Ventricular septal defect (VSD) is the persistence of one or more holes in the septum that separates the left and right ventricles of the heart. The ventricles are a single chamber at about four weeks of gestation but by eight weeks it has been divided into two. Failure of development of any part of the septum results in a defect. It may vary considerably in terms of size and haemodynamic conse...

In a patient with WPW, type A, pharmacological therapy and radioactive iodine failed to control the disabling, life-threatening arrhythmia. Surgical ligation of the A-V bundle was undertaken in view of the rapidly deteriorating clinical course. Failure to identify A-V block after several sutures were placed in the A-V junction and subsequent activation of the ventricles in a heart with known A-...

In the normal heart, an insulating barrier separates the atria and ventricles. The only way in which electrical impulses can cross this barrier is via the atrioventricular (AV) node, which delays impulse conduction to ensure the forward flow of the blood. However, in some individuals, additional muscular bundles (accessory pathways) allow rapid conduction of electrical impulses from the atria t...

The processes which are involved in the development of the normal outflow tracts of the ventricles are the following: The ostium bulbar torsion accounts for the concordant flow between the ventricles and the proximal conuses. The leftward shift of the ostium bulbi accounts for the partial overriding of the aorta over the left ventricle. The truncal rotation accounts for the twisted relationship...

A distinct, well-defined phase has been identified in a patient with heart block during which sinus impulses were conducted to the ventricles. This phase persisted during pacing but its onset and termination were delayed. No significant difference was found at varying pacing rates. On four occasions while pacing, two consecutive sinus impulses were conducted to the ventricles but this was not s...

The processes which are involved in the development of the normal outflow tracts of the ventricles are the following: The ostium bulbar torsion accounts for the concordant flow between the ventricles and the proximal conuses. The leftward shift of the ostium bulbi accounts for the partial overriding of the aorta over the left ventricle. The truncal rotation accounts for the twisted relationship...

Heart valves are thin, complex, layered connective tissues that direct blood flow in one di‐ rection through the heart. There are four valves in the heart, located at the entrance to and exit from the ventricular chambers. The normal function of the heart valves is essential to cardiovascular and cardiopulmonary physiology. The opening and closing of valve leaflets at precise times during the c...

This is an anatomic study of 96 hearts with straddling or displaced atrioventricular (AV) valves and orifices. In the complete form, both the annulus and the peripheral connections of either AV valve straddle a ventricular septal defect (VSD) and connect to both ventricles. In the annular form, only the annulus, and in the peripheral type only the peripheral connections of the valve are found i...

The idea that diastolic dysfunction may give rise to symptoms of cardiac disease independent of any impairment of systolic function is not new, and was appreciated centuries ago.2 Traditional definitions of heart failure have focused on abnormalities of systolic or pump function ofthe heart, emphasizing the failure of cardiac output to meet the metabolic requirements of the body at peak workloa...

Computational models of the heart, from cell-level models, through one-, two- and three-dimensional tissue-level simplifications, to biophysically-detailed ventricles, atria or whole allow simulation excitation propagation this excitation, have provided remarkable insight into normal pathological functioning heart. In article we present equations for modelling cellular (i.e. cell action potenti...