ABSTRACT
AIM: The aim of this paper was to compare the clinical impact of the different myocardial protection strategies in coronary artery bypass grafting (CABG) patients to facilitate decision-making for use of on- or off-pump technique. METHODS: Prospectively collected data for primary CABG patients between April 1, 1996 and December 30, 2010 (N.=8779) were analyzed. Early adverse cardiac and cerebrovascular events (ACCE) and late survival were compared between on-pump; cardioplegia (CPA, N.=3862, 44%), cross-clamp fibrillation (XCF, N.=3751, 43%), and off-pump (N.=1166, 13%) myocardial protection. Second, clinical profiling for the risk of ACCE with each strategy was performed using principal component analysis. Finally, a 1:1 matched cohort comparison of 1055 patients was done. RESULTS: There were vast differences in baseline characteristics between groups. Significantly fewer grafts per patient were constructed using off-pump. There were no remarkable differences in operative mortality and 10-year survival rates between the groups after restrictive matching. Principal component analysis identified high risk profiles; factor 1 (ejection fraction 30-50%, prior myocardial infarction, non-elective operation), and factors 4 (hypertension, hypercholesterolemia, Body Mass Index >30 kg/m2) and 5 (female, octogenarian, left main stem disease) to be strongly associated with ACCE after on-pump CABG while lower risk profiles; factors 5 and 6 (extracardiac arteriopathy, prior stroke) were associated with ACCE after off-pump CABG. CONCLUSION: Comparatively, on-pump techniques were associated with greater risk of adverse events in "high risk" patients defined by clinical characteristics, while off-pump was associated with increased risk of adverse events in "low risk" patients.
Subject(s)
Cardiopulmonary Bypass , Coronary Artery Bypass, Off-Pump , Coronary Artery Bypass , Coronary Artery Disease/surgery , Aged , Aged, 80 and over , Cardiopulmonary Bypass/adverse effects , Cardiopulmonary Bypass/mortality , Chi-Square Distribution , Coronary Artery Bypass/adverse effects , Coronary Artery Bypass/mortality , Coronary Artery Bypass, Off-Pump/adverse effects , Coronary Artery Bypass, Off-Pump/mortality , Coronary Artery Disease/diagnosis , Coronary Artery Disease/mortality , Databases, Factual , Female , Humans , Logistic Models , Male , Matched-Pair Analysis , Middle Aged , Multivariate Analysis , Patient Selection , Postoperative Complications/mortality , Principal Component Analysis , Retrospective Studies , Risk Assessment , Risk Factors , Time Factors , Treatment OutcomeABSTRACT
The effect of coronary artery bypass grafting (CABG) on absolute myocardial blood flow (MBF) has not been investigated previously. MBF (ml. min(-1). g(-1)) was measured at rest and during hyperemia (0.56 mg/kg iv dipyridamole) using H(2)(15)O and positron emission tomography in eight patients with three-vessel disease before surgery and 1 and 6 mo after full revascularization. Baseline MBF was 0.87 +/- 0.12 preoperatively and 1.04 +/- 0.14 and 0.95 +/- 0.13 at 1 and 6 mo after CABG, respectively (P < 0.05, 6 mo vs. preoperatively). Hyperemic MBF was 1.36 +/- 0.28 preoperatively and increased to 1.98 +/- 0.50 and 2.45 +/- 0.64 at 1 and 6 mo after CABG, respectively (P < 0.01, 6 mo vs. preoperatively). Coronary vasodilator reserve (hyperemic/baseline MBF) increased from 1.59 +/- 0.40 preoperatively to 1.93 +/- 0.13 and 2.57 +/- 0.49 at 1 and 6 mo, respectively (P < 0.05, 6 mo vs. preoperatively). Minimal (dipyridamole) coronary resistance (mmHg. min. g(-1). ml(-1)) fell progressively from 59.37 +/- 14.56 before surgery to a nadir of 35. 76 +/- 10.12 at 6 mo after CABG (P < 0.01 vs. preoperatively). The results of the present study confirm that CABG improves coronary vasodilator reserve progressively as a result of reduction in minimal coronary resistance. These data suggest persistent microvascular dysfunction that recovers slowly after surgery.
Subject(s)
Coronary Artery Bypass/adverse effects , Coronary Circulation/physiology , Coronary Disease/physiopathology , Coronary Disease/surgery , Adult , Aged , Coronary Disease/diagnostic imaging , Female , Humans , Hyperemia/physiopathology , Male , Microcirculation/physiology , Middle Aged , Stroke Volume , Tomography, Emission-Computed , Treatment Outcome , Vascular Resistance/physiology , Vasodilation/physiologyABSTRACT
Detrimental changes of blood and erythrocyte rheology, and fluid exchange between the vascular and interstitial spaces, which influence the rate that oxygen is supplied to the patient, occur during cardiac bypass surgery. Venous flow is subject to a pulsatile and uncertain variation, because the vena cava is more than 30 mmHg below atmospheric pressure. This occurs because the patient is about 1 m above the air-blood surface of the bypass reservoir. Before any reliable study of fluid exchange can be undertaken this effect must be controlled. It was then established that optimum oxygen exchange occurs when equilibration of the plasma oncotic pressure and the capillary hydrostatic pressure is achieved without alteration of the interstitial fluid volume. At the lower arterial blood pressures used during bypass, it is necessary to reduce the plasma oncotic pressure by using an appropriate volume of crystalloid prime.
