Myocardial blood flow in congestive and hypertrophic cardiomyopathy: relationship to peak wall stress and mean velocity of circumferential fiber shortening.

Abstract

SUMMARY Myocardial blood flow/unit mass (MBF) and the determinants of myocardial oxygen consumption were measured in seven control subjects (group I) and 15 patients (pts) with cardiomyopathy (CM), group II (group Ila-congestive CM: 10 pts; group Ilb-hypertrophic CM: 5 pts). In group I left ventricular (LV) MBF was 64±8 (SD) ml/lOg -min; it was significantly lower in Ila (45 ± 15 ml/lOOg. min, P < 0.01) and IIb (39±7 ml/100g min, P < 0.01). However, calculated total LV flow (LV mass X MBF) was increased in the two CM groups. In nine CM pts, LV MBF increased in response to atrial pacing from 41±7 to 63±13 ml/lOOg * min.PATIENTS WITH CARDIOMYOPATHY frequently complain of chest pain suggestive of ischemic heart disease despite the presence of widely patent coronary arteries.' In addition, these patients often manifest varying degrees of myocardial hypertrophy and impaired ventricular performance. The relationship between these abnormalities and myocardial perfusion is largely unknown. There have been only a few studies, each involving small numbers of patients, of the myocardial circulation in cardiomyopathies and these studies have yielded conflicting results.4The first purpose of this study was to measure average left ventricular as well as regional myocardial perfusion at rest in patients with cardiomyopathy and to compare the values obtained with those in a control group of patients with normal coronary arteriograms and normal ventricular performance. For the study, patients with cardiomyopathy were divided into two functional categories, congestive cardiomyopathy and hypertrophic cardiomyopathy, by criteria developed by Goodwin.8 In nine of the cardiomyopathy patients, myocardial blood flow was also measured during right atrial pacing in order to evaluate the circulatory response to an increase in myocardial oxygen consumption.The second purpose of this study was to investigate in man the relationship between myocardial blood flow and three of the major determinants of myocardial oxygen consumption: heart rate, myocardial contractility, and wall stress. '-12 For this purpose, heart rate, mean velocity of circumferential fiber shortening (MVcf), and peak left ventricular (LV) systolic wall stress were measured in the control sub- 484In group Ila, calculated peak wall stress was normal (4.39±0.77 dynes/cm' X 106) but mean velocity of circumferential fiber shortening (MVcf) was significantly reduced (0.53±0.18 vs 1.26±0.12 circum/sec, P < 0.01). In llb, MVcf was normal but peak stress was significantly reduced (2.80±0.75 vs 4.51±1.10 dynes/cm' X 106, P < 0.05). Multiple regression analysis based on all pts yielded, MBF = 16.9 MVcf + 9.30 Stress + 0.26 Heart Rate -26.4, (r = 0.79). The data indicate that MBF is reduced in CM patients and the regression analysis suggests that MBF in these 22 pts with normal coronary arteriograms was determined largely by heart rate, peak stress, and ventricular performance.jects and in the patients with congestive and hypertrophic cardiomyopathy. The aim of this part of the stu...

Increased production of nitric oxide in coronary arteries during congestive heart failure.

“…The present study examined responses to acetylcholine after 2 wk ofexperimental CHF and found that the threshold for relaxation to acetylcholine was decreased significantly in coronary arteries but was unchanged in femoral and renal arteries. Increases in blood flow in canine systemic arteries result in augmented endothelium-dependent relaxations to acetylcholine (26) and studies, while controversial (2,27), have demonstrated increased myocardial blood flow in CHF. A similar mechanism may operate to produce the augmented response to acetylcholine reported in this study.…”

“…Experiments were performed in two groups of mongrel dogs (18)(19)(20)(21)(22)(23)(24)(25)(26)(27) kg) that were fed standard diet and allowed free access to water. Dogs that had not been operated on served as the control group.…”

Global and regional myocardial oxygen consumption and blood flow in severe cardiomyopathy with left bundle branch block

“…Results showed a depressed MBF of 0.45F0.15 [30] and of 0.49F0.17 ml/ min/g [29], a normal flow of 0.78F0.17 ml/min/g [31] and a high normal flow of 1.02F0.21 ml/min/g [21]. This great variability was probably due to the different methods used and different states of the disease.…”

“…Measurements of MBF in nonischemic DCM have been performed with microspheres [29], with 13 N-ammonia [21], or inert gas washout techniques [30,31]. Results showed a depressed MBF of 0.45F0.15 [30] and of 0.49F0.17 ml/ min/g [29], a normal flow of 0.78F0.17 ml/min/g [31] and a high normal flow of 1.02F0.21 ml/min/g [21].…”

Assessment of coronary blood flow in non-ischemic dilated cardiomyopathy with the TIMI frame count method

“…Impairment of coronary flow reserve has been shown in patients with dilated cardiomyopathy (DCM) despite normal epicardial coronary arteries (1)(2)(3)(4)(5). Various methods have been used to measure coronary flow in these patients, including coronary sinus thermodilution (3,6), intracoronary Doppler flow wire (7)(8)(9), position emission tomography (PET) (10,11), and transesophageal echocardiography (12).…”