Mitral valve repair in redo cardiac surgery.

An increasing number of patients are being referred for mitral valve repair in the redo cardiac surgery setting. The most common clinical scenarios involve prior coronary bypass surgery or aortic valve replacement, each presenting special challenges in terms of gaining valve exposure to enable repair while limiting dissection as much as possible. A right anterior thoracotomy approach is preferred in most patients, coupled with hypothermic fibrillatory arrest. A repeat sternotomy may be favored in select circumstances such as when there is a need for bypass grafting or moderate aortic insufficiency is present. Special attention to cannulation techniques, perfusion conditions, valve exposure, and de-airing maneuvers are all important to ensure good clinical results. Using a tailored approach we have performed mitral valve repair in 22 patients with a patent left internal mammary artery graft following coronary artery bypass grafting between July 1992 and February 2000 with acceptable morbidity and low mortality.

The preferred approach for mitral valve surgery after CABG: right thoracotomy, hypothermia and avoidance of LIMA-LAD graft.

BACKGROUND AND AIM OF THE STUDY: An alternative to avoid redo sternotomy in patients with patent left internal mammary artery-left anterior descending coronary artery (LIMA-LAD) grafts undergoing mitral valve surgery is right thoracotomy with moderate-deep hypothermia (approximately 20 degrees C) and fibrillatory arrest without aortic cross-clamping. Few reports exist which directly compare re-sternotomy and right thoracotomy. METHODS: Between July 1992 and February 2000, 47 patients (39 males, eight females; median age 66 years; range: 41-83 years; 41 in NYHA class III or IV) with patent LIMA-LAD grafts underwent mitral valve surgery. Thirty-seven patients were approached through a right thoracotomy with moderate-deep hypothermia (median 20 degrees C) and fibrillatory arrest (right thoracotomy group), and 10 were approached through a re-sternotomy, with aortic cross-clamping and cardioplegic arrest. The median ejection fraction was 42% (range: 20-71%). Univariate analysis was used to determine predictors of outcome, as well as to evaluate differences in characteristics between groups. RESULTS: Operative mortality (OM) and perioperative myocardial infarction for the entire cohort was 11% and 10%, respectively, and there were no inter-group differences. No preoperative characteristics were associated with OM. Two LIMA-LAD graft injuries occurred in the re-sternotomy group compared with none in the right thoracotomy group (20% versus 0%, p = 0.04). Transfusion requirements were also greater in the redo sternotomy group (median 7 versus 2 packed red blood cell units, p = 0.04). CONCLUSION: Right thoracotomy with moderate-deep hypothermia and fibrillatory arrest is the preferred approach for reoperative mitral valve surgery after coronary artery bypass grafting in the presence of patent LIMA-LAD grafts. These data suggest that this approach is associated with decreased incidence of LIMA-LAD graft injury, as well as reduced transfusion requirements.

Aortic valve reoperation after homograft or autograft replacement.

BACKGROUND AND AIM OF THE STUDY: With increasing use of homograft and autograft aortic valves for aortic valve replacement (AVR), more patients will be presenting for aortic valve reoperation due to structural degeneration of the homograft or autograft valve. Management options include homograft re-replacement, which may require extensive surgery, versus AVR with a mechanical valve or a stented xenograft. Here, results are reported in 18 consecutive patients who underwent aortic valve re-replacement (AVreR) after previous homograft or autograft insertion. METHODS: Between May 1976 and March 2001, 18 patients underwent AVR after previous homograft (n = 16) or autograft (n = 2) insertion. The homograft or autograft had been implanted as a full root in eight patients (44%), as a mini-root in one (6%), and in the subcoronary position in nine (50%). Indication for the reoperation was structural valve degeneration (n = 14; 72%) in one occasion combined with aneurysm of the homograft, or endocarditis (n = 4; 22%), and seven (39%) presented as a non-elective procedure. The median interval between the two operations was 5.4 years (range: 0.3-10.8 years). RESULTS: Fourteen patients (78%) received either a mechanical valve (n = 12; 67%) or a stented xenograft valve (n = 2; 11%). Four others (22%) required root re-replacement with either another homograft (n = 3) or a mechanical valved conduit (n = 1) for endocarditis (n = 2) or an associated aneurysm (n = 2). Overall hospital mortality was 11% (n = 2) due to stroke (n = 1) or respiratory failure (n = 1). Two patients died 3.1 and 7.0 years after the procedure. CONCLUSION: Aortic valve reoperation after previous homograft or autograft implantation is a rare operation and presents a high-risk group. A simplified approach was preferred by utilizing mechanical or stented xenograft valves at reoperation, while homograft re-replacement was reserved for endocarditis or an associated aneurysm.

Minimal access aortic root, valve, and complex ascending aortic surgery.

We report our entire experience with minimal access aortic root, valve, and complex ascending aortic surgery. A total of 290 consecutive patients underwent aortic root, valve, and ascending aortic surgery between July 1996 and February 2000. Four groups were identified: isolated aortic valve replacement (AV group, n = 227), aortic root replacement (AR group, n = 44), aortic valve replacement with concomitant replacement of the supracoronary ascending aorta (V/A group, n = 9), and isolated ascending aortic replacement (AA group, n = 10). The procedures were performed through a partial upper hemisternotomy (87%) or a right parasternal approach (13%). Overall mortality was 3.1% (n = 7) for the AV group, 2.3% (n = 1) for the AR group, 0% for the V/A group, and 10.0% (n = 1) for the AA group. Complications included reoperation for bleeding in 10 (4.5%), two (4.7%), one (11.1%), and one (11.1%) for the four groups respectively; and sternal wound infection in eight (3.6%) patients of the AV group and one (2.3%) patient of the AR group. Five (2.3%) patients of the AV group suffered stroke. Isolated or more complicated aortic valve, root and ascending aortic surgery is feasible and safe through a minimally invasive approach with acceptable incidence of complications and mortality, without compromising the efficacy of the procedure.

Partial upper re-sternotomy for aortic valve replacement or re-replacement after previous cardiac surgery.

OBJECTIVE: We developed techniques for 'inverted T' partial upper re-sternotomy for aortic valve replacement (AVR) or re-replacement (AVreR) after previous cardiac surgery. We previously reported on decreased blood loss, transfusion requirements and total operative duration when compared to conventional full re-sternotomy. This report updates our series, one of the few to document a substantial benefit from a 'minimally-invasive' approach, refines a number of technical aspects of this new approach and reports follow-up. METHODS: Between November 1996 and December 1999, we performed 34 AVRs or AVreRs after previous cardiac surgery by use of an 'inverted T' partial upper re-sternotomy. There were 25 (74%) men. Median ejection fraction was 54%, range 15-80%. Median age was 72, range 38-93. All were New York Heart Association functional class (NYHA) functional class II or III. Twenty-one (62%) had previous coronary artery bypass grafts (CABG) while 14 (41%) had previous valve surgery. Follow-up was 100% complete for a total of 593 patient months (median 19 months). RESULTS: Twenty-three (66%) underwent AVR of the native aortic valve while 11 (33%) underwent AVreR of a prosthetic aortic valve. There were no intraoperative or valve-related complications, and no conversion to full re-sternotomy was necessary. There were two (5.9%) operative deaths from an arrhythmia on postoperative day 4 and a large stroke during surgery, respectively. Twenty-four (75%) patients were free of major complications. There was no need for reoperation for bleeding and patients required a median of two units of packed red blood cells. Complications included new atrial fibrillation (n=3, 9%), pacemaker implantation (n=3, 9%) and deep sternal wound infection (n=2, 6%). Median lengths of stay in the intensive care unit (ICU) and in the hospital were 1 and 7 days, respectively. There was one (3%) late deep sternal wound infection and 2/32 (6%) late deaths due to congestive heart failure at 22 months and myocardial infarction at 23 months, respectively. CONCLUSIONS: Partial upper re-sternotomy presents a safe and effective alternative approach to AVR and AVreR after previous cardiac surgery, and is associated with low morbidity and mortality.

Myocardial neutrophil sequestration during reperfusion of the transplanted rabbit heart.

BACKGROUND: Neutrophils are major participants in myocardial reperfusion injury, but the relationship between ischemic time and the extent of the neutrophil sequestration in heart transplantation has not yet been systematically studied. This study was designed to determine whether increased ischemic time would cause greater neutrophil sequestration during reperfusion of the globally ischemic heart. METHODS: Rabbit hearts were arrested with cardioplegia, explanted, and subjected to either 1 or 4 hours of global ischemia at 4 degrees C before being heterotopically transplanted into a recipient rabbit's abdomen for reperfusion. Each heart was reperfused for either 4, 8, or 12 hours. Between 3 and 7 hearts were studied (average = 5.8) for each combination of ischemic and reperfusion time (total = 35). A myeloperoxidase (MPO) assay was used to qualify neutrophil content. RESULTS: MPO activity (U/g wet weight) was not significantly different at 4, 8, and 12 hours of reperfusion (0.33 +/- 0.05, 0.20 +/- 0.04, 0.26 +/- 0.04: p = 0.13), but was significantly increased at 4 hours compared to 1 hour ischemia (0.34 +/- 0.04 vs 0.19 +/- 0.03: p = 0. 006). Interaction between ischemic and reperfusion times was not significant (p = 0.12). MPO activity was below the measurable threshold in 5 freshly excised control hearts. CONCLUSIONS: These results suggest that acute reperfusion injury will be more severe in the hearts subjected to 4 hours ischemia and indicate the need to consider neutrophil-mediated reperfusion injury when addressing cardioprotective interventions for cardiac preservation and reperfusion after transplantation. Neutrophil-mediated reperfusion injury of the rabbit myocardium after heterotopical transplantation is more severe in hearts subjected to 4 hours of ischemia vs 1 hour of ischemia prior to transplantation.