Selective cerebral perfusion for thoracic aortic surgery: Association with neurocognitive outcome

Hypothermic Circulatory Arrest in Adult Aortic Arch Surgery: A Review of Hypothermic Circulatory Arrest and its Anesthetic Implications

Diseases affecting the aortic arch often require surgical intervention. Hypothermic circulatory arrest (HCA) enables a safe approach during open aortic arch surgeries. Additionally, HCA provides neuroprotection by reducing cerebral metabolism and oxygen requirements. However, HCA comes with significant risks (eg, neurologic dysfunction, stroke, and coagulopathy), and the cardiac anesthesiologist must completely understand the surgical techniques, possible complications, and management strategies.

The Evaluation Value of Diffusion-Weighted Imaging for Brain Injury in Patients after Deep Hypothermic Circulatory Arrest

Objective

Cerebral complications may occur after surgery with deep hypothermic circulatory arrest (DHCA). Diffusion-weighted imaging (DWI) has shown promising results in detecting early changes of cerebral ischemia. However, studies in human models are limited. Here, we examined the significance of DWI for detecting brain injury in postoperative patients after DHCA.

Methods

Twelve patients who had undergone selective cerebral perfusion with DHCA were enrolled. All patients underwent magnetic resonance imaging (MRI) examinations before and after the operation with T1-weighted phase (T1W) and T2-weighted phase (T2W). Magnetic resonance angiography (3D TOF) was applied to observe intracranial arterial communication situations. DWI was employed to calculate the apparent diffusion coefficient (ADC) values. The neurocognitive function of patients was assessed preoperatively and postoperatively using the Montreal Cognitive Assessment Scale (MoCA), Hamilton Depression Scale (HAMD), and Hamilton Anxiety Scale (HAMA).

Results

The ADC values of the whole brain of patients after surgery were significantly higher than before surgery (P = 0.003). However, no significant difference in the ADC values of other regions before and after the operation was observed. There was no significant effect on the postoperative cognitive function of patients after surgery, but visual-spatial and executive abilities were significantly reduced, while psychological anxiety (P = 0.005) and depression levels (P < 0.05) significantly increased. Correlation analysis revealed a significant association between ADC change values and depression change values (P < 0.05).

Conclusion

DHCA demonstrated no significant effect on the cognitive function of patients but could affect the mood of patients. On the other hand, DWI demonstrated promising efficiency and accuracy in evaluating brain injury after DHCA.

Influence of moderate hypothermic circulatory arrest on outcome in patients undergoing elective replacement of thoracic aorta

Background

The ideal technique of cerebral protection in the surgical operation of the ascending aorta.is currently controversial. The current analysis evaluates the influence of moderate hypothermic circulatory arrest (MHCA) on elective replacement of the ascending aorta.

Methods

The study included 905 consecutive patients between 2001 and 2015, who underwent replacement of ascending aorta in MHCA. Patients were divided according to the postoperative 30-day mortality into survivor und non-survivor group.

Results

The average age was 66.5±11.1 in survivors vs. 70.0±10.5 years in non-survivors (P=0.057). The survivor group had a significantly lower Euro-SCORE II than non-survivors [4.0% (2.3, 6.6) vs. 9.5% (4.8, 20.9); P<0.001)]. The incidence of coronary heart disease (38.0% vs. 58.3%; P=0.022) and chronic renal failure (10.0% vs. 33.3%, P<0.001 was significantly higher in non-survivors. Intraoperatively, the cardiopulmonary bypass time [140 min (112, 185) vs. 194 min (164, 271); P<0.001] and cross-clamping time [91 min (64, 124) vs.119 min (94, 157); P<0.001] were significantly longer in non-survivors. However, the MHCA time was similar in both groups with statistical significance (P=0.023). Postoperatively, re-exploration due to bleeding was highly significant in non-survivors (5.4% vs. 33.3%; P<0.001) with a higher incidence of stroke (4.6% vs. 33.3%; P<0.001). The duration of mechanical ventilation was significantly shorter in survivors than in non-survivors [17 h (12, 26) vs. 147 h (49, 337); P<0.001] with a lower incidence of pulmonary infection (6.0% vs.16.7%; P=0.023). The multivariable logistic regression analysis showed age, female gender, aortic aneurysm, additional CABG, total arch replacement and cardiopulmonary bypass time were independent risk factors for 30-day mortality.

Conclusions

The acceptable morbidity and mortality rates show that MHCA can be considered as a safe technique for cerebral protection in surgical replacement of thoracic aorta.

Aortic Surgery and Deep-Hypothermic Circulatory Arrest: Anesthetic Update

Aortic arch surgery has become increasingly complex, and novel surgical approaches have been utilized. Efforts aimed at improving neurological outcomes in this patient population have been numerous, with varying degrees of success. This article summarizes the anesthetic considerations for procedures on the aortic arch, including evidence-based outcomes with respect to temperature management, perfusion strategies, hemodynamic goals, adjunct agents, and neuromonitoring.

Deep hypothermic circulatory arrest

Effective cerebral protection remains the principle concern during aortic arch surgery. Hypothermic circulatory arrest (HCA) is entrenched as the primary neuroprotection mechanism since the 70s, as it slows injury-inducing pathways by limiting cerebral metabolism. However, increases in HCA duration has been associated with poorer neurological outcomes, necessitating the adjunctive use of antegrade (ACP) and retrograde cerebral perfusion (RCP). ACP has superseded RCP as the preferred perfusion strategy as it most closely mimic physiological perfusion, although there exists uncertainty regarding several technical details, such as unilateral versus bilateral perfusion, flow rate and temperature, perfusion site, undue trauma to head vessels, and risks of embolization. Nevertheless, we believe that the convenience, simplicity and effectiveness of straight DHCA justifies its use in the majority of elective and emergency cases. The following perspective offers a historical and clinical comparison of the DHCA with other techniques of cerebral protection.