Cardiac contractility in noninsulin dependent diabetes mellitus evaluated using the relation between endsystolic wall stress and velocity of circumferential fiber shortening.

Abstract

The relation between left ventricular (LV) endsystolic wall stress (sigma es) and rate-corrected velocity of circumferential fiber shortening (Vcfc), which is independent of heart rate (HR) and loading conditions has previously been used to assess cardiac contractility in insulin dependent diabetes mellitus (IDDM). This study is the first report in which this relation has been utilized with data obtained by echocardiography in addition to the traditional indices, to evaluate the cardiac function in asymptomatic, middle-aged patients with noninsulin dependent diabetes mellitus (NIDDM) at baseline and during dobutamine stimulation. There were 16 NIDDM patients in our study and these patients were classified into 2 groups. Group 1 consisted of 11 patients without microvascular complications. Group 2 consisted of the remaining 5 patients with microvascular complications. Ten age- and sex-matched normal subjects were enrolled as a control group. At baseline, diabetic patients tended to have a faster HR and a greater LV enddiastolic dimension, though these values were not significantly different from the normal subjects. Ejection fraction (EF) in group 1 was significantly higher than that of the normal controls (73 +/- 2% vs 65 +/- 2%, p < 0.005). Mitral inflow pattern was normal (E/A > 1) in the normal subjects (1.11 +/- 0.06), but reversed in group 1 (0.87 +/- 0.07) and group 2 (0.95 +/- 0.12). Isovolumic relaxation time corrected for HR (IVRTc) and the slope of relation between sigma es and Vcfc were similar among the 3 groups. Comparing Vcfc at 50 g/cm2 of sigma es, it tended to increase from the normal subjects (0.883 +/- 0.057 cir/sec) to 0.969 +/- 0.048 in group 1 and 1.034 +/- 0.101 in group 2, though this result was not statistically significant. During dobutamine stimulation, EF increased and IVRTc shortened significantly only in the normal subjects. E/A became normalized in both diabetic groups. The increment in Vcfc representing cardiac reserve of contractility was significantly lower in the diabetics (0.110 +/- 0.040 in group 1 and 0.057 +/- 0.043 in group 2) than in normal subjects (0.244 +/- 0.044). In conclusion, using the index of relation between sigma es and Vcfc, the cardiac contractility of NIDDM was not impaired at baseline, and even had a tendency to increase. However, during dobutamine stimulation, the inadequate reserve of contractility was exposed, especially in those patients who had microvascular complications. These results indicate the importance of controlling diabetes, not only to prevent the development of microvascular complications but also to preserve cardiac function.