What could a short high-frequency click after the second heart sound during the beginning of diastole in an adult client indicate?

A Short High-Frequency Click After S2 in Early Diastole Indicates Mitral Valve Prolapse

This finding represents a diastolic sound from mitral valve prolapse (MVP), occurring when the prolapsed posterior mitral leaflet returns from the left atrium and recoaptates with the anterior leaflet in early diastole. 1

Timing and Acoustic Characteristics

• The high-frequency diastolic click occurs 70-110 msec (mean 94 msec) after the aortic component of S2 (A2), which places it in early diastole 1
• This sound is easily audible and high-pitched, best heard at the apex or left sternal border 1
• The click occurs 40-60 msec before the E point on echocardiography and even longer before the rapid-filling wave, distinguishing it from typical S3 gallops 1

Pathophysiology

• The diastolic sound results from sudden tensing of the mitral valve apparatus as the prolapsed leaflet returns to normal position and recoaptates with the opposing leaflet 1
• This mechanism is distinct from the more commonly recognized midsystolic click of MVP, which occurs when leaflets prolapse into the left atrium during systole 2

Associated Findings to Confirm MVP

• Look for the classic midsystolic click, which is the hallmark auscultatory feature of MVP and occurs during systole as leaflets prolapse 2, 3
• Listen for a late systolic murmur that is medium-to-high pitched, loudest at the apex, and may have a musical or honking quality 2, 4
• Perform dynamic auscultation: Standing (decreased LV volume) moves the systolic click-murmur complex earlier toward S1, while squatting (increased LV volume) moves it later toward S2 2, 3

Diagnostic Pitfall to Avoid

• Do not confuse this diastolic click with an S3 gallop: The MVP diastolic click is high-frequency and occurs much earlier (70-110 msec after A2) than a typical S3, which occurs during rapid ventricular filling 1
• Do not mistake it for aortic regurgitation: Some patients with MVP may have a brief, high-frequency, decrescendo early diastolic murmur that can simulate aortic insufficiency 1

Mandatory Next Step

• Obtain echocardiography immediately to confirm MVP diagnosis, assess mitral regurgitation severity, evaluate leaflet morphology (especially leaflet thickness ≥5mm which predicts complications), and determine ventricular compensation—this is a Class I indication per ACC/AHA guidelines 2, 3
• Echocardiography should demonstrate ≥2mm prolapse of the mitral valve above the annular plane in parasternal long-axis views 2

Clinical Significance

• The presence of both systolic and diastolic sounds indicates definite structural mitral valve abnormality requiring echocardiographic assessment 1, 5
• Patients with audible clicks from valvular abnormalities are at risk for infective endocarditis and require antibiotic prophylaxis consideration for dental or surgical procedures 5
• Risk stratification should focus on identifying high-risk features: leaflet thickness ≥5mm, moderate-to-severe mitral regurgitation, LV diameter ≥60mm, and leaflet redundancy 3