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Management Of Patent Internal Mammary Artery Grafts During Re-operative Valvular Surgery: A Comparison Of Two Approaches.
F. H. Cheema, A. Mangi, M. Argenziano, D. Spiliotopoulos, G. Murtaza, C. Foster, A. Benson, T. Naseem, E. Lowenstein, F. Younas, T. Umann, T. Martens, M. Oz, A. Stewart, Y. Naka, C. Smith. Columbia University College of Physicians & Surgeons - New York Presbyterian Hospital, New York, NY,
BACKGROUND:
The complexity of reoperative cardiac surgery is increased in patients with previous coronary artery bypass grafting. The further presence of patent pedicled IMA grafts presents particular challenges with respect to myocardial protection, necessitating either temporary occlusion of these grafts or alternative cardioplegic approaches. At our institution, these situations have been handled either by IMA isolation and clamping or by use of more profound hypothermia. The aim of this study was to compare the intraoperative morbidity and postoperative outcomes associated with each of these approaches.
METHODS:
This retrospective study focused on operations performed over a decade. This analysis is focused only on patients undergoing isolated valvular procedures in setting of patent IMA grafts from a previous CABG; pts having repeat revascularization were excluded. Data were analyzed using SPSS.
RESULTS:
164 patients with previous CABG and patent IMA grafts underwent reoperative valvular surgery. In 121 (74%) of these (Gp A), myocardial protection included IMA graft isolation and clamping; in 43 (26%), the IMA grafts were not isolated, and myocardial protection was achieved with a combination of more profound hypothermia and/or more frequent or continuous cardioplegia administration (Gp B). Choice of approach was driven by surgeon preference. Preoperative demographics and clinical characteristics did not differ between the two groups. Although there was no difference in aortic crossclamp time between the groups, patients in Gp B had significantly lower minimum core temperatures (26.0 ± 4.9 degrees C vs. 31.4 ± 3.1 degrees C, p<0.0001) and longer cardiopulmonary bypass times (163 ± 88 min. vs. 124 ± 51 min, p=0.001) than those in Group A. Despite increased dissection required for isolation of IMA grafts, patients in Gp A had similar rates of IMA or other graft injury (2 cases, 1.7%) as those in Gp B (1 case, 2.3%). There were no statistically significant differences between the groups with respect to perioperative complications or 30day mortality.
CONCLUSIONS:
Isolation and occlusion of patent IMA grafts during reoperative valvular surgery is associated with shorter CBP times and less profound hypothermia than approaches avoiding IMA dissection, and did not result in a higher incidence of bypass graft injury. We currently favor this approach in pts with patent IMA grafts, as it allows more reliable and expeditious myocardial protection while minimizing CPB time and extent of hypothermia.
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