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In order to compare ibopamine (IBO), a dopamine congener, with isosorbide mononitrate (ISMN) and to study their interaction in effects on the capacitance vasculature in congestive heart failure (CHF), a prospective, randomized, placebo-controlled, double-blind clinical trial was performed in 32 patients with New York Heart Association class II-IV CHF, randomly assigned to receive single oral doses of placebo, 200 mg IBO, 20 mg ISMN, or both IBO and ISMN. After labelling of red cells with 99mTc, changes in regional radioactivity, indicative of changes in blood volume, were recorded using a gamma-camera before and at 30, 60 and 120 min after drug administration. At 30 and 60 min, arterial systolic and pulse pressures were higher with IBO than with ISMN and placebo (for pulse pressure by mean 13.7 mmHg, 95% confidence interval 4.5-23.0 mmHg, at 30 min), probably reflecting an IBO-induced rise in stroke volume at unchanged heart rate and mean arterial pressure. IBO did not change regional radioactivity except for a transient increase of 4.4% (0.5-7.6%) in the thorax at 30 min. This was attenuated by concomitant ISMN treatment since, starting at 30 min, the drug increased radioactivity in the legs, compared with patients not receiving the drug, by 8.0% (95% confidence interval 0.2-15.8%), leading to a fall in thoracic and left ventricular radioactivity at 30 min of 3.4% (0.3-7.0%) and 6.4% (0.8-11.9%), respectively, and a fall of 5.5% (0.5-10.5%) in hepatic radioactivity at 60 min.(ABSTRACT TRUNCATED AT 250 WORDS)

In 14 anesthesized pigs, the effect of E. coli (2 X 10(8)/kg) and volume loading on hemodynamics and right and left ventricular performance were studied. Autologous red cells were labeled in vitro with 99mTC (15-20 mCi). Gated blood pool studies and hemodynamics were performed simultaneously. E. coli infusion resulted in an abrupt increase in pulmonary artery pressure, whereas systemic blood pressure fell gradually. Gated studies showed a transient increase in right ventricular end-diastolic volume (RVEDV) after 1 hour; left ventricular end-diastolic volume (LVEDV) declined gradually during sepsis. During volume loading, RVEDV and LVEDV both increased. As estimated from the altered Frank Starling relation between preload and SW, a depressed performance of both left and right ventricle was found. We conclude that volume expansion in porcine E. coli septic shock results in a uniform increase of left and right preload despite a substantial increase in pulmonary vascular resistance.

The effect of sublingually administered nitroglycerin (0.5 mg) on distribution of blood volume in 16 patients with congestive heart failure (NYHA class II and III), randomly assigned to placebo (N = 8) or nitroglycerin (N = 8) was studied 20 minutes after in vivo labelling of red blood cells with 99m-Tc pertechnetate. Count rates over thorax, abdomen and legs were collected with a large field gamma camera and expressed as percentage changes of baseline value. Changes in count rates, averaged for 5, 10 and 15 minutes after drug administration showed a significant decrease in the nitroglycerin group as compared to the placebo group over the thorax (mean 5%, P less than 0.01) and over the liver (mean 5%, P less than 0.05) and a significant increase over the abdomen (mean 4%, P less than 0.01) and the legs (mean 9%, P less than 0.01). After nitroglycerin, the changes in pulmonary activity were variable and did not differ from the placebo group. These results indicate that nitroglycerin causes a redistribution of blood volume in patients with congestive heart failure. An increase in the vascular capacitance in the abdomen and legs may be responsible for a decrease of blood volume of the thorax and the liver in these patients.