An External Aortic Root Device for Decreasing Aortic Regurgitation: In Vitro and In Vivo Animal Studies

Objectives: The purpose of this study was to determine if a device placed externally around the aortic root decreases regurgitant flow in acute aortic regurgitation. Background: Aortic regurgitant flow is dependent on central aortic pressure and the aortic root and leaflet geometry. It may be possible to decrease aortic regurgitant severity by reducing aortic root size or dimension changes. Methods: Aortic regurgitation was created in eight calf heart specimens suspended in a continuous flow system. Retrograde and antegrade aortic flow and distending aortic pressure were measured at baseline and after placement of an external aortic device at the level of the aortic annulus. In two additional specimens, the incompetent aortic valve was visualized fiberoptically before and after placement of the external device. Acute aortic regurgitation was created surgically in four live calves by excising a portion of the aortic leaflets. Antegrade and retrograde flow, left ventricular pressure, and central aortic pressure were measured at baseline, after creation of aortic regurgitation, and after placement of the external device. Results: In the in vitro calf specimens, regurgitant flow decreased from 46.9 cc/sec to 15.1 cc/sec (66.0%± 21.8% decrease) after placement of the external device (p < 0.001). The regurgitant orifice area decreased from 0.13 ± 0.04 cm² to 0.04 ± 0.02 cm² after device placement (p < 0.001). Antegrade flow was reduced to a smaller extent (20.0%± 19.2% decrease) by the device (p < 0.05). Placement of the device around the aorta resulted in improved coaptation of the leaflets with a marked reduction in defect size by endoscopic visualization. Use of the external aortic device was associated with improvement in aortic regurgitant severity in three of four calves with surgically created aortic regurgitation. Concluslons: In these preliminary studies, acute experimental aortic regurgitant severity is decreased by the use of an external aortic device, probably due to reduction in aortic annular dimension changes and improved aortic leaflet apposition. Further studies are needed to determine the effectiveness of this device in chronic aortic regurgitation. (J Card Surg 1994;9:304–313)     

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.     

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.     

One thousand minimally invasive valve operations: early and late results

OBJECTIVE: We sought to evaluate the potential benefits of minimally invasive approaches for treatment of isolated aortic and mitral valve disease. METHODS: From 7/96 to 04/03, we performed 1000 minimally invasive valve operations: 526 aortic (AV) procedures (64 years; mean, 25-95) and 474 mitral (MV) procedures (58 years; mean, 17-90). RESULTS: In the AV group, an upper ministernotomy was used in 492/526 patients (93%) and a right parasternal approach in 34 (7%). Sixty-three patients had reoperative aortic valve replacements. In the MV group lower sternotomy was used in 260/474 (55%), right parasternal in 200/474 (42%), and a right thoracotomy in 14 patients. MV repair was performed in 416 and MV replacement in 58 patients. Operative mortality was 12/526 (2%) in the AV and 1/474 (0.2%) in the MV group. Freedom from reoperation at 6 years was 99% and 95% in the AV and MV group, respectively. Late mortality was 5% in the AV and 3% in the MV group, respectively. CONCLUSIONS: Minimally invasive valve surgery can be performed at very low levels of morbidity and mortality, with results equal to or better than conventional techniques. All forms of valve repair and replacement operations can be performed. Long-term survival and freedom from reoperation are excellent.     

Management of mild aortic stenosis during coronary artery bypass surgery: an update, 1992-2001

BACKGROUND: "Prophylactic" aortic valve replacement (AVR) in patients with asymptomatic, mild-to-moderate aortic stenosis (AS) at the time of CABG is controversial. In 1994, we reported our initial experience involving 44 patients and have now updated our series in an attempt to further evaluate outcomes. METHODS: Between January 1992 and July 2001, 100 consecutive patients underwent reoperative AVR following previous CABG. Forty patients had their initial surgery at the Brigham & Women's Hospital (BWH) and 60 patients had their coronary surgery elsewhere. None of the 40 BWH patients had a mean valve gradient greater than 25 mmHg at the time of CABG. RESULTS: The mean time interval from CABG to AVR for the entire group was 9.0 years (range: 1.4-21 years). Overall operative mortality (OM) was 7% including 5 deaths (10.2%) among 49 patients requiring additional CABG at the time of AVR and 2 deaths (3.9%) among 51 patients without additional coronary artery intervention. This OM rate was a notable decrease from our earlier report of 18.2% (P = 0.07). Furthermore, operative mortality decreased progressively from 15.4% in 1992-1993 to 0% in 2000-2001 (P = NS). CONCLUSION: The OM of reoperative AVR following CABG has fallen in recent years. Given the relevance of newer techniques and approaches, it may be reasonable to adopt an expectant management approach in patients with asymptomatic mild-to-moderate AS (i.e., mean systolic gradient less than 25 mmHg) at the time of CABG.     

Evaluation of Trauma Care Resources in Health Centers and Referral Hospitals in Cambodia

Background  The aim of this study was to evaluate the available resources for trauma care at health centers (HCs) and referral hospitals (RHs) in rural Cambodia and to examine whether the resources at HCs are allocated on the basis of actual need based on the referral distance and number of severely injured patients referred to RHs. Methods  We conducted a cross-sectional facility survey by phone interview or mail using structured questionnaires at nationally representative samples of 85 HCs and 17 RHs from December 2006 to April 2007. The questionnaire included a modified checklist of the guidelines for essential trauma care as well as questions on distance for referral and the number of injured patients received and referred during the last 3 months. We analyzed the association between resource availability at HCs and their need using multivariate linear regression. Results  Median (interquartile range) numbers of available resources at HCs and RHs were 25.5 (22.0–27.5) and 35 (28–41) among 37 and 62 essential items, respectively. Basic equipment, including both consumable supplies and durable devices and life-saving knowledge/skills, were not satisfactory at either HCs or RHs. A longer distance to the RH was associated with more knowledge/skills but not with equipment supplies; the number of referred patients was not associated with equipment or knowledge/skills. Conclusions  Staff training emphasizing life-saving knowledge/skills and better organization and planning to supply physical resources are needed. There is a gap between resource allocation and need, which should be addressed through clear policies to prioritize remote areas and to allocate resources based on reliable injury data. Part of this study was presented at an annual conference of the Japan Association for the Surgery of Trauma, Okinawa, May 2008.     

Intraoperative detection of pulmonary thromboemboli with epicardial echocardiography.

We report a novel intraoperative use of epicardial echocardiography in detecting and guiding the removal of pulmonary arterial thromboemboli. We describe a patient with a right atrial thrombus that could not be visualized with intraoperative transesophageal echocardiography. Because we suspected acute pulmonary embolization, epicardial echocardiography was used to visualize the right and left pulmonary arteries. Pulmonary thromboemboli were identified, and pulmonary thromboembolectomy was successfully performed.