HEART FUNCTION AFTER INJECTION OF SMALL AIR BUBBLES IN CORONARY-ARTERY OF PIGS

By its nature, vaporization of atherosclerotic plaques by laser irradi ation or spark erosion may produce a substantial amount of gas. To eva luate the effect of gas embolism possibly caused by vaporization techn iques, air bubbles with diameters of 75, 150, or 300 mum, each in a vo lume of 2 mul/kg, were selectively injected subproximal in the left an terior descending coronary artery of seven anesthetized pigs (28 +/- 3 kg). Systemic hemodynamics such as heart rate, left ventricular press ure and its peak positive first derivative, and mean arterial pressure did not change after air injection, whereas there was a minor change in peak negative first derivative of left ventricular pressure. After injection of air bubbles there was a maximal relative reduction of sys tolic segment shortening (SS) in the myocardium supplied by the left a nterior descending coronary artery of 27, 45, and 58% for 75-, 150-, a nd 300-mum bubbles, respectively, and a relative increase of postsysto lic SS (PSS) of 148, 200, and 257% for 75-, 150-, and 300-mum bubbles, respectively. Recovery of SS and PSS started after 2 min and was comp leted after 10 min. A difference in SS and PSS changes between differe nt bubble size injections could be demonstrated. From this study it is clear that depression of regional myocardial function after injection of air bubbles could pass unnoticed on the basis of global hemodynami c measurements.