What are cardiac effects of general anesthesia relevant to perioperative cardiac management?

Updated: Feb 04, 2019
  • Author: Davinder Jassal, MD; Chief Editor: William A Schwer, MD  more...
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Answer

Answer

The cardiovascular effects of general anesthesia include changes in the arterial and central venous pressures, cardiac output, and varying heart rhythms, which occur by the following mechanisms: decreased systemic vascular resistance, decreased myocardial contractility, decreased stroke volume, and increased myocardial irritability.

Induction of general anesthesia lowers systemic arterial pressures by 20-30%, tracheal intubation increases the blood pressure by 20-30 mm Hg, and agents such as nitric oxide lower cardiac output by 15%.

The use of fentanyl, sufentanil, or alfentanil results in less myocardial depression compared to inhaled anesthetics. Yet, these intravenous agents still cause venodilation, thus reducing preload and, hence, depressing cardiac output. Patients with congestive heart failure (CHF) are particularly sensitive to these hemodynamic changes. By increasing the preoperative volume status and applying the Frank-Starling principle, this decrease in cardiac output can be offset. Additionally, inhalational and intravenous anesthetics along with muscle relaxants can be detrimental by sensitizing the myocardium to circulating catecholamines. As a result of the stress of the surgical procedure, circulating catecholamine levels are elevated, thereby increasing the risk of ventricular ectopy.


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