Strategies for endovascular mitral valve repair.

Technological advances have recently enabled mitral valve repair to be performed using endovascular techniques and thus open the possibility of nonsurgical treatment of mitral valve disease. While balloon valvotomy has been applied to mitral stenosis for over 20 years, a number of devices aimed at correcting mitral regurgitation are currently in preclinical and clinical development. While some of these, such as edge-to-edge repair, are catheter adaptations of established surgical techniques, others represent true departures from the current surgical paradigms of correcting mitral regurgitation. This review will summarize the current status of percutaneous transcatheter techniques for mitral valve repair. Included are balloon mitral valvotomy, indirect annuloplasty, direct annuloplasty, ventricular shape change, and edge-to-edge repair. These techniques certainly represent a new interdisciplinary paradigm between cardiac surgery and interventional cardiology and may be the next frontier in minimally-invasive cardiac surgery.

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.

Does coronary artery bypass grafting alone correct moderate ischemic mitral regurgitation?

BACKGROUND: The optimal management of moderate (3+ on a scale of 0 to 4+) ischemic mitral regurgitation (MR) remains controversial. Some advocate CABG alone, whereas others favor concomitant mitral annuloplasty. To clarify the optimal management of these patients, we evaluated the early impact of isolated CABG on moderate ischemic MR. METHODS AND RESULTS: Between January 1992 and August 1999, 136 patients (54% male, mean age 70.5 years, mean New York Heart Association class 2.7, mean ejection fraction 38.1%) with a preoperative diagnosis of moderate ischemic MR, without leaflet prolapse or pathology, underwent isolated CABG. Thirty-eight (28%) of 136 patients had intraoperative transesophageal echocardiography (TEE) before CABG, and 68 (50%) had postoperative transthoracic echocardiography (TTE) within 6 weeks of surgery. The subgroups of patients undergoing intraoperative TEE and postoperative TTE had preoperative characteristics similar to the overall group. The 30-day operative mortality was 2.9% (). Intraoperative TEE downgraded the severity of MR to mild or less (0 to 2+) in 89% (). On postoperative TTE, 40% () continued to have at least moderate MR (3 to 4+), 51% () improved somewhat to mild (2+) MR, and only 9% () had resolution of their MR (0 to 1+). The mean preoperative, intraoperative, and postoperative MR grades were 3.0+/-0.0, 1.4+/-1.0, and 2.3+/-0.8, respectively (P<0.001). CONCLUSIONS: CABG alone for moderate ischemic MR leaves many patients with significant residual MR and may not be the optimal therapy for most patients. Intraoperative TEE may significantly underestimate the severity of ischemic MR. A preoperative diagnosis of moderate MR may warrant concomitant mitral annuloplasty.

Sustained angina relief 5 years after transmyocardial laser revascularization with a CO(2) laser.

BACKGROUND: Although transmyocardial laser revascularization (TMR) has provided symptomatic relief of angina over the short term, the long-term efficacy of the procedure is unknown. Angina symptoms as assessed independently by angina class and the Seattle Angina Questionnaire (SAQ) were prospectively collected up to 7 years after TMR. METHODS: Seventy-eight patients with severe angina not amenable to conventional revascularization were treated with a CO(2) laser. Their mean age was 61+/-10 years at the time of treatment. Preoperatively, 66% had unstable angina, 73% had had >/=1 myocardial infarction, 93% had undergone >/=1 CABG, 42% had >/=1 PTCA, 76% were in angina class IV, and 24% were in angina class III. Their average pre-TMR angina class was 3.7+/-0.4. RESULTS: After an average of 5 years (and up to 7 years) of follow-up, the average angina class was significantly improved to 1.6+/-1 (P=0.0001). This was unchanged from the 1.5+/-1 average angina class at 1 year postoperatively (P=NS). There was a marked redistribution according to angina class, with 81% of the patients in class II or better, and 17% of the patients had no angina 5 years after TMR. A decrease of >/=2 angina classes was considered significant, and by this criterion, 68% of the patients had successful long-term angina relief. The angina class results were further confirmed with the SAQ; 5-year SAQ scores revealed an average improvement of 170% over the baseline results. CONCLUSIONS: The long-term efficacy of TMR persists for >/=5 years. TMR with CO(2) laser as sole therapy for severe disabling angina provides significant long-term angina relief.

Long-term results of multivalve surgery for infective multivalve endocarditis.

OBJECTIVE: The natural history of medically treated multivalvular endocarditis is associated with dismal short and long term survival. However, the impact of surgical intervention on these results is relatively unknown. The objective of this retrospective study was to report our long-term results in patients requiring multivalve surgery for multivalvular endocarditis. METHODS AND RESULTS: Over a 24 year period beginning in 1972, multivalve surgical procedures were performed on 63 patients for infective endocarditis. Prosthetic valve endocarditis was present in 25 (40%), and acute or active endocarditis in 38 (60%). The early mortality was 16%. Out of 53 patients discharged from the hospital 87+/-4% were alive at 5 years and 64+/-9% at 10 years. There was no difference in early or late mortality between patients with prosthetic and native endocarditis (P=0.15 and P=0.77 for early and late mortality, respectively). The presence of active endocarditis did not affect operative outcome or late mortality. Twenty-one patients (88%) were in NYHA FC I, and none were in NYHA FC IV. The only prognostic factor of early and late mortality was the presence of an abscess at the time of the surgery. CONCLUSIONS: These results indicate that multivalve infective endocarditis treated surgically is associated with acceptable early and late mortality and excellent postoperative functional status. The early surgical intervention prior to an abscess formation offers the best chance for survival of patients with multivalve endocarditis.

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.

Modified Glenn connection for acutely ischemic right ventricular failure reverses secondary left ventricular dysfunction.

BACKGROUND: Right heart failure after cardiopulmonary bypass can result in severe hemodynamic compromise with high mortality, but the underlying mechanisms remain poorly understood. After ischemia-induced right ventricular failure, alterations in the interventricular septal position decrease left ventricular compliance and limit filling but may also distort left ventricular geometry and compromise contractility and relaxation. This study investigated the effect of acute isolated right ventricular ischemia on biventricular performance and interaction and the response of subsequent right ventricular unloading by use of a modified Glenn shunt. METHODS: In 8 pigs isolated right ventricular ischemic failure was induced by means of selective coronary ligation. A modified Glenn circuit was then established by a superior vena cava-pulmonary artery connection. Ventricular performance was determined by conductance catheter-derived right ventricular pressure-volume loops and left ventricular pressure-segment length loops. Hemodynamic data at baseline, after right ventricular ischemia, and after institution of the Glenn circuit were obtained during inflow occlusion, and the load-independent contractile indices were derived. RESULTS: Right ventricular free-wall ischemia resulted in acute right ventricular dilation (118 +/- 81 mL vs 169 +/- 70 mL, P =.0008) and impairment of left ventricular contractility indicated by the reduced end-systolic pressure-volume relation slope (50.0 +/- 19 mm Hg/mm vs 18.9 +/- 8 mm Hg/mm, P =.002) and preload recruitable stroke work index slope (69.6 +/- 26 erg x cm(-3) x 10(3) vs 39.7 +/- 13 erg x cm(-3) x 10(3), P =.003). In addition, left ventricular relaxation (tau) was significantly prolonged (33.3 +/- 10 ms vs 53.0 +/- 16 ms, P =.012). Right ventricular unloading with the Glenn shunt reduced right ventricular dilation and significantly improved left ventricular contraction, end-systolic pressure-volume relation slope (18.9 +/- 8 mm Hg/mm vs 35.8 +/- 18 mm Hg/mm, P =.002), preload recruitable stroke work index slope (39.7 +/- 26 erg x cm(-3) x 10(3) vs 63.0 +/- 22 erg x cm(-3) x 10(3), P =.003), and diastolic performance (tau 53.0 +/- 16 ms vs 43.5 +/- 13 ms, P =.001). CONCLUSIONS: Right ventricular ischemia-induced dilation resulted in acute impairment of left ventricular contractility and relaxation. A modified Glenn shunt attenuated the left ventricular dysfunction by limiting right ventricular dilation and restoring left ventricular cavity geometry.

Reoperative CABG using left thoracotomy: a tailored strategy.

BACKGROUND: Reoperative coronary artery bypass grafting (CABG) through a left thoracotomy is a challenging operation with no one dominant approach. We developed a tailored strategy for this difficult group of patients, integrating the currently available newer technologies for each patient indication. METHODS: Between October 1991 and October 1999, 50 consecutive patients underwent reoperative CABG through a left thoracotomy. Age was 65 +/- 9 years, 40 (80%) were men, and preoperative ejection fraction was 40 +/- 13. In 36 patients (72%) the left internal mammary artery had been placed to the left anterior descending coronary artery during the primary CABG and in 25 of 36 patients (70%) this left internal mammary artery-left anterior descending coronary artery graft was patent. The mean duration from previous CABG was 8.0 +/- 4.8 years. Three approaches were used: (1) conventional cardiopulmonary bypass using fibrillatory or circulatory arrest (n = 33, 66%); (2) Heartport endoaortic balloon occlusion (n = 4, 8%); and (3) off-pump beating heart techniques (n = 13, 26%). RESULTS: The off-pump CABG technique was used in the majority of recent patients and 1 (7.7%) had to be converted to cardiopulmonary bypass due to hemodynamic instability. When cardiopulmonary bypass was used its duration was 122 +/- 59 minutes and mean temperature on bypass was 24 degrees +/- 6 degrees C. In the 4 patients in whom the Heartport system was used, the median endoaortic occlusion duration was 49 minutes. Patients received an average of 1.4 grafts/patient. In 60 of 70 patients (89%) distal anastomoses were performed to an anterolateral coronary target. There were 3 of 50 (6%) operative deaths, 2 in the conventional group and 1 in the endoaortic balloon occlusion group. The mean length of stay in the 47 survivors was 7.8 +/- 3.9 days (median, 7 days). CONCLUSIONS: Reoperative CABG by left thoracotomy remains a challenging operation. Several techniques, including off-pump CABG, conventional cardiopulmonary bypass, circulatory arrest, and endoaortic balloon occlusion, should be in the surgeon's armamentarium to allow a tailored approach for each operation based on patient indications.

Medium-term follow up of pulmonary autograft aortic valve replacement: technical advances and echocardiographic follow up.

BACKGROUND AND AIM OF THE STUDY: The Ross procedure (aortic valve replacement (AVR) with pulmonary autograft and pulmonary homograft replacement of pulmonary valve) was developed as a durable aortic valve substitute that avoids the need for anticoagulation and provides young patients with a long-lasting aortic valve substitute. Our seven-year follow up echocardiography data are reviewed. METHODS: Between May 1993 and March 2000, 40 adult patients (28 males, 12 females; mean age 33.3 years) underwent the Ross procedure at the Brigham and Women's Hospital for congenital aortic stenosis (n = 6), aortic insufficiency (n = 17) and mixed disease (n = 17). All patients had aortic root replacement with the pulmonary autograft and had no regurgitation after operation. Postoperative evaluation was conducted by transthoracic echocardiography, office visit and/or telephone interview. NYHA functional class, aortic and pulmonary valve function and aortic root dimensions were evaluated. RESULTS: One patient died postoperatively as a result of a low output state related to global left ventricular dysfunction. Four patients (10%) developed pulmonary homograft stenosis with a peak gradient >40mmHg; and six developed mild pulmonary stenosis. One patient had aortic insufficiency seven years postoperatively that required valve replacement. Eight patients developed mild dilatation (>37 mm) of the neoaortic root, and five of these had aortic insufficiency. One patient required transplantation at 40 months for restrictive cardiomyopathy. CONCLUSION: The Ross procedure is an effective means of AVR that can be accomplished with low perioperative morbidity and mortality if certain technical modifications are carried out. In this series of 40 patients with mid-term follow up, a significant number developed moderate pulmonary trunk stenosis, though echo characterization demonstrated good valve function.

Minimally invasive valve surgery.

BACKGROUND: Cardiac surgery has been the last area of clinical surgery to adopt and embrace minimally invasive surgical techniques. Since the onset of arterial embolectomy in 1965, arthroscopic knee surgery performed in 1975 and laparoscopic cholecystectomy in 1985, huge advances in videoscopic, thorascopic and small incision surgery has taken place in all specialties which now allow change in the traditional approaches to cardiac valve surgery. In 1996, the Brigham and Women's Hospital, along with other units, began minimally invasive cardiac valve surgery for patients who had isolated valve pathology without coronary disease. Our experience now totals 689 patients, including 353 minimally invasive mitral valve repair/replacements and 336 minimally invasive aortic valve replacements, including root replacement and reoperations. METHODS: This new operative approach involves smaller incisions, the mandatory use of transesophageal echocardiogram for the monitoring of operation quality and air removal, newer perfusion techniques and some modifications in the standard valve repair/replacement techniques. With this blending of TEE, better perfusion techniques and new exposure, the safety and quality of valve operations by these techniques have been excellent. RESULTS AND CONCLUSION: The operative mortality is equal to (AVR) or less than (MVP) conventional open sternotomy cases and there is a shorter length of stay in the ICU and post-ICU, leading to a lower cost than conventional procedures. There are also less blood transfusions, atrial fibrillation and posthospital rehabilitation requirements, and patients have indicated that there is a faster return to normality over the conventional operative approaches. This brief report summarizes our experience from July, 1996 to January 2001.

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.

Excimer versus carbon dioxide transmyocardial laser revascularization: effects on regional left ventricular function and perfusion.

BACKGROUND: Transmyocardial laser revascularization (TMR) has been established with the carbon dioxide (CO2) laser. The largely unstudied excimer laser creates channels through chemical bond dissociation instead of thermal ablation, thereby avoiding thermal injury. We sought to compare the effects of CO2 and excimer TMR in a porcine model of chronic ischemia. METHODS: Pigs underwent ameroid constrictor placement on the circumflex artery to create chronic ischemia. TMR was performed with CO2 (n = 8) or excimer (n = 8) laser 6 weeks later; controls (n = 7) had ameroid placement only. Regional myocardial blood flow (RMBF), determined by radioactive microspheres, and regional myocardial function, determined by percent segmental shortening (%SS), were assessed 18 weeks after ameroid placement. RESULTS: Values are mean +/- SD. In the ischemic zone, RMBF (mL/min/g) was improved in the CO2 (0.73 +/- 0.19) and excimer (0.78 +/- 0.22) groups when compared with controls (0.55% +/- 0.12%, p < 0.05). %SS was also improved in the CO2 (15.2% +/- 5.5%) and excimer (15.3% +/- 5.1%) groups when compared with controls (8.0% +/- 4.2%, p < 0.05). CONCLUSIONS: Excimer and CO2 TMR significantly improve RMBF and regional function in this porcine model of chronic myocardial ischemia despite fundamentally different tissue interactions.

LV-powered coronary sinus retroperfusion reduces infarct size in acutely ischemic pigs.

BACKGROUND: We developed a prosthetic left ventricle (LV) to coronary sinus (CS) shunt (LVCSS) that is autoregulating and provides LV-powered retrograde perfusion of the coronary sinus. METHODS: Each of 20 Yorkshire pigs underwent 1 hour of left anterior descending diagonal artery occlusion followed by 3 hours of reperfusion. The controls (n = 5) did not have shunt treatment. The LVCSS group (n = 9) underwent shunt treatment during the ischemic period. The LVCSS with partial coronary sinus occlusion (PCSO) group (LVCSS+PCSO, n = 6) underwent shunt treatment and PCSO during the ischemic period. Vital staining and planimetry techniques were used to determine the area at risk for infarction and the area of necrosis. RESULTS: The area at risk was not significantly different among groups. The area of necrosis was decreased by 53% in the LVCSS group and by 73% in the LVCSS+PCSO group when compared to controls (p<0.01 among all groups). CONCLUSIONS: The LVCSS reduces infarct size in pigs after acute coronary artery occlusion. The addition of PCSO to LVCSS further improves myocardial salvage.