Question

What parameter of cardiac function is detected when the sound start?

What parameter of cardiac function is detected when the sound stop?

Answer 1

Answer - parameter of cardiac function is detected when the sound is start and stop.

Heart sounds in healthy adults consist of two events: the first heart sound and the second heart sound. Together they are referred to as fundamental heart sound. A cardiac cycle or a single heartbeat is defined as the interval between the beginning of first heart sound to the beginning of the next first heart sound . The interval between the end of first heart sound to the beginning of the same cycle's second heart sound is called systole and the interval between the end of Second heart sound to the beginning of the next cycle's heart sound first is called diastole. In, general systole is shorter than diastole.

Cardiac cycles of abnormal heart sounds contain components that are not one of the fundamental heart sound . These components can be grouped into two types: extra heart sounds and murmur sounds. The second type of abnormal heart sound is called a murmur. They are caused by turbulence blood flow through a blocked (stenosis) valve, or backward flow through a leaking (regurgitation) valve. These sounds can be heard both in systole or diastole, depending on the underlying condition. The presence of murmur is a good indicator of valvular (valve related) disorders. This can cause problems for heart sound analysis in the segmentation state because most segmentation algorithms are based on determining the locations and types of fundamental heart sound. It can be seen that abnormal heart sounds are characterized by the presence of extra components in their cardiac cycles that are not fundamental heart sound . Thus one could formulate a heart sound analysis problem as detection of components other than fundamental heart sound in cardiac cycles.

* Depending on where and how hard the stethoscope is placed on the chest, the fundamental heart sound peaks may actually be smaller in magnitude than the extra peaks. Thus a threshold could be too high, so that one or more fundamental heart sound are missed. This means that the missing fundamental heart sound peaks must also be detected; if this is done by lowering the threshold, more extra peaks could be detected.

* In cases with severe murmur, one of the fundamental heart sound may become very large and the other may disappear from the envelope signal altogether.

* The assumption that systole is shorter than diastole is not always true. The length of diastole decreases with increasing heart rate; above a certain heart rate it becomes roughly the same length as systole.

* Extract heart sound signal features

According to the heart sound signal curve e'(n), we determine the start-stop points of and second heart sound ,calculate the latency and amplitude of first heart sound and second heart sound, and then obtain the durations of first heart sound -second heart sound interval and second heart sound -first heart sound interval.

These feature parameters can be used to evaluate the cardiac function.

The effective extraction of first heart sound and second heart sound is an important problem for the calculation of heart sound characteristics and the application of taking these parameters as cardiac evaluation index. The proposed was evaluated on heart sound data from clinically recorded signals and an open database. Results indicate that with the proposed reusing multi-resolution wavelet transform algorithm, it is possible to locate the start-end points of first hear sound. and second heart sound more accurately, and the heart sound features could be extracted effectively. Limitation occurs under the circumstances that the murmurs are continuous and severe, which is also an unresolved problem that would require further research.