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Ventricular effluent of retrograde cardioplegia in human hearts has traversed capillary beds
A Ardehali1, H Laks, D C Drinkwater
1Department of Surgery, University of California, Los Angeles, Medical Center 90024, USA.
Insights
Retrograde cardioplegia effluent in ventricular chambers has nutritive properties, contrary to prior belief. This finding suggests it aids metabolic homeostasis in arrested human hearts.
Area of Science:
- Cardiology
- Cardiovascular Surgery
- Physiology
Background:
- A significant portion of retrograde cardioplegia (up to two-thirds) shunts into ventricular cavities via Thebesian and arteriosinusoidal channels.
- This ventricular effluent has been traditionally considered nonnutritive, as it was thought to bypass myocardial capillary beds.
Purpose of the Study:
- To investigate the nutritive potential of ventricular effluent from retrograde cardioplegia.
- To determine if retrograde cardioplegia contributes to the metabolic homeostasis of the arrested heart.
Main Methods:
- Explanted human hearts from 9 cardiac transplant recipients were studied.
- Colored microspheres were introduced via the coronary sinus into arrested hearts perfused with 37°C blood cardioplegia.
- Microsphere concentration in coronary artery and ventricular chamber effluents was analyzed.
Main Results:
- Approximately 80% of retrograde cardioplegia was recovered from the ventricular chambers.
- Nearly 40% of the ventricular effluent had traversed capillary beds, indicating nutritive value.
- The total nutritive fraction of retrograde warm blood cardioplegia was approximately 55%.
Conclusions:
- Ventricular chamber effluent from retrograde blood cardioplegia possesses nutritive properties.
- This effluent contributes to the metabolic homeostasis of the arrested human heart.
Background:
In human hearts, as much as two thirds of retrograde cardioplegia is shunted through thebesian and arteriosinusoidal channels into the ventricular cavities. This ventricular effluent is believed to have bypassed the myocardial capillary beds and is therefore considered nonnutritive.
Methods:
To test this hypothesis, we studied the explanted hearts from 9 cardiac transplant recipients with the diagnosis of idiopathic cardiomyopathy. These hearts were arrested in situ with cold blood cardioplegia and excised with the coronary sinus intact. The left and right coronary ostia and the coronary sinus then were cannulated. Colored microspheres (15 +/- 5 microns) mixed in 37 degrees C blood cardioplegia were administered through the coronary sinus at a pressure of 30 to 40 mm Hg. Effluents from the coronary arteries and ventricular chambers were collected and analyzed for microsphere concentration.
Results:
Approximately 80% of retrograde cardioplegia solution was recovered in the ventricular chambers. Nearly 40% of this ventricular chambers effluent had traversed capillary beds and, thus, we believe has nutritive properties. Almost all of the coronary artery effluent of retrograde cardioplegia solution had traversed capillary beds. The total nutritive fraction of retrograde warm blood cardioplegia in this explanted human heart model was approximately 55%.
Conclusions:
These findings suggest that the ventricular chamber effluent of retrograde blood cardioplegia contributes to the metabolic homeostasis of the arrested human heart.