Question

If the heart sound recording and the ECO recordings are superimposed then the first heart sound would occur?

• A. At the P wave
• B. Just after the P wave
• C. Just before the QRS complex
• D. Just after the QRS complex

Answer 1

The correct option is D Just after the QRS complex

When you listen to the heart beat with a stethoscope, you can hear two main heart sounds, lub-dup, which repeat rhythmically. These sounds result from the heart valves closing. When the valves close, they cause turbulence in blood flow that sets up vibrations in the walls of the heart chambers. The first heart sound, lub, is low-pitched, not very loud, and fairly long-lasting. It is caused mainly by the closing of the AV ( mitral and tricuspid) valves and marks the beginning of ventricular systole. The lub sound is quickly followed by the higher-pitched, louder, sharper, and shorter dup sound. Heard almost as a quick snap, the dup marks the closing of the semi lunar valves and the beginning of ventricular diastole. The quality of these sounds tells a discerning physician much about the state of the valves. In the typical ECG recording the peaks "QRS" correspond to ventricular systole. The "lub" sound will be immediately followed by ventricular systole, corresponding to QRS peak in the ECG.