Right bundle branch block with normal, left or right axis deviation. Analysis by His bundle recordings

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)

The effect of metal detector gates on implanted permanent pacemakers

The effect of metal detector security gates, such as are used in airports, was tested in 103 nonselected pacemaker patients. Various types of single and dual chamber units were examined, using telemetry during the test. Pulse rate and duration were measured immediately before and after the procedure. No ill effect was seen on any of the units tested, pacemaker inhibition was not observed, and programmability was not affected. Metal detector security gates have no effect on implanted permanent pacemakers.

Normal electrophysiological findings in a patient with symptomatic intermittent advanced atrioventricular block

This report describes an otherwise healthy young woman who presented with syncope during episodes of advanced atrioventricular (AV) block. The His bundle recordings during normal sinus rhythm and atrial and ventricular pacing were normal. Carotid sinus massage produced no abnormality. Subsequently, the patient received a permanent pacemaker and has been free of symptoms. Intermittent advanced AV block has been observed on follow-up electrocardiograms. This unique case demonstrates a potential limitation of routine electrophysiologic investigation.

Significance of the HV interval in 517 patients with chronic bifascicular block

In January 1975, we reported results of a prospective follow-up study (mean 538 +/- 42 days) of 119 patients with chronic bifascicular block (BFB), and concluded that BFB patients with normal and prolonged HV (NHV and PHV) had a similar incidence of atrioventricular (AV) block and mortality. In this report, we update these findings in 517 patients with a follow-up of 21 days to 9.8 years (mean 3.4 +/- 0.2 years). Three hundred nineteen patients (61%) had NHV and 198 (39%) had PHV (greater than 55 msec). The NHV and PHV groups were similar in regard to age (NHV vs PHV, 61 +/- 1 vs 62 +/- 1 years) and sex (80% male, 20% female vs 82% male and 18% female). The following were more common (p less than 0.05) in patients with PHV (percent of patients with finding in NHV vs PHV groups): angina (18% vs 27%), congestive failure (27% vs 42%), cardiomegaly (48% vs 66%), New York Heart Association functional class II-IV (34% vs 56%), premature ventricular complexes (20% vs 29%), and organic heart disease (OHD) (75% vs 85%). Spontaneous trifascicular block (TFB) developed in two patients (0.6%) with NHV and nine patients (4.5%) with PHV (p less than 0.05). Cumulative 7-year incidence of TFB was 3% with NHV and 12% with PHV (p less than 0.01). Seven-year cumulative cardiovascular mortality was 32% in NHV patients and 57% in PHV patients (p less than 0.005). In conclusion, PHV in patients with chronic BFB was associated with a greater incidence and severity of OHD, and higher total and sudden death mortalities. The risk of spontaneous TFB was small in patients with either NHV or PHV, although it was significantly higher in the latter.

His bundle electrogram recording using a multipolar electrode catheter via the arm veins

In eighteen patients with atrioventricular conduction disturbance, His bundle electrograms were studied via the arm vein. A 6F Berkovits-Castellanos USCI hexapolar electrode catheter was introduced into the right atrium and looped across the tricuspid valve in a "golf club" shape. The main aim was to leave the two distal electrodes in contact with the atrial endocardium to perform atrial pacing, while displaying the other four electrodes along the superior angle of the tricuspid valve for proximal and distal His bundle recordings. His bundle electrograms were successfully obtained in all cases. The arm approach provides an alternate route whenever the femoral approach is not feasible. Moreover, the use of an hexapolar electrode catheter provides some practical advantages: 1) it enables atrial pacing to be performed, as well as proximal and distal His bundle recording to be obtained, by using the same multipolar electrode catheter; and 2) it allows long-term monitoring of His bundle potentials, in view of the stability of His bundle recordings. Finally, the arm approach could be the method of choice for the study of His bundle electrograms during leg supine exercise in selected patients.

Perioperative risk of complete heart block in patients with bifascicular block and prolonged PR interval

Because there is a paucity of information on the perioperative risk of developing complete heart block among patients with bifascicular block (either right bundle branch block and left anterior hemiblock or left bundle branch block) and a long PR interval on the surface electrocardiogram, we undertook an analysis of 76 such patients. Twenty-three patients had right bundle branch block and left axis deviation with a long PR interval and 53 had left bundle branch block with along PR interval. Thirty patients had 37 general anaesthetics, 23 had 32 spinal anaesthetics, and 50 had 64 local anaesthetics or endoscopic procedures. No patient developed complete heart block. Four patients developed sinus bradycardia during general anaesthetics, responsive to atropine or isoproterenol. Similarly, none of the 23 such patients in the literature reviewed had developed complete heart block. Because placement to temporary pacemakers is not without risk, we conclude that prophylactic pacing is not necessary in asymptomatic patients with bifascicular block even in the presence of a long PR interval. Since we did not study patients with recent syncope or myocardial infarction, caution should be exercised in applying these results to such patients.

Incidence and site of atrioventricular block in patients with chronic bifascicular block

Four hundred fifty-two patients with chronic bifascicular block and initially intact atrioventricular (AV) conduction were detected, studied, and prospectively followed between January 1970 and March 1978. There were 360 males and 92 females, ages 18--93 years (mean +/- SD, 62 +/- 15 years). Follow-up ranged from 29-2804 days (mean 1066 +/- 97 days). AV block (2 degrees or 3 degrees) developed in 29 patients, nine with apparent cause and spontaneously in 20. Cumulative annual incidence of all heart block for 1--5 years was, respectively, 4%, 5.9%, 8.7%, 10.1% and 11.3%, and for spontaneous block was 2%, 3.1%, 5.2%, 6.7%, and 7.1%. Sites of spontaneous block were probably or definitely AV nodal in ten, His bundle in one, and trifascicular in nine. Cumulative incidence of AV block in surviving bifascicular block patients is 11% at 5 years, with 7% reflecting spontaneous block. The probable or definite site of AV block varies and is trifascicular in less than half of the patients. The small incidence of trifascicular block probably explains the difficulty in predicting this complication with electrophysiological studies.

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.

Right bundle branch block with periods of alternating left anterior and left posterior hemiblock. Clinical evidence of incomplete fascicular block

The case presented had an electrocardiographic pattern of complete right bundle branch block with alternating periods of left anterior hemiblock and left posterior hemiblock. During one of the periods of alternating hemiblock, an His bundle electrogram was recorded and the His Purkinje (H-V interval) conduction time was within normal limits. In a second episode of alternating hemoblock, periods of Mobitz type II second-degree A-V block were noted. It is postulated that this case provides clinical evidence that incomplete block of a fascicle may occur in spite of an electrocardiographic pattern of complete fascicular block. It is thought that the periods of alternating hemiblock result from a changing relationship between conduction velocity and refractory period.

Prognostic value of infranodal conduction time in patients with chronic bundle branch block

His bundle recordings were obtained in 121 patients with chronic bundle branch block and the patients were followed for a mean period of 18 months. Seventy-nine patients had an infranodal conduction time (H-Q) less than 70 msec while 42 had H-Q greater than or equal to 70 msec. There was no significant difference in mean age, smoking history, diabetes, syncope, dizziness, blood pressure, and serum cholesterol or triglyceride levels between the two groups. There was a significantly greater incidence of progresssion to second degree or third degree atrioventricular block (9/42, 21%), and of severe congestive heart failure (16/42, 38%) in patients with H-Q greater than or equal to 70 compared with those with H-Q less than 70 (1/79, 1.3%; and 13/79, 16%, respectively). The risk of sudden death was significantly greater only in the group with H-Q greater than or equal to 70 and severe congestive heart failure. There was no correlation between the presence of first degree atrioventricular block and/or any particular type of bundle branch block pattern with sudden death and/or progression to second degree or third degree atrioventricular block. Analysis of the surface electrocardiogram is only of limited value in predicting high risk patients with chronic bundle branch block. Electrophysiologic studies are of greatest value in patients with bundle branch block with transient neurologic symptoms in whom no cause for the symptoms is evident.

Follow-up studies in patients with right bundle branch block and left anterior hemiblock: significance of H-V interval

Thirty-eight patients with right bundle branch block and left anterior hemiblock who had undergone His bundle recordings were prospectively followed for development of heart block. Twenty-five were male and thirteen female. Their ages ranged from 35 to 92 with an average age of 74 years. The mean follow-up period was 28.5 months (range 2-52 months). The H-V interval was 55 msec or less in 17 patients (Group A), between 56 and 75 msec in 13 (Group B), and more than 75 msec in eight (Group C). Ten patients (26%) died during the follow-up period. Of these, three were in Group A (mortality rate 8% per year), three in Group B 10% per year), and four in Group C (21% per year). None of the deaths in Groups A and B were sudden, while one possible sudden death occurred in Group C. Mode of death in one patient each from Groups B and C remained unknown. Heart block was not seen in any patient from Group A and B, while two patients from Group C progressed to complete heart block during the follow-up period. It is concluded that patients with right bundle branch block and left anterior hemiblock with prolonged H-V intervals tend to show a higher mortality when compared to those with normal H-V intervals. A definite risk of heart block exists in patients with H-V intervals of more than 75 msec.

Significance of A-H interval in patients with chronic bundle branch block. Clinical, electrophysiologic and follow-up observations

His bundle electrograms were recorded in 308 adults with chronic bundle branch block. The A-H interval was normal in 249 patients and prolonged in 59. Comparison of patients with normal and prolonged A-H intervals revealed a greater incidence of demonstrable organic heart disease in the latter (P less than 0.01). Dyspnea, cardiomegaly and congestive heart failure were more frequent in patients with A-H prolongation. These patients also had longer P-R intervals and atrioventricular (A-V) nodal effective refractory periods, lower paced rates producing second degree A-V block proximal to the His bundle and a greater frequency of H-V prolongation. All patients were prospectively followed up in a conduction disease clinic with mean follow-up periods (+/- standard error of the mean) of 523 +/- 23 and 588 +/- 47 days in the patients with normal and prolonged A-H intervals, respectively. Seven (3 percent) of the patients with a normal A-H interval had A-V block with probable or definite site of block proximal to the His bundle in three and distal to the His bundle in four. In five of the six patients with a prolonged A-H interval who experienced A-V block (10 percent), the probable or definite site of block was proximal to the His bundle. Mortality (both sudden and nonsudden) was not significantly different in the patients with normal and prolonged A-H intervals. In summary, A-H prolongation was associated with increased incidence of organic heart disease and myocardial dysfunction. The risk of development of A-V nodal block was greater in patients with a prolonged A-H interval but appeared to be of minimal clinical significance.

Progressive improvement of His-Purkinje conduction during recovery from catheter-induced heart block

Complete heart block developed during HBE studies in a patient with left bundle branch block, after inadvertent catheter-induced trauma to the right bundle branch. Normal intraventricular conduction (HV interval) was documented during the initial part of the study, and was demonstrated to be markedly prolonged after the appearance of heart block. Conduction through the right bundle branch improved over a short period of time as manifested by steplike shortenings of the HV interval, until the original conduction velocity was re-established. This case strongly supports the concept that the His-Purkinje system is capable of varying its conduction velocity and further demonstrates that, in patients with bundle branch block, a prolonged HV interval indicates disease of the remaining bundle branch.

Prolonged His-Q interval in chronic bifascicular block. Relation to impending complete heart block

Although prolonged infra-His conduction time in bifascicular block is suspected of denoting trifascicular disease, adquate documentation is lacking concerning the correlation between lengthened His-Q interval (H-Q) and the risk of development of complete heart block (CHB). H-Q in conducted sinus beats in patients with bifascicular block associated with Mobitz II or intermittent CHB represents the approximation of maximal H-Q prolongation prior to onset of trifascicular block. To assess this relationship between prolongation of H-Q and trifascicular block, His bundle electrocardiography (HBE) was performed in 50 patients with chronic bifascicular block exhibiting Mobitz II block or transient CHB. Mobitz II or episodic CHB was shown in all patients: within two days prior to HBE in 45/50 patients; in 39/50 patients during HBE; and following HBE in five patients. In 49/50 patients H-Q was prolonged (greater than 55 msec) and in 47 this interval was substantially lengthened (65 msec or greater). Since marked H-Q prolongation in conducted sinus beats was documented in nearly all patients with bifascicular block associated with intermittent complete trifascicular block, we conclude that a considerably lengthened H-Q interval in bifascicular block is not only a usual prerequisite but strong evidence, for impending complete heart block.

Chronic right bundle branch block and left posterior hemiblock. Clinical, electrophysiologic and prognostic observations

Twenty-one patients with long-term right bundle branch block and left posterior himiblock were studied electrophysiologically and then followed up prospectively. The group consisted of 19 men and 2 woman aged 61 +/- 2.7 years (mean +/- standard error of the mean). The majority of patients had either hypertensive cardiovascular disease (48 percent) or primary conduction disease (33 percent). Initial electrophysiologic studies revealed A-H intervals of 58 to 152 msec (mean 98 +/- 7.7) and H-V intervals of 40 to 80 msec (mean 52 +/- 2.1). Six patients (29 percent) had prolonged H-V intervals. The follow-up period ranged from 91 to 1,231 days (mean 671 +/-68). Three of 21 patients (14 percent) needed a permanent pacemaker after development of the following symptomatic conduction disease: sinoatrial block on day 3 of follow-up; second degree atrioventricular (A-V) block, site undetermined, on day 118; and second degree A-V block proximal to the His bundle on day 398. One patient died suddenly (on day 571), and two others died of noncardiac causes. In conclusion, combined right bundle branch block and left posterior hemiblock was associated with less trifascicular disease than reported previously. The clinical course of most of the patients was benign and the incidence of sudden death was relatively small. Symptomatic conduction disease occurred but could be definitely related to trifascicular disease in only one patient. These short-term data suggest that prophylactic pacemaker insertion is not routinely indicated in patients with chronic right bundle branch block and left posterior hemiblock.

Indications for prophylactic preoperative insertion of pacemakers in patients with right bundle branch block and left anterior hemiblock

To determine the need for prophylactic temporary pacing in bifascicular block during surgical and other procedures, a retrospective analysis was carrried out in 38 patients who underwent a total of 74 procedures. The male:female sex ratio was 3.2:1 and mean age was 74 (range 48-96) years. Known organic heart disease was absent in 45 percent of the total group. Patients were divided into four groups on the basis of their preoperative electrocardiograms. Of the 74 procedures, 19 were carried out under general, 22 under spinal and 29 under regional anesthesia; four endoscopic procedures were done without anesthesia. There was only one complication relating to deterioration of AV conduction. It is concluded that asymptomatic patients with right bundle branch block and left anterior hemiblock do not require prophylactic preoperative pacemaker insertion. Though experience is limited, the same may be true of patients with the additional finding of prolongation of PR interval.

Surgical bifascicular block

Electrophysiological studies were performed in 18 patients who developed bifascicular block after repair of ventricular septal defect (VSD) or tetralogy of Fallot (TF). Two had transient complete heart block (CHB) in the immediate postoperative period. The P-A intervals were normal in all. A-H and H-V intervals were prolonged in three and four cases, respectively. Atrial pacing at progressively increasing heart rates was performed in 15 patients; two developed type II block distal to the His bundle (H). The effective and functional refractory periods (ERP and FRP) of the atrium (11 cases) were normal in all. The ERP of the A-V node (seven cases) was prolonged in found and the FRP was increased in three. The ERP of the ventricular specialized conduction system was measured in two cases and was prolonged in one. In all, seven cases had abnormalities indicating disease of the A-V node and/or His-Purkinje system. Recording of intervals, atrial pacing, and determination of refractory periods (RPs) was necessary to reveal all conduction abnormalities. One patient died of unrelated causes. The others are alive and in sinus rhythm with intact conduction 3 to 16.5 years following surgery (mean follow-up of 8.3 plus or minus 0.95 years). The clinical course in patients with normal and abnormal findings was equally benign. Prophylactic insertion of demand pacemakers does not appear indicated in these patients.

[Clinical value of His bundle electrography (author's transl)]

Methodical problems, indication and clinical implication of His bundle electrography are discussed. In 200 successive patients undergoing His bundle electrography and atrial stimulation the indication was as follows: Intraventricular conduction defects in 24%, A-V block in 21%, sick sinus syndrome in 20%, preexcitation in 17%, and complex arrhythmias in the remaining cases. In 38% of the patients did the HBE prove to be of help by providing information not available after analysis of the surface ECG. In 22% this technique contributed essentially to the management of these patients. In spite of dificiencies of our knowledge of the basic mechanisms, specific therapy, and prognosis of various arrhythmias His bundle electrography is clinically useful in selected patients. Therefore, this method has become a routinely used clinical tool.

Sinus node recovery time in the elderly

Measurement of the sinus node recovery time has been proposed as a diagnostic tool for recognition of the sick sinus syndrome. The latter is most frequently encountered in elderly patients with hypertension, coronary heart disease, and atherosclerosis. In order to provide normal values for the sinus node recovery time in this particular population group, atrial pacing studies were carried out in 30 subjects over 50 years of age, all with peripheral vascular disease and some with angina pectoris (10), residua of infarction (6), or hypertension (7). On stimulation, 7 patients maintained a I:I atrioventricular conduction up to the rate of 180/min. Second degree atrioventricular block developed in all other cases. On six occasions, Wenckebach's periods appeared at the relatively slow pacing rate of 120/min. The maximum postoverdrive pause ranged from 680 to 1600 ms with an average of 1100 ms plus or minus 190 (10). For each pacing speed, a correlation was found between the duration of the pause and the control intrinsic cardiac rate, longer pauses being associated with longer resting PP intervals. Beyond 120/min, the duration of the pause was seen to shorten progressively as the driving rate was increased. Finally, the behavior of the sinus node pacemaker following interruption of pacing showed individual variations. After pacing at relatively slow rates, a prompt return to near control values was consistently observed, whereas, after fast rates of driving, a phase of secondary depression developed in about one-half of the studied cases.

Atrioventricular block (first of two parts)

The development of His-bundle (H) electrocardiography and the concept of hemiblocks have prompted a re-examination of conventional thinking about the indications for treatment of atrioventricular (AV) block. The technic of treatment is not the issue; ventricular pacemaking is the only really effective and reliable method. The problem for this review is what these recent developments have contributed to deciding when and if a pacemaker should be installed.

Wenckebach phenomenon within the atria

A patient with a history of fainting and a bifacicular block (CRBBB plus LPH) was analyzed by His Bundle electrograms. During atrial pacing at a rate of 138/min, a Wenckebach type of block occurred within the atrium or at the electode-atrium junction, or both. The sinus intra-atrial conduction time (P-A inverval) was normal. During atrial pacing (pacing rate of 138 to 148/min), St-A interval progressively lengthened and ultimately a second degree Wenckebach type of block was obtained. The surface electrocardiogram (ECG) was normal and only electrical pacing brought on the intra-atrial conduction defect. Simultaneous with this atrial block, a second degree (Mobitz II) block developed.

H-V interval in patients with bifascicular block (right bundle branch block and left anterior hemiblock). Clinical, electrocardiographic and electrophysiologic correlations

Electrophysiologic studies were performed in 119 adults with chronic bifascicular block manifested by right bundle branch block and left anterior hemiblock. The H-V interval was normal in 86 patients and prolonged in 33. The following clinical variables were more frequent (P less than 0.05) in patients with a prolonged H-V interval: cardiac third sound, mitral systolic murmur, cardiomegaly on chest roentgenogram, congestive heart failure and cardiac functional class III or IV (New York Heart Association criteria). The following differences in the electrocardiographic and electrophysiologic findings were found: Patients with a prolonged H-V interaval had a longer mean P-R interval, QRS duration and A-H interval (P less 0.02). All patients were followed up prospectively in a cardiac conduction disease clinic after initial evaluation. The mean follow-up periods were (mean plus or minus standard error of the mean) 514 plus or minus 49 and 563 plus or minus 34 days for the patients with a prolonged and normal H-V interval, respectively. Progression of conduction disease occurred in three patients (4 percent) with a normal H-V interval and in four (12 percent) with a prolonged interval. The cumulative 3 year mortality rate for the entire group was 25 percent. The patients with a prolonged H-V interval had a higher cumulative 2 year mortality rate than those with a normal H-V interval but the difference was not statistically significant. In summary, a prolonged H-V interval was often associated with serious myocardial dysfunction and a high mortality rate. The risk of progression of conduction disease was slight with either a prolonged or a normal H-V interval during this relatively short follow-up period.

Complete His-Purkinje block produced by carotid sinus massage. Report of a case

A case of complete heart block (CHB), localized in the His-Purkinje system, induced by carotid sinus massage (CSM) is presented. A 63-year-old male with right bundle branch block and left anterior hemiblock was evaluated for recurrent syncope. Right or left CSM produced brief periods of CHB with presyncopal symptoms. His bundle (HB) studies during normal sinus rhythm revealed normal conduction times (A-H interval = 80 msec; H-V interval = 48 msec). Carotid sinus massage produced progressive slowing of the sinus rate, and complete heart block below the HB occurred whenever the sinus rate fell below 42 beats/min. During atrial pacing at 70 beats/min, CSM produced 2:1 block above the HB with an effective rate to the HB of 35 and complete block below the HB. Atrial pacing at rates above 93 beats/min resulted in 2:1 block below the HB. Administration of intravenous atropine produced an apparent junctional tachycardia with 2:1 block below the HB. Thus, complete heart block related to both bradyCardia (phase 4) and tachycardia (phase 3) was demonstrated. The complete heart block induced by CSM was thought to be secondary to bradycardia-induced left posterior fascicular or intra-His block. However, the possibility of a direct vagal effect on ventricular conduction could not be ruled out.

Late postoperative conduction distrubances after repair of ventricular septal defect and tetralogy of Fallot. Analysis by his bundle recordings

His bundle electrograms were recorded in five children who developed complete heart block (CHB) five months to five years after cardiac surgery. In four children who had an electrocardiographic pattern of right bundle branch block and left axis deviation (RBBB and LAD) preceding the appearance of CHB, the site of block was distal to the area generating the His potential. The fifth child, who had an electrocardiographic pattern of RBBB with normal axis prior to the development of CHB, had block occurring proximal to the area generating His potential. All five children had had transient CHB in the immediate postoperative period.

In an additional 17 postoperative patients, His bundle recordings were obtained during sinus rhythm. Five out of ten patients with RBBB and LAD on the electrocardiogram and one patient with LBBB had H-V interval prolongation, a recording suggesting incomplete bilateral bundle branch block or trifascicular block. Six patients with RBBB only on the electrocardiogram had normal H-V intervals. All the patients with H-V interval prolongation had had CHB transiently in the immediate postoperative period.

This study suggests that patients with an electrocardiographic pattern of RBBB and LAD who have had transient CHB postoperatively may have, more extensive residual damage to the conduction system than suspected on the basis of the surface electrocardiogram alone and because of the risk of late recurrence of CHB should be given a guarded prognosis.

A new catheter technique for His bundle recordings via the arm veins

Images

His bundle recordings in patients with bundle branch block and transient neurologic symptoms

His bundle electrograms were recorded in 19 patients with bundle branch block (BBB) and transient neurologic symptoms allowing for determination of intra-atrial (P-A), atrioventricular (A-V), nodal (A-H) as well as infranodal conduction (H-Q) times. The patients were initially monitored in a coronary care unit and have been followed for a mean period of 8 ± 4 months. In six patients (Group I) neurologic symptoms were observed in the absence of electrocardiographic evidence of A-V block. In six patients (Group II) the cause of symptoms was uncertain; two of these patients had relief of symptoms after permanent cardiac pacemaker insertion and were presumed to have episodic high grade A-V block. In seven subjects (Group III) complete A-V block was documented as the cause of the symptoms; these patients were studied when 1:1 antegrade A-V conduction returned. There was no significant difference between mean P-A, A-H, and QRS durations among the patients in the three groups. Mean H-Q (89 ± 20 msec) for Group III was significantly longer than that for Group I (56 ± 9 msec) or Group 11 (64 ± 11 msec) ( P < .001). All patients with presumed or documented episodes of high grade A-V block had abnormal H-Q intervals, and six of the nine patients with presumed or documented complete A-V block had H-Q intervals >80 msec. The present data suggest that patients with transient neurologic symptoms, bifascicular or left BBB associated with marked prolongation of H-Q (≧80 msec), should be seriously considered as candidates for insertion of a permanent cardiac pacemaker even in the absence of documented high grade or completeA-V block.