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Heart sounds are the noises generated by the beating heart and the resultant flow of blood through it. Specifically, the sounds reflect the turbulence created when the heart valves snap shut. In cardiac auscultation, an examiner may use a stethoscope to listen for these unique and distinct sounds that provide important auditory data regarding the condition of the heart.
In healthy adults, there are two normal heart sounds, often described as a lub and a dub (or dup), that occur in sequence with each heartbeat. These are the first heart sound (S1) and second heart sound (S2),
produced by the closing of the atrioventricular valves and semilunar valves, respectively. In addition to these normal sounds, a variety of other sounds may be present including heart murmurs, adventitious sounds, and gallop rhythms S3 and S4.
Heart murmurs are generated by turbulent flow of blood and a murmur to be heard as turbulent flow must require pressure difference of at least 30 mm of hg between the chambers and the pressure dominant chamber will out flow the blood to non dominant chamber in diseased condition which leads to Left-to-right shunt or Right-to-left shunt based on the pressure dominance. Turbulent may occur inside or outside the heart if its outside heart its called Bruit. Murmurs may be physiological (benign) or pathological (abnormal). Abnormal murmurs can be caused by stenosis restricting the opening of a heart valve, resulting in turbulence as blood flows through it. Abnormal murmurs may also occur with valvular insufficiency (regurgitation), which allows backflow of blood when the incompetent valve closes with only partial effectiveness. Different murmurs are audible in different parts of the cardiac cycle, depending on the cause of the murmur.
The heart-sounds, as heard through the stethoscope, in valvular disease, will, of course, be more distinctly ascertained at the locality of F, the right ventricle, which is immediately substernal.
Other sounds may be audible there, but the character and the rate of the heart-sounds are distinctive.
Before the significance of fertilization was understood, it was perhaps not unreasonable to believe that life began with quickening or about the time the fetal heart-sounds could be heard.
By means of a series of painless manipulations through the abdominal wall of the mother, the head, the body, and the extremities of the child may be mapped out, and the conclusions verified by locating the fetal heart-sounds.
The need of its employment in behalf of the child may be determined by careful observation of the fetal heart-sounds, which are heard over the mother's abdomen, and by means of which one may learn the condition of the child.
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