LV Diastolic Function Grading and LAP Estimation
The 2016 ASE/EACVI guidelines provide a simplified algorithmic approach using four key parameters to grade diastolic dysfunction and estimate left atrial pressure: septal e' velocity, average E/e' ratio, LA volume index, and peak TR velocity. 1
Grading Algorithm for Diastolic Dysfunction
The grading system uses a stepwise approach that prioritizes feasibility and reproducibility over complexity 1:
Step 1: Assess Mitral Inflow Pattern
- Mitral E velocity, A velocity, and E/A ratio serve as the initial screening parameters 1
- E/A ratio <0.8 with peak E velocity <50 cm/s suggests impaired relaxation (Grade I) 1
- E/A ratio 0.8-2.0 requires further evaluation with additional parameters 1
- E/A ratio >2.0 suggests restrictive physiology (Grade III) 1
Step 2: Apply Four Key Parameters
When mitral inflow is indeterminate, use these four parameters to determine elevated LAP 1:
- Septal e' velocity <7 cm/s (or lateral e' <10 cm/s) 1
- Average E/e' ratio >14 1
- LA volume index >34 mL/m² 1
- Peak TR velocity >2.8 m/s 1
If >50% of available parameters are positive, LAP is elevated (>15 mmHg) 1
Grading Classification
- Grade I (Impaired Relaxation): E/A <0.8, septal e' <7 cm/s, E/e' ≤14, normal LA volume 1
- Grade II (Pseudonormal): E/A 0.8-2.0 with elevated filling pressures (≥2 positive parameters) 1, 2
- Grade III (Restrictive): E/A ≥2.0, E velocity DT <160 ms, elevated filling pressures 1, 2
LAP Estimation Methods
Primary Approach: E/e' Ratio
- Average E/e' >14 indicates elevated mean LAP (>15 mmHg) 1
- Average E/e' <8 indicates normal LAP 1
- E/e' 8-14 is indeterminate and requires additional parameters 1
Adjunctive Parameters for LAP Estimation
Pulmonary Vein Flow 1:
- S/D ratio <1 suggests elevated LAP in reduced LVEF 1
- Ar-A duration >30 ms indicates elevated LVEDP 1
- Systolic filling fraction <40% indicates elevated LAP 1
Pulmonary Artery Pressures 1:
- Systolic PA pressure (via TR velocity) correlates with LAP when >35 mmHg 1
- Diastolic PA pressure (via PR end-diastolic velocity) provides adjunctive LAP estimation 1
LA Volume Index 1:
- Reflects cumulative effects of chronically elevated filling pressures 1
34 mL/m² indicates diastolic dysfunction 1
- Provides prognostic information independent of LVEF 1
Critical Distinctions in Pressure Measurements
Different diastolic pressures correlate with different Doppler parameters 1, 3:
- End-diastolic parameters (mitral A velocity, Ar velocity, Ar-A duration) correlate with LVEDP 1
- Early diastolic parameters (E velocity, E/A ratio, E/e' ratio) correlate with mean LAP and mean PCWP 1
- In early diastolic dysfunction, LVEDP may be elevated while mean LAP remains normal due to large atrial pressure waves 1, 3
Common Pitfalls and Caveats
Technical Limitations 1:
- Pulmonary vein recordings may be suboptimal in ICU patients 1
- LA foreshortening in apical views precludes accurate volume measurements 1
- TR jet envelope quality depends on adequate acoustic windows; agitated saline contrast improves yield 1
Clinical Context Matters 1:
- LA dilation occurs in athletes, bradycardia, high-output states, and atrial fibrillation despite normal diastolic function 1
- Mitral valve disease and hypertrophic cardiomyopathy alter standard parameter interpretation 1
- Age-related changes affect e' velocity; use age-adjusted cutoffs 3
Atrial Fibrillation Considerations 1, 4:
- Ar-A duration cannot be assessed 1
- Average 5-10 cardiac cycles for E/e' measurements 4
- Pulmonary vein D-wave deceleration time can estimate PCWP 1
Mechanical Ventilation 3:
- Positive pressure ventilation affects PCWP-LVEDP relationship 3
- Interpret filling pressures cautiously in ventilated patients 3
Integration and Clinical Application
The comprehensive approach requires integrating multiple parameters rather than relying on single measurements 1, 5: