (LASM) and the left atrial systolic velocity (LASV), were determined in the following groups of patients: 34 normals; eight patients with either coronary artery disease or aortic stenosis; six patients with aortic insufficiency; and three patients with ventricular septal defect. The results obtained were compared to 15 patients with angiographically documented mitral regurgitation. In the last group, the LAD (4.2 ± .19 cm) and LASV (12.3 ± 1.23 cm) and LASM (1.2 ± .04 cm) were significantly greater reflecting the early accentuated filling of the left atrium induced by mitral regurgitation. As well, the product of these three parameters was greater in the mitral regurgitation group (63.2 ± 7.34 cm3/sec) than in the other groups and patients with mild to moderate regurgitation had a significantly lower value than those with moderate to severe regurgitation (45.7 ± 4.1 vs 78.5 ± 10.9, P < 0.02). The left atrial echocardiogram, therefore, is an aid in the diagnosis of mitral regurgitation and provides a rough index of the severity of the lesion.

The Study of Heart Block in Man Using His-Bundle Recordings.

The technique of recording His bundle electrograms in man by a tripolar electrode catheter was applied in a study of patients with first, second, and third-degree heart block. In all patients with first-degree heart block (congenital, acquired, or induced by atrial pacing), the delay in A-V conduction occurred proximal to the His bundle as evidenced by a prolonged P-H interval. The enhancement of A-V conduction (shortening the P-H interval) due to isoproterenol was qualitatively similar in the three forms of first-degree block. In cases of Wenckebach phenomenon the P-H interval progressively increased until a dropped beat occurred. The nonconducted P wave was not followed by a His deflection, indicating block proximal to the His bundle. Cases of 2:1 and 3:1 block occurring proximal to the His bundle were also studied. The usefulness of His-bundle recordings in the diagnosis of cases of complete and incomplete bilateral bundle-branch block is also demonstrated.

Bundle of His Electrograms: A New Method for Analyzing Arrhythmias

Abstract Aberrant conduction and infranodal block complicate the diagnosis of certain arrhythmias. Bundle of His electrograms enable the physician to recognize supraventricular beats and localize the site of block above or below the bundle of His. Four cases are presented to demonstrate the application of this technique in the analysis of difficult atrioventricular arrhythmias.