Effect of arterial blood pressure and ventilation gases on cardiac depression induced by coronary air embolism

Abstract

In this study the time course of cardiac depression after selective intracoronary injection of air bubbles was investigated in six anesthetized pigs (30 +/- 2 kg) with different mixtures of ventilation gases and different mean arterial blood pressures (MAP). Air bubbles of 150 microns diam were injected into the left anterior descending coronary artery (LADCA) in a volume of 2 microliters/kg body wt. In each animal an injection of air bubbles was applied during ventilation with N2-O2 and a MAP of 77 +/- 3 mmHg (N2-O2/low pressure) or 111 +/- 3 mmHg (N2-O2/high pressure) and during ventilation with pure O2 and a MAP of 77 +/- 3 mmHg (O2/low pressure) or 110 +/- 3 mmHg (O2/high pressure). Systemic hemodynamic variables such as left ventricular pressure, its peak first derivatives, and MAP changed < 10% after injection of air bubbles. During N2-O2/low pressure, systolic segment length shortening in the LADCA region (SS-LADCA) decreased from baseline and did not return to baseline within the 10 min after injection of air bubbles. During N2-O2/high pressure and O2/low pressure, SS-LADCA was decreased between 60 and 120 s, whereas for O2/high pressure this period was from 60 to 90 s. By calculating the time integral of the deviation from baseline of SS-LADCA, it could be demonstrated that the depression of regional myocardial function was less severe during O2/high pressure and O2/low pressure than during N2-O2/low pressure. We conclude that, when coronary air embolism occurs during hypertension and during ventilation with pure O2 instead of a normal N2-O2 mixture, the resulting depression of regional myocardial function is reduced.