P9.3 Lower Subendocardial Viability Ratio in Diabetic Women–contributing to the Abrogated Cardioprotective Effect of Female Gender in Diabetes?

Abstract

Arterial wall viscosity (AWV) of central arteries, as well as distensibility, is important to properly buffer systolic ejection pressure. AWV is measured either by the area within the hysteresis of distension-pressure (DD-P) loop, defined as the viscous energy (AWVZVe) or the ratio of Ve/Ve+energy stored during systole (ZAWV%). We record DD-P loop via echotracking; averaged over 30 cardiac cycles, AWV and AWV% are calculated via MatLab software. Here we perform a post analysis of the DD-P loop in 12 groups of rats (nZ5-8): normo-or hypertensive, with and without arterial remodeling, at different operating blood pressures (BP), using different compounds. AWV decreases and DD-P loop is flattened with increased BP; moreover it is differently altered if pulse pressure (PP) is altered and remains low at any operating BP in models with vascular wall remodeling. However in all conditions the ratio AWV% is poorly modified. Our results suggest that the AWV as the Ve (hysteresis loop area) is the most relevant in defining the viscous properties of the artery; they indicate that mean operating BP, PP and structural distensibility independently participate in modifying the shape of the loop which is largely dependent on the delay between peak systolic pressure and peak systolic diameter, apparent in the higher BP of the loop. This suggests that isobaric distensibility cannot be compared in the lower and upper part of the loop but only at a similar mean BP. Further studies will aim to confirm these suggestions and determine how to improve loop hysteresis evaluation P8.13Cardiovascular diseases are often studied at a pre-clinical stage using dedicated mouse models. However, (non-)invasive measurements in the murine cardiovascular system are difficult to obtain, limited to a restricted number of aortic locations, and need to be justified from an ethical perspective. In this work we present a 1-D model of the systemic circulation in mice. Murine arterial tree dimensions have been acquired and averaged from the segmentation of Micro-Computed Tomography (m-CT) scans of 3 wild-type C57Bl/6 mice (12-15 weeks old). The resulting geometry consists of 85 arterial segments, including all major aortic branches as well as the tail and the cerebral tree. The remaining input to the model has been obtained from a wide range of literature data. An empirical relationship has been fitted to estimate the local arterial wall distensibility in all segments. Peripheral vessels are terminated with three-element windkessel models to account for the resistance and compliance of the distal vasculature. The integrated form of the momentum and continuity equations is solved numerically to yield pressures and flows throughout the arterial network. The model predicts pressure and velocity waveforms in good qualitative and semi-quantitative agreement with invasive pressure measurements as well as high-frequency ultrasound Pulsed-Wave Doppler aortic velocity and M-mode aortic distensibility measurements. In conclusion, a well-tuned and appropriately validate...