J. David Bristow

Prevalence and etiology of idiopathic dilated cardiomyopathy (summary of a National Heart, Lung, and Blood Institute Workshop)

Idiopathic dilated cardiomyopathy (IDC) is the primary indication for cardiac transplantation, with associated costs of approximately

Long-Term Digitalis Therapy Improves Left Ventricular Function in Heart Failure

177 million per year. Recognizing the economic implications of IDC, the increasing incidence, and the limited information on pathogenesis and prognosis, the National Heart, Lung, and Blood Institute convened a workshop on the Prevalence and Etiology of Idiopathic Dilated Cardiomyopathy on June 13 to 14, 1991. The difficulties of studying the disease were reviewed, including its relatively low prevalence, its potentially pluricausal nature, and the fact that it is often a diagnosis of exclusion. Still, it presents significant challenges to the cardiovascular scientific community, since the mechanism of myocardial damage and related etiologic and prognostic factors are virtually unknown. The development of more reliable measures of immune-mediated damage and noninvasive measures of impaired cardiac function present new research opportunities in this disorder. Standardized diagnostic criteria for use in observational and interventional trials were developed, and priorities for future research were proposed. Population-based registries and nested case-control studies, where feasible, are appropriate study designs for tracking incidence and prevalence, and for identifying risk factors, respectively. Interventional studies should focus on secondary prevention, through modifying immune-mediated damage in clinically evident dilated cardiomyopathy, and through prevention of sudden death in patients with the disorder. Primary prevention trials must await the identification of modifiable risk factors and of appropriate and effective interventions.

The Role of Left Atrial Transport in Aortic and Mitral Stenosis

To clarify the controversy regarding the benefits of long-term oral digoxin in the treatment of heart failure, we evaluated hemodynamics at rest and during exercise in nine patients in sinus rhythm with symptomatic heart failure. Patients were studied during long-term digoxin therapy, after withdrawal of the drug, and six hours after readministration. Upon withdrawal of digoxin, pulmonary capillary-wedge pressure increased from 21 +/- 8 to 29 +/- 10 mm Hg, and cardiac index decreased from 2.4 +/- 0.7 to 2.1 +/- 0.6 liters per minute per square meter of body-surface area, suggesting a deterioration in left ventricular function. In addition, heart rate tended to increase and stroke-work index, stroke-volume index, and radioangiographic ejection fraction decreased. Acute readministration restored the hemodynamic values to those observed during long-term digoxin therapy. The improvement in hemodynamics during long-term digoxin administration was also observed during exercise. This improvement demonstrated the value of long-term oral digoxin therapy in congestive heart failure.

Pulmonary edema in coronary-artery disease without cardiomegaly. Paradox of the stiff heart.

The relationship of left atrial contraction to ventricular filling was studied in 24 patients. Eight patients had aortic stenosis, eight had mitral stenosis, and eight others served as a control group. All had normal sinus rhythm. Cineangiocardiographic volumetric determinations of the left ventricle were done throughout the cardiac cycle, and the rate of left ventricular filling before and during left atrial contraction was calculated.In the group with aortic stenosis 39% of the left ventricular stroke volume entered the ventricle during left atrial contraction; in the group with mitral stenosis 24% was contributed during left atrial contraction, and in the control patients, 26%.The rate of left ventricular filling more than doubled during left atrial contraction in aortic stenosis, while no consistent change in the rate of filling occurred during left atrial contraction in mitral stenosis and in the control group.The character of the resistance to left ventricular filling in aortic stenosis and mitral stenosis is discussed. An important contribution by left atrial contraction to left ventricular performance in aortic stenosis is suggested.

Left Ventricular Wall Motion Assessed by Using Fixed External Reference Systems

ACUTE pulmonary edema usually is accompanied by cardiomegaly unless it is of noncardiac origin, or occurs in special cases of heart failure1 , 2 such as restrictive cardiomyopathy, mitral stenosis,...

Problems in the hemodynamic diagnosis of tricuspid insufficiency

Of two methods utilized to assess ventricular wall motion, one (method A) assumes the left ventricular wall moves symmetrically during contraction toward the approximate geometric center of the left ventricle. The other (method B) assumes the left ventricular wall moves symmetrically toward the base of the heart. Clearly, both methods cannot be correct in all patients. We are presenting a method (R) which utilizes two external markers and the diaphragm as an internal marker to evaluate left ventricular contraction pattern.Of 44 patients studied, the diaphragm moved in four and ventricular wall motion could not be assessed. Fifteen patients had valvular heart disease; six were normal. Findings in method R corresponded to those determined by method B in five of eight patients (63%) with left ventricular hypertrophy and by method A in eight of 13 patients (62%) without left ventricular hypertrophy. This difference was significant (P < 0.05). The remaining 19 patients had coronary artery disease; twelve of them had a previous myocardial infarction. In the latter, method R detected an area of asynergy (akinesis or dyskinesis) at ventriculography in ten of 12 patients (84%). The area of asynergy corresponded to the site of infarction determined by electrocardiogram in all patients. Methods A and B detected asynergy in only five of 12 patients (42%) and six of 12 patients (50%), respectively. Using two fixed external reference points and the diaphragm as an internal marker, a better evaluation of left ventricular wall motion can be obtained.

A study of the normal Frank vectorcardiogram

Abstract The dependability of RVA in the evaluation of TI was studied in 141 patients with congenital or rheumatic disease. In patients over age 10, angiocardiography revealed TI in 13 and was negative in 27. Eight with positive RVA had cardiac operation and TI was confirmed in seven; three not having been operated upon were probably false positives. Six with negative RVA had an operation and no TI was detected. In 20 per cent of 95 younger patients, RVA revealed TI, often believed catheter induced. RA pressure criteria commonly employed in the hemodynamic diagnosis of TI were tested. RA pressure level and contour were analyzed in 27 cases proved negative for TI by RVA and in seven proved positive by operation. An X descent shallower than Y correlated better with atrial fibrillation than with TI; X deeper than Y correlated better with sinus rhythm than with tricuspid competence. RVA can exclude TI but yields false positive studies. RA pressure contour is believed not to have the usually accepted significance.

Left Ventricular Volume Measurements in Man by Thermodilution

Abstract An investigation was performed with spatial vectorcardiographic recording of Frank leads in a group of 72 subjects who were free of cardiovascular disease. Study of the vectorcardiograms included measurement of the angle of the half-area vectors in each planar projection of the QRSsE loop. This parameter provided a narrower range of distribution in the horizontal and sagittal projections than the angle of the maximum QRS vector. Information concerning QRS and T vector magnitudes is presented. The results of this study are compared with the limited information available from application of this lead system to normal subjects, and with published data for the SVEC-III and lead-field methods.

Serial Cardiac Output and Blood Volume Studies Following Cardiac Valve Replacement

A safe, rapid method for estimating left ventricular volume in man during the course of hemodynamic studies should prove helpful in the assessment of cardiac disease and useful in physiological research. It is the purpose of this report to present left ventricular volume measurements in man that were obtained by an indicator dilution method which employs cold as the indicator. This circulatory indicator has been studied by several workers (1-4) and has been used for left ventricular volume determinations in animals previously (5-10). The method employed was adapted from those used by Rapaport and his co-workers for left ventricular volume measurements in the dog (7) and right ventricular studies in man (11).

Ejection fraction response to supine exercise in asymptomatic aortic regurgitation: Relation to simultaneous hemodynamic measurements

The cardiac output and blood volume were measured preoperatively and sequentially during the early postoperative period in 45 patients undergoing cardiac valve replacement. Most patients showed a prompt, highly significant increase in cardiac output. Those with uncorrected valvular disease, even though apparently trivial, had lower cardiac outputs. The blood volume was sharply reduced from the preoperative level in almost every patient. When this was associated with low cardiac output, replacement of the blood volume deficit was usually accompanied by a prompt increase in cardiac output. Failure to respond in this way occurred only in patients with residual valvular lesions or myocardial disease.