Assessment of left ventricular function with M-mode echocardiography in a selected group of diabetic patients

Left Ventricular Systolic Function in a Population Sample of Elderly Men

BACKGROUND: The present study was designed to evaluate the usefulness and discriminatory power of different echocardiographic indices of left ventricular (LV) systolic function in a healthy screening sample of 584 men who were 70 years old. METHODS: Ejection fraction (EF), fractional shortening (FS), stroke index (SI), left ventricular diameter in systole (LVESD), and cardiac index (CI) were evaluated, in addition to LV wall motion score and atrioventricular plane displacement (AVPD). RESULTS: Subjects with hypertension or coronary heart disease (CHD), but not those with diabetes mellitus, showed impairments in EF, FS, LVESD, AVPD, and LV wall motion scores compared with the healthy subjects in the sample (P < 0.01-0.001). SI and CI findings in those with hypertension or CHD were, however, no different from those in the healthy group. The index of LV systolic function that discriminated best between diseased and healthy subjects was LV wall motion score, being correlated with EF, LVESD, and AVPD but only poorly with SI and CI. SI evaluated with use of the Teichholz formula was correlated to LV end-diastolic diameter (r = 0.72, P < 0.0001), whereas the corresponding correlation between SI measured with Doppler (aortic flow) and LVEDD was weak. The difference between the Teichholz and Doppler evaluations of SI was dependent on LV end-diastolic diameter (r = 0.51, P < 0.001) but not on LV systolic function. An index, the systolic two-dimensional index, which takes into account both the longitudinal motion (AVPD) and movement along the short axis (LVESD) during systole, was suggested by the formula AVPD + 5/LVESD. CONCLUSIONS: Impaired LV systolic function was found in both elderly men with hypertension and those with CHD. SI was normal in these groups, however, although overestimated when measured with the Teichholz formula in this population with a large proportion of subjects with LV dilatation. AVPD appears to be applicable in the present population, and a new systolic index consisting of LVESD and AVPD is suggested for the evaluation of LV systolic function in two dimensions.

Cardiomyopathy associated with noninsulin-dependent diabetes

Cardiovascular disease represents the major cause of morbidity and mortality in noninsulin-dependent diabetic patients. While it was once thought that atherosclerotic vascular disease was responsible for all of these adverse effects, recent studies support the notion that one of the major adverse complications of diabetes is the development of a diabetic cardiomyopathy characterized by defects in both diastolic and systolic function. Contributing to the development of the cardiomyopathy is a shift in myosin isozyme content in favor of the least active V3 form. Also defective in the noninsulin-dependent diabetic heart is regulation of calcium homeostasis. While transport of calcium by the sarcolemmal and sarcoplasmic reticular calcium pumps are minimally affected by noninsulin-dependent diabetes, significant impairment occurs in sarcolemmal Na(+)-Ca2+ exchanger activity. This defect limits the ability of of the diabetic heart to extrude calcium, contributing to an elevation in [Ca2+]i. Also promoting the accumulation of calcium by the diabetic cell is a decrease in Na+, K+ ATPase activity, which is known to increase [Ca2+]i secondary to a rise in [Na+]i. In addition, calcium influx via the calcium channel is stimulated. Although the molecular mechanisms underlying these defects are presently unknown, the possibility that they may be related to aberrations in glucose or lipid metabolism are considered. The evidence suggests that classical theories of glucose toxicity, such as excessive polyol production or glycosylation, appear to be insignificant factors in heart. Also insignificant are defects in lipid metabolism leading to accumulation of toxic lipid amphiphiles or triacylglycerol. Rather, the major defects involve membrane changes, such as phosphatidylethanolamine N-methylation and protein phosphorylation, which can be attributed to the state of insulin resistance.

Diabetic heart muscle disease

Diabetic patients may have various abnormalities in left ventricular systolic and diastolic function not attributable to coronary heart disease, hypertension or other known cardiac disease. Although the exact causes of this diabetic heart muscle disease or "diabetic cardiomyopathy" are still incompletely understood, several mechanisms may contribute to it including disturbed myocardial energy metabolism, microvascular changes, structural changes in collagen, increased myocardial fibrosis, and cardiac autonomic neuropathy. Perhaps the most typical feature of diabetic heart muscle disease is an abnormal filling pattern of the left ventricle, suggesting reduced compliance or prolonged relaxation. Left ventricular systolic function is commonly normal at rest in asymptomatic diabetic patients, but it frequently becomes abnormal during exercise. The abnormalities in left ventricular systolic function may be partly reversible along with an improvement of metabolic control of diabetes. It is not known how frequently subclinical abnormalities in left ventricular function in diabetic patients result in clinically manifest heart failure.

Impairment of diastolic function in middle-aged type 1 (insulin-dependent) and type 2 (non-insulin-dependent) diabetic patients free of cardiovascular disease

Left ventricular systolic and diastolic function was studied using systolic time intervals and echocardiography in 19 male and 17 female patients with Type 1 (insulin-dependent) diabetes, 24 male and 15 female patients with Type 2 (non-insulin-dependent) diabetes and 24 male and 24 female control subjects. The subjects for the present study were selected from a population based study in which 117 Type 1 and 510 Type 2 diabetic patients and 649 non-diabetic subjects were originally examined. After exclusions, none of the subjects had any evidence of coronary heart disease, hypertension or other diseases known to affect left ventricular function. There were no consistent differences in systolic time intervals or echocardiographic variables of systolic function between patients with Type 1 diabetes and non-diabetic control subjects; but patients with Type 2 diabetes showed an increased fractional shortening. Female patients with Type 2 diabetes showed an increased left ventricular mass not explicable by hypertension. Isovolumic relaxation period was longer in male (86 +/- 3 ms; mean +/- SEM) and female patients (84 +/- 6 ms) with Type 2 diabetes than in male (76 +/- 3 ms; p less than 0.05) and female (71 +/- 3 ms; p less than 0.05) control subjects. Peak diastolic filling rate was lower in female patients with Type 1 diabetes (12.8 +/- 0.8 cm/s, p less than 0.05) and in male (11.5 +/- 0.8 cm/s; p less than 0.01) and female patients (11.5 +/- 0.6 cm/s; p less than 0.001) with Type 2 diabetes as compared to male (14.4 +/- 0.7 cm/s) and female (14.9 +/- 0.5 cm/s) control subjects.(ABSTRACT TRUNCATED AT 250 WORDS)

Vectorcardiographic evaluation of diabetic cardiomyopathy and of its contributing factors

In order to investigate the prevalence of vectorcardiographic bites, expression of small areas of fibrosis, atrophy or degeneration of the myocardium, we studied, using the vectorcardiograms (VCG) of 101 diabetic patients (35 with insulin-dependent and 66 with non-insulin-dependent diabetes mellitus, aged from 25 to 60 years, without hypertension, coronary artery disease, or intraventricular conduction defects) and 228 normal control subjects, matched for age and sex. The prevalence of bites was 38.6% in diabetic patients and 10.0% in the control group (p less than 0.001). Diabetic patients were also subdivided into groups according to age, sex, metabolic control, risk factors for coronary heart disease, type of diabetes, duration of diabetes and diabetic microangiopathy. No correlation was found between any of the variables investigated nor of a combination of these, and the presence of bites. We conclude that VCG is a sensitive test for cardiac involvement in diabetic patients but that it cannot be used to identify any specific factor able to influence the onset and evolution of this involvement.