No difference in cardiac innervation of diabetic patients with painful and asymptomatic coronary artery disease.

OBJECTIVE: To test the hypothesis that diabetic autonomic neuropathy interfering with sensory impulses from the heart by sympathetic denervation is the major cause of the high prevalence of asymptomatic coronary artery disease (CAD) in diabetic patients. RESEARCH DESIGN AND METHODS: We evaluated cardiac sympathetic innervation in a population-based group of 10 asymptomatic diabetic patients with angiographically proven CAD and in an age- and sex-matched group of 10 diabetic patients with symptomatic CAD using [123I]metaiodobenzylguanide (MIBG) scintigraphy. Exercise electrocardiography and myocardial perfusion imaging by 201Tl were used to detect myocardial ischemia, and standard cardiovascular tests were used to diagnose autonomic nervous dysfunction. RESULTS: Thallium scintigraphy revealed perfusion defects in all 10 symptomatic patients and in 9 of the asymptomatic patients. MIBG accumulation defects were found in all cases with painless and with painful disease. In the asymptomatic group, the denervation area exceeded the ischemic area in six cases and areas with total MIBG accumulation defects were seen in four cases. In one case, the MIBG defect was not in the ischemic region. In the symptomatic group, the denervation area exceeded the area of the ischemic region in all cases and areas of total denervation were seen in six cases. The autonomic nervous function tests were abnormal in two asymptomatic and three symptomatic patients with CAD. CONCLUSIONS: Cardiac sympathetic denervation is common in both patients with painful CAD and patients with asymptomatic CAD regardless of diabetic autonomic neuropathy. This finding supports the view that sympathetic innervation of the heart is highly sensitive to ischemia and this profound effect of ischemia masks the potential effects of autonomic neuropathy on sympathetic innervation. Mechanisms leading to the lack of ischemic pain in diabetic patients with CAD are complex and are not solely explained by autonomic neuropathy.

Prevalence and significance of gallium-67 uptake in the heart after open-heart surgery.

Radioactive gallium-67 (Ga-67) has been shown to accumulate within areas of pericardial inflammation. The present study estimated prospectively the prevalence and clinical significance of Ga-67 uptake in the heart in 62 patients 10 to 16 days after open-heart surgery. Of 62 patients studied, markedly diffuse Ga-67 uptake was detected in 21 (34%) and focal or mild diffuse uptake in 23 (37%). Results were negative in 18 (29%). Nine patients with a negative scan result (50%) had received corticosteroid therapy before imaging, whereas only 2 patients with a positive scan result (5%) were receiving steroids. The erythrocyte sedimentation rate and C-reactive protein level were both higher in patients with Ga-67 uptake compared with those with a negative scan result (p less than 0.01 in both). No other clinical, echocardiographic or electrocardiographic indicators of postpericardiotomy syndrome were related to Ga-67 uptake. No patient developed cardiac tamponade or constrictive pericarditis during the 12-week follow-up and the Ga-67 scan results did not predict the occlusion of coronary artery bypass grafts. Thus, pericardial inflammation manifested as Ga-67 uptake is a common finding after open-heart surgery and appears to be a benign condition.

Early cardiac changes related to radiation therapy.

To investigate the incidence and severity of possible radiation-induced cardiac changes, 21 women without heart disease were investigated serially by echocardiography and by measuring systolic time intervals before and up to 6 months after postoperative radiation therapy because of breast cancer. Radiation was associated with a decrease in fractional systolic shortening of the left ventricular (LV) minor-axis diameter, from 0.35 +/- 0.05 to 0.32 +/- 0.06 (p less than 0.005), and in the systolic blood pressure/end-systolic diameter ratio, from 4.4 +/- 1.2 to 3.9 +/- 0.9 mm Hg/mm (p less than 0.005). The mitral E point-septal separation increased, from 2.8 +/- 1.5 to 4.2 +/- 2.5 mm (p less than 0.005). The preejection period/LV ejection time ratio of systolic time intervals increased, but only the decrease within 6 months after therapy was significant (p less than 0.005). All these changes reflect slight transient depression of LV function, which became normalized within 6 months after therapy. Up to 6 months after therapy, a slight pericardial effusion was found in 33% of the patients. Hence, conventional radiation therapy appeared to cause an acute transient and usually symptomless decrease in LV function, and later, slight pericardial effusion in one-third of the patients.

Left ventricular response to isometric exercise and its value in predicting the change in ventricular function after mitral valve replacement for mitral regurgitation.

Reduced left ventricular (LV) afterload and its effect on the resting ejection fraction may lead to overestimation of LV function in mitral regurgitation (MR). To evaluate LV function during increased afterload of the heart, an isometric handgrip test was performed during cardiac catheterization in 15 patients with mitral regurgitation (MR group) and in 9 normal subjects (normal group). Twelve months after successful mitral valve replacement (MVR) the patients were recatheterized, and the value of preoperative stress testing in predicting the change in resting ventricular function after surgery was estimated. Isometric exercise caused an increase in endsystolic wall stress, a measure of ventricular afterload, in both the MR group and the control group (p less than 0.001). The ejection fraction remained unchanged in the control group, but decreased from 0.58 +/- 0.08 to 0.53 +/- 0.08 in the MR group (p less than 0.001). After MVR, end-systolic wall stress increased significant (p less than 0.001) and the ejection fraction decreased from 0.58 +/- 0.05 to 0.51 +/- 0.1 (p less than 0.05). A positive correlation existed between the change in the ejection fraction during preoperative stress testing and the change in the resting ejection fraction after MVR (r = 0.65, p less than 0.01). In 8 patients whose resting ejection fraction was within normal limits (greater than 0.55) preoperatively, the ejection fraction was depressed (less than 0.55) 1 year after surgery. In all but 1 of these patients the isometric exercise revealed the reduced ventricular response to afterload stress preoperatively (decrease of the ejection fraction greater than 0.03 during exercise). Therefore, the isometric exercise-induced change in LV function appears to predict the influence of MVR on LV function.

The influence of heart rate, age, blood pressure, obesity, and work on systolic and diastolic time intervals.

Systolic and diastolic time intervals were measured in 655 men who did not have coronary or hypertensive heart disease. The correlation between systolic and diastolic intervals (STI) and the heart rate, age, height, weight, weight/height index, blood pressure and work heaviness were calculated using multiple stepwise regression analysis. There was a significant correlation between heart rate and the majority of STI. Also there was a significant influence of systolic and diastolic blood pressure and age on the ejection variables (QS2, LVET, S1S2). The PEP and ICT were influenced by heart rate, and systolic and diastolic blood pressure. The PEP/LVET ratio was dependent on diastolic and systolic blood pressure. The height of the A wave of apex cardiogram was significantly dependent on diastolic and systolic blood pressure, obesity, heart rate, and age. The IRT was dependent on heart rate, obesity, and height. When interpreting systolic time intervals one must use systolic time interval indices which are calculated by using the effect of heart rate on them, but in some cases the effect of other factors must be taken into account because blood pressure, age, and obesity also have a significant physiological effect on the STI values.