These experiments tested the hypothesis that differences in the distribution of subepicardial and subendocardial microvascular resistances may alter the transmural distributions of microvascular pressures. Isolated blood- and physiological saline-perfused porcine hearts were surgically incised to enable exposure of the subendocardial and subepicardial microcirculations. Microvascular pressures ...

BACKGROUND Although first isolated from the porcine brain, brain natriuretic peptide (BNP) is also found in the heart, particularly in the atria. METHODS AND RESULTS We examined the immunocytochemical localization of BNP in relation to atrial natriuretic peptide (ANP) in five porcine atria using highly specific monoclonal antibodies. With the use of an indirect immunoperoxidase method, serial...

In an attempt to provide a better understanding of our finding that regions with contracting left ventricular myofibers need not develop a significant transmural systolic wall thickening gradient, the analytic approach of Costa et al. was applied to the four-dimensional dynamic data obtained 1 and 8 wk after surgical implantation of transmural radiopaque beads in the lateral equatorial left ven...

The effects of left ventricular hypertrophy (LVH) on the generation of phase 2 early afterdepolarization (EAD) and transmural dispersion of repolarization (TDR) were assessed using arterially perfused rabbit ventricular wedge preparations. Transmembrane action potentials from epicardium, subendocardium, and endocardium were simultaneously recorded together with a transmural ECG. Transmural acti...

Cardiomyopathy To The Editor: We note with interest Nagueh et al’s1 recent observation that the reduction of tissue Doppler (TD) velocities in mitral annulus excursion was highly sensitive and specific for the detection of individuals carrying hypertrophic cardiomyopathy (HCM)–causing mutations in HCM families, even in the prehypertrophic phase. Any clinical tool that can reliably identify subt...

BACKGROUND The adaptation of cardiac mass to hemodynamic overload requires an adaptation of protein turnover, ie, the balance between protein synthesis and degradation. We tested 2 hypotheses: (1) chronic left ventricular hypertrophy (LVH) activates the proteasome system of protein degradation, especially in the myocardium submitted to the highest wall stress, ie, the subendocardium, and (2) th...

BACKGROUND The aim of this study is to analyse spatial distribution of myocardial velocities (MV) and myocardial velocity gradient (MVG) with color M-mode Doppler tissue imaging (DTI) and to analyse the influence of age in such parameters. METHODS AND RESULTS A prospective study including 66 healthy volunteers was carried out with color M-mode DTI. Postprocessing of images was performed using...

The purpose of this study was to determine whether a quantitative relationship existed between a reduction in regional myocardial blood flow, measured by radiolabeled microspheres, and the degree and type of changes in myocardial activation recorded in bipolar left ventricular subepicardial and subendocardial electrograms, in open-chest dogs following acute coronary artery occlusion. We found t...

The present study assessed the mechanisms responsible for the initiation and maintenance of premature ventricular complexes (PVCs) and ventricular tachycardia (VT) during early ischemia using a unique computerized mapping system capable of recording simultaneously from 232 individual intramural sites. In the chloralose-anesthetized cat, during normal sinus rhythm prior to ischemia, ventricular ...