Recent Clinical Projects – Cardiac

Below are a few of our publications on cardiac surgery. A more comprehensive list can be found on our Clinical Publications webpage.

Outcomes of reoperative aortic valve replacement after previous sternotomy.  LaPar DJ, Yang Z, Stukenborg GJ, Peeler BB, Kern JA, Kron IL, Ailawadi G. J Thorac Cardiovasc Surg.139(2):263-72, 2010

OBJECTIVE: Increasingly, patients with previous sternotomy require aortic valve replacement. We compared outcomes of reoperative aortic valve replacement after previous sternotomy and primary aortic valve replacement by surgical era. Effect of initial cardiac operation on reoperative aortic valve replacement was also investigated.  METHODS: Between January 1996 and December 2007, a total of 1603 patients undergoing elective aortic valve replacement were entered prospectively into our clinical database. Patients were divided into eras A (1996-1999), B (2000-2003), and C (2004-2007). A total of 191 patients (12%) had previous sternotomy for coronary artery bypass grafting (n = 88), coronary artery bypass grafting with aortic valve replacement (n = 16), aortic valve replacement with or without other aortic procedure (n = 70), and other cardiac procedures (n = 17). Mean ages were 66.5 +/- 13.1 years in reoperative group and 65.5 +/- 14.9 years in primary group.  RESULTS: Mortality in reoperative group decreased significantly with time (A 15.4% vs B 15.1% vs C 2.0%, P = .004) and was equivalent to primary group in era C (3.5% vs 2.0%, P = .65). Major complications also significantly decreased with time in reoperative group (A 25.6% vs B 17.0% vs C 6.1%, P = .006). Importantly, patients had more comorbidities with time and increased preoperative risk in era C. There were no differences in outcome by initial cardiac operation in reoperative group.  CONCLUSIONS: Reoperative aortic valve replacement now carries similar morbidity and mortality to primary replacement. Risk of reoperation is not affected by primary operation.

Is mitral valve repair superior to replacement in elderly patients?  Ailawadi G, Swenson BR, Girotti ME, Gazoni LM, Peeler BB, Kern JA, Fedoruk LM, Kron IL.  Ann Thorac Surg. 86(1):77-85, 2008.

BACKGROUND: Mitral valve replacement is more frequently performed and perceived to be equivalent to repair in elderly patients, despite the superiority of repair in younger patients. Our objective was to compare mitral repair to replacement in elderly patients age 75 years or older. Patients younger than 75 years undergoing mitral valve surgery served as a reference population.  METHODS: Consecutive elderly patients undergoing operation for mitral regurgitation at our institution from 1998 to 2006 were reviewed. Elderly patients (mean age, 78.0 +/- 2.8 years) who underwent mitral repair (n = 70) or replacement (n = 47) were compared with cohorts of young patients (mean age, 58.9 +/- 9.3 years) who underwent repair (n = 100) or replacement (n = 98) during the same period. Patient details and outcomes were compared using univariate, multivariate, and Kaplan-Meier analyses.  RESULTS: Mitral replacement in elderly patients had higher mortality than repair (23.4%, 11 of 47 versus 7.1%, 5 of 70; p = 0.01) or as compared with either operation in the reference group (p < 0.0001). Postoperative stroke was higher in elderly replacement patients compared with repair (12.8%, 6 of 47 versus 0%; p = 0.003) or compared with either young cohort (p = 0.02). Compared with elderly repair patients, elderly replacement patients had more cerebrovascular disease (21.3%, 10 of 47 versus 4.3%, 3 of 70; p = 0.005) and rheumatic mitral valves (21.3%, 10 of 47 versus 0%; p = 0.0001). In the young group, overall complication and mortality were no different between replacement and repair. Long-term survival favored repair over replacement in elderly patients (p = 0.04). One elderly repair patient experienced late recurrence of persistent mitral regurgitation.  CONCLUSIONS: In patients age 75 years or older, mitral repair is associated with a lower risk of mortality, postoperative stroke, and prolonged intensive care unit and hospital stay compared with mitral replacement. Mitral repair can be performed in preference over replacement even in patients older than the age of 75.

Central cannulation is safe in acute aortic dissection repair.  Reece TB, Tribble CG, Smith RL, Singh RR, Stiles BM, Peeler BB, Kern JA, Kron IL. J Thorac Cardiovasc Surg. 133(2):428-34, 2007.

OBJECTIVE: The site of cannulation for the repair of ascending aortic dissection remains controversial. It is not clear whether cannulation of the dissected vessel is safe or even preferred. We hypothesized that cannulation of the dissected aorta could be done safely with acceptable complication and mortality rates in this high-risk population.  METHODS: The charts of repairs of acute ascending aortic dissections (n = 70) from 1996 to 2005 were reviewed. Cannulation was accomplished in 24 patients via the dissected aorta (central) and in 46 patients through cannulation of the femoral or axillary artery (peripheral). All were converted to sidearm cannulation of the graft for reperfusion. Groups were compared on the basis of comorbidities in addition to mortality, complications, hospital stays and final disposition.  RESULTS: The groups were comparable on the basis of age and preoperative comorbidities. Similarly, there were no differences in bypass time, crossclamp time, or hypothermic circulatory arrest time between groups. Hospital mortality and postoperative complications, including stroke, were similar between groups, but the peripheral group experienced more cardiac events (peripheral 15% vs central 0%; P < .05) and higher mortality than the central group (peripheral 19.5% vs central 4.2%; P < .05).  CONCLUSIONS: Direct cannulation of the dissected aorta was safe compared with peripheral cannulation in these patients. Inasmuch as these data demonstrate that cannulation of the dissected ascending aorta is safe, this technique can be used to tailor the cannulation approach to specific anatomic and patient characteristics that might optimize postoperative outcomes in this disease entity.

Early repair of complete atrioventricular septal defect is safe and effective.  Singh RR, Warren PS, Reece TB, Ellman P, Peeler BB, Kron IL. Ann Thorac Surg. 82:1598-601, 2006.

BACKGROUND: Surgical repair of complete atrioventricular septal defect (CAVSD) is a well-established procedure performed on young children. Our hypothesis is that with modern techniques, the current risks of CAVSD repair in children aged younger than 3 months and in children older than 3 months are equal. METHODS: This was a retrospective review of 65 infants and children with a mean age of 10.9 months (range, 1 month to 15.5 years) who underwent CAVSD repair from 1990 to 2004. Twenty-six repairs (40%) were done on or before 3 months of age (group A) and 39 repairs (60%) were done after 3 months of age (group B). In all patients, the ventricular septal defect was repaired with an individualized approach according to each patient's specific anatomy: direct suturing without a patch, interposition of a small pericardial patch with a running suture, or both. The atrioventricular commissure was closed with interrupted sutures, and all atrial defects were closed with a pericardial patch. Data were analyzed using the chi2 analysis and the Fisher exact test. RESULTS: Three hospital deaths occurred (<30 days), 2 in group A and 1 in group B (7.7% vs 2.6%, respectively, p = 0.33). One death in group A occurred during another noncardiac surgery. Early reoperation (<1 year of initial surgery) for residual ventricular septal defect or significant mitral regurgitation, or both, occurred in 3 group A patients and in 4 group B patients (11.5% versus 10.3% respectively, p = 0.68). CONCLUSIONS: These results suggest that repair of CAVSD defects in children 3 months of age or younger had similar outcomes compared with those who underwent surgical repair after 3 months of age.

Elimination of fat microemboli during cardiopulmonary bypass. Kaza AK, Cope JT, Fiser SM, Long SM, Kern JA, Kron IL, Tribble CG. Ann Thorac Surg. 75:555-9, 2003.

BACKGROUND: Fat emboli have been implicated in cerebral dysfunction after cardiopulmonary bypass (CPB). We sought to identify the source of fat emboli during CPB and devise a technique for their elimination. METHODS: Patients undergoing CPB were prospectively randomized to either cardiotomy suction (n = 7) or cell-saving suction device (n = 6). Blood was collected at various intervals during CPB, and the fat emboli were identified using oil red O stain. These emboli were grouped based on their diameter into 10- to 50-microm and more than 50-microm particles. The number of fat emboli per slide examined was graded according to the following scale: 1 (1 to 10), 2 (11 to 20), 3 (21 to 30), and 4 (> 30 emboli). In the second phase of the experiment, a 21-microm filter was attached in series, distal to the cardiotomy reservoir (n = 6), and fat emboli were quantified. RESULTS: Blood from the pericardial well was saturated with fat emboli of both sizes. Patients randomized to the cardiotomy suction had a significantly higher number of fat emboli at the end of CPB when compared with those randomized to the cell-saving suction device and dual-filter group. Processed blood from both the cardiotomy reservoir and cell-saving device was noted to have an abundance of fat emboli when compared with blood processed through the dual filters. CONCLUSIONS: Processed blood from both the cardiotomy reservoir and cell-saving device appear to have an abundance of fat emboli that are completely eliminated by using a 21-microm arterial filter in series with the cardiotomy reservoir. This intervention could potentially reduce neurocognitive dysfunction associated with CPB.

When to Discontinue Postcardiotomy Extra-corporeal Membrane Oxygenation. Fiser SM, Tribble CG, Kaza AK, Long SM, Zacour RK, Kern JA, and Kron IL. Ann Thorac Surg. 71(1):210-4, 2001.

BACKGROUND: Extracorporeal membrane oxygenation (ECMO) has demonstrated limited success in adult postcardiotomy shock. The goal of this study was to determine when to discontinue ECMO for postcardiotomy support. METHODS: During a 7-year period ECMO was used in 51 postcardiotomy patients, of whom 16 (31%) weaned and 8 (16%) survived. RESULTS: Patients in the heart transplant group were more likely to wean compared with patients in the non-heart transplant group (p = 0.03). Patients aged greater than 65 years (p = 0.04) or with ejection fractions of less than 30% after 48 hours of ECMO (p < 0.001) were less likely to wean. Time on ECMO was significantly longer for survivors in the heart transplant group (101.3 +/- 7.5 hours) compared with survivors in the non-heart transplant group (28.3 +/- 11.9 hours, p < 0.001). CONCLUSIONS: After 48 to 72 hours, consideration should be given to discontinuing ECMO, either by moving to an implantable ventricular assist device or by withdrawal of support, except in those patients with heart transplants. In the latter, both severe postoperative pulmonary hypertension and reperfusion injury may take as long as 120 hours to reverse.

Does the additive risk mitral valve repair in patients with ischemic cardiomyopathy prohibit surgical intervention? Gangemi JJ Tribble CG, Ross SD, McPherson JA, Kern JA, and Kron IL. Annals of Surgery. 231(5):710-4, 2000.

Objective: To assess the surgical risk of additional mitral valve repairs in patients with ischemic cardiomyopathy.
Summary and Background Data: Severe mitral regurgitation in patients with ischemic cardiomyopathy increases the death rate and symptomatic status. The 1-year survival rate for medical therapy in this subset of patients is less than 20%. Transplantation is usually not feasible because of donor shortage and death while on the waiting list.
Methods: To assess additive risk, a retrospective chart review from 1993 to 1998 was performed comparing patients with ischemic cardiomyopathy (ejection fraction [EF] <25%) and severe mitral regurgitation undergoing mitral valve repair and coronary artery bypass graft operations with patients with an EF of <25% undergoing coronary artery bypass graft alone. These groups were also compared with 140 patients receiving heart transplants since 1993 (group 3).
Results: The overall hospital death rate for group 1 was 6.3%. The one death occurred 2 weeks after surgery secondary to sepsis. This was not significantly different from the death rate of 4.1% in group 2. In group 1, there were two deaths at 1 year (87% survival rate), one related to heart failure. One patient was New York Heart Association (NYHA) class IV at 1 year; the remainder of patients were NYHA class I-II. These results were not significantly different than the 8% death rate noted with transplantation. There was no change in EF and minimal residual mitral regurgitation in group 1 based on postoperative transesophageal echocardiography, whereas group 2 had an average 11.7% improvement in EF.
Conclusions: Previously, severe mitral regurgitation in the setting of ischemic cardiomyopathy has been associated with poor survival. In these authors' experience, repairing the mitral valve along with coronary artery bypass grafting does not increase the surgical risk, yields improvement in symptomatic status, and compares favorably to coronary artery bypass grafting alone and cardiac transplantation. However, the lack of change in EF in these patients probably represents an overestimation of the EF before surgery secondary to severe mitral regurgitation.