What is the appropriate evaluation and management for a patient presenting with a loud S2 (second heart sound) and ejection click?

Evaluation and Management of Loud S2 with Ejection Click

A loud S2 with an ejection click most commonly indicates pulmonary hypertension or congenital heart disease (particularly bicuspid aortic valve, pulmonary stenosis, or atrial septal defect), and requires immediate transthoracic echocardiography as the first-line diagnostic test. 1

Key Diagnostic Considerations

Differential Diagnosis Based on Physical Findings

The combination of a loud S2 and ejection click narrows your differential significantly:

• Pulmonary hypertension: Produces a loud P2 component of S2 with a pulmonary ejection click occurring approximately 0.18 seconds from the Q wave 2
• Bicuspid aortic valve: Generates an aortic ejection click at 0.13 seconds from the Q wave, though typically A2 is preserved unless stenosis is severe 1, 2
• Pulmonary stenosis: Creates an ejection click at 0.10 seconds from the Q wave with variable S2 intensity depending on severity 3, 2
• Atrial septal defect: Presents with fixed split S2 (loud P2) and may have associated ejection sounds from increased flow across the pulmonary valve 1, 4
• Congenitally corrected transposition (L-TGA): Characterized by a single loud S2, though this typically lacks a separate ejection click 1

Critical Physical Examination Details

Immediately assess these specific findings:

• Respiratory variation of S2: Fixed splitting suggests ASD, while normal splitting excludes severe aortic stenosis 5, 6
• Timing of ejection click: Early clicks (0.10 sec from Q wave) suggest pulmonary stenosis; later clicks (0.13 sec) suggest aortic valve disease 2
• Carotid pulse character: Delayed, dampened upstroke indicates severe aortic stenosis, which would contradict a loud S2 1, 5
• Right ventricular lift: Suggests pulmonary hypertension or right ventricular volume overload from ASD 4
• Associated murmurs: Midsystolic ejection murmur location (right upper sternal border vs. left upper sternal border) helps differentiate aortic from pulmonary pathology 1

Diagnostic Algorithm

Step 1: Immediate Echocardiography

Order transthoracic echocardiography immediately as recommended by the American College of Cardiology for evaluation of abnormal heart sounds and suspected valvular disease. 1

The echocardiogram must assess:

• Valve morphology (bicuspid vs. tricuspid aortic valve, pulmonary valve structure) 1
• Presence of intracardiac shunts (ASD, VSD) 1, 4
• Right ventricular size and function 1
• Pulmonary artery pressures via tricuspid regurgitant jet velocity 1
• Left ventricular size and function 1

Step 2: ECG Analysis

Obtain 12-lead ECG looking for specific patterns:

• Right axis deviation and incomplete RBBB suggest ASD with right ventricular volume overload 4
• Right ventricular hypertrophy indicates chronic pressure overload from pulmonary stenosis or pulmonary hypertension 7
• Absent Q waves in left precordial leads with Q waves in aVR suggests L-TGA 1
• Complete or first-degree heart block may indicate L-TGA or complex congenital disease 1, 7

Step 3: Integration with Pre-Test Probability

Critical pitfall to avoid: If physical examination strongly suggests one diagnosis but echocardiography shows discordant findings, the echocardiogram has likely underestimated disease severity due to technical limitations (poor Doppler alignment, eccentric jets). 1

For example, if you hear a loud S2 with ejection click and the echo shows only mild abnormalities but the patient has symptoms or other concerning physical findings, pursue additional imaging (cardiac CT, cardiac MRI, or cardiac catheterization). 1

Management Based on Etiology

If Pulmonary Hypertension Confirmed

• Investigate underlying cause (left heart disease, chronic lung disease, chronic thromboembolic disease, pulmonary arterial hypertension) 1
• Refer to pulmonary hypertension specialist for targeted therapy consideration 1

If Congenital Heart Disease Identified

Bicuspid aortic valve:

• Follow-up echocardiography every 3-5 years if mild stenosis, every 1-2 years if moderate, yearly if severe 5
• Monitor for progression to severe stenosis (bimodal distribution with presentation in fourth decade) 1

Atrial septal defect:

• Consider closure (percutaneous or surgical) even in older adults, as repair improves quality of life, NYHA class, and ventricular function with low complication rates 1
• Monitor for atrial arrhythmias and mitral valve competence post-repair 1

Pulmonary stenosis:

• Severity determines intervention timing; severe stenosis may require balloon valvuloplasty or surgical correction 1

If L-TGA Suspected

• Recognize this presents with single loud S2 (not split), often with holosystolic murmur of systemic AV valve regurgitation 1
• Manage heart failure with standard medications, though benefit in systemic morphological right ventricles continues to be assessed 1
• Monitor for complete heart block development 1

Follow-Up Strategy

Do not perform exercise testing in symptomatic patients with suspected severe stenotic lesions (Class III recommendation), but consider it in asymptomatic patients to elicit exercise-induced symptoms (Class IIb). 5

Endocarditis prophylaxis: Patients with structural valve abnormalities producing clicks are at considerable risk for infective endocarditis and should receive antibiotics prior to dental or surgical procedures. 8