TOPICAL HYPOTHERMIA - INEFFECTIVE AND DELETERIOUS AS ADJUNCT TO CARDIOPLEGIA FOR MYOCARDIAL PROTECTION

Background. Topical hypothermia, an early method developed for myocard ial protection by virtue of its reduction of cardiac metabolic rate, i s not without sequelae such as phrenic nerve paralysis and pulmonary c omplications. Methods. The hospital records of 505 nonrandomized conse cutive patients undergoing coronary artery bypass grafting between 199 1 and 1995 at the University of South Alabama were reviewed to evaluat e the effectiveness of topical hypothermia and its relationship to pul monary complications. Group A included 191 patients between 1991 and 1 992 who received systemic hypothermia and topical hypothermia with ice d slush in addition to cold blood cardioplegia. Group B included 314 p atients between 1993 and 1995 who received systemic hypothermia and in termittent cold blood cardioplegia without iced slush. Results. Myocar dial temperature mapping did not reveal any difference between the two groups. Postoperative cardiac morbidity, manifested as intraaortic ba lloon use, low cardiac output, inotrope use, and perioperative myocard ial infarction, was decreased in group B, but the difference failed to achieve statistical significance. Mortality (group A, 3.14%; group B, 3.82%) and rates of significant morbidity such as sternal infection, stroke, reoperation for bleeding, renal failure, and prolonged ventila tion were comparable between the two groups. However, there was a stat istically significant difference in the incidence of diaphragmatic par alysis between group A and group B. Group A had a 25% incidence of dia phragmatic paralysis on the first postoperative day, 18% on the 15th p ostoperative day, and 8% at 6 months, as opposed to group B, which had incidences of 2% on the first postoperative day, 1% on the 15th posto perative day, and 1% at 6 months (p < 0.001). Also, there was a signif icant difference in incidence of pleural effusions (60% versus 25%) an d rate of thoracentesis (25% versus 8%) between groups A and B (p < 0. 0001). Conclusions. We conclude that topical hypothermia did not offer any additional cardioprotective benefit above systemic hypothermia an d cold blood cardioplegia alone in coronary bypass patients, but signi ficantly increased the incidence of diaphragmatic paralysis and associ ated pulmonary complications. (C) 1998 by The Society of Thoracic Surg eons.