How is diastolic function calculated by echocardiography?

Assessment of Left Ventricular Diastolic Function by Echocardiography

Diastolic function assessment requires multiple echocardiographic parameters including mitral inflow patterns, tissue Doppler velocities, left atrial volume, and tricuspid regurgitation velocity to determine both the presence of dysfunction and left ventricular filling pressures.

Core Parameters for Diastolic Function Assessment

Mitral Inflow Measurements

• Peak E-wave velocity: Measured at mitral leaflet tips using pulsed-wave Doppler in the apical four-chamber view 1
• Peak A-wave velocity: Measured at the same location following the P wave on ECG 1
• E/A ratio: Calculated by dividing E velocity by A velocity 1
• Deceleration time (DT): Time interval from peak E-wave to baseline along the slope of LV filling 1

Tissue Doppler Measurements

• Mitral annular e' velocity: Measured at septal and lateral mitral annulus using pulsed-wave tissue Doppler 1, 2
• E/e' ratio: Calculated by dividing mitral E velocity by average e' velocity (septal and lateral) 1, 2
• Different cutoff values apply depending on sampling site (septal e' < 7 cm/sec, lateral e' < 10 cm/sec indicate abnormal relaxation) 1

Left Atrial Assessment

• LA maximum volume index: Measured using the method of disks or area-length method from apical four- and two-chamber views, indexed to body surface area 1
• LA volume > 34 mL/m² indicates chronically elevated filling pressures 1, 2

Additional Parameters

• Tricuspid regurgitation velocity: Measured using continuous-wave Doppler from multiple views 1
• Pulmonary vein flow: S wave, D wave, and S/D ratio provide additional information about filling pressures 1

Grading Diastolic Dysfunction

Grade I (Impaired Relaxation with Normal Filling Pressures)

• E/A ratio ≤ 0.8 with peak E velocity ≤ 50 cm/sec 1, 3
• Average E/e' ratio < 8 3, 2
• LA volume index normal (< 34 mL/m²) 1, 3
• TR velocity < 2.8 m/sec 1, 3

Grade II (Pseudonormal Pattern with Elevated Filling Pressures)

• E/A ratio between 0.8 and 2.0 1
• Average E/e' ratio > 14 1, 2
• LA volume index > 34 mL/m² 1
• TR velocity > 2.8 m/sec 1
• If more than half of these parameters meet cutoff values, filling pressures are elevated 1

Grade III (Restrictive Pattern with Significantly Elevated Filling Pressures)

• E/A ratio ≥ 2.0 1
• DT < 160 msec (especially in patients with reduced EF) 1
• Average E/e' ratio > 14 1
• LA volume index > 34 mL/m² 1
• TR velocity > 2.8 m/sec 1

Special Considerations for Different Patient Populations

Patients with Reduced Ejection Fraction

• Transmitral inflow pattern is usually sufficient to identify elevated filling pressures 1
• DT < 160 msec indicates restrictive filling and is an important predictor of outcome 1
• Pulmonary vein S/D ratio < 1 indicates increased filling pressures 1

Patients with Preserved Ejection Fraction

• Multiple parameters are needed to estimate filling pressures 1
• E/e' ratio, LA volume index, and TR velocity are particularly valuable 1
• Consider diastolic stress testing if symptoms persist despite normal resting parameters 3

Hypertrophic Cardiomyopathy

• Average E/e' > 14, LA volume index > 34 mL/m², pulmonary vein atrial reversal duration ≥ 30 msec longer than mitral A duration, and TR velocity > 2.8 m/sec are key parameters 1
• These parameters apply regardless of presence or absence of dynamic obstruction 1

Common Pitfalls and Limitations

• E/e' ratio has limited accuracy in normal subjects, patients with heavy annular calcification, mitral valve disease, and pericardial disease 2
• Fusion of E and A waves during tachycardia can make assessment difficult 1
• LA enlargement may persist despite normalization of filling pressures after treatment 1
• Single parameters should never be used in isolation; a comprehensive approach using multiple parameters is essential 4, 5
• Proper sample volume positioning is critical for accurate tissue Doppler measurements 2

Technical Considerations

• Use color flow imaging for optimal alignment of Doppler with blood flow 1
• Use low wall filter setting (100-200 MHz) and low signal gain 1
• Obtain measurements during end-expiration when possible 5
• Average multiple cardiac cycles (at least 3) for patients in sinus rhythm and 5-10 cycles for patients in atrial fibrillation 5
• Ensure optimal spectral waveforms without spikes or feathering 1