What heart sound is most characteristic of grade II (pseudonormal) left‑ventricular diastolic dysfunction?

Heart Sounds in Grade 2 Diastolic Dysfunction

Grade 2 (pseudonormal) diastolic dysfunction is not reliably associated with any specific heart sound on auscultation, and the fourth heart sound (S4) is neither sensitive nor specific for identifying this condition. 1

Key Auscultatory Findings

S4 (Fourth Heart Sound)

• S4 may be present but is unreliable: The fourth heart sound can occur in 35% of patients with normal diastolic function, 42% with mild (grade 1) dysfunction, and 70% with moderate dysfunction, but is paradoxically absent in severe dysfunction 1
• The S4 has only 43% sensitivity and 65% specificity for detecting any diastolic dysfunction, making it an inaccurate clinical indicator 1
• S4 is eliminated with firm pressure on the stethoscope, distinguishing it from split S1 or ejection sounds which persist with pressure 2
• S4 is most frequently found in coronary heart disease and hypertension, but does not denote heart failure 2

S3 (Third Heart Sound)

• S3 indicates more advanced dysfunction: When present, S3 suggests elevated left atrial pressures and is more characteristic of grade 3 (restrictive) diastolic dysfunction rather than grade 2 3
• S3 occurs during rapid early diastolic filling deceleration and is associated with ventricular dysfunction 4
• S3 denotes cardiac decompensation, unlike S4 2

Grade 2 Diastolic Dysfunction Characteristics

Hemodynamic Profile

• Pseudonormalization pattern: Grade 2 dysfunction shows a normal-appearing Doppler transmitral flow pattern due to elevated left atrial pressures that oppose impaired relaxation 3
• This creates a diagnostic challenge because marked diastolic dysfunction can be easily missed on routine examination 3
• Elevated LAP is confirmed when more than half of the following parameters meet cutoff values: average E/e′ >14, LA volume index >34 mL/m², TR jet velocity >2.8 m/sec 5

Clinical Pitfalls

• Auscultation is inadequate for diagnosis: Physical examination cannot reliably differentiate grade 2 from normal diastolic function or distinguish it from other grades 3, 1
• Both S3 and S4 may occur together in patients with cardiac decompensation from coronary disease, hypertensive heart disease, or dilated cardiomyopathy, creating a summation gallop that can be misinterpreted 2
• Objective testing is required: Doppler echocardiography is essential for accurate diagnosis of grade 2 diastolic dysfunction 3

Diagnostic Approach

• Listen at the xiphoid or epigastric area if gallops are not detected over the usual precordial areas, particularly in patients with emphysematous chests 2
• Use the "inching" technique, moving the stethoscope from aortic area to apex while keeping S2 as a reference point to accurately time any extra sounds 2
• Do not rely on heart sounds alone: Proceed directly to echocardiography with Doppler interrogation of mitral inflow, tissue Doppler, and pulmonary vein flow for definitive diagnosis 3, 1