The Role of Deep Hypothermia in Cardiac Surgery

Abstract

Hypothermia is defined as a decrease in body core temperature to below 35 °C. In cardiac surgery, four stages of hypothermia are distinguished: mild, moderate, deep, and profound. The organ protection offered by deep hypothermia (DH) enables safe circulatory arrest as a prerequisite to carrying out cardiac surgical intervention. In adult cardiac surgery, DH is mainly used in aortic arch surgery, surgical treatment of pulmonary embolism, and acute type-A aortic dissection interventions. In surgery treating congenital defects, DH is used to assist aortic arch reconstructions, hypoplastic left heart syndrome interventions, and for multi-stage treatment of infants with a single heart ventricle during the neonatal period. However, it should be noted that a safe duration of circulatory arrest in DH for the central nervous system is 30 to 40 min at most and should not be exceeded to prevent severe neurological adverse events. Personalized therapy for the patient and adequate blood temperature monitoring, glycemia, hematocrit, pH, and cerebral oxygenation is a prerequisite and indispensable part of DH.

Keywords: DHCA; cardiac arrest; cardiac surgery; deep hypothermia.

Figure 1

Aortic arch aneurysm. (A) computerized tomography angiography of the thoracic aorta with aortic arch aneurysm, (B) total arch replacement involving aortic arch replacement with concomitant re-implantation of arch vessels. The authors’ own archives.

Figure 2

Selective unilateral antegrade cerebral perfusion (unilateral SACP) with brachiocephalic trunk cannulation. Authors’ own graphic.

Figure 3

Diagram of retrograde cerebral perfusion (RCP). Oxygenated blood is delivered through the superior vena cava, whereas deoxygenated blood is returned through the cerebral arteries. Authors’ own graphic.