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D Kravetz

Publications and source records attributed to D Kravetz.

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Nitroglycerin improves the hemodynamic response to vasopressin in portal hypertension.

This study was designed to investigate whether the addition of nitroglycerin to vasopressin infusion could avoid the deleterious systemic effects of vasopressin while maintaining or enhancing the therapeutic benefits of portal pressure reduction. The effect of nitroglycerin on splanchnic and systemic hemodynamics was studied in cirrhotic patients and portal hypertensive dogs receiving i.v. vasopressin. During i.v vasopressin infusion (0.4 units per min), the cardiac output decreased in patients by 14% from 7.6 +/- 0.9 (mean +/- S.E.) to 6.5 +/- 0.7 liters per min, p less than 0.01, the mean arterial pressure increased 21% from 87 +/- 2 to 105 +/- 4, p less than 0.01, and the heart rate decreased 11% from 79 +/- 3 to 71 +/- 3, p less than 0.01. The administration of sublingual nitroglycerin (0.4 mg) returned all the systemic hemodynamic parameters to baseline values. In dogs, vasopressin infusion significantly reduced portal pressure and flow while increasing portal venous resistance. Nitroglycerin when added to the vasopressin infusion reduced portal venous resistance and further decreased portal pressure in dogs. In patients, vasopressin reduced the hepatic blood flow (44%), wedged hepatic venous pressure (11%), and the gradient between wedged and free hepatic venous pressures (23%). Nitroglycerin administration caused a further reduction of the wedged hepatic venous pressure (23.6 +/- 2.3 to 21.1 +/- 2.0, 11%, p less than 0.01). There was a small but not significant further decline (7%) in the hepatic venous pressure gradient. These results provide evidence that the addition of nitroglycerin to an i.v. infusion of vasopressin reversed the detrimental effects of vasopressin while preserving the beneficial effects.

Animals↗

Splanchnic and hepatic metabolism of somatostatin: a study in cirrhotic patients with a portacaval shunt.

Experimental data suggest that somatostatin is metabolized by both liver and kidneys. Results in humans are conflicting. By studying a group of cirrhotic patients with surgically induced end-to-side portacaval shunts, basally and during a somatostatin infusion, we have been able to analyze separately the hepatic and splanchnic metabolism of this peptide. After catheterization, samples were obtained from the pulmonary artery, portal and hepatic veins. Basal pulmonary artery immunoreactive somatostatin (IRS) was significantly higher (p less than 0.001) in the cirrhotic patients (96 +/- 11 pg per ml) than in a sex- and age-matched control group (31.4 +/- 5.8 pg per ml). During the infusion of exogenous somatostatin, IRS values were higher in arterial (12,269 +/- 1,198 pg per ml) than in hepatic venous blood (7,648 +/- 1,234 pg per ml), indicating hepatic extraction of the peptide; but there was also a substantial splanchnic extraction demonstrated by higher arterial (12,269 +/- 1,532 pg per ml) than portal values (6,754 +/- 1,040 pg per ml) of IRS. During the somatostatin infusion, at very high circulation IRS levels, the liver was able to extract 38% of the peptide. This suggests that the high basal IRS levels found in liver cirrhosis are not likely to be due to hepatic failure. Possible mechanisms may involve increased somatostatin secretion, predominance of high molecular weight moieties of IRS which may not be as effectively removed by the liver, and/or portal-systemic shunting.

Adult↗

Comparison of intravenous somatostatin and vasopressin infusions in treatment of acute variceal hemorrhage.

The present trial compared the effectiveness and complications of intravenous somatostatin and vasopressin in treatment of variceal bleeding. Sixty-one cirrhotic patients with endoscopically proven active variceal bleeding were included. Both drugs were given as continuous intravenous infusions for 48 hr. Thirty patients received somatostatin (250 micrograms per hr after a bolus of 50 micrograms) and 31 vasopressin (0.4 units per min). Initial control of bleeding was achieved in 26 (87%) patients receiving somatostatin and in 23 (74%) of those treated with vasopressin. However, 10 patients [not significant statistically] in the somatostatin group and 5 in the vasopressin group rebled during treatment, after a mean of 15 and 20 hr, respectively. Therefore, complete control of bleeding during the 48 hr of therapy was achieved in 16 (53%) patients treated with somatostatin and in 18 (58%) of those receiving vasopressin. Mortality during hospitalization was similar in both groups (somatostatin 47%, vasopressin 45%). Differences were observed in complications associated with each therapy. Vasopressin produced major complications in 8 patients (left ventricular failure in 4 and severe abdominal pain requiring drug withdrawal in 4), and minor complications in 14; somatostatin infusion produced minor complications in 3 patients (p less than 0.01). In addition, the serum sodium concentration was significantly reduced by vasopressin (from 134.3 +/- 1.6 to 128.3 +/- 1.4 mEq per liter, p less than 0.001) but not by somatostatin (134.6 +/- 1.1 vs. 133.2 +/- 1.1 mEq per liter). This study shows that somatostatin is as effective as vasopressin in controlling variceal hemorrhage, but has a much lower rate of complications.

Esophageal and Gastric Varices↗

Effects of propranolol on azygos venous blood flow and hepatic and systemic hemodynamics in cirrhosis.

The effects of propranolol on blood flow through gastroesophageal collaterals and on systemic and hepatic hemodynamics were investigated in 23 cirrhotic patients with portal hypertension. Gastroesophageal collateral blood flow was evaluated by the measurement of azygos venous blood flow by continuous thermal dilution. Azygos venous blood flow was markedly increased in these patients (544 +/- 48 ml per min, as compared with 132 +/- 18 ml per min in subjects without portal hypertension (p less than 0.001). Propranolol at doses achieving effective beta-blockage (83 +/- 5 mg) (mean +/- S.E.M.) markedly reduced azygos venous blood flow (to 354 +/- 34 ml per min, p less than 0.001). Reduction of azygos venous blood flow (-34.2 +/- 3.6%) was significantly greater (p less than 0.01) than reductions in cardiac output (-22.6 +/- 1.9%), hepatic venous pressure gradient (-11.5 +/- 2.4%) and hepatic blood flow (-13.4 +/- 7.4%). The hemodynamic effects of propranolol were not related to plasma norepinephrine levels. Reduction of gastroesophageal collateral blood flow may be the mechanism by which oral propranolol therapy reduces the risk of repeated episodes of variceal bleeding in cirrhotic patients with portal hypertension.

Azygos Vein↗

Noninvasive measurement of the pressure of esophageal varices using an endoscopic gauge: comparison with measurements by variceal puncture in patients undergoing endoscopic sclerotherapy.

Measurements of variceal pressure with a noninvasive endoscopic pressure gauge and by direct variceal puncture were performed in 20 cirrhotic patients with portal hypertension in the course of the first session of therapeutic sclerotherapy following an episode of variceal bleeding. Endoscopic gauge measurements of the pressure of esophageal varices gave similar values (15.5 +/- 2.7 mm Hg) than measurements by variceal puncture (15.4 +/- 2.4 mm Hg; not statistically significant), and there was a highly significant linear correlation between both measurements (r = 0.9, p less than 0.001). Azygos blood flow, that was markedly increased in these patients (852 +/- 399 ml per min), was directly related to variceal pressure (r = 0.73, p less than 0.01). Variceal pressure was significantly lower than portal pressure (18.8 +/- 5.0 mm Hg) (p less than 0.05), indicating that measurements of variceal pressure cannot substitute measurements of portal pressure. The study demonstrates that the noninvasive endoscopic gauge technique allows an accurate estimation of variceal pressure in patients with portal hypertension. This technique may provide additional useful information in the evaluation of portal hypertension as well as on the mechanism of variceal bleeding.

Adult↗

Effects of metoclopramide and domperidone on azygos venous blood flow in patients with cirrhosis and portal hypertension.

The effects of pharmacological manipulation of the lower esophageal sphincter pressure on the esophageal circulation in patients with cirrhosis and portal hypertension were investigated in 33 patients by measuring the azygos venous blood flow, which is an index of blood flow through esophageal varices and periesophageal collaterals draining into the azygos venous system. Measurements were performed in baseline conditions and after the blind administration of metoclopramide (20 mg i.v.) (12 patients), domperidone (10 mg i.v.) (12 patients) and placebo (9 patients). Both metoclopramide and domperidone caused a significant reduction of azygos blood flow, that decreased by 11.5% (p less than 0.01) and 15.6% (p less than 0.02) respectively, while no change was observed in patients receiving placebo (+1.4%, not statistically significant). Reduction of azygos blood flow represents a selective effect of metoclopramide and domperidone on the esophageal circulation, since portal pressure, hepatic blood flow, cardiac output, heart rate and arterial blood pressure were unchanged by the administration of metoclopramide, domperidone or placebo. These results indicate that the administration of drugs that increase the lower esophageal sphincter pressure may reduce the inflow of blood into the esophageal varices in cirrhotic patients with portal hypertension.

Azygos Vein↗

Effects of vasopressin on the intravariceal pressure in patients with cirrhosis: comparison with the effects on portal pressure.

The present study investigated to what extent measurements of wedged and free hepatic venous pressures adequately reflect the effects of vasopressin at the esophageal varices in patients with cirrhosis. Eleven patients undergoing therapeutic sclerotherapy were studied by measuring wedged hepatic venous pressure, intravariceal pressure, free hepatic venous pressure, superior vena cava pressure and the intravascular pressure gradients wedged hepatic venous pressure-free hepatic venous pressure and intravariceal pressure-superior vena cava pressure, prior to and after vasopressin injection (1 IU, iv). Vasopressin caused a significant reduction in intravariceal pressure (from 22.5 +/- 9.4 to 19.2 +/- 8.4 mm Hg, p less than 0.001). Measurement of wedged hepatic venous pressure and free hepatic venous pressure closely reflected the reduction in variceal pressure. Thus, wedged hepatic venous pressure decreased by 16 +/- 11%, which is close to the 14 +/- 7% change in intravariceal pressure, and the 23 +/- 12% fall in the pressure gradient wedged hepatic venous pressure-free hepatic venous pressure was mirrored by the 26 +/- 10% change in intravariceal pressure-superior vena cava pressure. These pressure gradients decreased more than the absolute pressures (intravariceal pressure and wedged hepatic venous pressure) due to concomitant increases in superior vena cava pressure (1.9 +/- 1.9 mm Hg) and free hepatic venous pressure (0.6 +/- 1.9 mm Hg).(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗

[Enzyme induction].

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Animals↗