Left Ventricular Diastolic Function
To evaluate left ventricular diastolic function, a PW Doppler sample volume is placed at the mitral valve leaflet tips and the following measurements recorded:
- E/A ratio : Normal 1.1 to 1.5
- Deceleration time : 160 to 240 msec
- IVRT (isovolumic relaxation time) : 76 ± 13 (> 40 yrs); 69 ± 12 (<40yrs)
- Pulmonary vein "a" wave flow reversal : < 25 cm/sec
Abnormal Function
Three patterns or stages indicate abnormal diastolic filling
Stage I : Impaired early left ventricular relaxation
- Reduced left ventricular filling in early diastole
- Significance: Impaired (slow) early left ventricular relaxation
- Signs and symptoms: None at rest
- Functional status: Mild impairment
- Left atrium: Normal dimension (may be hypercontractile)
- Filling pressures: Normal
- PW Doppler findings:
- E/A ratio < 1.0
- Deceleration time > 240 msec
- IVRT > 90 msec
- Pulmonary Vein "a" wave flow reversal < 25 cm/sec
The stage I filling pattern represents impaired (slow) early left ventricular relaxation. At this point, the patient is usually asymptomatic, with normal filling pressures.
Stage II: Pseudonormalization
- Significance: Suggests impaired (slow) early left ventricular with decreased left ventricular compliance
- Signs and symptoms: Exertional dyspnea
- Functional status: Moderate impairment
- Left atrium: Enlarged and hypocontractile
- Filling pressures: increased
- PW Doppler findings
- E/A ratio: 1.0 to 1.5
- Deceleration time: 160 to 240 msec
- IVRT: 76±13 (>40yrs), 69 ± 12 (< 40 yrs)
- Pulmonary vein "a" wave flow reversal: > 25 cm/sec
At stage II, the effects of impaired (slow) early left ventricular relaxation on early diastolic filling become opposed by the elevated left atrial pressure, and the early diastolic transmitral pressure gradient and mitral flow velocity pattern return to normal. This phenomenon is called pseudonormalization to indicate that although left ventricular filling appears normal significant abnormalities of diastolic function are present. In most patients, left atrial and left ventricular end-diastolic filling pressures are elevated, the left atrium is increased in size, and patients often complain of exertional dyspnea. Stage II suggests a decrease in left ventricular compliance, especially when there is a large pulmonary vein "a" wave flow reversal.
Stage III: "Restricted" Filling Pattern
- Significance: Severe decrease in left ventricular compliance and impaired (slow) early left ventricular relaxation
- Signs and symptoms: Dyspnea with minimal exertion
- Functional status: Marked impairment
- Left atrium: Enlarged and hypocontractile
- Filling pressures: Markedly increased
- PW Doppler findings
- E/A ratio: > 1.5
- Deceleration time: < 160 msec
- IVRT: < 60 msec
- Pulmonary' vein "a" wave flow reversal: > 25 cm/sec (Variable: Depending on atrial systolic function)
Stage III represents a severe decrease in left ventricular chamber compliance. Diastolic filling pressures are elevated and patients markedly symptomatic and demonstrate a severely reduced functional capacity. The left atrium is dilated and hypocontractile. Despite the presence of impaired left ventricular relaxation, the markedly elevated left atrial pressure results in a high velocity of early diastolic filling, which stops abruptly because of an abnormally rapid rise in ventricular pressure and atrial dysfunction.