Dynamic Changes in Three-Dimensional Architecture and Vascular Volume of Transmural Coronary Microvasculature Between Diastolic- and Systolic-Arrested Rat Hearts

Abstract

Background-The phase difference of coronary arterial and venous flows indicates the importance of intramyocardial capacitance vessels in storing diastolic flow and in discharging volume in systole. However, the anatomic and functional characteristics of the capacitance vessels are unclear. We aimed to clarify those characteristics with their transmural difference by 3D visualization of transmural microvessels under diastole and systole. Methods and Results-We performed complete intracoronary filling of a contrast medium into Langendorff's Wistar rat hearts under (1) St Thomas-perfused diastolic arrest (D-mode) and (2) BaCl 2 -induced systolic arrest (S-mode). Precise transmural 3D architectures of capillaries and of pre-and post-capillary microvessels (ie, microvessels larger than capillaries) were visualized clearly with a confocal laser scanning microscope and x-ray microcomputed tomography (microCT), respectively. Vascular volume fraction (VF) and systolic-induced VF reduction rate from D-to S-mode were analyzed. The net capillary VF in D-mode (20.4Ϯ0.9%) was 10 times that of larger microvessels and was reduced in S-mode by 32% without capillary collapse. Systolic-induced VF reduction rate was smaller in capillaries than in larger microvessels (48%; PϽ0.05). The larger microvessel VF in D-mode (2.2Ϯ0.2%) was reduced in S-mode, accompanied by complicated 3D deformation. Conclusions-Capillaries were relatively resistant to the systolic extravascular compression compared with pre-and post-capillary microvessels, conveniently beneficial for the myocardial oxygen delivery throughout a cardiac cycle. Nevertheless, a larger change in the absolute volume of capillaries may function as effective capacitance. On one hand, the pre-and post-capillary microvessels showed a larger phasic change in resistance, which may function to maintain the capillary patency during systole. (Circulation. 2002;105:621-626.)

Relation between branching patterns and perfusion in stochastic generated coronary arterial trees

“…The large variability in myocardial flow per 100 g tissue that is found indicates variation in anatomical characteristics of the coronary arterial tree [7,16]. Recent studies visualized the anatomical structure of the coronary arterial tree in the intact heart [10,14]. Rodriguez-Porcel et al [10] found that myocardial architecture was altered in experimental hypercholesterolemia; hypercholesterolemia increased sub-endocardial microvascular density and sprouting.…”

Detection of Myocardial Ischemia Using 64-Slice MDCT

“…15,16 The capillary microvessels show a greater phasic change in microvascular resistance, which may function to maintain the capillary patency during systole. 17 Consequently, the increase in subendocardial resistance induced by ischemia causes a decrease in the capacitance of microvessels during systole.…”

Optimal Planar Flow Network Designs for Tissue Engineered Constructs with Built-in Vasculature

“…In all the computational work so far, we have considered α = β = 1 cm, so the arteriole and venule sections are each 1 cm × 1 cm in dimension, and Q = 0.025W (ml min −1 ) Similarly, we can obtain the flow rate for square ducts as Q = 0.025W (ml min −1 ) 2.3.2 Porosity-We restrict the porosity to a specified value γ. The value of γ is varied from 0.4 to 0.7 [8,25,33,36]. Porosity of the network is indicative of the percent of blood in microvasculature and, in general, can vary depending on the permeability of vasculature.…”