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A heart valve is a biological one-way valve that allows blood to flow in one direction through the chambers of the heart.A mammalian heart usually has four valves. Together, the valves determine the direction of blood flow through the heart.
Attempts to improve the design of the valve and speed manufacturing, however, led to a weaker structure, with serious consequences. Beginning in 1979, Björk–Shiley valves with the convexo-concave design had a tendency to develop fractures in the outflow strut which could result in catastrophic valve failure and possibly sudden cardiac death.
Asystole (New Latin, from Greek privative a "not, without" + systolē "contraction" [1] [2]) is the absence of ventricular contractions in the context of a lethal heart arrhythmia (in contrast to an induced asystole on a cooled patient on a heart-lung machine and general anesthesia during surgery necessitating stopping the heart).
Diagram of the human heart. Several adaptations of the Ross procedure have evolved, but the principle is essentially the same; to replace a diseased aortic valve with the person's own pulmonary valve (autograft), and replace the person's own pulmonary valve with a pulmonary valve from a cadaver (homograft) or a stentless xenograft.
Tetralogy of Fallot (TOF), formerly known as Steno-Fallot tetralogy, [9] is a congenital heart defect characterized by four specific cardiac defects. [4] Classically, the four defects are: [4]
The first heart sound, or S 1, forms the "lub" of "lub-dub" and is composed of components M 1 (mitral valve closure) and T 1 (tricuspid valve closure). Normally M 1 precedes T 1 slightly.
Heart rate variability visualized with R-R interval changes Electrocardiogram (ECG) recording of a canine heart that illustrates beat-to-beat variability in R–R interval (top) and heart rate (bottom).