Dimitri Novitzky

On-Pump versus Off-Pump Coronary-Artery Bypass Surgery

BACKGROUND Coronary-artery bypass grafting (CABG) has traditionally been performed with the use of cardiopulmonary bypass (on-pump CABG). CABG without cardiopulmonary bypass (off-pump CABG) might reduce the number of complications related to the heart-lung machine. METHODS We randomly assigned 2203 patients scheduled for urgent or elective CABG to either on-pump or off-pump procedures. The primary short-term end point was a composite of death or complications (reoperation, new mechanical support, cardiac arrest, coma, stroke, or renal failure) before discharge or within 30 days after surgery. The primary long-term end point was a composite of death from any cause, a repeat revascularization procedure, or a nonfatal myocardial infarction within 1 year after surgery. Secondary end points included the completeness of revascularization, graft patency at 1 year, neuropsychological outcomes, and the use of major resources. RESULTS There was no significant difference between off-pump and on-pump CABG in the rate of the 30-day composite outcome (7.0% and 5.6%, respectively; P=0.19). The rate of the 1-year composite outcome was higher for off-pump than for on-pump CABG (9.9% vs. 7.4%, P=0.04). The proportion of patients with fewer grafts completed than originally planned was higher with off-pump CABG than with on-pump CABG (17.8% vs. 11.1%, P<0.001). Follow-up angiograms in 1371 patients who underwent 4093 grafts revealed that the overall rate of graft patency was lower in the off-pump group than in the on-pump group (82.6% vs. 87.8%, P<0.01). There were no treatment-based differences in neuropsychological outcomes or short-term use of major resources. CONCLUSIONS At 1 year of follow-up, patients in the off-pump group had worse composite outcomes and poorer graft patency than did patients in the on-pump group. No significant differences between the techniques were found in neuropsychological outcomes or use of major resources. (ClinicalTrials.gov number, NCT00032630.).

Hemodynamic and metabolic responses to hormonal therapy in brain-dead potential organ donors.

An evaluation of the beneficial effects of hormonal therapy, consisting of T3 2 micrograms, cortisol 100 mg, and insulin 20 units, administered at hourly intervals intravenously, was assessed in brain-dead patients referred for organ donation. Twenty-six conventionally treated donors (group A) showed a progressive hemodynamic deterioration requiring significant increments of inotropic support in order to maintain cardiovascular stability, necessitating a significant increase in bicarbonate requirements in order to maintain a normal acid-base balance. Of this group, 20% of the donors were considered unsuitable as cardiac donors due to progressive cardiovascular deterioration or sudden ventricular fibrillation. Hormonal therapy was administered to 21 donors (group B) resulting in a significant improvement of cardiovascular status, requiring less inotropic support and significantly less bicarbonate. A significant reduction of serum lactate-pyruvate followed the initiation of the hormonal therapy. In group B, organs from all donors (heart, heart and lungs, and kidneys) were suitable for transplantation, with excellent organ function following implantation of the graft.

Change From Aerobic To Anaerobic Metabolism After Brain Death, And Reversal Following Triiodothyronine Therapy

Brain-dead organ donors are depleted of circulating triiodothyronine (T3) and show features suggestive generally of anerobic metabolism at the tissue level, accompained by derteriorating hemodynamic function. The principle of single-bolus kinetics with labeled carbon compounds (14C-R), with subsequencet measurement of both plasm activity an dof exhaled 14C O2 has therefore been used to study glucose, pyruvate, and palmitate utilization under conditions of (1) sedation, (2) brain death, and (3) brain death with T3 therapy in the baboon. Serum lactate and plasma-free fatty acid concetrations were also measured. There was a major change in metabolic oxiodative processes folowing brin death. The rate of glucose, pyruvate, and palmitate untilization was markeldy reduced, and there was an accumulation of lactate and free fatty acids in th plasma, indicating a general change from aerobic to anerobic metabolism. The administration of T3 to th brain-dead baboon resulted in a dramatic increase in the rate of metabolite utilization, and a reduction in the plasma conctrations of plasma lactate and free fatty acids, indicating an apparent reversal from tissue anaerobic to aerobic metabolism. We suggest that T3 should be adminstered to all brain-dead potential ortgan donors to correct and maintain a more physiologic metabolic status and thus to improve oragan function.

Off-Pump Coronary Artery Bypass Surgery Is Associated With Worse Arterial and Saphenous Vein Graft Patency and Less Effective Revascularization Results From the Veterans Affairs Randomized On/Off Bypass (ROOBY) Trial

Background— The Department of Veterans Affairs Randomized On/Off Bypass (ROOBY) trial compared clinical and angiographic outcomes in off-pump versus on-pump coronary artery bypass graft (CABG) surgery to ascertain the relative efficacy of the 2 techniques. Methods and Results— From February 2002 to May 2007, the ROOBY trial randomized 2203 patients to off-pump versus on-pump CABG. Follow-up angiography was obtained in 685 off-pump (62%) and 685 on-pump (62%) patients. Angiograms were analyzed (blinded to treatment) for FitzGibbon classification (A=widely patent, B=flow limited, O=occluded) and effective revascularization. Effective revascularization was defined as follows: All 3 major coronary territories with significant disease were revascularized by a FitzGibbon A-quality graft to the major diseased artery, and there were no new postanastomotic lesions. Off-pump CABG resulted in lower FitzGibbon A patency rates than on-pump CABG for arterial conduits (85.8% versus 91.4%; P=0.003) and saphenous vein grafts (72.7% versus 80.4%; P<0.001). Fewer off-pump patients were effectively revascularized (50.1% versus 63.9% on-pump; P<0.001). Within each major coronary territory, effective revascularization was worse off pump than on pump (all P⩽0.001). The 1-year adverse cardiac event rate was 16.4% in patients with ineffective revascularization versus 5.9% in patients with effective revascularization (P<0.001). Conclusions— Off-pump CABG resulted in significantly lower FitzGibbon A patency for arterial and saphenous vein graft conduits and less effective revascularization than on-pump CABG. At 1 year, patients with less effective revascularization had higher adverse event rates. Clinical Trial Registration— URL: http://www.clinicaltrials.gov. Unique identifier: NCT00032630.

Impact of endoscopic versus open saphenous vein harvest technique on late coronary artery bypass grafting patient outcomes in the ROOBY (Randomized On/Off Bypass) Trial

OBJECTIVE In the Randomized On/Off Bypass (ROOBY) Trial, the efficacy of on-pump versus off-pump coronary artery bypass grafting was evaluated. This ROOBY Trial planned subanalysis compared the effects on postbypass patient clinical outcomes and graft patency of endoscopic vein harvesting and open vein harvesting. METHODS From April 2003 to April 2007, the technique used for saphenous vein graft harvesting was recorded in 1471 cases. Of these, 894 patients (341 endoscopic harvest and 553 open harvest) also underwent coronary angiography 1 year after coronary artery bypass grafting. Univariate and multivariable analyses were used to compare patient outcomes in the endoscopic and open groups. RESULTS Preoperative patient characteristics were statistically similar between the endoscopic and open groups. Endoscopic vein harvest was used in 38% of the cases. There were no significant differences in both short-term and 1-year composite outcomes between the endoscopic and open groups. For patients with 1-year catheterization follow-up (n=894), the saphenous vein graft patency rate for the endoscopic group was lower than that in the open harvest group (74.5% vs 85.2%, P<.0001), and the repeat revascularization rate was significantly higher (6.7% vs 3.4%, P<.05). Multivariable regression documented no interaction effect between endoscopic approach and off-pump treatment. CONCLUSIONS In the ROOBY Trial, endoscopic vein harvest was associated with lower 1-year saphenous vein graft patency and higher 1-year revascularization rates, independent of the use of off-pump or on-pump cardiac surgical approach.

Injury of myocardial conduction tissue and coronary artery smooth muscle following brain death in the baboon

Experimental brain death was induced in 36 chacma baboons. In group A (n=17), brain death was induced with no pharmacologic or surgical manipulation. Group B (n=7) underwent bilateral vagotomy, unilateral left cardiac sympathectomy, or bilateral adrenalectomy before induction of brain death. Group C (n=7) underwent total cardiac sympathectomy. Group D (n=5) was pre-treated with verapamil hydrochloride. Following induction of brain death, group A animals were maintained on a ventilator for a mean of 12 hr and 6 hr for the remaining groups. At the end of the experiment, the heart was excised, and tissue blocks were examined with light microscopy at (A) the atriaventricular node-bundle of His; (B) the major coronary arteries; and (C) myocardial tissue from the ventricular septum or left ventricular wall. In group A, 41% of the hearts showed histologic features of injury to the conduction tissue, 70% presented contraction band necrosis of the smooth muscle of the coronary arteries, and an incidence of 100% of the groups showed myocyte injury, more evident in the subendocardial area. In group B animals, conduction tissue injury was seen in 6 animals; the coronary arteries were not examined in this group; the incidence of myocyte injury was seen in 80% of the animals. Animals in groups C and D show no histopathologic injury in the conduction tissue (group A vs. C P < 0.04), nor in the coronary arteries (group A vs. C P < 0.002; group A vs. D P < 0.01), preserving the myocytes (P < 0.001). The cathecholamine storm associated to acute increment of the endocranial pressure at the time of induction of brain death induces major histopathologic changes in the myocardium, as a result of endogenous cathecholamines released inducing calcium overflow injury, affecting the conduction tissue, the smooth muscle of the coronary arteries, and the contractile myocardium. This can be prevented by calcium blockers or cardiac denervtion.

Cognitive Outcomes After On- Versus Off-Pump Coronary Artery Bypass Surgery

BACKGROUND The Randomized On versus Off Bypass trial found no difference for a global cognitive outcome measure for patients receiving on-pump versus off-pump coronary artery bypass graft surgery (CABG). In this report, we present the baseline patient characteristics that were predictive of post-CABG cognitive decline as well as compare cognitive outcomes between treatment arms. METHODS A neuropsychological battery was administered preoperatively and at 1 year after undergoing CABG. Stepwise regression was used to identify demographic or clinical risk factors associated with cognitive decline. Neuropsychological data were converted to demographically corrected T scores to provide impairment levels. RESULTS Overall 1,156 patients (581 on-pump, 575 off-pump) completed match-paired neuropsychological assessments at baseline and 1-year follow-up. Baseline cognitive score, age, education level, and ethnicity predicted cognitive decline after CABG. Only 20% of either group had mild impairment at baseline on three of the test scores, and less than 10% had severe impairment on individual tests at either time. Few subjects in either group transitioned to clinically impaired levels at follow-up on individual tests. CONCLUSIONS At baseline, lower cognitive function, older age, lower education, and ethnicity other than white were predictive of cognitive decline after CABG. Patients in both groups demonstrated low frequencies of cognitive impairment on individual tests at baseline and follow- up, and few patients in either group were classified as impaired at 1-year follow-up on individual tests. In general, the Randomized On versus Off Bypass study documented that neither on-pump nor off-pump CABG adversely impacts long-term brain function.

Impact of triiodothyronine on the survival of high-risk patients undergoing open heart surgery.

Experimental and clinical studies have shown the beneficial effects of triiodothyronine (T3) following myocardial revascularization on cardiopulmonary bypass (CPB). In this study, open-label T3 was administered to 68 high-risk patients undergoing open heart surgery. The New Jersey Risk Assessment was used to calculate the preoperative estimated surgical mortality. A loading dose of T3 was administered: (a) at release of the aortic cross-clamp, (b) whenever the patient became CPB dependent, (c) if the patient exhibited low cardiac output after discontinuing CPB and (d) as pretreatment before initiating CPB. All therapeutic modalities were followed by a continuous T3 infusion. Following T3 therapy, CPB was discontinued in all patients. Based upon discriminant analysis, a total of 26 deaths were expected from the entire group, but only 7 patients died, therefore, the observed mortality was reduced by 72% (p < 0.007). The use of T3 had a major impact on reducing surgical mortality, and may be advocated as a new therapeutic modality in patients with high estimated mortality undergoing open heart surgery.

IMPAIRMENT OF RENAL SLICE FUNCTION FOLLOWING BRAIN DEATH, WITH REVERSIBILITY OF INJURY BY HORMONAL THERAPY

The effects of the agonal period and subsequent donor management on renal slice function, using the K+ - Na+ ratio, have been studied in the pig. Brain ischaemia or death resulted in a reduction in renal slice function, whether the pig was maintained normovolemic or hypovolemic by i.v. fluid and dobutamine therapy. This deterioration in function was, however, reversed or prevented by a period of therapy with thyroxine (T3), insulin, and cortisol. A period of 24 hr storage of the kidney slice in a low ionic strength solution in ice resulted in a further deterioration in slice function in all groups studied.

Thyroid hormone therapy in the management of 63,593 brain-dead organ donors: a retrospective analysis.

Background Hormonal therapy to the brain-dead potential organ donor can include thyroid hormone (triiodothyronine [T3] or levothyroxine [T4]), corticosteroids, antidiuretic hormone, and insulin. Methods Data on 66,629 donors (2000–2009) were retrospectively reviewed. Documentation on T3/T4 was available in 63,593 (study 1), but 23,469 had incomplete documentation of other hormones. In 40,124, details of all four hormones were recorded (study 2). In this cohort, group A (received T3/T4) consisted of 23,022, and group B (no T3/T4) consisted of 17,102 donors. A multivariate analysis was performed to determine whether age, sex, ethnicity, cause of death, body mass index, Organ Procurement Organization region, or other hormonal therapy influenced procurement. Posttransplantation organ graft survival at 1 and 12 months was compared. Results In study 1, 30,962 (48.69%) received T3/T4, providing a mean of 3.35 organs per donor, and 32,631 (51.31%) did not receive T3/T4, providing a mean of 2.97 organs per donor, an increase of 12.8% of organs from T3/T4–treated donors (P<0.0001). In study 2, group A provided a mean of 3.31 organs per donor and group B provided a mean of 2.87 organs per donor, an increase of 15.3% in group A (P<0.0001). T3/T4 therapy was associated with procurement of significantly greater numbers of hearts, lungs, kidneys, pancreases, and intestines, but not livers. Multivariate analysis indicated a beneficial effect of T3/T4 independent of other factors (P<0.0001). T3/T4 therapy of the donor was associated with improved posttransplantation graft survival or no difference in survival, except for pancreas recipient (but not graft) survival at 12 months in study 2. Conclusion T3/T4 therapy results in more transplantable organs, with no detriment to posttransplantation graft survival.