30.1 - Function of the heart valves. Heart sounds. Methods of examination. Stenosis and insufficiency of valves. Correlation between a synchronous phonocardiographic and electrocardiographic record.

sections

Av valves

semilunar valves

valves of heart

heart sounds

phonocardiography

stenosis

Av valves (tricuspid and mitral)

• prevent backflow of blood from the ventricles to the atria during systole

• These valves close and open passively due to the pressure differences in front of and behind the valve

• Due the AV valves being relatively thin they close without the need of heavy backflow

semilunar valves

• prevent backflow from the aorta and pulmonary arteries into the ventricles during diastole

• the high pressures in the arteries at the end of systole cause the semilunar valves to snap to the closed position

• The much heavier semilunar valves require rather rapid backflow for a few milliseconds for closure.

• Due to the rapid closure and rapid ejection, the edges of the aortic and pulmonary valves are subjected to much greater mechanical abrasion than the A-V valves

• Constructed with an especially strong yet very pliable fibrous tissue base to withstand the extra physical stresses.

valves of heart

• aortic valve - right 2nd intercostal space parasternal

• Pulmonary valve - left 2nd interostal space parasternal

• Tricuspid - left 4th intercostal- parasternal

• Mitral - left 5th intercostal space midclavicular

heart sounds

• We can only hear valves closing

• 1st Lub = when the ventricles contract (QRS complex) we can hear the AV Valves closing.

• 2nd Dub = when semilunar valves (aortic and pulmonary ) at the end of systole BEST heard at ERB’S point

• Listening to heart sounds with the stethoscope is auscultation

phonocardiography

In Phonocardiography- The heart sounds can be amplified and recorded by a high-speed recording apparatus. The recording is called a phonocardiogram, and the heart sounds appear as waves and can be used to detect murmurs

stenosis

• stenosis- narrowing of a channel

• Aortic valve stenosis — occurs when the heart's aortic valve narrows.

• Decreased cardiac output

• does not close fully

• So valves do not open properly which reduces or blocks blood flow from your heart into the main artery to your body (aorta) and onward to the rest of your body.

• valve stenosis due to old age build up of calcium deposits on the aortic valve

• caused by rheumatic disease