Anesthetic Management in Combined Off-Pump CABG and EC-IC Bypass for CAD and Moyamoya Disease

Abstract

Background

Surgical treatment of moyamoya disease combined with coronary heart disease presents unique anesthetic challenges.

Case Summary

A 56-year-old woman underwent combined off-pump coronary artery bypass grafting and extracranial-intracranial arterial bypass surgery. The challenges in this surgery included maintaining cerebral oxygenation (regional cerebral oxygen saturation: >75% of baseline), controlled heart rate (60-70 beats/min), lung-protective ventilation (partial arterial pressure of carbon dioxide: 40-45 mm Hg), and mean arterial pressure >70 mm Hg. The patient experienced 2 intraoperative emergencies: hypotension and cerebral oxygen desaturation. The first episode was caused by cardiac displacement and was managed with fluid resuscitation and norepinephrine. The second episode likely resulted from myocardial ischemia-reperfusion injury and was treated with inotropes and coronary vasodilators.

Discussion

The key to anesthetic management in combined heart-brain surgery lies in balancing the heart-brain perfusion conflict while integrating cerebral function monitoring and myocardial protection.

Graphical Abstract

History of Presentation

A 56-year-old woman presented to our hospital with a 1-year history of episodic right-sided limb weakness. She had a myocardial infarction 2 years ago, treated conservatively with medication. Physical examination revealed a 3/6 systolic murmur at the apex, mild edema in both lower limbs, and a 6-minute walk distance of 375 m. Muscle strength in the left upper and lower limbs was graded III to IV. The patient had no history of surgery or anesthesia.

Past Medical History

The patient had an over 10-year history of hypertension, diabetes, and cerebral infarction.

Differential Diagnosis

The differential diagnosis included aortic dissection, reversible cerebral vasoconstriction syndrome, and intracranial atherosclerosis.

Investigation

Coronary angiography showed 3 major vessel occlusions (Figure 1). Magnetic resonance angiography (Figure 2A) and digital subtraction angiogram (Figure 2B) showed left internal carotid artery occlusion. The digital subtraction angiogram showed a collateral vessel network ingrowth at the base of the skull (Figure 2C). Figure 3 shows the results of T1-weighted magnetic resonance imaging; the compensatory dilation of leptomeningeal vessels is an important indirect sign of chronic ischemia in moyamoya disease (MMD). Considering the patient's MMD combined with coronary heart disease, a multidisciplinary team decided to perform combined off-pump coronary artery bypass grafting (3 grafts) and extracranial-intracranial arterial bypass under general anesthesia. The combined heart-brain treatment prioritized resolving cardiac issues, followed by the extracranial-intracranial bypass.

Figure 1.

Preprocedural Coronary Angiography

(A) Left coronary artery angiography in RAO 29° with CRA 37° projection reveals diffuse stenosis in the midsegment of the left anterior descending artery (arrows). (B) Left coronary artery angiography in CRA 37° demonstrates critical stenosis in the left main coronary artery (arrow). (C) Left coronary angiogram in LAO 35° with CRA 38° projection shows severe critical stenosis in the main trunk of the left circumflex artery (arrows). (D) Right coronary angiogram in LAO 45° projection displays severe critical stenosis in the main trunk of the right coronary artery (arrow). CRA = cranial; LAO = left anterior oblique; RAO = right anterior oblique.

Figure 2.

MRA and DSA of Intracranial Vascular Assessment

(A) MRA and (B) DSA showing left internal carotid artery occlusion. (C and D) DSA showing collateral vessel network ingrowth at the base of the skull. DSA = digital subtraction angiogram; MRA = magnetic resonance angiography.

Figure 3.

Cranial T1-Weighted Magnetic Resonance Images

The images showed impressive enhancement of increased leptomeningeal collaterals in the left hemisphere compared with the right hemisphere with injection of contrast.

Management

The patient's initial noninvasive blood pressure was 186/80 (130) mm Hg because of anxiety. After intravenous administration of midazolam 3 mg, her noninvasive blood pressure stabilized at approximately 130/80 mm Hg. Intraoperative monitoring included invasive blood pressure, continuous bispectral index, regional cerebral oxygen saturation (rSO₂), and transesophageal echocardiography. Real-time measurement of cardiac output and stroke volume were conducted using the FloTrac system (Edwards Lifesciences).

The key points of cerebral oxygen saturation are shown in Figure 4. At 10 minutes after surgical incision, the patient's mean arterial pressure suddenly decreased to 65 mm Hg. Norepinephrine infusion was started at 0.03 μg/kg/min to maintain mean arterial pressure >70 mm Hg, with cardiac output and stroke volume fluctuations within ± 20% of baseline values, and stroke volume variation <13%. Esmolol was continuously infused to maintain the heart rate between 60 and 70 beats/min. Lung protection ventilation strategy was adopted to maintain partial pressure of carbon dioxide between 40 and 45 mm Hg. Concurrent intraoperative blood conservation and temperature maintenance were implemented throughout the procedure. Furthermore, rSO₂ was maintained at >75% of baseline values.

Figure 4.

Cerebral Oxygen Saturation at Important Nodes

Five time points are shown: before surgery, at heart repositioning, after cardiac bypass, while handling the second critical incident, and during extracranial-intracranial arterial bypass. L = left regional cerebral oxygen saturation; R = right regional cerebral oxygen saturation.

During the mobilization of the left internal mammary artery, the patient was systemically heparinized with 160 mg of heparin, achieving an activated clotting time of 581 seconds. While performing the bypass to the posterior descending artery, the patient's heart was manipulated, causing it to rotate, and blood pressure dropped to 75/51 mm Hg. The rSO₂ dropped to 52% (left) and 55% (right). Fluid resuscitation and an intravenous injection of norepinephrine 6 μg were administered, resulting in a partial recovery of blood pressure. Once the heart was returned to its physiological position, both blood pressure and cerebral oxygen levels returned to baseline.

During the anastomosis of the inferior wall vessels, the patient's blood pressure suddenly dropped to 65/42 mm Hg, and rSO₂ fell to 45% (left) and 47% (right). The FloTrac indicated a decline in left ventricular systolic function, with decreases in cardiac output, stroke volume, and stroke volume index, and increases in stroke volume variation and central venous pressure. We administered nitroglycerin (0.5 μg/kg/min), dopamine (5 μg/kg/min), intermittent intravenous injections of norepinephrine (4 μg per dose), and 200 mL of fluid. These interventions resulted in an increase in cerebral oxygen saturation to rSO₂ 52% (left) and 55% (right), and hemodynamic stability was restored. During the surgery, significant drops in hemoglobin and hematocrit were observed, necessitating the transfusion of 2 U of red blood cells and autologous blood recovery.

The cardiac bypass surgery was completed in 3 hours, followed by a superficial temporal artery to cortical artery anastomosis under microscopic guidance. During the intracranial surgery, the patient's blood pressure was maintained at approximately 85% of baseline. When clamping the middle cerebral artery, blood pressure was kept 5 to 10 mm Hg above baseline to ensure perfusion to the contralateral brain supplied by the middle cerebral artery. Fluid management was guided by pulse pressure variation, and blood gas analysis was used to monitor hematocrit, maintaining it at approximately 30%.

Outcome and Follow-Up

The patient was extubated 15 hours postoperatively. Detailed neurological examinations conducted within the first week postoperatively showed no additional neurological abnormalities. The patient was discharged 2 weeks after surgery.

Discussion

MMD is a rare condition of unknown etiology, the association between coronary artery disease and MMD is rare.¹ Previous case reports have shown that patients with MMD combined with heart disease underwent either on-pump or off-pump cardiac surgery without simultaneous treatment of cerebrovascular lesions. In this case report, both cardiac and intracranial vascular lesions had surgical indications.

We choose off-pump coronary artery bypass grafting because hypothermia during cardiopulmonary bypass can cause cerebral vasospasm, increasing the risk of stroke. Moreover, the priming fluid used in cardiopulmonary bypass can cause hemodilution and a decrease in hematocrit, further increasing the risk of cerebral hypoxia and complicating anesthesia management in patients with MMD. The combined heart-brain surgery presents challenges for anesthesia management owing to the conflicting demands on vital signs. Firstly, during off-pump coronary artery bypass grafting, a slower heart rate provides better operating conditions for the surgeon,² and our center generally controls the heart rate at 50 to 70 beats/min and systolic blood pressure at 90 to 100 mm Hg. However, we maintain the mean arterial pressure above 70 mm Hg considering the cerebral perfusion. Secondly, it is essential to maintain adequate cerebral perfusion. Hemodynamic changes caused by heart manipulation may affect cerebral perfusion. Therefore, real-time monitoring of cerebral oxygen saturation and timely and effective circulatory management are necessary. We observed a significant increase in cerebral oxygen saturation after continuous nitroglycerin infusion. We speculate that nitroglycerin may dilate peripheral vessels, leading to increased cerebral oxygen saturation. Thirdly, it is important to control the blood carbon dioxide partial pressure. Normal blood carbon dioxide partial pressure can promote cerebral vasodilation, which has a positive brain-protective effect.³ Last, preserving normothermia aids in avoiding hypothermia-triggered cerebrovascular constriction.³ The cerebral vasoconstriction caused by hypothermia is also a factor that anesthesiologists need to consider. The selection of off-pump coronary artery bypass grafting is critically important for maintaining normothermia and preventing hypothermia during procedures.

Conclusions

We have described the anesthesia management for the first reported case to our knowledge of off-pump coronary artery bypass grafting combined with extracranial-intracranial bypass surgery in a patient with coronary artery disease and MMD. This report provides a reference for addressing both cardiac and cerebral issues in such patients, for the development of anesthesia management plans, and for the handling of intraoperative emergencies during combined heart-brain surgeries.

Funding Support and Author Disclosures

The authors have reported that they have no relationships relevant to the contents of this paper to disclose.

Take-Home Messages

• •A single procedure for addressing both cardiac and cerebral issues provides convenience for patients.
• •This report highlights strategies to enhance anesthesia safety during complex multiorgan vascular surgeries.

Visual Summary.

Timeline of Treatment

Admission/Day 1	A 56-year-old woman presented with right-sided limb weakness for 1 year
Days 2-4	Coronary angiography showed 3 major vessel occlusions; magnetic resonance angiography and digital subtraction angiogram showed left internal carotid artery occlusion.
Day 5	The multidisciplinary team discussed surgical approaches and decided to perform combined off-pump coronary artery bypass grafting and extracranial-intracranial arterial bypass.
Day 7	The patient underwent surgical treatment and was transferred to the recovery unit in stable condition.
Day 21	The patient was discharged in good condition and without any cardiovascular or neurological complications.
Day 51	At the 30-day follow-up, the patient was assessed as being NYHA functional class II, with intact limb mobility and independent performance of daily activities.