Systemic and pulmonary hemodynamics in patients with extrahepatic portal vein obstruction is similar to compensated cirrhotic patients

Abstract

Background: Patients with cirrhosis and portal hypertension exhibit a hyperdynamic circulation manifesting as increased cardiac output, heart rate and plasma volume; and decreased arterial blood pressure, systemic vascular resistance, and pulmonary vascular resistance. It is believed that these changes are related to both hepatocellular dysfunction and portal hypertension. However, the role of portal hypertension per se in producing these changes in circulation has not been clear. Extrahepatic portal vein obstruction (EHPVO), a vascular disorder of the liver characterized by cavernomatous transformation of the main portal vein, is an excellent model to study the role of portal hypertension per se in producing these changes because there is no hepatic dysfunction in EHPVO. The main aim of our study was, therefore, to evaluate alterations of systemic and pulmonary vascular systems in patients with EHPVO and compare them with patients with compensated cirrhosis. Patients and methods: Consecutive patients of EHPVO, 15 years or older, and past variceal bleeders were studied. For comparison, consecutive patients with compensated cirrhosis and history of variceal bleed, matched for variceal status, and body surface area were included. The hemodynamic studies included the measurements of cardiac index (by Fick's oxygen method), and systemic and pulmonary vascular resistance indices. Results: Fifteen patients of EHPVO and same number of controls (compensated cirrhotics) were included in the study. The baseline parameters in the two groups were comparable. Both EHPVO patients and cirrhotics had similar values in all the measured systemic and pulmonary hemodynamic parameters. The median (range) cardiac index in EHPVO was 3.8 (2.3-7.7) l min^-1 m^-2, whereas it was 4.4 (2.8-8.9) l min^-1 m^-2 in cirrhosis (P = 0.468). The median (range) systemic vascular resistance index in EHPVO was 1,835 (806-3400) dyne s cm^-5 m^-2, which was similar to that in cirrhotic patients (1,800 [668-3022], P = 0.520). Similarly, the values of median (range) pulmonary vascular resistance index were comparable in the two groups (71 [42-332] vs. 79 [18-428], P = 0.885). A subgroup analysis was done for 8 patients of EHPVO and 8 age-matched compensated cirrhotic patients, which also revealed similar values of cardiac index, cardiac output, systemic vascular resistance index, systemic vascular resistance, pulmonary vascular resistance index, and pulmonary vascular resistance in the two groups. Conclusions: EHPVO patients have hyperdynamic circulation manifested by high cardiac index and low systemic and pulmonary vascular resistance indices. These hemodynamic changes are comparable with compensated cirrhotic patients who have similar grade of portal hypertension. This suggests a predominant role of portal hypertension per se in the genesis of systemic and pulmonary hemodynamic alterations.