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Augmenting cardiac contractility hastens myocardial edema resolution after cardiopulmonary bypass and cardioplegic
S J Allen1, H J Geissler, K L Davis
1Department of Anesthesiology, University of Texas-Houston Medical School, 77030, USA. sallen@anes1.med.uth.tmc.edu
Insights
Dobutamine administration enhanced cardiac contractility, improving lymphatic function and reducing myocardial edema after cardiopulmonary bypass (CPB) and cardioplegic arrest (CPA). This suggests inotropic drugs can accelerate cardiac recovery post-surgery.
Area of Science:
- Cardiology
- Cardiovascular Surgery
- Physiology
Background:
- Myocardial edema is a known complication of cardiopulmonary bypass (CPB) and cardioplegic arrest (CPA).
- Impaired lymphatic function due to reduced contractility can exacerbate myocardial edema.
- Interventions to accelerate edema removal after CPB have not been extensively studied.
Purpose of the Study:
- To investigate whether enhancing cardiac contractility improves myocardial lymphatic function and speeds up edema resolution following CPB.
- To determine the role of organized ventricular contraction in myocardial edema removal.
Main Methods:
- Sixteen dogs underwent CPB and 1-hour hypothermic CPA.
- Post-CPB, 10 dogs received dobutamine infusion; 6 served as controls.
- Measurements included myocardial lymph driving pressure, myocardial water content, and peak left ventricular pressure increase (dP/dmax).
Main Results:
- Dobutamine-treated dogs showed significantly increased dP/dmax.
- This enhanced contractility correlated with higher lymph driving pressures.
- Dobutamine administration resulted in lower myocardial water gain 1 hour after CPB compared to controls.
Conclusions:
- Dobutamine administration hastened the resolution of myocardial edema after CPB in dogs.
- Organized ventricular contraction and cardiac contractility are crucial for lymphatic function and edema removal.
- Inotropic drug administration post-CPB may be a viable strategy to expedite cardiac recovery.
Unlabelled:
Although myocardial edema is associated with cardiopulmonary bypass (CPB) and cardioplegic arrest (CPA), interventions to expedite edema removal have not been investigated. The primary mechanism for the removal of excess interstitial fluid in the heart is myocardial lymphatic drainage, but lymphatic function can be impaired by decreased contractility because of edema. The purpose of this study was to determine whether enhancing cardiac contractility would increase myocardial lymphatic function and hasten edema resolution after CPB. Sixteen dogs were subjected to CPB and 1 h of hypothermic CPA. After weaning from CPB, 10 dogs received an intravenous dobutamine infusion and 6 dogs received no inotropic support. We determined myocardial lymph driving pressure from the major cardiac lymphatic, myocardial water content by using microgravimetry, and the peak rate of left ventricular pressure increase (dP/dmax) by using micromanometry. Measurements were taken at baseline, during CPA, and 60 min after CPB. Compared with controls, dobutamine-treated dogs had an increased dP/dmax (P < 0.05), which was associated with higher lymph driving pressures (P < 0.05), resulting in lower myocardial water gain 1 h after CPB (P < 0.05). We conclude that the resolution of myocardial edema after CPB was hastened by dobutamine. Organized ventricular contraction and myocardial contractility seem to be important determinants of myocardial lymphatic function and myocardial edema removal. These findings suggest that the administration of inotropic drugs after CPB may hasten cardiac recovery.
Implications:
Myocardial edema, which develops during cardiopulmonary bypass and cardioplegic arrest, contributes to cardiac dysfunction after heart surgery. This study demonstrated that enhancement of cardiac contractility by the administration of dobutamine after cardiopulmonary bypass and cardioplegic arrest was associated with increased myocardial lymphatic function and hastened edema resolution in dogs.