Đánh giá chức năng tâm trương thất trái

Left Ventricular Diastolic Function

Để đánh giá chức năng tâm trương thất trái, cổng doppler xung được đặt ở mỏm van 2 lá, ghi nhận các thông số:

• 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
Ba giai đoạn bất thường đổ đầy tâm trương:
b]Stage I[/b] : Suy thư giản thất trái giai đoạn đầu :
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.
Ghi chú:
IVRT (thời gian giãn đồng thể tích) được tính từ khi đóng van động mạch chủ đến thời điểm bắt đầu mở van 2 lá.
Tỷ số S/D: là vận tốc sóng S (sóng tâm thu) chia cho vận tốc sóng D (sóng tâm trương) của dòng tĩnh mạch phổi đo được bằng phương pháp Doppler.
Vận tốc sóng A: là vận tốc dòng tĩnh mạch phổi được đo bằng phương pháp Doppler thời kỳ nhĩ thu.