Atrial excitability and conduction in patients with interatrial conduction defects

Prolongation of P-wave duration is an accepted indicator of an interatrial conduction disturbance and may predispose patients to atrial arrhythmias. This study was performed to monitor electrophysiologic characteristics of the atria in patients with a prolonged P-wave duration. Atrial excitability and conduction times were compared in 7 patients with a P-wave duration < 115 ms (Group I) and 13 patients with a duration ≥ 115 ms (Group II). In contrast to the Group I patients, most of the 13 patients in Group II had atrial arrhythmias, including sinus nodal dysfunction (3 patients) and a history of atrial fibrillation or ectopic atrial tachycardia (6 patients). Electrophysiologic differences between the 2 groups included a higher late diastolic threshold in Group II (0.8 ± 0.2 mA versus 1.3 ± 0.2 mA; p < 0.005), and a greater increase in intraatrial conduction time (5 ± 10 ms versus 30 ± 20 ms; p < 0.005) and interatrial conduction time (5 ± 15 ms versus 30 ± 15 ms; p < 0.05) of early premature responses. There were no differences between the 2 groups in refractory periods, shape of the strength interval curve, or conduction times of premature responses occurring late in diastole.

These abnormalities in conduction time and excitability found in patients with a prolonged P-wave duration may predispose to the initiation of certain atrial tachyarrhythmias.     

Incidence of conduction disorders in patients who underwent surgery for hypertrophic obstructive cardiomyopathy

Thirteen non-consecutive patients, aging 7 to 61 (average 27) years, underwent left ventricular myotomy-myectomy for a severely symptomatic idiopathic hypertrophic subaortic stenosis (IHSS). In all patients the resting ECG before surgery showed P-R less than 0.18 sec, QRS duration less than 0.11 sec, QRS axis ranging from +10 to +80 degrees. In the immediate post-surgical period 3 patients has complete heart block and 1 had 2nd degree type 2 atrio ventricular block. Lesion was infra-Hisian in 3 patients and intra-Hisian in 1 patient. In the remaining 9 patients an immediate post-surgical left bundle branch block appeared; in 3 out of these patients ECG and an electrophysiologic study documented severe infra-Hisian conduction impairments after an average period of 4 years from surgery. During follow-up 3 patients died suddenly.     

Left-ventricular relaxation in patients with ischemic heart disease, congestive cardiomyopathy and mitral and aortic valve defects

Left ventricular relaxation was studied in 105 patients with coronary heart disease (CHD), 42 with mitral and aortic valvular diseases, and 14 with congestive cardiomyopathy. To assess the left ventricular relaxation, the values of dP/dt and T time constants for isovolumic exponential fall in intraventricular pressure were defined in the patients. Depressed left ventricular relaxation was found in the majority of the patients with CHD whatever the status of global and segmental pumping function of the left ventricle. Abnormal left ventricular relaxation turned out to be a characteristic feature in patients with congestive cardiomyopathy and valvular diseases that contributed to the generation of left ventricular overload by its pressure and volume. In CHD patients, depressed relaxation was accompanied by lower volume and slower early diastolic filling of the left ventricle.     

Pharmacologic therapy for patients with congestive cardiomyopathy

Treatment in congestive heart failure is directed at improving cardiac output and decreasing preload and afterload without significantly increasing the oxygen requirements of the heart. This paper reviews the current approach to heart failure with inotropic and vasodilator drugs in patients with heart failure.     

Long-term benefit of dobutamine in patients with congestive cardiomyopathy

Dobutamine was given intravenously for three days to 38 patients with congestive cardiomyopathy. The patients were followed by serial determinations of functional class and by non-invasive measurements of left ventricular function-systolic time intervals ($\text{PEP}\text{LVET}$) and echocardiogram (%ΔD). The average functional class (FC) of this group was 3.8 prior to dobutamine, but two days after completion, the average FC was 2.7, by four weeks the average FC was 3.1, and by 10 weeks it was 3.4.The average $\text{PEP}\text{LVET}$ declined significantly (p < 0.001) at three days, four and nine weeks, and at 10 months after the discontinuation of dobutamine infusion. Also, 67% (20 of 30) of patients had improvement of the $\text{PEP}\text{LVET}$ by greater than ?0.04 at seven days. Even two and six months after dobutamine, 58% (15 of 26) and 39% (seven of 18) were improved. Similarly, the %ΔD was improved by at least 2% in 60% (18 of 30) at seven days and 55% (16 of 29) at four weeks. At two and six months, 50% (14 of 28) and 42% (10 of 24) were improved. Those patients who did not improve their FC were more likely (five of nine) to have left ventricular free wall thickness (by echocardiogram) less than 0.5 cm./M². Those who responded usually (22 of 29) had a ventricular wall thickness greater than 0.5 cm./M². Although the mechanism of the prolonged improvement after a three day infusion of dobutamine is not understood, this study suggests that dobutamine has a role in the therapy of chronic congestive heart failure.     

Survival in patients with intraventricular conduction defects

All 42,000 electrocardiograms taken at the University of Oregon Health Sciences Center from 1969 through 1971 were reviewed; 325 patients (0.77%) had left bundle-branch block (LBBB) or right bundle-branch block (RBBB) with axis deviation (AD). In December 1974, 90% were contacted or found to be dead. The five-year survival rate (actuarial technique) (mean +/- SE) was 45.5 +/- 2.9%. It was significantly worse than that of age- and sex-matched "controls." In most patients the cause of death could not be determined. Survival of 164 LBBB patients (40.7 +/- 4.1%) at five years was not significantly worse than that of 161 RBBB and AD patients (49.5 +/- 4.2%). Those with syncope did no worse in terms of survival than did those without. The five-year survival in coronary artery disease patients was 33.7 +/- 4.4%, in those with primary conduction system disease (20% of patients), it was 50.6 +/- 6.6%. It will be necessary to know the causes of death and of syncope in conduction disease patients before it can be determined whether or not pacemakers can prevent either.     

Ventricular function and arterial compliance in patients with congestive cardiomyopathy

In order to study the interrelationship between left ventricular afterload, estimated from the mean left ventricular wall stress, and the mechanical properties of the aorta, we have simultaneously measured systemic arterial compliance and left ventricular wall stress in 19 patients with congestive cardiomyopathy. The strong linear relationship between the ejection fraction of the left ventricle and systemic arterial compliance, and between left ventricular wall stress and systemic arterial compliance, suggests that systemic arterial compliance is an important determinant of left ventricular afterload and thus of left ventricular function.     

Adverse effects of beta-blockade withdrawal in patients with congestive cardiomyopathy

Fifteen patients with congestive cardiomyopathy who had improved conspicuously on chronic administration of a beta-blocker were studied after withdrawal of the drug. In six patients there was a pronounced deterioration of their clinical condition, and in all of the remaining patients there was a significant decrease in ejection fraction, and signs of compromised diastolic function with pathological apex curves and an increase in third heart sound. All these changes were reversed within a few weeks to a few months after readministration of beta-blocking drugs. This study supports the idea that an aetiological factor in congestive cardiomyopathy may be a pathological response to sympathetic stimulation which could be partly controlled by administration of beta-blocking drugs.     

Suppressor T lymphocyte function in patients with idiopathic congestive cardiomyopathy

Suppressor T lymphocyte function was examined in 11 patients with idiopathic congestive cardiomyopathy and in 11 age and sex matched patients with a similar degree of heart failure resulting from ischaemic heart disease. Suppressor T lymphocyte function was also assessed in a control population of 11 normal subjects. Suppressor T lymphocyte function was reduced in both groups of patients with heart failure but not significantly, and a wide range of suppression was demonstrated in all groups. These data do not support the hypothesis that there is a defect in T lymphocyte function in patients with congestive cardiomyopathy, but they do suggest that there may be a non-specific reduction in T lymphocyte suppressor function associated with heart failure in general.     

Incidence of sleep-disordered breathing in patients with hypertrophic cardiomyopathy

The authors investigated the prevalence of sleep-disordered breathing (SDB) together with its clinical correlations in patients with hypertrophic cardiomyopathy (HCM). A total of 113 consecutive patients including 63 patients with HCM (40 men; mean age, 59.5±13.0 years; New York Heart Association class, 2.0±0.9) underwent cardiorespiratory polygraphy in addition to their clinical work-up including echocardiography. Patients with an apnea-hypopnea-index (AHI) ≥5/h were considered to have SDB. If thoracic and abdominal inspiration efforts were documented, SDB was considered to be obstructive sleep apnea (OSA), otherwise SDB was considered to be central sleep apnea (CSA). The age- and sex-matched control group of 50 patients had exclusion of coronary artery disease by angiography, and normal left ventricular (ejection fraction ≥55%) and valvular function. SDB was diagnosed in 52 patients (82.5% vs 72% in the control group; P =not significant) with a mean AHI of 23.0±17.8/h. Severity of SDB was higher in patients with HCM than in the control group (AHI 12.2±7.6/h; P =.003). OSA was documented in 39 patients (AHI 21.2±16.5/h) and CSA in 13 (AHI 28.4±20.9/h). The severity of SDB correlated with New York Heart Association functional class (η=0.9, η(2) =0.811) and with left ventricular end-diastolic (r=0.6, P <.01) and left atrial (r=0.4, P <.01) diameter. No correlations were found between SDB and other clinical or echocardiographic parameters. SDB is common in patients with hypertrophic cardiomyopathy, with a predominance of OSA and correlations with markers of left ventricular function.     

Pacing for patients with congestive heart failure and dilated cardiomyopathy

Considerable evidence has now accumulated that permanent pacing may provide symptomatic benefit for at least some patients with CHF. Recently, the most promising results with left ventricular or biventricular pacing have been obtained. The data for improvement in survival with pacing is less compelling. The mortality of CHF associated with systolic dysfunction of the left ventricle remains high and arrhythmic deaths are frequent. Clinical trials such as the Sudden Cardiac Death Heart Failure Trial (SCD-HeFT) are currently underway to investigate the role of the implantable defibrillator in patients with heart failure. The development and general availability of ICDs with biventricular pacing capability may play an increasingly important role in the overall therapeutic plan for this group of patients to allow for optimization of functional status with pacing and protection from sudden cardiac death with defibrillation.     

LV-function and development of congestive cardiomyopathy in HIV-infected patients

Abstracts

LV-function and development of congestive cardiomyopathy in HIV-infected patients     

Adverse effects of beta-blockade withdrawal in patients with congestive cardiomyopathy.

Fifteen patients with congestive cardiomyopathy who had improved conspicuously on chronic administration of a beta-blocker were studied after withdrawal of the drug. In six patients there was a pronounced deterioration of their clinical condition, and in all of the remaining patients there was a significant decrease in ejection fraction, and signs of compromised diastolic function with pathological apex curves and an increase in third heart sound. All these changes were reversed within a few weeks to a few months after readministration of beta-blocking drugs. This study supports the idea that an aetiological factor in congestive cardiomyopathy may be a pathological response to sympathetic stimulation which could be partly controlled by administration of beta-blocking drugs.     

Incidence of persistent atrial fibrillation and conduction defects in coronary heart disease

Permanent atrial fibrillation and conduction defects (bundle branch block and A-V block, classified according to Blackburn and associates¹⁰) have been studied in a patient series of 916 patients with coronary heart disease.     

Correlations of hemodynamic parameters with plasma catecholamines in patients with congestive cardiomyopathy

Noradrenaline and adrenaline blood levels, as well as central hemodynamics (Swan-Ganz semi-floating balloon-tipped catheter), were measured at rest and during moderate exercise in 8 male patients suffering with idiopathic congestive cardiomyopathy (COCM), and in 12 healthy male control subjects. The stroke volume and the cardiac output in COCM were, on the average, one-half that of the control subjects; adrenaline, noradrenaline, pulmonary capillary wedge pressure, as well as the roentgenographically determined heart volume (at rest) in COCM were, on the average, increased more than twice the control values. The noradrenaline and adrenaline responses in COCM reached at the 25-W exercise level the response of controls at the 150-W level. Direct correlations were observed between the cate-cholamine responses and the capillary wedge pressure as well as the heart volume; inverse correlations existed between the catecholamines and the stroke volume or the cardiac output. The results may be indicative of a causal relationship between the reduced function of the left heart and a compensatorily increased sympathetic activity, but they are not at all conclusive for a definite cause-effect response. The differences in catecholamine levels and the correlations are more significant for noradrenaline during both exercise and rest, whereas for adrenaline significance only occurred during exercise. The noradrenaline and adrenaline levels may serve as indicators (especially in the chronic stage) in the diagnosis of reduced left ventricular function.     

Myocardial asynchrony in patients with postinfarction intraventricular conduction defects

BACKGROUND: Postinfarction intraventricular conduction defects lead to asynchronous activation of the myocardium.Hypothesis: The aim of the current study is to evaluate contraction asynchrony in postinfarction patients with intraventricular conduction defects. METHODS: A total of 158 patients 6 months postmyocardial infarction and 15 healthy subjects underwent echocardiography to evaluate atrioventricular, interventricular, intraventricular asynchrony, and myocardial performance index (MPI). A subgroup of 126 patients had intraventricular conduction defects in ECG, whereas 32 with normal QRS complex served as controls. RESULTS: All patients postmyocardial infarction showed intraventricular asynchrony and markedly higher MPI. Comparing groups with and without intraventricular conduction defects postmyocardial infarction, those with left bundle branch block (BBB) had significantly higher parameters of all asynchrony types; those with right BBB and left posterior hemiblock (LPH) had significantly higher interventricular asynchrony parameters; those with left anterior hemiblock did not show significant differences in asynchrony parameters as compared with subjects without postinfarction conduction defects. CONCLUSIONS: (1) Patients 6 months postmyocardial infarction show intraventricular asynchrony and markedly higher MPI. (2) Postinfarction patients with LBBB have the highest parameters of atrioventricular, interventricular and intraventricular asynchrony as compared with postinfarction patients with other and without conduction defects. (3) In postinfarction patients with RBBB or LPH parameters of interventricular asynchrony are significantly higher as compared with postinfarction patients without intraventricular conduction defects.