The Annals of Thoracic Surgery, Vol 40, 566-573, Copyright © 1985 by The Society of Thoracic Surgeons
Enhanced functional recovery with venting during cardioplegic arrest in chronically damaged hearts
SA Mills, K Hansen, J Vinten-Johansen, HR Howe, KR Geisinger and AR Cordell
Thirty dogs with experimental myocardial infarction underwent
cardiopulmonary bypass, hypothermic asanguineous K+ cardioplegia (1 hour),
and reperfusion (30 minutes). Ten hearts were vented throughout, 5 only
during arrest, and 5 only during reperfusion; 10 were not vented. Left
ventricular (LV) performance and compliance were assessed by isovolumic (LV
balloon) indexes before bypass and after reperfusion. Vented hearts
recovered 116 +/- 8.3% of prearrest developed LV systolic pressure (DLVSP)
and 131 +/- 13.6% of prearrest rate of rise of LV pressure (dP/dt).
Nonvented hearts allowed to develop pressure during arrest (11.6 +/- 1.6 mm
Hg) and reperfusion (65 +/- 4 mm Hg) recovered 50 +/- 3.9% of prearrest
DLVSP and 55 +/- 5% of prearrest dP/dt (p less than 0.05). Reduction in LV
compliance was comparable in both groups. Mitochondrial architecture
(electron microscopy) was preserved in vented hearts, but was modestly
disrupted in nonvented hearts, thus suggesting slight metabolic impairment.
Functional recovery was nearly complete in hearts vented only during
reperfusion (DLVSP, 94 +/- 10.4%; dP/dt, 89 +/- 12.6%), but venting only
during arrest led to functional depression (DLVSP, 50 +/- 6.6%; dP/dt, 51
+/- 8%; p = 0.01). We conclude that venting chronically infarcted hearts
during cardiac operations affords better myocardial protection by avoiding
the damage that occurs during nonvented reperfusion.