Publications (101) View all
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Article: Quantitative Segmentation of Principal Carotid Atherosclerotic Lesion Components by Feature Space Analysis Based on Multicontrast MRI at 1.5 T
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ABSTRACT: The purpose of this paper is to evaluate the capability of feature space analysis (FSA) for quantifying the relative volumes of principal components (thrombus, calcification, fibrous, normal intima, and lipid) of atherosclerotic plaque tissue in multicontrast magnetic resonance images (mc-MRI) acquired in a setup resembling clinical conditions ex vivo. Utilizing endogenous contrast, proton density, T1-weighted, and T2-weighted images were acquired for 13 carotid endarterectomy (CEA) tissues under near-clinical conditions (human 1.5 T GE Excite scanner with sequence parameters comparable to an in vivo acquisition). An FSA algorithm was utilized to segment and quantify the principal components of atherosclerotic plaques. Pilot in vivo mc-MRI images were analyzed in the same way as the ex vivo images for exploring the possible adaptation of this technique to in vivo imaging. Relative abundance of principal plaque components in CEA tissues as determined by mc-MRI/FSA were compared to those measured by histology. Mean differences plusmn standard deviations were 5.8 plusmn 4.1% for thrombus, 1.5 plusmn1.4 % for calcification, 4.0 plusmn2.8% for fibrous, 8.2 plusmn 10% for normal intima, and 2.4 plusmn 2.2% for lipid. Reasonable quantitative agreement between the classification results obtained with FSA and histological data was obtained for near-clinical imaging conditions. Combination of mc-MRI and FSA may have an application for determining atherosclerotic lesion composition and monitoring treatment in vivo.IEEE Transactions on Biomedical Engineering 03/2009; · 2.28 Impact Factor -
Article: Mitral valve repair: the multimodal approach and the role of minimally invasive procedures.
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ABSTRACT: In recent years mitral valve repair has gained increasing acceptance as the preferred treatment for mitral insufficiency. Mitral valve repair has many advantages. The surgical risk is lower than prosthetic valve replacement. Improved preservation of left ventricular function due to maintenance of the papillary muscle - mitral annular continuity - has been demonstrated. Thromboembolism is rare after mitral repair in patients in sinus rhythm. These patients receive no coumadin and thus are free from bleeding complications. The repaired valves have been shown to have durability comparable to or better than prosthetic valves.Surgical technology international 01/2000; 9:215-23. -
Article: Can retrograde cardioplegia alone provide adequate protection for cardiac valve surgery?
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ABSTRACT: When aortic insufficiency is present, antegrade delivery of cardioplegia requires coronary cannulation. Use of retrograde cardioplegia simplifies administration. The efficacy of the retrograde route alone in ensuring adequate myocardial protection may be assessed by the clinical outcome. We used closed transatrial coronary sinus perfusion as the sole method of cardioplegia delivery in 100 patients who underwent valve operations, either isolated or combined with coronary (n=24), ascending aortic aneurysm (n=8), or other procedures. Eighty-one patients were in New York Heart Association (NYHA) Class III or IV; 23 had undergone previous heart operations; 23 were admitted from the coronary care unit (CCU); and 20 had left ventricular ejection fraction (LVEF) of < or = 40%. Operative mortality was 2%. An intra-aortic balloon pump was required in eight patients. On univariate analysis, perioperative use of inotropes (n=26) was related to age > or = 70 years (p=0.02), COPD (p=0.05), pulmonary hypertension (p=0.005), higher NYHA Class (p=0.0006), preoperative heart failure (p=0.006), lower LVEF (p=0.0003), urgency (p=0.00001), admission from the CCU (p=0.006), repeat operation (p=0.03), coronary artery disease (p=0.02), and longer ischemic (p=0.02) and bypass times (p=0.0003). On multivariate stepwise logistic regression analysis, use of inotropes was related to preoperative lower LVEF (p=0.02) and urgency of operation (p=0.0002). Perioperative complications included ventricular arrhythmia in six, heart block in one, renal dysfunction in nine, and stroke in two patients; no patient had myocardial infarction. Good clinical results can be obtained by using retrograde cardioplegia alone without prior doses of antegrade cardioplegia in all valve operations.Chest 02/1999; 115(1):135-9. · 5.25 Impact Factor -
Article: Mitral valve repair vs replacement. Current recommendations and long-term results.
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ABSTRACT: Techniques now exist to correct abnormalities of all components of the mitral valvular apparatus except extensive loss of pliable leaflet area. Thus, paradoxically, myxomatous valves with redundant leaflets represent the ideal candidates for mitral valve repair. Repair for mitral insufficiency can be performed for some rheumatic valves, but patient selection is critical. Loss of leaflet area, leaflet thickening, and extensive calcification of the leaflets or commissures are contraindications to repair. The abnormalities of the subvalvular apparatus are less important because a complete set of new chordae can be reconstructed using PTFE suture material. Some cases of endocarditis are ideal for repair using localized débridement and pericardial patch repair with or without PTFE chordal replacement. True ischemic mitral regurgitation of the Carpentier type I category is still something of a surgical enigma. Because it is a restrictive leaflet motion problem, annuloplasty alone is not always effective, and the outcome of any given repair attempt is less predictable. Repairs in patients with small annuli and multiple leaflet defects requiring complex series of maneuvers have a low probability of success. Furthermore, such patients with small left ventricular cavities are more prone to experience SAM. Several factors contributing to which therapy is chosen for mitral valve disease are summarized in Table 1. Patient selection, accurate evaluation of the cause or causes of mitral regurgitation, and well-executed application of the appropriate techniques for repair are all critical factors in the early and late success of mitral valve repair.Cardiology Clinics 09/1998; 16(3):437-48. · 1.36 Impact Factor -
Article: Assessment of myocardial viability with 99mTc-sestamibi tomography before coronary bypass graft surgery: correlation with histopathology and postoperative improvement in cardiac function.
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ABSTRACT: Assessment of myocardial viability by 99mTc-sestamibi remains controversial. Accordingly, we investigated the use of sestamibi as a marker of myocardial viability, defined by histopathology, and for predicting improvement of myocardial function after coronary artery bypass graft surgery (CABG). 99mTc-sestamibi perfusion tomography and radionuclide angiography were performed within 2 days before CABG in 21 patients with > or = 75% stenosis of the left anterior descending coronary artery and resting anterior wall dyssynergy. During CABG, transmural myocardial biopsies were obtained from the dyssynergic anterior wall and from normal myocardial segments to determine the extent of viable myocardium by histopathology. Improvement of regional left ventricular function was evaluated by radionuclide angiography at 6 to 8 weeks after CABG. There was a good correlation (r=.85, P<.001) between the quantified sestamibi activity and the extent of viable myocardium determined morphometrically. Among 21 biopsied dyssynergic myocardial segments, 11 improved their function after CABG and 10 failed to improve. Biopsied segments with improved postoperative function had significantly higher sestamibi activity (81+/-5% versus 49+/-16%, P<.0001) and significantly lower extent of interstitial fibrosis (7+/-4% versus 31+/-21%, P=.0002) than segments that failed to improve. A 55% threshold of 99mTc-sestamibi activity had positive and negative predictive values of 79% and 100%, respectively, for recovery of function after CABG in the biopsied segments. Myocardial 99mTc-sestamibi activity correlates well with the extent of viable myocardium and predicts improvement in regional function after CABG. This lends support to the use of sestamibi as a myocardial viability agent.Circulation 11/1997; 96(9):2892-8. · 14.74 Impact Factor
