Atrioventricular valve

One of the remarkable features of the heart, which is about the size of a fist, is that the pumping action or contractions (- 70 times/min) of atria and ventricles are simultaneous. Deoxygenated blood is pumped out to the lungs from one side of the heart at the same time oxygenated blood is pumped out from the other side to the aorta and onward through the body. The entire process of blood flow between the atria, ventricles, and the principal vessels is in unison, controlled in part by four one-way valves. The atrioventricular valves, tricuspid on the right and mitral on the left, prevent blood from flowing... 

Classically, vegetations typically are located on the line along valve closure on the atrial surface of the atrioventricular valves (tricuspid and mitral) or on the ventricular surface of the semilunar valves (pulmonary and aortic) (Fig. 71-2). The vegetations can vary significantly in size from only millimeters to several centimeters and may be single or multiple masses. Often, destruction of underlying tissue occurs and may cause... 

The cardiac pump theory states that the active compression of the heart between the sternum and vertebrae creates an artificial systole in which intraventricular pressure increases, the atrioventricular valves... 

Schnittger I, Appleton CP, Hatle LK, Popp RL. Diastolic mitral and tricuspid regurgitation by Doppler echocardiography in patients with atrioventricular block new insight into the mechanism of atrioventricular valve closure. J. Am. Coll. Cardiol. 1988 11 83-8. 

Check the cardiac valves. The tricuspidal atrioventricular valve on the right side comprises three cusps. The mitral AV valve on the left side comprises two cusps. Both AV valves are linked to papilla-shaped muscles via tendinous ligaments. The pulmonal and aortic valves also have three semilunar cusps, respectively. 

Then heart Pericardium, atrium, ventricle, ventricular septum, atrioventricular valve, and semilunar valve. 

The heart is inspected internally following a longitudinal section into the right and left ventricles. The exposed papillary muscles and atrioventricular valves are examined. 

The cardiac pump theory states that the active compression of the heart between the sternum and vertebrae creates an artificial systole in which intraventricular pressure increases, the atrioventricular valves close, the aortic valve opens, and blood is forced out of the ventricles. When ventricular compression ends, the decline in intraventricular pressure causes the mitral and tricuspid valves to open, and ventricular fining begins. 

The heart has four valves— two atrioventricular (tricuspid and mitral) and two semilunar (pulmonic and aortic). Atrioventricular valves control bloodflow between the atria and ventricles. Semilunar valves control the bloodflow between the ventricles and the pulmonary artery and the aorta. 

The model 106 valve with the thicker more durable struts has been available since 1974 for atrioventricular valve replacement,... 

The cardiac pump theory advocates that there is (direct) pressure on the ventricles. This is supported by indications that compression depth is related to output, that cardiac (or more specifically ventricular) deformation is related to stroke volume, that the duration of compression has no effect, and that an increased compression rate will increase flow [17]. In the original manuscripts, as well as over time, 1.5 to 2 in. (4 to 5 cm) has been maintained as standard. Forward flow of blood is assumed to be caused by competent atrioventricular valves and sufficient competence of the aortic and pulmonary valves to avoid regurgitation during CPR diastole. Implicitly, ventricular filling is essential and artificial systole must be sufficiently frequent to generate acceptable flow, as stroke volumes may be relatively small compared to the normal 60 to 100 ml per beat at ejection fractions of 40 to 75%. Mitral valve closure during CPR systole is deemed essential for the cardiac pump theory to work. 

The human heart contains four unidirectional valves that are anatomically grouped into two types the atrioventricular valves and the semilunar valves. The tricuspid and mitral (bicuspid) valves... 

The three most commonly occurring types of ASD are ostium secundum/ fossa ovalv, ostium primum and sinus venous defects. Ostium secundum/ fossa ovali accounts for approximately 80% of all ASDs. It is also one of the most common cardiac malformations occurring in adults (approximately 30-40% of cases). Generally, defects that are found midseptally, near the fossa ovalis, are classified as this type. Ostium primum type defects are typically found flanking the atrioventricular valves and generally occur in Down... 

The second governing principle relates to the simultaneous reciprocation of atrioventricular volumes during the cardiac cycle such that the four-chambered heart (i.e., the contents of the pericardial sack) operates as a near-perfect constant-volume pump [4]. That means that while the two ventricles eject and the closed atrioventricular valves move toward the apex, the two atria fill. This is accomplished by keeping the epicardial apical portion of the heart fixed in space within the pericardial sack, while the backs of the two atria are similarly anchored in the mediastinum by the pulmonary veins and cavae. The nearperfect constant-volume physiology by which the epicardial surface has minimal radial displacement in the normal heart provides the mechanism that relates diastolic transmitral flow to simultaneous, mandatory ascent of the mitral annulus. 

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