EFFECTS OF WRAPPING TIGHTNESS ON ACUTE CARDIAC-FUNCTION IN DYNAMIC CARDIOMYOPLASTY

Background. It has not been clarified how tightly the heart should be wrapped for maximal augmentation of cardiac function in cardiomyoplast y. Methods. Hearts in acute failure induced by propranolol were wrappe d with the left latissimus dorsi muscle, loosely (loose CMP), moderate ly (moderate CMP), and tightly (tight CMP) in each of 5 pigs. To measu re the pressure between the latissimus dorsi muscle and the left ventr icle (LV), a Millar pressure catheter with a latex balloon was placed on the anterior wall of the LV. Left ventricular waif tension was calc ulated according to Laplace's law using the difference between the LV pressure and the balloon pressure. Results. In the loose CMP, moderate CMP, and tight CMP groups, the mean balloon pressures during unassist ed beats were 8.2, 10.4, and 13.2 mm Hg, respectively. During unassist ed beats, the mean LV wall tension values were 38,683, 29,938 (p < 0.0 5 versus lease CMP), and 26,652 (p < 0.05 versus loose CMP) dynes/cm, respectively, the peak LV pressures were 76.8, 73.8, and 65 (p < 0.05 versus loose CMF) mm Mg, respectively, and the stroke volumes were 12. 8, 9.2, and 8.5 (p < 0.05 versus loose CMP) mL, respectively, During a ssisted beats, the mean LV wall tension values were 20,059, 11,290, an d 7,893 (p < 0.05 versus loose CMP) dynes/cm, respectively, the peak L V pressures were 94.1, 98.1, and 92.0 mm Mg, respectively, and the str oke volumes were 13.8, 11.6, and 9.4 (p < 0.05 versus loose CMP) mk, r espectively. Conclusions. During unassisted beats, tight CMP (13 mm Hg ) had the advantage of diminishing LV wall tension, but the disadvanta ge of diminishing LV pressure and stroke volume, compared with loose C MP (8 mm Mg). Moderate CMP (10 mm Mg), however, had the advantage of d iminishing LV wall tension without a decrease in LV pressure and strok e volume. (C) 1997 by The Society of Thoracic Surgeons.