Study of the Acute Hemodynamic Effects of Inhaled Milrinone versus Inhaled Nitroglycerin on Mechanically Ventilated Patients with Pulmonary Hypertension after Mitral Valve Replacement Surgeries.

Abstract

Pulmonary hypertension is a usual complication of long-standing mitral valve disease. Perioperative pulmonary hypertension is a risk factor for right ventricular failure and is an important cause of morbidity and mortality in patients undergoing mitral valve surgery Pulmonary hypertension is defined as an increase in mean pulmonary arterial pressure ≥ 25 mm Hg at rest as assessed by right heart catheterization .In the latest classification by WHO, there are five subtypes of pulmonary hypertension depending on its etiology. The most common cause of pulmonary hypertension worldwide is type 2 pulmonary hypertension from left heart disease, and valvular heart disease. Pulmonary hypertension affects virtually all patients with severe symptomatic mitral valve disease and up to 65% of those with symptomatic aortic stenosis. Mitral and aortic valve diseases increase left atrial pressure which, in turn, leads to an initially passive and potentially reversible increase in pulmonary pressures. Vascular injury then triggers a cascade of venous and small artery remodelling, irreversible arterial pulmonary hypertension, and eventually, right ventricular dysfunction. The perioperative use of inhaled vasodilators to reduce pulmonary artery pressure, therefore, appears to be an ideal treatment option for achieving selective pulmonary vasodilatation. The purpose of the study was to compare inhaled milrinone and inhaled nitroglycerin hemodynamic effects on mechanically ventilated patients with pulmonary hypertension after mitral valve replacement surgery by measuring invasive blood pressure, heart rate, central venous pressure and bedside transthoracic echocardiography to assess pulmonary artery pressure.