The effect of venous occlusion with tourniquets on peripheral blood pooling and ventricular function.

Rotating tourniquets were once part of the traditional treatment of acute pulmonary edema. Their effectiveness has been questioned and vasodilator therapy has replaced them, but early favorable results suggested that they may play a beneficial role. A radioisotope technique was used to evaluate blood volume increments in the leg after venous occlusion at 60 mm Hg in 26 patients with left ventricular dysfunction following myocardial infarction. Mean radionuclide counts (reflecting the blood volume distal to the occlusion) increased from the preocclusion value. Thus, satisfactory trapping of blood is achieved. However, mean left ventricular ejection fraction (EF) decreased slightly but significantly and this decrease in EF was observed in 18 of 26 patients. Left ventricular end-diastolic and end-systolic volume equivalents tended to decrease slightly but not in all patients. Mean stroke volume and cardiac output equivalents were reduced by 14 percent while peripheral resistance increased significantly. The present study thus fails to support the hypothesis that preload reduction by tourniquets improves left ventricular function; the exact opposite effect may occur because of increased afterload.

Effects of the dipyridamole test on left ventricular function in coronary artery disease.

The dipyridamole stress test is used with thallium-201 to detect areas of inhomogeneity of blood flow that point to coronary artery disease (CAD). It is unclear whether dipyridamole produces inhomogeneous perfusion only or whether it actually decreases net flow in the obstructed vessels and produces true ischemia. It is also unclear what effect dipyridamole has on global and segmental left ventricular function. Therefore, ejection fraction, segmental wall motion and ventricular volume equivalents were measured before and after dipyridamole in 113 patients and 32 normal subjects. Ejection fraction responded in an abnormal fashion in 98 patients (87%), decreasing from 49 +/- 11% to 43 +/- 13% (p less than 0.0001), whereas it increased in 29 normal subjects (90%) from 57 +/- 6% to 64 +/- 10% (p less than 0.0001). Wall motion worsened distinctly in 75 patients (66%), and pressure/volume ratio deteriorated in 72%. The effect of dipyridamole lasted between 10 and 25 minutes, but was promptly reversed by aminophylline. These findings indicate that dipyridamole generally induces true ischemia in CAD. Furthermore, the degree of dysfunction is related to the angiographically assessed severity of CAD. The shortness of breath (seen in 10% of patients) may be partially explained by the findings, and it seems advisable to give aminophylline to every patient in order to promptly correct left ventricular dysfunction.

[Effect of tourniquet occlusion on peripheral blood pooling and ventricular function].

Rotating tourniquets are traditionally part of the treatment of acute pulmonary edema. However, their effectiveness has been questioned. A radioisotope technique was therefore used to evaluate directly the increments in the blood volume of the leg after venous occlusion using a pressure of 60 mmHg in 26 patients with left ventricular (LV) dysfunction following myocardial infarction. The increment in mean radionuclide count at serial 15-second intervals (reflecting the blood volume in the leg distal to the occlusion) increased significantly from the pre-occlusion value by 46 +/- 26% (p less than 0.0005). Thus satisfactory trapping of blood is achieved even in LV failure. However, mean ejection fraction decreased slightly but significantly from 0.23 +/- 0.10 to 0.21 +/- 0.10 (p less than 0.05), a decrease observed in 18 of the 26 patients. LV end-diastolic and end-systolic volume equivalents tended to decrease slightly, but not in all patients. Mean stroke volume and cardiac output equivalents were reduced by 14% (p less than 0.0005), while calculated peripheral resistance increased significantly. The present study fails to support the hypothesis that preload reduction by tourniquets improves LV function.

Prolonged hemodynamic effect of a slow-release nitroglycerin ointment.

Nitroglycerin (NTG) ointment has been shown to be effective in the treatment of angina pectoris and congestive heart failure. Its duration of action is usually 4 to 6 hours. This study presents data that show that a new slow-release NTG ointment produces hemodynamic improvement over at least 24 hours. Twenty patients with coronary artery disease were tested with serial gated equilibrium radionuclide ventriculography before and at various stages of continuous, once-a-day use of slow-release NTG ointment and 4 days after cessation of therapy. NTG ointment significantly (p less than 0.005) decreased left ventricular end-diastolic and end-systolic volumes both at rest (23% and 33%) and during handgrip exercise (22% and 32%) when examined after continuous usage of at least 24 hours. Ejection fraction increased 21% at rest, from 0.42 +/- 0.15 to 0.51 +/- -0.18, p less than 0.0005). The ratio of peak systolic pressure to end-systolic volume increased 85% at rest (p less than 0.05) and 54% during exercise (p less than 0.01). All values had returned to baseline 4 days after cessation of treatment. Thus, slow-release NTG ointment may be useful in the treatment of angina pectoris and congestive heart failure on a once-a-day basis.

The early recognition of right ventricular infarction: diagnostic accuracy of the electrocardiographic V4R lead.

The sensitivity and specificity of ST-segment elevation in the right precordial lead V4R as an early indicator of right ventricular infarction were examined in a consecutive series of 110 patients admitted for acute inferior myocardial infarction. The sensitivity was 82.7%, the specificity 76.9% and the positive predictive value 70% in 58 patients with right ventricular infarction documented by autopsy or a combination of radionuclide ventriculography and one or more of the following tests: echocardiography, technetium-99m pyrophosphate scintigraphy and hemodynamic monitoring. The negative predictive value was 87.7%. Because of its simplicity and its high sensitivity and specificity, recording of V4R should be an intrinsic part of the early evaluation and electrocardiographic examination of acute inferior wall infarction.

The acute hemodynamic effects of intravenous verapamil in coronary artery disease. Assessment by equilibrium-gated radionuclide ventriculography.

The acute hemodynamic effects of an i.v. bolus of verapamil, 0.1 mg/kg or 0.06-0.075 mg/kg, were examined by serial radionuclide studies in 46 patients with coronary artery disease. In 20 patients with ejection fractions (EFs) greater than 35% (group 1A), verapamil, 0.1 mg/kg given over 1-11/2 minutes, had a biphasic effect: first, a transient decrease in EF accompanied by increased left ventricular (LV) volumes and cardiac output equivalents; then, an overshoot of EF to values above control, accompanied by a decrease in peripheral vascular resistance and a drastic decrease in LV volumes, while cardiac output equivalent remained slightly elevated. In eight patients with EFs less than 35% (group 1B), only the first effect on EF was noted. In 10 patients with EFs greater than 35% (group 2), verapamil, 0.06-0.075 mg/kg, exerted qualitatively similar but milder effects on hemodynamic function. Finally, verapamil, 0.1 mg/kg given more slowly, over 2-21/2 minutes, produced no significant changes in EF or LV volumes in another eight patients (group 3). The acute effects of verapamil are thus both time-related and dose-dependent. They are also related to the baseline functional reserve of the left ventricle. This study documents that verapamil exerts a depressant effect on LV function. However, the transient nature of this depression and the quick recovery to normal or above-normal values indicate that verapamil, in the doses used in this study, is safe to use intravenously in patients with coronary artery disease.