In view of the possibility that the mechanism of mitral regurgitation following premature ventricular contractions may contribute to the understanding of mitral regurgitation in clinically important causes of nonrheumatic mitral insufficiency, we studied 320 premature ventricular contractions in eight dogs. Since the papillary muscle is an important component of the mitral valvular complex, the...

UNLABELLED The U wave is still an electrocardiographic deflection of enigmatic origin. Numerous hypotheses on its origin have been formulated, but to date none has been conclusively proven. Recently, a report described the first case of bifid (or notched) U waves. Until then this phenomenon has only been described in the T wave. This is the first report of double U waves-two separate deflection...

An accessory papillary muscle is an uncommon congenital anomaly usually found incidentally on routine cardiac imaging. While frequently asymptomatic, it is occasionally associated with mitral regurgitation, left ventricular dynamic outflow obstruction and hypertrophic cardiomyopathy1 and it is important to differentiate it from other pathological processes including papillary fibroelastoma, lef...

Interactions between Purkinje fibers and ventricular muscle were studied in canine Purkinje-papillary muscle preparations. The change in duration of action potentials across the junctions between Purkinje fibers and papillary muscle was continuously graded, not abrupt. The transmembrane action potentials were longest in the false tendons and progressively shorter in more peripheral fibers. The ...

BACKGROUND Hypertrophic cardiomyopathy (HCM) is characterized by an asymmetrically hypertrophied left ventricle and is regarded as a disease of cardiac muscle. METHODS AND RESULTS To assess the possibility that the mitral valve itself may be involved in the disease process, we studied mitral valves from 94 patients with HCM and 45 normal control subjects. The area of the mitral leaflets was i...

Rabbits, ages 4-24 weeks, were injected with saline or thyroxine (150 micrograms/kg) for 7 days, and force-velocity curves were generated using papillary muscles from these hearts by a method described previously. In addition, the structure and relative amounts of myosin isozymes from papillary muscles and from 3- to 5-mg segments of the left and right ventricular free wall were analyzed by pol...

Introduction: The tricuspid valve is a heterogeneous structure with great variability in its structure and has remained unexamined despite intense interest in cardioanatomy. The tricuspid valve complex is of great clinical importance in the light of progress in cardiosurgery and the development of novel operating techniques. Materials and methods: The present work was done by dissecting 42 form...

Mitral papillary muscle rupture is usually caused by ischaemia as a complication of myocardial infarction. In a 76 year old patient with no significant disease or major cardiovascular risk factors, papillary muscle rupture was caused by obstructive intramural coronary amyloidosis, an unusual cause.

The present investigation was carried out on the papillary muscles of ten healthy mature dromedary camels. Anatomically, the papillary muscles are muscular projections from the walls of the right and left ventricles into their cavities. They are processing many nipples like processes. The apex of each muscle process is attached to cord-like tendons; chordae tendineae. The latter, are string-lik...