Background: Contrast echocardiography is a useful tool for assessing repeatedly patients with coronary artery disease. Nevertheless, elevated pulmonary artery and systemic blood pressures likely to be associated with cardiac ischemia may limit the left ventricular opacification (LVO) because of the microspheres' sensitivity to pressure.
Objective: To determine the effects of systemic and pulmonary artery blood pressures on LVO.
Methods: We performed 55 intravenous injections (0.08 and 0.22 ml/kg) of a new transpulmonary contrast agent (Albunex), during two separated exposures, into 20 cardiac ischemic patients while monitoring invasively their cardiac indexes, and intracardiac, systemic, and pulmonary artery blood pressures. LVO was graded qualitatively from faint to full.
Results: A logistic model with the grade of LVO as the dependent variable and a selection from among the dose, exposure, right and left atrial blood pressures, systolic systemic and pulmonary artery blood pressures (ranges 94-208 and 14-45 mmHg, respectively), cardiac index, stroke index, and pulmonary and systemic vascular resistances as the explanatory variables demonstrated that increasing the dose gives an increasing probability of LVO (P = 0.02) and that increasing the pulmonary artery pressure reduces that probability (P = 0.006). A decreased cardiac index tended also to be associated with decreased LVO. The systemic blood pressure and the pulmonary and systemic vascular resistances had no statistically significant effect on the grade of LVO.
Conclusions: LVO after intravenous administration of Albunex is dose-dependent and limited by an elevated pulmonary artery pressure. These data suggest that one should use higher doses for cardiac ischemic patients with elevated pulmonary artery pressures and that use of Albunex has the potential to detect pulmonary hypertension in patients.