The hemodynamics and cardiac metabolism in cardiomyopathies

Dysfunction of the ADP/ATP carrier as a causative factor for the disturbance of the myocardial energy metabolism in dilated cardiomyopathy

The adenine nucleotide translocator (ADP/ATP carrier) plays a key role in nucleotide transport across the mitochondrial membrane. The quantity and function of this transport protein were investigated in myocardium from hearts with endstage failing dilated and ischemic cardiomyopathy, and were compared to measurements in nonfailing myocardium. In addition, lactate dehydrogenase (LDH) isoenzymes were determined. The concentration of the ADP/ATP carrier was significantly increased by 48% in myocardium from dilated cardiomyopathic hearts compared to control myocardium. The concentration of the carrier in explanted hearts with ischemic cardiomyopathy did not differ from values in the normal human hearts. Analysis of carrier function revealed similar nucleotide exchange rates in control hearts and hearts with ischemic cardiomyopathy, whereas carrier function was reduced in most hearts with dilated cardiomyopathy. Compared to control hearts, in hearts with dilated cardiomyopathy and decreased nucleotide exchange rate, the carrier content was significantly higher, whereas the carrier content was only slightly increased compared to control in cardiomyopathy hearts with unchanged transport activity. Compared to hearts, in dilated cardiomyopathy there was a significant increase in LDH5 and a decrease in LDH1 isoforms, indicating more anaerobic metabolism in failing dilated cardiomyopathic hearts. In summary, in hearts with dilated cardiomyopathy disturbed function of the ADP/ATP-carrier may result in altered myocardial energy metabolism and, thus, may be the cause of impaired myocardial function.

Effect on the myocardial energy metabolism of angiotensin-converting enzyme inhibition in chronic heart failure

There is substantial evidence that the failing heart is in an energy-depleted state. The imbalance between myocardial oxygen supply and demand might be the cause for adaptive metabolic changes seen in patients with severe chronic heart failure. By analyzing the lactate dehydrogenase (LDH) isoenzyme pattern, an increase of LDH5 and a decrease of LDH1 was seen in myocardium from patients with chronic heart failure. Additionally, the concentration of the adenosine diphosphate (ADP)/adenosine triphosphate (ATP) carrier was significantly elevated. After treatment with the angiotensin-converting enzyme inhibitor enalapril in 33 patients with chronic heart failure, LDH1 increased from 38.7 +/- 6.7 to 42.3 +/- 5.5 (p less than 0.005), paralleled by a decrease in LDH5 from 20.8 +/- 7.0 to 15.8 +/- 4.7 (p less than 0.001). The ADP/ATP carrier concentration also decreased significantly within the normal range. There was a good correlation between the hemodynamic data and the LDH isoenzyme pattern. The shift of the LDH isoenzyme pattern and the decrease of the ADP/ATP concentration can be taken as an indication for an improvement of the myocardial energy balance in chronic heart failure with angiotensin-converting enzyme inhibitor therapy.

Abnormal coronary hemodynamics and myocardial energetics in patients with chronic heart failure caused by ischemic heart disease and dilated cardiomyopathy

Coronary sinus blood flow, transmyocardial oxygen extraction, myocardial oxygen consumption, and transmyocardial lactate extraction were determined, along with systemic hemodynamics, in 34 patients with chronic stable angina without heart failure (group 1), in 66 patients with heart failure associated with coronary artery disease (group 2), and in 28 patients with heart failure caused by dilated cardiomyopathy without coronary artery disease (group 3). Compared with group 1 patients, in patients with heart failure in groups 2 and 3, resting coronary sinus blood flow was 30% and 24% higher, respectively (p less than 0.05), myocardial oxygen consumption was 25% higher (p less than 0.01), and coronary sinus oxygen content was 33% lower (p less than 0.01). The rate-pressure product was not different between the three groups. In eight patients with heart failure (five in group 2 and three in group 3), myocardial lactate production was observed without angina. Thus in patients with chronic heart failure resulting from either chronic coronary artery disease or dilated cardiomyopathy, resting coronary blood flow and myocardial oxygen consumption tend to increase probably because of an increase in myocardial oxygen requirements. Silent myocardial ischemia may also occur in both the presence and absence of coronary artery disease in patients with chronic heart failure. The abnormal coronary hemodynamics and myocardial metabolic function may play a role in causing progressive deterioration in cardiac function in dilated cardiomyopathy.

Coronary dilatory capacity in idiopathic dilated cardiomyopathy: analysis of 16 patients

Hemodynamic function and overall coronary blood flow (argon technique) were measured in 16 patients with idiopathic dilated cardiomyopathy (IDC) and in 12 patients without detectable heart disease (control subjects) referred for precordial pain. In patients with IDC, coronary blood flow was normal at rest (78 +/- 17 ml/100 g-min versus 78 +/- 9 in control subjects). During maximal inducible coronary vasodilation (dipyridamole, 0.5 mg/kg), coronary blood flow was significantly reduced (142 +/- 38 ml/100 g.min versus 301 +/- 64 in control subjects; p less than 0.001). Consequently, obtainable minimal coronary resistance was increased in IDC (0.54 +/- 0.20 mm Hg/ml/100 g.min versus 0.23 +/- 0.04 in control subjects; p less than 0.001). In patients with IDC, left ventricular (LV) end-diastolic pressure was significantly increased (19 +/- 11 mm Hg versus 6 +/- 3 in control subjects; p less than 0.005), and the LV ejection fraction was diminished (36 +/- 11% versus 72 +/- 3% in control subjects; p less than 0.001). In patients with IDC, LV end-diastolic pressure correlated significantly with the obtained minimal coronary resistance after application of dipyridamole (r = 0.85; p less than 0.001). LV catheter biopsy specimens revealed no alterations in myocardial microvasculature. Thus, coronary dilatory capacity is impaired in patients with IDC, due partially to an increase in extravascular component of coronary resistance.

Thallium-201 myocardial scintigraphy: fractional uptake by the myocardium at rest and during exercise in patients with coronary artery disease and hypertrophic cardiomyopathy

Fractional myocardial uptake of thallium-201 was estimated by routine scintigraphic evaluation at rest and during exercise in 10 control subjects, 15 patients with coronary artery disease (CAD) and 12 patients with hypertrophic cardiomyopathy (HCM). Fractional myocardial uptake of the total dose administered at rest was 3.59 +/- 0.98% in the controls, 4.43 +/- 1.17% in patients with CAD and 5.68 +/- 1.29% in patients with HCM, and uptake during exercise was 5.07 +/- 1.23% in the controls, 4.67 +/- 1.04% in the CAD group and 7.50 +/- 1.68% in the HCM group. The value in the HCM group was significantly higher than in the controls (P < 0.001 at rest) or in the CAD group (P < 0.02 at rest). A percentage increment of fractional uptake during exercise was significantly smaller in the CAD group than in the controls or the HCM group (P < 0.01). Thus, assessment of the fractional uptake appears to be a valuable adjunct to myocardial imaging when attempting a clinical assessment of CAD or HCM.

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

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 IIa-congestive CM: 10 pts; group IIb-hypertrophic CM: 5 pts). In group I left ventricular (LV) MBF was 64 +/- 8 (SD) ml/100g-min; it was significantly lower in IIa (45 +/- 15 ml/100g-min, P less than 0.01) and IIb (39 +/- 7 ml/100g-min, P less than 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/100g-min. In group IIa, calculated peak wall stress was normal (4.39 +/hortening (MVcf) was significantly reduced (0.53 +/- 0;18 vs 1.26 +/- 0.12 circum/sec, P less than 0.01). In IIb, MVcf was normal but peak stress was significantly reduced (2.80 +/- 0.75 vs 4.51 +/- 1.10 dynes/cm2 X 10(5), P less than 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.

Electrocardiogram in alcoholism and accompanying physical disease

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The cardiomyopathy of progressive muscular dystrophy

A prospective study was undertaken in order to examine the histories, physical signs, phonocardiograms, electrocardiograms, vectorcardiograms, X-rays, serum enzymes, pulmonary ventilatory findings, and hemodynamics in a group of 55 patients selected solely on the basis of one of the major types of progressive muscular dystrophy (table 9). The classification included: (1) the classic Duchenne type, (2) the limb girdle type, (3) the facioscapulohumeral type, and (4) a group of patients in whom clinical distinction between benign Duchenne dystrophy and limb girdle dystrophy with pseudohypertrophy could not be made. No patient had recognized heart disease prior to selection. Follow-up periods ranged from a few months to 5 years. The pertinent literature was extensively reviewed.

In all groups clinical evidence of heart disease had to be interpreted in the context of the influence of the somatic musculoskeletal defects on "cardiac" symptoms, cardiovascular physical signs, and radiological appearance of the heart. On the other hand, convincing evidence of intrinsic heart disease-subtle to overt-was found in each of the major categories of progressive muscular dystrophy. Detection of cardiomyopathy was simplest and most frequent in the classic Duchenne group because of the highly characteristic features of the scalar electrocardiogram which might direct attention to the systemic myopathy prior to its clinical recognition. However, the presence of heart disease in patients with forms of dystrophy other than the classic Duchenne deserves particular emphasis. Evidence of cardiomyopathy in these latter forms varied from subtle quadruple gallop rhythms in the limb girdle and facioscapulohumeral groups to cardiomyopathic death in the benign Duchenne and limb girdle-pseudohypertrophic group.

Currently available information on the heart in muscular dystrophy has as a rule depended upon retrospective studies, upon reviews of published reports of incompletely classified cases, upon discussions of individual cardiovascular features, or upon observations of individual types of dystrophy. The present prospective study was undertaken to obviate some of these shortcomings. Comprehensive assessment of a large and carefully classified group of dystrophic subjects has provided additional information regarding the clinical spectrum of dystrophic cardiomyopathy.