Current era minimally invasive aortic valve replacement: techniques and practice.

BACKGROUND: Since the first aortic valve replacement through a right thoracotomy was reported in 1993, upper hemisternotomy and right anterior thoracotomy have become the predominant approaches for minimally invasive aortic valve replacement. Clinical studies have documented equivalent operative mortality, less bleeding, and reduced intensive care/hospital stay compared with conventional sternotomy despite longer procedure times. However, comparative trials face challenges due to patient preference, surgeon bias, and the lack of a standardized minimally invasive surgical approach. METHODS: Twenty cardiothoracic surgeons from 19 institutions across the United States, with a combined experience of nearly 5000 minimally invasive aortic valve replacement operations, formed a working group to develop a basis for a standardized approach to patient evaluation, operative technique, and postoperative care. In addition, a stepwise learning program for surgeons was outlined. RESULTS: Improved cosmesis, less pain and narcotic use, and faster recovery have been reported and generally accepted by patients and by surgeons performing minimally invasive aortic valve replacement. These benefits are more likely to be verified with standardization of the procedure itself, which will greatly facilitate the design and implementation of future clinical studies. CONCLUSIONS: Surgeons interested in learning and performing minimally invasive aortic valve replacement must have expertise in conventional aortic valve replacement at centers with adequate case volumes. A team approach that coordinates efforts of the surgeon, anesthesiologist, perfusionist, and nurses is required to achieve the best clinical outcomes. By first developing fundamental minimally invasive skills using specialized cannulation techniques, neck lines, and long-shafted instruments in the setting of conventional full sternotomy, the safest operative environment is afforded to patients.

Cross-sectional survey on minimally invasive mitral valve surgery.

BACKGROUND: Minimally invasive mitral valve surgery (MIMVS) has become a standard technique to perform mitral valve surgery in many cardiac centers. However, there remains a question regarding when MIMVS should not be performed due to an increased surgical risk. Consequently, expert surgeons were surveyed regarding their opinions on patient factors, mitral valve pathology and surgical skills in MIMVS. METHODS: Surgeons experienced in MIMVS were identified through an electronic search of the literature. A link to an online survey platform was sent to all surgeons, as well as two follow-up reminders. Survey responses were then submitted to a central database and analyzed. RESULTS: The survey was completed by 20 surgeons. Overall results were not uniform with regard to contraindications to performing MIMVS. Some respondents do not consider left atrial enlargement (95% of surgeons), complexity of surgery (75%), age (70%), aortic calcification (70%), EuroSCORE (60%), left ventricular ejection fraction (55%), or obesity (50%) to be contraindication to surgery. Ninety percent of respondents believe more than 20 cases are required to gain familiarity with the procedure, while 85% believe at least one MIMVS case needs to be performed per week to maintain proficiency. Eighty percent recommend establishment of multi-institutional databases and standardized surgical mentoring courses, while 75% believe MIMVS should be incorporated into current training programs for trainees. CONCLUSIONS: These results suggest that MIMVS has been accepted as a treatment option for patients with mitral valve pathologies according the expert panel. Initial training and continuing practice is recommended to maintain proficiency, as well as further research and formalization of training programs.

Human myxomatous mitral valve prolapse: role of bone morphogenetic protein 4 in valvular interstitial cell activation.

Myxomatous mitral valve prolapse (MVP) is the most common cardiac valvular abnormality in industrialized countries and a leading cause of mitral valve surgery for isolated mitral regurgitation. The key role of valvular interstitial cells (VICs) during mitral valve development and homeostasis has been recently suggested, however little is known about the molecular pathways leading to MVP. We aim to characterize bone morphogenetic protein 4 (BMP4) as a cellular regulator of mitral VIC activation towards a pathologic synthetic phenotype and to analyze the cellular phenotypic changes and extracellular matrix (ECM) reorganization associated with the development of myxomatous MVP. Microarray analysis showed significant up regulation of BMP4-mediated signaling molecules in myxomatous MVP when compared to controls. Histological analysis and cellular characterization suggest that during myxomatous MVP development, healthy quiescent mitral VICs undergo a phenotypic activation via up regulation of BMP4-mediated pathway. In vitro hBMP4 treatment of isolated human mitral VICs mimics the cellular activation and ECM remodeling as seen in MVP tissues. The present study characterizes the cell biology of mitral VICs in physiological and pathological conditions and provides insights into the molecular and cellular mechanisms mediated by BMP4 during MVP. The ability to test and control the plasticity of VICs using different molecules may help in developing new diagnostic and therapeutic strategies for myxomatous MVP.

Identifying patients with degenerative mitral regurgitation for mitral valve repair and replacement: a transesophageal echocardiographic study.

OBJECTIVE: We sought to preoperatively identify the suitability of patients with degenerative mitral valve (MV) regurgitation for MV repair (MVR) and MV replacement. BACKGROUND: MVR is the preferred method of treatment over MV replacement, if surgically feasible. MVR preserves left ventricular function and decreases risk of hemolysis, thromboembolism, and-in the absence of anticoagulation-hemorrhage. However, the ability to identify patients suitable for MVR preoperatively is somewhat limited. METHODS: In all, 76 patients underwent MV operation for severe symptomatic mitral regurgitation. The decision to operate was at the discretion of the referring physician in consultation with respective cardiothoracic surgeons at two separate, nonrelated institutions. All patients underwent preoperative and/or intraoperative transesophageal echocardiographic studies. RESULTS: In all, 35 patients (46%) underwent MVR and 41 (54%) underwent MV replacement. There was no difference in the percentage of MVRs between the two institutions: 17 cases (41%) at Hahnemann University Hospital, Philadelphia, Pa, versus 18 cases (53%) at Northwestern University Memorial Hospital, Chicago, Ill (P = not significant). Age was found to be a significant univariate predictor with older age favoring MV replacement. On average, patients who underwent MVR were 11 years younger then those who underwent MV replacement. Heart failure was also found to be a significant univariate predictor: as New York Heart Association functional class worsened, MV replacement was more likely. Echocardiographic variables favoring MVR included chordal length (>29 mm, P <.001), length of posterior mitral leaflet (>17 mm, P <.008), and length of anterior leaflet (>25 mm, P <.01). The only echocardiographic parameter favoring replacement was the presence of anterior mitral annular calcification. Using multivariate analysis, older age (>63 years) was again a significant predictor favoring MV replacement (P <.002; odds ratio [OR] 20). Longer chordal length (>29 mm) was the strongest predictor favoring MVR (P <.001; OR 11.2). Longer length of the posterior leaflet (>17 mm; OR 5.07) and mitral annulus size > 35 mm (OR 7.75) were also significant multivariate predictors favoring MVR. The presence of anterior mitral annular calcification favored MV replacement using multivariate analysis (OR 25). CONCLUSIONS: Patients suitable for MVR can be identified preoperatively using a combination of clinical and echocardiographic parameters.