Cole Streiff

Sympathetic cardiac hyperinnervation and atrial autonomic imbalance in diet-induced obesity promote cardiac arrhythmias

Obesity increases the risk of arrhythmias and sudden cardiac death, but the mechanisms are unknown. This study tested the hypothesis that obesity-induced cardiac sympathetic outgrowth and hyperinnervation promotes the development of arrhythmic events. Male Sprague-Dawley rats (250-275 g), fed a high-fat diet (33% kcal/fat), diverged into obesity-resistant (OR) and obesity-prone (OP) groups and were compared with rats fed normal chow (13% kcal/fat; CON). In vitro experiments showed that both OR and OP rats exhibited hyperinnervation of the heart and high sympathetic outgrowth compared with CON rats, even though OR rats are not obese. Despite the hyperinnervation and outgrowth, we showed that, in vivo, OR rats were less susceptible to arrhythmic events after an intravenous epinephrine challenge compared with OP rats. On examining total and stimulus-evoked neurotransmitter levels in an ex vivo system, we demonstrate that atrial acetylcholine content and release were attenuated in OP compared with OR and CON groups. OP rats also expressed elevated atrial norepinephrine content, while norepinephrine release was suppressed. These findings suggest that the consumption of a high-fat diet, even in the absence of overt obesity, stimulates sympathetic outgrowth and hyperinnervation of the heart. However, normalized cardiac parasympathetic nervous system control may protect the heart from arrhythmic events.

Quantitative Assessment of Mitral Inflow and Aortic Outflow Stroke Volumes by 3-Dimensional Real-time Full-Volume Color Flow Doppler Transthoracic Echocardiography An In Vivo Study

Noninvasive quantification of left ventricular (LV) stroke volumes has an important clinical role in assessing circulation and monitoring therapeutic interventions for cardiac disease. This study validated the accuracy of a real‐time 3‐dimensional (3D) color flow Doppler method performed during transthoracic echocardiography (TTE) for quantifying volume flows through the mitral and aortic valves using a dedicated offline 3D flow computation program compared to LV sonomicrometry in an open‐chest animal model.

Evaluation of a New 3-Dimensional Color Doppler Flow Method to Quantify Flow Across the Mitral Valve and in the Left Ventricular Outflow Tract An In Vitro Study

The aim of this study was to assess the accuracy, feasibility, and reproducibility of determining stroke volume from a novel 3‐dimensional (3D) color Doppler flow quantification method for mitral valve (MV) inflow and left ventricular outflow tract (LVOT) outflow at different stroke volumes when compared with the actual flow rate in a pumped porcine cardiac model.

Assessment of Interventricular Dyssynchrony by Real Time Three-Dimensional Echocardiography: An In Vitro Study in a Porcine Model

Background: Loss of synchronous contraction between or within the right and left ventricle (RV, LV) leads to adverse ventricular function. We used real time three‐dimensional echocardiography (RT3DE) for evaluation of severity of interventricular dyssynchrony and function in a porcine heart model. Methods: Six fresh in vitro porcine hearts were used to create a controlled model of LV and RV dyssynchrony using two sets of pulsatile pumps. Synchronized and dyssynchronized pump settings were used with two different dyssynchronized settings: LV filled first and RV filled first. Results: There was good correlation between actual measurement and RT3DE for interventricular time difference (r = 0.95, P < 0.0001) and stroke volume (SV) for LV and RV (0.89, 0.85; P < 0.0001, respectively). RT3DE data showed a small but significant underestimation for actual volume (P < 0.05). The intra‐ and interobserver variabilities are 2.9 ± 1.5% and 3.1 ± 5.4% for LV and RV SVs, and 1.7 ± 2.4% and 2.2 ± 3.2% for time differences by RT3DE. There was significant difference in RV SV between synchrony and dyssynchrony when the RV filled first (P < 0.05), but not in other groups. The same pattern was found in RT3DE derived SVs (synchrony versus dyssynchrony with RV filled first, P < 0.05). Conclusions: There is no compromise in LV SV during interventricular dyssynchrony; but RV SV was significantly diminished when the RV filled first. RT3DE is a feasible, robust and reproducible method to identify interventricular dyssynchrony and to evaluate ventricular SVs. (Echocardiography 2010;27:709‐715)

Quantification of Shunt Volume Through Ventricular Septal Defect by Real-Time 3-D Color Doppler Echocardiography: An in Vitro Study

Quantification of shunt volume is important for ventricular septal defects (VSDs). The aim of the in vitro study described here was to test the feasibility of using real-time 3-D color Doppler echocardiography (RT3-D-CDE) to quantify shunt volume through a modeled VSD. Eight porcine heart phantoms with VSDs ranging in diameter from 3 to 25 mm were studied. Each phantom was passively driven at five different stroke volumes from 30 to 70 mL and two stroke rates, 60 and 120 strokes/min. RT3-D-CDE full volumes were obtained at color Doppler volume rates of 15, 20 and 27 volumes/s. Shunt flow derived from RT3-D-CDE was linearly correlated with pump-driven stroke volume (R = 0.982). RT3-D-CDE-derived shunt volumes from three color Doppler flow rate settings and two stroke rate acquisitions did not differ (p > 0.05). The use of RT3-D-CDE to determine shunt volume though VSDs is feasible. Different color volume rates/heart rates under clinically/physiologically relevant range have no effect on VSD 3-D shunt volume determination.

Real Time Three-Dimensional Echocardiographic Evaluations of Fetal Left Ventricular Stroke Volume, Mass, and Myocardial Strain: In Vitro and In Vivo Experimental Study.

Left ventricular stroke volume, mass, and myocardial strain are valuable indicators of fetal heart function. This study investigated the feasibility of nongated real time three‐dimensional echocardiography (RT3DE) to determine fetal stroke volume (SV), left ventricular mass (LVM), and myocardial strain under different conditions.

Mitigation of Variability among 3D Echocardiography-Derived Regional Strain Values Acquired by Multiple Ultrasound Systems by Vendor Independent Analysis

Introduction This study compared the variability of 3D echo derived circumferential and longitudinal strain values computed from vendor-specific and vendor-independent analyses of images acquired using ultrasound systems from different vendors. Methods Ten freshly harvested porcine hearts were studied. Each heart was mounted on a custom designed phantom and driven to simulate normal cardiac motion. Cardiac rotation was digitally controlled and held constant at 5°, while pumped stroke volume (SV) ranged from 30-70ml. Full-volume image data was acquired using three different ultrasound systems from different vendors. The image data was analyzed for longitudinal and circumferential strains (LS, CS) using both vendor-specific and vendor-independent analysis packages. Results Good linear relationships were observed for each vendor-specific analysis package for both CS and LS at the mid-anterior segment, with correlation coefficients ranging from 0.82–0.91 (CS) and 0.86–0.89 (LS). Comparable linear regressions were observed for results determined by a vendor independent program (CS: R = 0.82–0.89; LS: R = 0.86–0.89). Variability between analysis packages was examined via a series of ANOVA tests. A statistical difference was found between vendor-specific analysis packages (p<0.001), while no such difference was observed between ultrasound systems when using the vendor-independent program (p>0.05). Conclusions Circumferential and longitudinal regional strain values differ when quantified by vendor-specific analysis packages; however, this variability is mitigated by use of a vendor-independent quantification method. These results suggest that echocardiograms acquired using different ultrasound systems could be meaningfully compared using vendor-independent software.

Quantification of the area and shunt volume of multiple, circular, and noncircular ventricular septal defects: A 2D/3D echocardiography comparison and real time 3D color Doppler feasibility determination study

Quantification of defect size and shunt flow is an important aspect of ventricular septal defect (VSD) evaluation. This study compared three‐dimensional echocardiography (3DE) with the current clinical standard two‐dimensional echocardiography (2DE) for quantifying defect area and tested the feasibility of real time 3D color Doppler echocardiography (RT3D‐CDE) for quantifying shunt volume of irregular shaped and multiple VSDs.

Image-Derived Assessment of Left Ventricular Mass in Fetal Myocardial Hypertrophy by 4-Dimensional Echocardiography An In Vitro Study

This study tested the accuracy of new 4‐dimensional fetal echocardiography to evaluate left ventricular (LV) mass in an experimental model of fetal myocardial hypertrophy.

FEASIBILITY OF 4D ECHOCARDIOGRAPHY FOR EVALUATION OF RIGHT VENTRICULAR MECHANICS: VALIDATION AGAINST SONOMICROMETRY

This study tested the feasibility of 4D echocardiography to evaluate right ventricular (RV) strain mechanics using both vendor-dependent and vendor-independent analysis packages. Ten freshly harvested porcine hearts were studied in a water bath with three sonomicrometry (sono) crystals sutured in a