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Left ventricular filling as assessed by pulsed Doppler echocardiography after coronary artery bypass grafting
A Owall1, R Anderson, L A Brodin
1Department of Cardiothoracic Anaesthetics, Karolinska Hospital, Stockholm, Sweden.
Insights
Left ventricular diastolic filling is impaired immediately after coronary artery bypass grafting surgery. However, Doppler echocardiography shows gradual recovery of diastolic function within 6 hours in the intensive care unit.
Area of Science:
- Cardiology
- Cardiac Surgery
- Echocardiography
Background:
- Left ventricular diastolic filling is crucial for cardiac function.
- Coronary artery bypass grafting (CABG) can impact diastolic function.
- Transesophageal pulsed Doppler echocardiography is a valuable tool for assessing diastolic filling.
Purpose of the Study:
- To investigate changes in left ventricular diastolic filling after CABG surgery.
- To assess the recovery of diastolic function in the early postoperative period.
Main Methods:
- Nine patients without valvular disease or left ventricular hypertrophy underwent transesophageal pulsed Doppler echocardiography.
- E:A ratio and early diastolic deceleration time were calculated as indices of diastolic filling.
- Hemodynamic parameters including heart rate and systemic vascular resistance were monitored.
Main Results:
- The E:A ratio significantly decreased after anesthesia induction and immediately post-surgery, indicating impaired diastolic filling.
- The E:A ratio gradually increased in the intensive care unit (ICU) over 6 hours.
- Deceleration time also showed changes consistent with impaired and then recovering diastolic function.
Conclusions:
- Diastolic filling of the left ventricle is impaired immediately following CABG.
- Gradual, though incomplete, recovery of diastolic function is observed within the first 6 hours post-surgery.
- Doppler echocardiography indices effectively track these dynamic changes in diastolic filling.
Abstract:
Diastolic filling of the left ventricle, as assessed by transesophageal pulsed Doppler echocardiography during and in the early phase following coronary artery bypass grafting, was investigated in nine patients without valvular disease or left ventricular hypertrophy. The ratio between the maximal heights of the early diastolic flow-velocity peak and the late (atrial) diastolic flow-velocity peak, the E:A ratio, and also the deceleration time of the early peak were calculated as indices of left ventricular filling. The E:A ratio decreased from 1.01 +/- 0.06 after induction of anesthesia to 0.46 +/- 0.06 on arrival in the intensive care unit (ICU). The E:A ratio then increased and reached 0.87 +/- 0.08 after 6 hours in the ICU. This increase in E:A ratio in the ICU was due to an increasing peak velocity of the E wave. The deceleration time decreased after surgery and increased from 111 +/- 25 to 145 +/- 12 milliseconds in the ICU. Pulsed Doppler indices of diastolic filling are known to be altered by changes in hemodynamic parameters, to be load-dependent, and to vary with heart rate. In the ICU, pulmonary capillary wedge pressure remained unchanged, heart rate decreased by approximately 12%, and systemic vascular resistance decreased by approximately 40%. The changes in hemodynamic parameters could have affected the E:A ratio, but it is unlikely that they could explain the marked increase in the E:A ratio that occurred in the ICU. The results, therefore, imply the presence of impaired diastolic filling immediately after cardiopulmonary bypass with gradual, but not complete, recovery during the first 6 hours in the ICU.