Patterns and timing of Doppler-detected intracavitary and aortic flow in hypertrophic cardiomyopathy

This study describes the velocity characteristics of left ventricular and aortic outflow in 25 patients with hypertrophic “obstructive” cardiomyopathy. Systematic pulsed and continuous wave Doppler analysis combined with phonocardiography and M-mode echocardiography was used to establish the pattern and timing of outflow in the basal and provoked states. This analysis suggests that 1) the high velocity left ventricular outflow jet can be reliably discriminated from both aortic flow and the jet of mitral regurgitation using Doppler ultrasound; 2) the Doppler velocity contour responds in a characteristic fashion to provocative influences including extrasystole and Valsalva maneuver; 3) the onset of mitral regurgitation occurs well before detectable systolic anterior motion of the mitral valve; 4) left ventricular flow velocities are elevated at the onset of systolic anterior motion of the mitral valve, suggesting a significant contribution of the Venturi effect in displacing the leaflets and chordae; 5) the high velocities of the outflow jets are largely dissipated by the time flow reaches the aortic valve; and 6) late systolic flow in the ascending aorta is nonuniform, with formation of distinct eddies that may contribute to “preclosure” of the aortic valve

Intravascular ultrasound imaging: In vitro validation and pathologic correlation

AbstractIntravascuiar ultrasound imaging is a new method in which high resolution images of the arterial wall are obtained with use of a catheter placed within an artery. An in vitro Plexiglas well model was used to validate measurements of the luminal area, and an excellent correlation was obtained. One hundred thirty segments of fresh peripheral arteries underwent ultrasound imaging and the findings were compared with the corresponding histopathologic sections. luminal areas determined with ultrasound imaging correlated well with those calculated from microscopic slides (r = 0.98).Three patterns were identified on the ultrasound images: 1) distinct interface between media and adventitia, 2) indistinct interface between media and adventitia but different echo density layers, and 3) diffuse homogeneous appearance. The types of patterns depended on the relative composition of the and adventitia. Calcification of intimal plaque obscured underlying structures. Atherosclerotic plaque was readily visualized but could not always be differentiated from the underlying media

Intracoronary and retrograde coronary venous myocardial delivery of adipose-derived stem cells in swine infarction lead to transient myocardial trapping with predominant pulmonary redistribution

OBJECTIVES: To examine the comparative fate of adipose-derived stem cells (ASCs) as well as their impact on coronary microcirculation following either retrograde coronary venous (RCV) or arterial delivery. BACKGROUND: Local delivery of ASCs to the heart has been proposed as a practical approach to limiting the extent of myocardial infarction. Mouse models of mesenchymal stem cell effects on the heart have also demonstrated significant benefits from systemic (intravenous) delivery, prompting a question about the advantage of local delivery. There has been no study addressing the extent of myocardial vs. systemic disposition of ASCs in large animal models following local delivery to the myocardium. METHODS: In an initial experiment, dose-dependent effects of ASC delivery on coronary circulation in normal swine were evaluated to establish a tolerable ASC dosing range for intracoronary (IC) delivery. In a set of subsequent experiments, an anterior acute myocardial infarction (AMI) was created by balloon occlusion of the proximal left anterior descending (LAD) artery, followed by either IC or RCV infusion of 10(7) (111)Indium-labeled autologous ASCs 6 days following AMI. Indices of microcirculatory resistance (IMR) and coronary flow reserve (CFR) were measured before sacrifices to collect tissues for analysis at 1 or 24 hr after cell delivery. RESULTS: IC delivery of porcine ASCs to normal myocardium was well tolerated up to a cumulative dose of 14 × 10(6) cells (approximately 0.5 × 10(6) cells/kg). There was evidence suggesting microcirculatory trapping of ASC: at unit doses of 50 × 10(6) ASCs, IMR and CFR were found to be persistently altered in the target LAD distribution at 7 days following delivery, whereas at 10 × 10(6) ASCs, only CFR was altered. In the context of recent MI, a significantly higher percentage of ASCs was retained at 1 hr with IC delivery compared with RCV delivery (57.2 ± 12.7% vs. 17.9 ± 1.6%, P = 0.037) but this initial difference was not apparent at 24 hr (22.6 ± 5.5% vs. 18.7 ± 8.6%; P = 0.722). In both approaches, most ASC redistributed to the pulmonary circulation by 24 hr postdelivery. There were no significant differences in CFR or IMR following ASC delivery to infarcted tissue by either route. CONCLUSIONS: Selective intravascular delivery of ASC by coronary arterial and venous routes leads to similarly limited myocardial cell retention with predominant redistribution of cells to the lungs. IC arterial delivery of ASC leads to only transiently greater myocardial retention, which is accompanied by obstruction of normal regions of coronary microcirculation at higher doses. The predominant intrapulmonary localization of cells following local delivery via both methods prompts the notion that systemic delivery of ASC might provide similarly beneficial outcomes while avoiding risks of inadvertent microcirculatory compromise

Preintervention arterial remodeling affects clinical outcome following stenting: an intravascular ultrasound study

AbstractOBJECTIVESThe study was done to elucidate the relationship between baseline arterial remodeling and clinical outcome following stenting.BACKGROUNDThe impact of preintervention arterial remodeling on subsequent vessel response and clinical outcome has been reported following nonstent coronary interventions. However, in stented segments, the impact of preintervention remodeling on clinical outcome has not been clarified.METHODSPreintervention remodeling was assessed in 108 native coronary lesions by using intravascular ultrasound (IVUS). Positive remodeling (PR) was defined as vessel area (VA) at the target lesion greater than that of average reference segments. Intermediate or negative remodeling (IR/NR) was defined as VA at the target lesion less than or equal to that of average reference segment. Remodeling index expressed as a continuous variable was defined as VA at the target lesion site divided by that of average reference segments.RESULTSPositive remodeling was present in 59 (55%) and IR/NR in 49 (45%) lesions. Although final minimal stent areas were similar (7.76 ± 1.80 vs. 8.09 ± 1.90 mm2, p = 0.36), target vessel revascularization (TVR) rate at nine-month follow-up was significantly higher in the PR group (22.0% vs. 4.1%, p = 0.01). By multivariate logistic regression analysis, higher remodeling index was the only independent predictor of TVR (p = 0.02).CONCLUSIONSLesions with PR before intervention appear to have a worse clinical outcome following IVUS-guided stenting. Intravascular ultrasound imaging before stenting may be helpful to stratify lesions at high risk for accelerated intimal proliferation