The pathophysiology of infarct-related reentrant ventricular tachycardia (VT) includes myocardial cell death and ventricular remodeling, resulting in inhomogeneous scarring with variable degrees and configurations of surviving myocardial bundles within the areas of fibrosis. This provides the necessary electrophysiological substrate for formation of reentrant VTs that are predominantly located ...

The pathophysiology of infarct-related reentrant ventricular tachycardia (VT) includes myocardial cell death and ventricular remodeling, resulting in inhomogeneous scarring with variable degrees and configurations of surviving myocardial bundles within the areas of fibrosis. This provides the necessary electrophysiological substrate for formation of reentrant VTs that are predominantly located ...

We tested the hypothesis that reductions of perfusion pressure distal to a flow-limiting coronary artery stenosis can directly impair perfusion of the subendocardial myocardium. Dogs were instrumented with an electromagnetic flowmeter probe and a variable occluder on the proximal left circumflex coronary artery. Coronary perfusion pressure was measured with a catheter distal to the occluder. Co...

Coronary vessels have /?2-adrenergic receptors, but their role in distributing flow across the ventricular wall independently of cardiac metabolic and mechanical factors that influence coronary resistance is unknown. We studied the working heart of open-chest dogs and measured blood flow with radioactive microspheres in four layers across the left ventricular wall before and during /32-receptor...

We assessed transmurally the coronary autoregulatory response to elevated perfusion pressure in 85 anesthetized, open-chest dogs. Steady state and transient flow distributions were measured with 9 ± 1 /im radioactive microspheres. Steady state distributions of myocardial blood flow were uniform transmurally (P > 0.05) at perfusion pressures of 103 ± 1 (n = 81) and 146 ± 2 (n = 34) mm Hg, wherea...

BACKGROUND Halothane inhibits the 4-aminopyridine-sensitive transient outward K(+) current (I(to)) which in many species, including humans, plays an important role in determining action potential duration. As I(to) is greater in the ventricular subepicardium than subendocardium, halothane may have differential effects on action potential duration and, therefore, contraction in cells isolated fr...

BACKGROUND Development of left ventricular hypertrophy in aortic stenosis (AS) is accompanied by coronary microcirculatory dysfunction, demonstrated by an impaired coronary vasodilator reserve (CVR). However, evidence for regional abnormalities in myocardial blood flow (MBF) and the potential mechanisms is limited. The aims of this study were to quantitatively demonstrate differences in subendo...

Figure 2: Histopathological testing. Left ventricular (LV) myocardial tissue with endocardial fibroelastosis, dilated type. (a) Hypocellular fibrous tissue with multiple lamellae of coarse elastic fibres arranged parallel to the luminal surface (van Gieson’s stain, ×200). (b) The endocardium is extremely thickened extending in the subendocardium (Masson’s trichrome stain, ×200). Note that this ...

RATIONALE Genome-wide association studies previously identified an association of rs9388451 at chromosome 6q22.3 (near HEY2) with Brugada syndrome. The causal gene and underlying mechanism remain unresolved. OBJECTIVE We used an integrative approach entailing transcriptomic studies in human hearts and electrophysiological studies in Hey2+/- (Hey2 heterozygous knockout) mice to dissect the und...