New method protects the heart during open heart surgery

Polarizing blood cardioplegia with esmolol, adenosin and magnesium could reduce cardiac damage following open heart surgery, according to Terje Aass‘ research.


MAIN RESULTS:

  1. Left ventricular contractility is better preserved with polarizing than depolarizing blood cardioplegia in pigs.
  2. Polarizing blood cardioplegia improves energy status during and following cardiac surgery.
  3. During prolonged heart surgery, polarizing blood cardioplegia preserves left ventricular efficiency better than depolarizing blood cardioplegia.

THESIS DEFENCE:

Thesis: Polarizing versus depolarizing blood cardioplegia. An experimental study of myocardial function, metabolism and ultrastructure following cardiopulmonary bypass and cardioplegic arrest
Candidate: Terje Aass
Time: January 11, 2019 at 11:15
Place: Haukeland University Hospital, Armauer Hansen House: Auditorium
Link to university website (in Norwegian)


SUMMARY:

Potassium-based depolarizing oxygenated blood cardioplegia is the standard method used to protect an arrested heart during open-chest surgery. In his research, Aass has tested an experimental method of polarizing oxygenated blood cardioplegia with the beta blocker esmolol, adenosin and magnesium in the cardioplegic solution.

(1) Myocardial function is equally well preserved after polarizing and depolarizing cardiac arrest. Arrested pig hearts treated with the polarizing solution had increased contractility three hours after the surgical procedure. Troponin T levels were equal in the two groups following surgery.

The study randomized 20 pigs to either polarizing or depolarizing cardioplegic arrest for one hour. Based on the results, the researchers recommend that the polarizing method is evaluated also in humans.

(2) Biopsies from the pigs’ hearts revealed higher levels of biochemical energy substrates during and shortly following polarized cardioplegic arrest compared to depolarized cardioplegic arrest. Creatine phosphate and ATP increased, whereas mitochondrial surface-to-volume ratio decreased. Three hours after surgery these differences were no longer present.

(3) In the final experiment, the cardiac arrest was prolonged to two hours. The polarized method improved left ventricular mechanical efficiency by improving the ratio between total pressure-volume area and blood flow rate compared to the depolarized method.


REFERENCES:

(1) Aass, T., Stangeland, L., Moen, C. A., Salminen, P. R., Dahle, G. O., Chambers, D. J., Markou, T., Eliassen, F., Urban, M., Haaverstad, R., Matre, K., og Grong, K. (2016). Myocardial function after polarizing versus depolarizing cardiac arrest with blood cardioplegia in a porcine model of cardiopulmonary bypassEuropean Journal of Cardio-Thoracic Surgery50(1), 130-139.

(2) Aass, T., Stangeland, L., Chambers, D. J., Hallström, S., Rossmann, C., Podesser, B. K.,  & Grong, K. (2017). Myocardial energy metabolism and ultrastructure with polarizing and depolarizing cardioplegia in a porcine modelEuropean Journal of Cardio-Thoracic Surgery52(1), 180-188.

(3) Aass, T., Stangeland, L., Moen, C. A., Solholm, A., Dahle, G. O., Chambers, D. J., Urban, M., Nesheim, K., Haaverstad, R., Matre, K. & Grong, K. (2018). Left ventricular dysfunction after two hours of polarizing or depolarizing cardioplegic arrest in a porcine modelPerfusion34(1), 67-75.