The last of the heart sounds in the “Big 12” essential bedside cardiology findings, is the mid-systolic click. Now, you may hear one, you may hear several. This is a young lady whose mom and dad insisted she get a good check-up before she goes to college, totally asymptomatic. You examine her, no abnormal findings with the arterial pulses, venous pulses, chest wall movements. You listen at the apex with firm pressure on the diaphragm, timing systole, again, with the carotid vessel, listen carefully. Let’s listen together. [sounds]
What we heard at the apex was not just [sounds]. We heard an extra sound in mid-systole. It was [sounds]. Just a little high-frequency sound, it is not easy to mimic, but you ought to try it, because it does put the timing in your head and reminds you that it’s high-frequency. So it was not just [sounds], it was [sounds]. Try that. [sounds]
And what does that mean? That is a mid-systolic click. Sometimes you hear multiple mid-systolic clicks, and when you hear that, you want to listen hard to see if you also hear a murmur. In this case we did not. And what’s the pathophysiology? This is a young woman with mitral valve prolapse. The valve is a bit more redundant that normal, the chordae a bit elongated, and as the ventricle contracts, those structures snap back and generate that mid-systolic click. Concentrate, listen in mid-systole, tune in.
Systolic Click
The systolic click has a sharp, high frequency "clicking" quality; although it is often best heard over the cardiac apex, it can be transmitted widely. There may be a single click occurring as an isolated finding in mid to late systole, or there may be multiple clicks.
The mechanism of the click is abrupt tensing of the prolapsed portion of the mitral valve during mid-to-late systole. This is similar to the popping sound created by a sail or parachute just as it reaches the point of full expansion.
Systolic Click and S2
This is a graphic example of a mid systolic click followed by an S2. Let us listen together.