Richard Bae

Regional asynchrony during acute myocardial ischemia quantified by ultrasound strain rate imaging.

OBJECTIVES We propose a new method to easily quantify asynchronous wall motion due to postsystolic shortening (PSS). We also studied the relationship of the spatial and temporal extent of PSS to the extent of myocardium at ischemic risk after variable duration of ischemia. BACKGROUND Postsystolic shortening is a sensitive marker of asynchrony during ischemia. Current techniques for detection of asynchrony are either subjective, or invasive and time-consuming. Strain rate imaging (SRI) can noninvasively depict PSS as prolonged compression/expansion crossover. METHODS Nineteen open-chest pigs were scanned from apical views, before and after left anterior descending coronary artery occlusion. Strain rates were derived offline from tissue Doppler velocity cineloops. The time from electrocardiographic R-wave to the occurrence of compression/expansion crossover (TCEC) was calculated. Prolonged TCEC during ischemia was identified using a standardized analysis and both spatial (% of left ventricle) and temporal extent were quantified. The extent of myocardium at risk was measured in seven animals from dye-stained specimens. RESULTS Prolonged TCEC was found in all ischemic segments. There was a good correlation (r = 0.91; p < 0.001) and good agreement between the spatial distributions of prolonged TCEC and myocardium at risk. The extent of myocardium at risk was better approximated by TCEC measurement (36 +/- 7% vs. 39 +/- 8%, respectively; p = NS) than by wall motion analysis (47 +/- 17%, p < 0.05). The duration of occlusion did not prolong TCEC. CONCLUSIONS Prolonged TCEC consistently occurs in ischemic myocardium and is apparently not affected by the duration of ischemia. Standardized analysis of TCEC in SRI closely quantifies the extent of ischemic myocardium. This new method may be a useful tool in other cardiac conditions associated with regional diastolic asynchrony.

Three-Dimensional Echocardiography: Precision and Accuracy of Left Ventricular Volume Measurement Using Rotational Geometry with Variable Numbers of Slice Resolution.

We developed a new, rapid (6 seconds) acquisition technique allowing collection of approximately six through nine apical rotational tomograms for three‐dimensional (3‐D) echocardiography. To justify an appropriate sampling density for precise and accurate measurement of chamber volumes in left ventricles with complicated shape, we designed a validation study in vitro using six canine heart specimens with irregular, asymmetric left ventricles with known volumes (28.5 to 104.3 ml; mean, 71.2 ml). The number of equally spaced slices were incrementally deleted from the original high resolution scans (48 slices) to 2 slices in 3‐D reconstruction. We created subgroups of 48‐ and 36‐, 24‐ and 16‐, 12‐ and 8‐, 6‐ and 4‐, and 3‐ and 2‐component slices to compare left ventricular (LV) volumes measured in 3‐D images with different slice resolution with the reference standard measured in the specimen. The accuracy and precision of LV volume were relatively constant in the subgroup of 4‐ and 6‐ through 36‐ and 48‐component slices. When the subgroup with 6‐ and 4‐component slices was used, the correlation was r = 0.991, P < 0.0001, root mean‐square percent error of 5.0%, bias of 0.5 ± 3.7 ml, and interobserver variability of 5.0%. With the reduction in component slices equal or less than three, the accuracy decreased significantly (root‐mean‐square percent error = 8.1% and bias = ‐2.0 ± 5.7 ml) compared with higher slice resolutions. This study demonstrated that 3‐D echocardiography using apical rotational techniques can accurately quantify LV volume in the canine heart specimens with irregular shapes with as few as 4–6 axial slices. The rapid 3‐D acquisition technique is therefore anticipated to yield precise and accurate LV volumetry.

IMPACT OF THE COMMERCIAL INTRODUCTION OF TRANSCATHETER MITRAL VALVE REPAIR ON MITRAL SURGICAL PRACTICE

With the commercial introduction of transcatheter mitral valve repair with MitraClip into the U.S. in 2013, there has been uncertainty regarding the effect of this therapy on cardiac surgical practice. The present investigation was undertaken to examine the impact of this introduction in the context

TCT-667 Causes and Clinical Outcomes of Patients with Mitral Regurgitation Who are ineligible for Transcatheter Mitral Valve Replacement

Despite the increasing availability of transcatheter mitral valve replacement (TMVR) under research investigation, patients with mitral regurgitation (MR) frequently are not eligible for such therapy. The characteristics of these patients who fail qualification and their clinical outcomes are

SURGICAL RISK AND THERAPY OF SEVERE SYMPTOMATIC DEGENERATIVE MITRAL VALVE REGURGITATION IN THE CONTEMPORARY ERA

Background: Severe degenerative mitral valve regurgitation (DMR) carries an adverse prognosis, yet afflicted patients may not undergo treatment despite availability of contemporary therapy. We sought to examine the relationship between surgical risk, therapeutic penetrance, and survival for patients