Vascularity of myocardium and gastrocnemius muscle in rats selectively bred for endurance running capacity.

We tested the hypothesis that changes in the arteriolar branching architecture contributed to increased running capacity of rats subjected to two-way artificial selection for intrinsic aerobic endurance treadmill running capacity resulting in strains of low-capacity and high-capacity endurance rats. Hearts and gastrocnemius muscles were harvested from each strain, and the microvasculature's branching geometry measured from micro-CT images. The vascular branching geometry of the hearts and skeletal muscle from the high capacity was indistinguishable from low-capacity rats.

Relationship between surface area of nonperfused myocardium and extravascular extraction of contrast agent following coronary microembolization.

Myocardial microvascular permeability and coronary sinus concentration of muscle metabolites have been shown to increase after myocardial ischemia due to epicardial coronary artery occlusion and reperfusion. However, their association with coronary microembolization is not well defined. This study tested the hypothesis that acute coronary microembolization increases microvascular permeability in the porcine heart.

Microvascular development in porcine right and left ventricular walls.

Patients with congenital heart disease who have a morphological right ventricle (RV) serving as a systemic ventricle have an increased incidence of RV dysfunction. A different structural response of microvessels to increased pressure load in the RV is a possible mechanism for this dysfunction. To examine the merit of this hypothesis, we explored the possibility that in the normal heart, the branching architecture of microvasculature in walls of the left ventricle (LV) and RV mature differently.

Correlation of vasa vasorum neovascularization and plaque progression in aortas of apolipoprotein E(-/-)/low-density lipoprotein(-/-) double knockout mice.

Objective: We hypothesized that apolipoprotein E (apoE)(-/-)/low-density lipoprotein (LDL)(-/-) double knockout mice might develop vasa vasorum (VV) in association with advanced lesion formation.

Methods And Results: Aortas from apoE(-/-)/LDL(-/-) mice aged 16, 18, 20, or 80 weeks were infused in situ with Microfil, harvested, and scanned with micro-computed tomography (CT). We characterized plaque volume and CT "density" as well as VV luminal volume along the aorta using Analyze 6.

Relation of nonperfused myocardial volume and surface area to left ventricular performance in coronary microembolization.

Background: After occlusion of an epicardial artery, left ventricular (LV) dysfunction is closely related to the volume of nonperfused myocardium (NPM). The impact of coronary microembolization (ME) on LV function, however, is larger relative to the total volume of NPM. We hypothesized that the total surface area (SA), rather than the total volume, of NPM is the major determinant of ME-induced LV dysfunction.

Role of vasa vasorum in transendothelial solute transport in the coronary vessel wall: a study with cryostatic micro-CT.

Using cryostatic microscopic computed tomography (micro-CT), we sought to determine the role of coronary vasa vasorum (VV) in transendothelial solute transport in arteries with normal and increased permeability due to high plasma cholesterol levels. In 6-mo-old pigs on a normal (n=23) and 2% high cholesterol (HC) diet (n=8), 2-cm segments of the proximal left anterior descending coronary arteries were removed in vivo after a selective injection of X-ray contrast solution. Harvesting of the specimens occurred at 0, 15, 25, 35, or 45 s after completion of the contrast injection.

Relationship between arterial diameter and perfused tissue volume in myocardial microcirculation: a micro-CT-based analysis.

The volume of myocardial tissue that is perfused by an epicardial coronary artery has been shown to be predictably related to the diameter of the epicardial arterial lumen. However, to what extent the intramyocardial microvasculature follows the epicardial rules remains unclear. To explore the relationship between the diameter of coronary arterioles and their subsequent perfused myocardial volumes, we quantified the volume of nonperfused myocardium resulting from an embolized arteriole of a certain diameter.

Functional anatomy and hemodynamic characteristics of vasa vasorum in the walls of porcine coronary arteries.

In this study vasa vasorum in the walls of porcine coronary arteries were examined, using three-dimensional (3D) micro-CT scanning techniques. These techniques leave the 3D structure of the vasa vasorum tree intact and thus provide a much more direct view of this structure than is possible from conventional histological sections. The study demonstrates-for the first time, we believe-both the different types and the fine architecture of these vasa vasorum.

Intramyocardial blood volume, perfusion and transit time in response to embolization of different sized microvessels.

Objective: To study the role of the coronary microcirculation in response to different-sized microemboli, we measured changes in intramyocardial microvascular blood volume (Bv), perfusion (F) and transit time (TT) and also microvascular patterns of injury.

Methods: Bv, F and TT were quantitated in 24 pigs at baseline and again 2 min after repeat injections of 10- or 100-microm microspheres at rest or during intracoronary adenosine infusion. The association of Bv and TT was assessed in the microsphere pigs and in nine control pigs.