Camille L. Hancock Friesen

Coronary Bypass Surgery Performed off Pump Does Not Result in Lower In-Hospital Morbidity Than Coronary Artery Bypass Grafting Performed on Pump

Background—There is increasing evidence that cardiopulmonary bypass (CPB) may be responsible for the morbidity associated with coronary artery bypass grafting (CABG) surgery. Recent developments in cardiac stabilization devices have made CABG without CPB feasible. However, there is conflicting evidence to date from published trials comparing outcomes between CABG performed with and without CPB, with some trials indicating an advantage to the avoidance of CPB and others showing little benefit. Methods and Results—In a single-center randomized trial, 300 patients requiring CABG surgery at a single institution were prospectively randomized to have the procedure performed with CPB (n=150) or on the beating heart (n=150). Exclusion criteria for the trial included emergency procedure, concomitant major cardiac procedures, ejection fraction <30%, and reoperation. In-hospital outcomes were analyzed on an intention-to-treat basis. A mean of 3.0±0.9 grafts were performed in the CPB group compared with 2.8±0.9 grafts in the beating-heart group (P =0.06). There were no significant differences between the CPB group and the beating-heart group in mortality (0.7% versus 1.3%; P =1.0), transfusion (8.7% versus 9.3%), perioperative myocardial infarction (0.7% versus 2.7%; P =0.37), permanent stroke (0% versus 1.3%; P =0.50), new atrial fibrillation (32% versus 25%; P =0.20), and deep sternal wound infection (0.7% versus 0%; P =1.0). The mean time to extubation was 4 hours, the mean stay in the intensive care unit was 22 hours, and the median length of hospitalization was 5 days in both groups (P =NS). Conclusions—In contrast to published trials, we were unable to demonstrate any advantage with CABG performed without CPB in terms of patient morbidity. Excellent results can be obtained with either surgical approach.

Is it safe to train residents to perform cardiac surgery

BACKGROUND The impact of surgical training on patient outcomes in cardiac surgery is unknown. METHODS All cases performed by residents from 1998 to 2001 were compared to staff surgeon cases using prospectively collected data. Operative mortality and a composite morbidity of: reoperation for bleeding perioperative myocardial infarction, infection, stroke, or ventilation more than 24 hours were compared using multivariate analysis. RESULTS Four residents performed 584 cases. The cases were as follows: coronary artery bypass grafting (CABG), 366 cases; aortic valve replacement (AVR) with or without CABG (AVR +/- CABG), 86 cases; mitral valve replacement, 31 cases; mitral valve repair, 25 cases; thoracic aneurysm/dissection, 22 cases; aortic root, 20 cases; transplantations, 14 cases; and adult congenital defect repairs, 20 cases. There were 2,638 CABGs and 363 AVR +/- CABG performed by the staff during the same period. Crude operative mortality in CABG patients was 2.5% (resident) and 2.9% (staff) (p = 0.62). In multivariate analysis, resident was not associated with operative mortality odds ratio (OR) of 0.59 (p = 0.19). Resident cases had a higher incidence of the composite morbidity outcome for CABG cases (19.4% vs 13.6% for staff; p = 0.003). However, in multivariate analysis, resident was not associated with increased morbidity (OR = 1.23, p = 0.16). The AVR +/- CABG crude mortality was 3.6% (resident) and 2.8% (staff) (p = 0.69). Because of the small number of cases (n = 447), operative mortality was combined with the composite morbidity outcome for the AVR +/- CABG model. In all, 16.7% of resident cases and 19.8% of staff cases had the composite outcome or died (p = 0.51). In multivariate analysis resident was not associated with this outcome (OR = 0.74, p = 0.35). CONCLUSIONS In this analysis of our experience with residency training, the operative morbidity and mortality in CABG and AVR patients was similar for residents and staff. Training residents to perform cardiac surgery appears to be safe.

Pediatric Cardioplegia Strategy Results in Enhanced Calcium Metabolism and Lower Serum Troponin T

BACKGROUND Pediatric myocardium is unique from mature myocardium; thus, the use of adult cardioplegia for pediatric cardiac operations may provide suboptimal myocardial protection. We evaluated our standard adult cardioplegia (AC; modified Buckberg) and a pediatric cardioplegia (PC) solution (del Nido solution, Baxter) in vitro in rat cardiomyocytes and compared short-term outcomes in pediatric cardiac surgical patients. METHODS Contractions, intracellular calcium, and action potentials were recorded from isolated rat cardiomyocytes exposed to PC or AC, followed by reperfusion. Pediatric patients (n = 118) undergoing cardiac operations using PC (group PC, n = 59) or AC (group AC, n = 59) were matched 1:1 for age, diagnosis, and duration of cardiopulmonary bypass. RESULTS PC-perfused rat ventricular cardiomyocytes had lower diastolic calcium during cardioplegia and early reperfusion than AC-perfused cardiomyocytes. Cardiomyocytes remained excitable despite introduction of AC but not PC. The mean age in each pediatric group was 3.7 years (range, 3 days to 17 years; p = 0.95). Median serum troponin T levels at intensive care admission were significantly lower in group PC (0.83 +/- 0.25 microg/L) than in group AC (13.8 +/- 12.7 microg/L, p = 0.0001), which persisted at 24 hours postoperatively. There were no significant differences in duration of intubation or length of stay in intensive care or the hospital. CONCLUSIONS Pediatric cardioplegia is associated with reduced intracellular diastolic calcium during arrest and reperfusion and more complete arrest during exposure in rat cardiomyocytes. Pediatric patients receiving pediatric cardioplegia had reduced troponin T release compared with those receiving adult cardioplegia.

Protecting the aged heart during cardiac surgery: The potential benefits of del Nido cardioplegia

OBJECTIVE Aged hearts are more vulnerable than mature hearts to reperfusion injury during cardiac surgery because of altered cardiomyocyte Ca(2+) homeostasis. Inasmuch as immature cardiomyocytes have similar properties, a specialized cardioplegic solution (del Nido cardioplegia) designed to protect childrens hearts may also be beneficial for elderly patients. Our objective was to evaluate the ability of del Nido cardioplegic solution, containing lidocaine and less Ca(2+) than our standard cardioplegic solution, to protect aged cardiomyocytes during cardioplegic arrest and reperfusion. METHODS We used our novel isolated cell model of cardioplegic arrest and reperfusion to compare the effect of del Nido cardioplegic solution with that of our standard cardioplegic solution on intracellular Ca(2+) concentration, contractions, and membrane potential in cardiomyocytes from senescent rat hearts. RESULTS The incidence of spontaneous contractions during cardioplegic arrest was lower with del Nido cardioplegia (3/11 vs 9/11 cells; P < .05) than with standard cardioplegia, and contractions could not be induced by field stimulation of cardiomyocytes arrested with del Nido cardioplegia (0/11 vs 9/11 cells; P < .05). Intracellular diastolic Ca(2+) levels were lower during arrest with del Nido cardioplegia (57.10 ± 3.06 vs 76.19 ± 3.45 nmol/L; P < .05). During early reperfusion, a potentially injurious rapid recovery of intracellular Ca(2+) associated with hypercontraction in cardiomyocytes arrested with standard cardioplegic solution was avoided in cells treated with del Nido cardioplegia (81.42 ± 2.99 vs 103.15 ± 4.25 nM; P < .05). CONCLUSIONS Del Nido cardioplegic solution has the potential to provide superior myocardial protection in senescent hearts by preventing electromechanical activity during cardioplegic arrest and Ca(2+)-induced hypercontraction during early reperfusion.

Traumatic coronary artery fistula management

Traumatic coronary artery-cameral fistulas (TCAF) are uncommon sequelae of trauma that require early surgical intervention to prevent complications. The etiology of traumatic coronary artery-cameral fistulas may be classified as accidental or iatrogenic and have distinctly different courses depending on the etiology. The two operations described for definitive surgical closure of a traumatic coronary-cameral fistula are external ligation/obliteration of the fistula (with or without bypass grafting to the coronary artery distal to the fistula) and direct repair of the fistula from within the recipient chamber. The technique of fistula closure from within the recipient chamber is associated with a reduced incidence of fistula recurrence. A case report and a collective literature review are presented.

Complete revascularization is compromised in off-pump coronary artery bypass grafting

OBJECTIVE Patients who undergo off-pump coronary artery bypass grafting (OPCAB) commonly receive fewer bypass grafts and are more often incompletely revascularized compared with those receiving conventional coronary artery bypass (CCAB) recipients. Because this can compromise survival, we sought to determine whether patients undergoing OPCAB are incompletely revascularized and whether this affects long-term survival and freedom from cardiac events. METHODS OPCAB cases (n = 411) performed from January 1, 1997 to June 30, 2003 were considered for inclusion and matching with 874 randomly selected, contemporary CCAB cases. After propensity matching, 308 OPCAB cases and 308 CCAB cases were included in the final analysis. We compared the number of bypass grafts and the completeness of revascularization by coronary territory. Survival and readmission for cardiac causes were monitored for up to 10 years postoperatively, with a median follow-up period of 5.9 years. RESULTS On average, the patients undergoing OPCAB received significantly fewer distal anastomoses than did those undergoing CCAB (mean ± standard deviation, 2.6 ± 0.9 vs 3.0 ± 1.0, P < .0001). The circumflex territory was the most likely territory to be ungrafted during OPCAB in patients with angiographically significant obstruction (P = .0006). The frequency of complete revascularization was significantly different between the 2 groups (OPCAB, 79.2% vs CCAB, 88.3%; P = .0.002). The OPCAB group had a significantly greater rate of total arterial grafting (OPCAB, 66.6% vs CCAB, 49.7%; P = .0001). No difference was seen in 8-year survival or freedom from cardiac cause hospital readmission between the 2 groups. CONCLUSIONS Despite receiving fewer distal anastomoses and the decreased frequency of complete revascularization, OPCAB and CCAB techniques produced comparable results.

Rationale and Design of the Canadian Outcomes Registry Late After Tetralogy of Fallot Repair: The CORRELATE Study

BACKGROUND Chronic hemodynamically relevant pulmonary regurgitation (PR) resulting in important right ventricular dilation and ventricular dysfunction is commonly seen after tetralogy of Fallot (TOF) repair. Late adverse clinical outcomes, including exercise intolerance, arrhythmias, heart failure and/or death accelerate in the third decade of life and are cause for considerable concern. Timing of pulmonary valve replacement (PVR) to address chronic PR is controversial, particularly in asymptomatic individuals, and effect of PVR on clinical measures has not been determined. METHODS Canadian Outcomes Registry Late After Tetralogy of Fallot Repair (CORRELATE) is a prospective, multicentre, Canada-wide cohort study. Candidates will be included if they are ≥ 12 years of age, have had surgically repaired TOF resulting in moderate or severe PR, and are able to undergo cardiovascular magnetic resonance imaging. Enrollment of > 1000 individuals from 15 participating centres (Toronto, Montreal, Quebec City, Sherbrooke, Halifax, Calgary, Edmonton, and Vancouver) is anticipated. Clinical data, health-related quality of life metrics, and adverse outcomes will be entered into a web-based database. A central core lab will analyze all cardiovascular magnetic resonance studies (PR severity, right ventricular volumes, and ventricular function). Major adverse outcomes (sustained ventricular tachycardia and cardiovascular cause of death) will be centrally adjudicated. RESULTS To the best of our knowledge, CORRELATE will be the first prospective pan-Canadian cohort study of congenital heart disease in children and adults. CONCLUSIONS CORRELATE will uniquely link clinical, imaging, and functional data in those with repaired TOF and important PR, thereby enabling critical evaluation of clinically relevant outcomes in those managed conservatively compared with those referred for PVR.

Early innate immune events induced by prolonged cold ischemia exacerbate allograft vasculopathy

BackgroundIschemia/reperfusion induced innate immune injury is inescapable in solid organ transplantation. Prolonged cold ischemia exacerbates the primary manifestation of late graft rejection, allograft vasculopathy (AV). The relationship between prolonged cold ischemia and late graft events is unclear and the subject of this study.MethodsAortic interposition transplants were performed between fully disparate mice treated with CyclosporineA. Allografts were exposed to 20 min or 60 min of cold ischemia and harvested between 1 d-6 wk. Lesion size, smooth muscle cells (SMC), neutrophils (N∅), and CD8+ T cells were quantified.ResultsEarly SMC loss was identical in both groups. When compared to 20 min cold ischemia, grafts exposed to 60 min exhibited greater early N∅ influx, greater SMC proliferation but fewer medial SMC at 1 wk and 2 wk. Subsequently, earlier and greater CD8+ T cell infiltration were seen in the 60 min group with larger lesions at every time point.ConclusionsThese data suggest that the larger neointimal lesions in grafts exposed to 60 min cold ischemia result from enhanced early innate immune events resulting in impaired SMC recovery and subsequent increased adaptive immune response.

Neutrophil mediated smooth muscle cell loss precedes allograft vasculopathy

BackgroundCardiac allograft vasculopathy (AV) is a pathological process of vascular remodeling leading to late graft loss following cardiac transplantation. While there is consensus that AV is alloimmune mediated, and evidence that the most important alloimmune target is medial smooth muscle cells (SMC), the role of the innate immune response in the initiation of this disease is still being elucidated. As ischemia reperfusion (IR) injury plays a pivotal role in the initiation of AV, we hypothesize that IR enhances the early innate response to cardiac allografts.MethodsAortic transplants were performed between fully disparate mouse strains (C3H/HeJ and C57BL/6), in the presence of therapeutic levels of Cyclosporine A, as a model for cardiac AV. Neutrophils were depleted from some recipients using anti-PMN serum. Grafts were harvested at 1,2,3,5d and 1,2wk post-transplant. Ultrastructural integrity was examined by transmission electron microscopy. SMC and neutrophils were quantified from histological sections in a blinded manner.ResultsGrafts exposed to cold ischemia, but not transplanted, showed no medial SMC loss and normal ultrastructural integrity. In comparison, allografts harvested 1d post-transplant exhibited > 90% loss of SMC (p < 0.0001). SMC partially recovered by 5d but a second loss of SMC was observed at 1wk. SMC loss at 1d and 1wk post-transplant correlated with neutrophil influx. SMC loss was significantly reduced in neutrophil depleted recipients (p < 0.01).ConclusionsThese novel data show that there is extensive damage to medial SMC at 1d post-transplant. By depleting neutrophils from recipients it was demonstrated that a portion of the SMC loss was mediated by neutrophils. These results provide evidence that IR activation of early innate events contributes to the etiology of AV.

Surgical management of the single ventricle

The vast majority of neonates with single ventricle physiology require some form of surgical intervention to realize long term survival. Surgical options are limited as septation of the single ventricle has been described but is an option available for only a small subset of patients with ideal anatomy w1x. Orthotopic cardiac transplant is another approach which because of limited organ availability eliminates many potential candidates by attrition on the waiting list w2x. The most common approach to palliation