Abstract
Background LV performance is coupled to loading conditions (i.e. preload and afterload) and myocardial contractility (1,2). Therefore load-independence is an important means to isolate and study LV contractility in preclinical studies of cardiovascular pharmaceuticals and devices (3). Precise and rapid assessment of LV pressure is achieved with high fidelity catheter-based pressure transducers but measurements of LV volume are more difficult and less reliable. Thus far, MRI has not demonstrated sufficient spatiotemporal resolution to measure beat-to-beat changes of the pressure-volume (PV) loop to measure left ventricular (LV) elasticity or preload-recruitable stroke work (PRSW). Our aim was to develop a realtime (rtMRI) approach to measure PV and FrankStarling relationships in a preclinical model of heart disease under normal and stressed physiologic conditions.
Highlights
left ventricular (LV) performance is coupled to loading conditions and myocardial contractility (1,2)
We found PV loops could be accurately measured using an image exposure time Te < 100 ms (< 34 projections) and frame rate Tr < 50 ms at elevated heart rates (~140 bpm)
With an optimized exposure time (Te = 95 ms and frame rate Tr = 2.8 ms), we found that there was no significant difference between cine and rtMRI at rest in end-diastolic volume (EDV), end-systolic volume (ESV), ejection fraction (EF), stroke volume (SV) or cardiac output (CO) (n = 8, p < 0.05) at either normal or elevated heart rates
Summary
Walter R Witschey1*, Francisco Contijoch, Jeremy R McGarvey, Victor A Ferrari, Michael Hansen, Julio Chirinos, Paul Yushkevich, Joseph H Gorman, Robert C Gorman, James J Pilla. From 17th Annual SCMR Scientific Sessions New Orleans, LA, USA. From 17th Annual SCMR Scientific Sessions New Orleans, LA, USA. 16-19 January 2014
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