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 and treatment of nocturnal angina preceding myocardial infarction

The presence of nocturnal angina and congestive heart failure within the month prior to admission was evaluated in the 174 patients with acute myocardial infarction. Heart size was evaluated radiographically at the time of admission. Twenty-three patients (13 per cent) experienced nocturnal angina. The incidence of nocturnal angina was significantly higher in those with anterior myocardial infarction (p less than 0.005) and subendocardial infarction (p less than 0.02) when compared with patients with inferior MI. Congestive heart failure was more common prior to admission in those with nocturnal angina (9/23) as opposed to those without (3/141) (p less than 0.001). Cardiomegaly was seen in 9/23 patients with nocturnal angina and 22/141 without (p less than 0.02). We conclude that the presence of nocturnal angina in those who develop MI increases the likelihood that the infarction will be either anterior or subendocardial rather than inferior. The association of nocturnal angina and congestive heart failure to anterior myocardial infarction is probably due to more severe and probably significant left coronary artery disease.

Chronic His bundle block. Clinical, electrocardiographic, electrophysiological, and follow-up studies on 16 patients

This report describes 16 patients with block within the His bundle seen over a period of 55 months. Ten were women and 6 men, with an average age of 76 years, range, 42 to 98 years. All patients had His bundle recordings showing split His bundle potentials (H and H) (13 patients) or narrow QRS with block distal to the His bundle potential (3 patients). Of the 16 patients, 10 had complete heart block, 4 second degree AV block (2 patients with Mobitz type II, and 2 with 2:1), and 2 first degree AV block. Ten patients had a narrow QRS in the conducted beats or escape rhythms. Intravenous atropine (1 to 2 mg) had a variable effect on AV conduction and the rate of the escape rhythm. Twelve patients have had a permanent pacemaker implanted. During the follow-up period, 10 patients died 1 to 31 months from the time of initial examination. The remaining 6 patients (5 with pacemaker) are alive 3 to 58 months later.

The natural history of trifascicular disease following permanent pacemaker implantation. Significance of continuing changes in atrioventricular conduction

Seventy-two patients with trifasicular disease were followed for an average of 40 months following permanent pacemaker insertion. The indications for pacemaker insertion were either electrocardiographic evidence of complete heart block with a wide QRS escape complex or a pattern of bifasicular block with either periods of Mobitz type II atrioventricular (A-V) block or a documented history of syncope. The patients were then divided into three groups depending on subsequent change in A-V conduction. There were 31 (43%) patients with no change in A-V conduction, 17 (24%) with increasing A-V block, and 24 (33%) with decreasing A-V block. The characteristics of these three groups, including age and sex distribution, were compared and found to be similar. The incidence of previous transmural myocardial infarction as determined by electrocardiographic criteria was higher in the group with decreasing block. Survival curves showed a significantly decreased probablity of surviving for those with decreasing block compared to both those with increasing block and those with no charge in conduction (P less than 0.03). We conclude that the probability of long-term survival was less in the group with decreasing block. This finding may be related to the greater prevalence of coronary heart disease in the patients.

Diabetic treatment and primary ventricular fibrillation in acute myocardial infarction

The relation between mode of therapy and mortality rate and incidence of primary ventricular fibrillation was studied in 265 patients with diabetes mellitus and acute myocardial infarction. Sixty patients were being treated with diet only, 54 were receiving insulin and 151 were taking oral hypoglycemic agents. Fourteen patients (5.3 percent) had primary ventricular fibrillation, and all but one died. No statistically significant association was found between the incidence of primary ventricular fibrillation and the type of treatment for diabetes mellitus. Sixty-four (24.2 percent) of the 265 patients died during hospitalization. Mortality was greater among diabetic patients receiving oral therapy. However, after adjusting for age and sex, the difference among these three treatment regimens did not reach the P less than 0.05 level of significance.

Heart block complicating acute inferior wall myocardial infarction

Heart block was noted in 60 (35 complete and 25 second-degree) of 410 patients with acute inferior wall myocardial infarction. This group with heart block was compared to a control group of 30 patients with acute inferior wall infarction without heart block. The incidences of prior myocardial infarction and hypertension, in addition to the highest level of serum creatine phosphokinase and a maximum degree of ST-segment elevation in the inferior leads, were all greater in patients with heart block, as compared to the controls. The incidences of various complications, including dizziness and syncope, transient hypotension, cardiogenic shock, and congestive heart failure, were also higher in the group with heart block, while sinus nodal distrubances and atrial arrhythmias occurred with equal frequency. The mortality in those with heart block was 28 percent compared to 13 percent for the control. It is concluded that patients with heart block complicating acute inferior myocardial infarction have a greater amount of myocardial necrosis, a higher incidence of complications, and a higher mortality. Insertion of a temporary pacemaker should be considered when specific indications are present and not routinely.

Incidence and significance of left anterior hemiblock complicating acute inferior wall myocardial infarction

The hospital course and serial vectorcardiograms of 56 consecutive patients with acute inferior wall myocardial infarction were reviewed. Left anterior hemiblock (LAH) complicating inferior wall myocardial infarction was diagnosed by vectorcardiographic criteria. Seven patients (12.5%) developed LAH between the first and third hospital day, while 49 patients did not. There was no significant difference between these two groups when compared for age, sex, incidence of congestive heart failure, atrial and ventricular arrhythmias, atrioventricular (A-V) block, hospital mortality, and previous hypertension, diabetes mellitus, and myocardial infarction. We conclude that LAH is a relatively common complication of acute inferior wall myocardial infarction, with no apparent effect on the clinical course.

Transient atrioventricular standstill. Etiology and management

Four patients with different clinical conditions had transient cardiac standstill for periods of up to 22.5 seconds. All patients showed signs of cerebral ischemia and required cardiac resuscitation. In one patient, the standstill was thought to be the result of a transient increase in the vagal tone, and no long-term therapy was required. In the second patient, cardiac standstill occurred during hospitalization for impending myocardial infarction. Coronary arteriography followed by coronary artery surgery was performed, and there was no further episodes of standstill. In the third patient, standstill was probably related to long-term ingestion of propranolol hydrochloride, and was not observed after this medication was discontinued. In the fourth patient, standstill was the result of the sick sinus syndrome, and a permanent pacemaker was inserted. Standstill of both atria and ventricles may occur under different clinical settings, and management of arrhythmia should be guided by thf etiology of the arrhythmia.

Long-term survival of patients with incomplete bundle-branch block complicating acute myocardial infarction

Electrocardiograms and His bundle electrograms were reviewed in 28 patients with incomplete bilateral bundle-branch block complicating acute myocardial infarction. All had a His bundle electrogram at the time of pacemaker insertion; 10 had a second one. Of 23 patients with an initially abnormal HV interval (55 ms or greater), 15 died (65%), while only one died (20%) in the group of 5 with a normal HV interval. This difference is not statistically significant. Sequential His bundle electrograms were done in 6 of the 8 survivors with an initially abnormal HV interval, and 4 showed 10 to 15 ms decrease in HV interval. The disappearance of incomplete bilateral bundle-branch block occurred significantly more often in patients who survived (7 of 12) when compared with those who did not survive (2 of 16) (P less than 0.05). It is concluded that long-term survival is po-sible after incomplete bilateral bundle-branch block complicating acute myocardial infarction. The characteristics of the survivors include an initially normal HV interval, transient incomplete belateral bundle-branch block and a decreasing HV interval if it were initially abnormal.

Bradycardia-hypotension syndrome in acute myocardial infarction. Reappraisal of the overdrive effects of atropine

Sixty-eight (17 per cent) of 380 patients with acute myocardial infarction had the bradycardia-hypotension syndrome (ventricular rate below 60/min and systolic blood pressure less than 100 mm Hg) during the first 24 hours of admission to a large general hospital. In 61 of the 68 patients, the administration of atropine significantly increased the heart rate (from 46 plus or minus 14 to 79 plus or minus 12/min) (p less than 0.01) and systolic blood pressure (from 70 plus or minus 15 to 105 plus or minus 13 mm Hg) (p less than 0.001). In 26 of the 68 patients, ventricular premature complexes decreased from 9.4 plus or minus 3/min to 2.4 plus or minus 0.7/min (p less than 0.001) after the administration of atropine. It is concluded that the bradycardia-hypotension syndrome is not an uncommon complication following acute myocardial infarction and that selected doses of atropine may have a beneficial effect without significant complications.

Refractory reentrant atrial tachycardia. Successful treatment with a permanent radio frequency triggered atrial pacemaker

This 68 year old man had recurrent episodes of paroxysmal atrial tachycardia, probably due to chronic pericarditis, persisting over a 7 year period. These episodes were resistant to all conventional medical therapy and at times produced ischemic chest pain. There was no evidence of Wolff-Parkinson-White syndrome either on the standard electrocardiogram or on the His bundle electrogram performed with atrial pacing. Rapid atrial pacing at a rate of 200/min was found to promptly terminate the tachycardia and restore normal sinus rhythm. Because of the refractoriness of the patient's tachycardia, in addition to the presence of ischemic chest pain during these episodes, a permanent radio frequency triggered atrial pacemaker was inserted which enables him to initiate rapid atrial pacing by pressing an external control. The patient has been maintained on antiarrhythmic medications in an attempt to decrease the frequency of these episodes; during an 8 month follow-up period, he has done well with approximately one episode of tachycardia each month requiring radio frequency atrial pacing for termination.

Incidence and description of accelerated ventricular rhythm complicating acute myocardial infarction

One hundred and nineteen episodes of accelerated ventricular rhythm (less than 125/min) were noted in 37 patinets with acute myocardial infarction during a 1 year period. The incidence was 12.7 per cent. Twenty-seven episodes of fast ventricular tachycardia (less than 125/min) were noted in 16 of these patients. Eighteen patients had anterior myocardial infarction and 19 inferior myocardial infarction. The mechanism of onset of accelerated ventricular rhythm was classified as escape in 65 episodes. Ventricular premature beats were noted close to episodes of accelerated ventricular rhythm in 31 patients and fast ventricular tachycardia in 14 patients. The morphology of accelerated ventricular rhythm was similar to the ventricular premature beats in 27 patients and similar to the fast ventricular tachycardia in 12. In 11 patinets the morphology of ventricular premature beats, accelerated ventricular rhythm and fast ventricular tachycardia were all the same. In six patients the coupling time of the ventricular premature beats and the onset of the accelerated ventricular rhythm were the same. In seven patients the morphology of the accelerated ventricular rhythm and fast ventricular tachycardia were the same, and the rate of the accelerated ventricular rhythm was exactly half that of the fast ventricular tachycardia. There were three deaths due to shock and heart failure. Three episodes of fast ventricular tachycardia progressed to ventricular fibrillation and were successfully cardioverted. It is concluded that accelerated ventricular rhythm and fast ventricular tachycardia were all the same. In six patients the coupling time of the ventricular premature beats and the onset of the accelerated ventricular rhythm were the same. In seven patients the morphology of the accelerated ventricular rhythm and fast ventricular tachycardia were the same, and the rate of the accelerated ventricular rhythm was exactly half that of the fast ventricular tachycardia. There were three deaths due to shock and heart failure. Three episodes of fast ventricular tachycardia progressed to ventricular fibrillation and were successfully cardioverted. It is concluded that accelerated ventricular rhythm is a relatively common complication of both anterior and inferior myocardial infarction. The high incidence of concomitant fast ventricular tachycardia, the frequency of ventricular premature beats with similar morphology and coupling time, and the instances of two arrhythmias having common rate multiples, suggest that at least in some instances accelerated ventricular rhythm may represent an ectopic focus with exit block.