Biomedical subjects

R Chuquimia

Publications and source records attributed to R Chuquimia.

At least 19 recordsLinked to original sources

PubMed1979

Clinical electrophysiological effects of propranolol on normal sinus node function.

In 35 patients aged 18 to 69 years (mean 48) with clinical, electrocardiographic, or electrophysiological evidence of normal sinus node function, the effect of intravenous propranolol (0.1 mg/kg) was assessed on 3 indices of sinus node function. The drug significantly prolonged sinus node cycle length (12%), slightly prolonged the corrected sinus node recovery time (15%), and slightly but insignificantly lengthened sinuatrial conduction time. Propranolol may be administered safely in patients with normal sinus node function without the fear of producing severe sinus bradycardia, sinuatrial block, sinuatrial pauses, or prolonged sinus asystole, after spontaneous or stimulation-induced conversion of a tachycardia.

Adolescent↗

PubMed1976

Electrophysiological and clinical observations in patients with alternating bundle branch block.

Electrophysiological studies (His bundle recordings and atrial stimulation) were performed in nine patients who manifested periods of both right and left bundle branch block (RBBB and LBBB). In seven of the patients, alternating bundle branch block appeared to reflect intermittent or chronic bundle branch block superimposed on incomplete (but electrocardiographically complete) block of the contralateral bundle branch. In three of these seven, shift from one bundle branch block pattern to the other was associated with reproducible change in H-V (mean change 30 msec), and could be induced by alteration of cardiac rate with carotid massage, coupled atrial stimulation, and rapid atrial pacing. In one of the seven, RBBB with a P-R of 0.20 seconds preceded chronic LBBB with a P-R of 0.24 seconds, implying that RBBB had been incomplete. In three of the seven, although a definite mechanism of alternation could not be demonstrated, transient contralateral bundle branch block occurred superimposed on chronic ipsilateral bundle branch block, implying that the ipsilateral block was incomplete. Two patients manifested periods of narrow QRS, LBBB, RBBB, and paroxysmal A-V block. Based upon pathological data (one case), this pattern appeared to reflect a lesion involving the distal His bundle and proximal bundle branches. In the total group of patients, clinical course was primarily determined by the severity of heart disease and not by occurrence of A-V block. The conduction defect in the majority of patients was surprisingly benign.

Adult↗

PubMed1976

The clinical spectrum of chronic His bundle block.

This report details our total experience with documented chronic His bundle block in 24 patients. Ten patients had second-degree block (eight with 2:1 block and two with type-1 block), and 14 patients had complete heart block. There were 16 women (67 percent) and eight men (33 percent) with ages ranging from 17 to 87 years. Diagnoses were as follows: hypertensive cardiovascular disease, nine patients (38 percent); arteriosclerotic heart disease, six patients (25 percent); aortic valvular disease, three patients (13 percent); primary conduction disease, two patients (8 percent); primary myocardial disease, two patients (8 percent); congenital heart block, one patient (4 percent); and traumatic heart block, one patient (4 percent). Pacing was instituted in 20 patients because of the following; congestive heart failure, seven patients; syncope, seven patients; fatigue, four patients; and recurrent dizziness, two patients. Permanent pacing was indicated within ten days of initial diagnosis in 13 patients, from 20 to 80 days in four patients, and later than 100 days in three patients. An additional two asymptomatic patients were treated with prophylactic pacing.

Adolescent↗

PubMed1975

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.

Adult↗

PubMed1975

Alternating Wenckebach periodicity: A common electrophysiologic response.

Alternating Wenckebach periods are defined as episodes of 2:1 atrioventricular (A-V) block in which conducted P-R intervals progressively prolong, terminating in two or three blocked P waves. In this study, His bundle recordings were obtained in 13 patients with pacing-induced alternating Wenckebach periods. Three patterns were noted: Pattern 1 (one patient with a narrow QRS complex) was characterized by 2:1 block distal to the H deflection (block in the His bundle) and Wenckebach periods proximal to the H deflection, terminating with two blocked P waves. Pattern 2 (four patients) was characterized by alternating Wenckebach periods proximal to the His bundle, terminating with three blocked P waves. Pattern 3 (eight patients) was characterized by alternating Wenckebach periods proximal to the His bundle, terminating with two blocked P waves. Alternating Wenckebach periods are best explained by postulating two levels of block. When alternating Wenckebach periods are terminated by three blocked P waves (pattern 2), the condition may be explained by postulating 2:1 block (proximal level) and type I block (distal level). When alternating Wenckebach periods are terminated by two blocked P waves (patterns 1 and 3), the condition may be explained by postulating type I block (proximal level) and 2:1 block (distal level). Pattern 1 reflects block at two levels, the A-V node and His bundle. Patterns 2 and 3 most likely reflect horizontal dissociation within the A-V node.

Adult↗

PubMed1975

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.

Adolescent↗

PubMed1975

Electrophysiologic and pathologic correlations in two cases of chronic second degree atrioventricular block with left bundle branch block.

This study concerns two cases of chronic 2 degrees atrioventricular (A-V) block with left bundle branch block (LBBB). Pathological studies included serial section of the conduction systems. Case 1 had type I 2 degrees block with LBBB. Electrophysiological studies revealed type I 2 degrees block proximal to the His bundle recording site and a prolonged H-V interval (60 msec). Pathologically there was a moderate to marked fibrosis of the approaches to the A-V node and of the A-V node, marked fibrosis of the left bundle branch, and moderate involvement of the right bundle branch. The changes proximal to the His bundle were more marked than the changes distal to this bundle. Case 2 had type II and 2:1 2 degrees A-V block with LBBB. Electrophysiologically the site of block was distal to the His bundle recording site, and there was a prolonged A-V node and severe involvement of both bundle branches. The changes distal to the His bundle were more severe than the changes proximal to the His bundle. This study reveals that the electrophysiologic data more closely approximated the pathologic findings than did surface electrocardiographic data alone. It also emphasizes that there may be multiple sites of disease in chronic 2 degrees block with bundle branch block.

Aged↗

PubMed1974