A Case of Subclavian Artery Aneurysm with History of Ischemic Heart Disease Operated Under Cervical Epidural Anesthesia.

Subclavian artery aneurysm is usually operated under general anesthesia (GA), but in specific situations, it can also be conducted under regional anesthesia (RA) such as cervical epidural anesthesia (CEA). A 48-year-old male presented with chief complaint of progressive swelling in the right side of the neck for the past 3 months following trauma. He was diagnosed as subclavian artery aneurysm, and surgical intervention was advised. He had previous history of angina 4 months back for which tablet aspirin 75 mg and tablet clopidogrel 75 mg once daily was prescribed. Cardiological evaluation revealed of an ejection fraction of around 30% with mild left ventricular hypokinesia and grade 2 diastolic dysfunction. Due to the poor cardiac functional status of the patient, RA with CEA was planned. The risk with GA in cases with a history of myocardial ischemia is more than RA, hence, it is better to use CEA which is equally efficacious in such high-risk cases.

INTRODUCTION

Subclavian artery aneurysm is a very rare condition with an incidence of around 1% of all aneurysms.[1] Subclavian artery surgeries are commonly performed under general anesthesia (GA).[2] However if certain situation arises where GA is contraindicated then other modes of anesthesia are considered. In regional anesthesia (RA) techniques, the role of cervical epidural anesthesia (CEA) in subclavian artery aneurysm surgery is limited but has been widely used for carotid artery endarterectomy.[3] Studies have shown that RA techniques offer the advantage of allowing reliable monitoring of brain perfusion, selective intraluminal shunting and better perioperative cardiovascular stability with lower morbidity and mortality rates.[3]

CASE REPORT

A 48-year-old male weighing 60 kg presented to surgery outdoor with chief complaint of progressive swelling in the right side of the neck since last 3 months following trauma. The swelling was initially of small size which gradually progressed to the current size. On the basis of clinical finding and radiological report, it was diagnosed as subclavian artery aneurysm and surgical intervention was advised. The patient also had a history of angina 4 months back for which he was hospitalized and treated. He was advised tablet aspirin 75 mg and tablet clopidogrel 75 mg once daily on a regular basis. On local examination, the mass was around 3 cm × 3 cm × 4 cm, diffuse, pulsatile, soft in consistency, and mobile [Figure 1]. Magnetic resonance imaging angiography of the neck showed the aneurysm of subclavian artery, 1 cm lateral to the origin of internal carotid artery [Figure 2]. On two-dimensional echocardiography an ejection fraction of around 30% with mild left ventricular hypokinesia and grade 2 diastolic dysfunction was found. In view of poor cardiac functional status of the patient, RA with CEA was planned as the anesthetic technique. The patient was advised to stop tablet clopidogrel 7 days before the day of surgery. Coagulation profile was done, and it was found to be within the normal limit. Informed and written consent were obtained and the patient was explained about nil per oral. Tablet alprazolam 0.5 mg and tablet ranitidine 150 mg were advised to be taken on the night before and morning on the day of surgery. After taking the patient to the operation theater, all standard ASA monitors were attached and vitals were continuously recorded. Heart Rate was 100/min and electrocardiogram showed sinus rhythm, blood pressure was 140/80 mmHg, and SpO2 of 99% on room air. An 18-gauge intravenous cannula was inserted and ringer lactate drip was started. The patient was placed in the sitting position with the head flexed and resting on the thorax, to open the lowest cervical interspaces. After achieving cutaneous local anesthesia by injecting 3 ml of 2% lignocaine with adrenaline (1:200,000), an 18-gauge Tuohy needle was inserted through the midline approach into the C7-T1 interspace. The needle was advanced slowly, and epidural space was identified by the loss of resistance technique with a glass syringe [Figure 3]. Careful aspiration ensured that the needle had neither entered the subarachnoid space nor penetrated any epidural vein. Then, 8 ml of injection ropivacaine 0.5% with injection fentanyl 50 µg/kg was given in graded doses over 10 min and was left for 15 min after which the effect was checked. The upper limit and lower limit of the block were achieved from C3 to T4, respectively. The surgery was proceeded during which vitals remained stable throughout and the patient was comfortable.

Figure 1

Subclavian artery aneurysm.

Figure 2

Magnetic resonance imaging angiography.

Figure 3

Insertion of cervical epidural needle.

DISCUSSION

The surgery of subclavian artery aneurysm is usually done under GA. Several cases of subclavian artery aneurysm surgery performed under GA are reported, but due to the previous history of myocardial ischemia and to avoid the myocardial depressant action of general anesthetic agents, we planned the surgery under RA technique using cervical epidural with graded dose of the local anesthetic agent.

The cardiac sympathetic blockade is induced by CEA and consequently decreased arterial blood pressure and heart rate are observed. Incomplete impairment in baroreflex sensitivity has also been noticed. Cardiac sympathetic blockade induced by epidural block has been shown to reduce myocardial ischemia in dogs[4] and it decreases the incidence of myocardial ischemia in patient undergoing vascular surgery.[5] It is suggested that patients with coronary artery disease who are commonly scheduled for CAS may benefit from CEA. By contrast, major decrease in blood pressure may compromise coronary and cerebral perfusion and have to be controlled. As the patient has a history of previous angina episode, we planned for CEA to minimize the risk of intraoperative myocardial infarction. There is a very low incidence of cardiovascular complications of CAS with cervical block in comparison with GA with a decrease in the incidence of postoperative hypertension and reduction in the duration of hospital stay have been reported.[6] In experienced hands, sole use of CEA for various neck and chest surgeries is documented, highlighting the advantages such as stable cardio-respiratory status by avoiding airway instrumentation, less blood loss, and postoperative morbidity.[7]

The safety features of ropivacaine over bupivacaine are greater sensory motor differentiations with decreased potential for central nervous system and cardiac toxicity.[8] Efficacy of epidural ropivacaine is comparable to bupivacaine for postoperative pain relief and is well documented.[9] Ropivacaine 0.5–0.75% is reported to have a favorable effect on hemodynamic variables by blocking the sympathetic innervations of the heart.[10] Racemic bupivacaine is an equal mixture of R+ and S− enantiomers, where R+ isomer is mainly responsible for the systemic toxicity due to differential affinity for ion channels of Na+, K+ and Ca2+. Ropivacaine being a pure S− enantiomer has less toxicity profile, and it is 40–50% less potent than bupivacaine with stronger differentiation between sensory and motor blockade. Thus, we preferred ropivacaine 0.5% over bupivacaine because of its better hemodynamic stability. In our case, the swelling was in the cervical region but with a history of angina, so there was higher risk with GA than RA. The CEA can be used with proper precautions and appropriate measures for such high-risk case where the application of GA is risky.

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Conflicts of interest

There are no conflicts of interest.