Beta-Blockade as an Alternative to Cardioplegia

Abstract

As an alternative to cardioplegic arrest, "cardiac surgical conditions" (i.e. a flaccid heart which facilitates surgery) have been created by continuously perfusing the coronary arteries with normothermic blood and suppressing myocardial chronotropy and inotropy with the ultra-short acting beta-blocker esmolol. In contrast to cardioplegic arrest, minimal cardiac contraction is maintained. Using this technique, the myocardium is protected against ischemia by antegrade coronary blood flow and reduced metabolism. In addition, the presence of minimal cardiac contractions protects the myocardium against edema formation by maintaining myocardial fluid balance. This paper presents both the rationale for and the application of "beta-blocker-induced cardiac surgical conditions" as an alternative concept for myocardial protection during coronary artery surgery.

Myocardial protection with oxygenated esmolol cardioplegia during prolonged normothermic ischemia in the rat

“…The total volume of esmolol required to induce and maintain cardiac arrest is quite low (the addition of a suitable volume of esmolol to oxygenated blood to make up a 1 mmol/L concentration) relative to potassium cardioplegia, for which volumes in excess of 1000 mL are required. Consequently, additional hemodilution during cardiopulmonary bypass should be avoided with esmolol arrest, in contrast to warm continuous-infusion of blood cardioplegia or the cardiac surgical condition induced with esmolol added to blood for continuous infusion, [14][15][16] multidose intermittent esmolol infusion would provide a still and blood-free operating field during warm (normothermic) heart surgery. This technique of multidose esmolol infusion can be used for coronary artery bypass surgery, or any other type of cardiac surgery.…”

“…High doses of esmolol were intravenously infused during continuous perfusion of the coronary arteries with normothermic blood to suppress cardiac inotropy and chronotropy, such that the heart rate was slowed sufficiently (without inducing cardiac arrest) to perform the operation. Since then, experimental and clinical studies [15][16][17] have shown that the induction by high-dose esmolol of adequate cardiac surgical conditions has provided myocardial preservation equivalent to or better than cold crystalloid or blood cardioplegia. With this technique, however, which consists of continuous coronary infusion of blood containing esmolol, the surgeon is not provided with a still and blood-free operating field.…”

Beta-bloqueadores em anestesiologia: aspectos farmacológicos e clínicos

“…O esmolol tem sido usado durante ressecção de feocromocitoma em associação com alfa-bloqueadores 26,27 , no manuseio da hipertensão provocada por tireotoxicose 28 e na toxicidade cardiovascular provocada pela adrenalina ou cocaí-na. Pode ser utilizado ainda como alternativa à cardioplegia em cirurgia coronariana 29 , na hipotensão controlada 30 , como adjuvante na eletroconvulsoterapia 31 e na broncoscopia rígida, e no controle de taquidisritmias e de hipertensões arterial e intra-ocular, entre outras 6,10,13,32 .…”

“…Esmolol has been used during pheochromocytoma resection in association with alpha-blockers 26,27 , to treat thyrotoxicosis-induced hypertension 28 and cardiovascular toxicity caused by epinephrine or cocaine. It can also be used as an alternative to cardioplegia in coronary surgery 29 , in controlled hypotension 30 , as an adjuvant for electroconvulsive therapy 31 and rigid bronchoscopy, and in controlling tachiarhythmias and arterial and intra-ocular hypertension, among others 6,10,13,32 .…”

Myocardial protection: The efficacy of an ultra-short-acting β-blocker, esmolol, as a cardioplegic agent

“…This short half-life of esmolol led Sweeney and Frazier 14 to use high-dose esmolol infusion in hearts of patients with compromised left ventricular (LV) function who were supported by an LV assist device to suppress cardiac inotropy and chronotropy during myocardial revascularization. Subsequently, experimental 15,16 and clinical [17][18][19][20] studies have shown that esmolol can be used to obtain minimal myocardial contraction during cardiac operations while maintaining continuous normothermic coronary perfusion to avoid ischemia. With this technique, myocardial protection was equivalent to or better than that obtained with cold crystalloid or blood cardioplegia.…”