Takayasu's arteritis: Anesthetic significance and management of a patient for cesarean section using the epidural volume extension technique.

Takayasu's arteritis (TA) is a rare, chronic progressive pan-endarteritis involving the aorta and its main branches. Anesthesia for patients with TA is complicated by severe uncontrolled hypertension, end-organ dysfunction, stenosis of major blood vessels, and difficulties in monitoring arterial blood pressure. We present the successful anesthetic management of a 23-year-old woman having TA with bilateral subclavian and renal artery stenosis posted for emergency cesarean section by using the epidural volume extension technique, which offers the combined advantage of both spinal and epidural anesthesia and, at the same time, also avoids the need of sophisticated neurological monitors like EEG and transcranial Doppler.

INTRODUCTION

Takayasu's arteritis (TA) is a progressive inflammatory vasculitis, with a specific predilection for young Asian women. It mainly affects the aorta and its branches, leading to a varying degree of narrowing, occlusion, or dilatation. It is also known as aortic arch syndrome, pulseless disease, occlusive thromboaortopathy (OTAP), young female arteritis, idiopathic aortitis, reversed coarctation, and Martorell syndrome.[12] The involvement of the vascular system results in multiorgan dysfunction and thus has special implications for anesthetists.

CASE REPORT

A 23-year-old primigravida diagnosed with TA type III along with bilateral subclavian and renal artery involvement presented to the obstetric clinic for safe confinement. She had renovascular hypertension and dilated cardiomyopathy secondary to TA.

Pre-anesthetic evaluation for elective cesarean section revealed a 68-kg, 164-cm-tall lady with a 38-weeks gestation-sized uterus. Her blood pressure was recorded as 160/96 mmHg and 164/94 mmHg in the upper and lower limbs, respectively, with a heart rate of 90/min. A detailed cardiovascular evaluation, including a review of the angiography recorded for unexplained tachycardia and high BP recording (following an attack of enteric fever 5 years back), revealed 70% and 100% occlusion of the left and right renal artery, respectively, along with bilateral subclavian artery stenosis. Records of 2D echo performed earlier revealed severe myocardial dysfunction, with ejection fraction ranging from 25% to 34%. The 2D echo performed after admission to the obstetric unit revealed an ejection fraction of 40%, dilated left ventricle, and type II diastolic dysfunction. She was on nifedipine 10 mg PO OD, digoxin 0.25 mg PO OD, levo-carnitine 500 mg PO OD, and prednisolone 30 mg PO OD. Serial abdominal ultrasound examinations at 18, 24, and 36 weeks showed normal fetal development. There were no features suggestive of cerebral involvement/ischemia with head and neck extension. All the laboratory and clinical parameters were within normal limits. Her airway was graded as Mallampatti class 2 and she was accepted for anesthesia in ASA class 2.

Because of the development of sudden fetal distress, she was taken up for emergency cesarean section. She was administered non-particulate antacid 30 ml of 0.3 M sodium citrate along with ranitidine 50 mg IV and metclopromide 10 mg IV before shifting her to the OR. A wide bore peripheral IV line was secured and hydrocortisone 25 mg was administered IV. The patient was preloaded with 500 ml of intravenous crystalloids. Under aseptic precaution, an 18 G epidural catheter was introduced through the 16 G Touhy needle via L2-L3 interspace using the loss of resistance to saline technique, followed by subarachnoid block with 1 ml of 0.5% hyperbaric bupivacaine injected intrathecally via the L3-L4 interspace through a 25 G Quincke's needle. The patient was placed in the left lateral position by keeping a wedge under the right hip and thigh. Five minutes later, 8 ml of normal saline was injected via an epidural catheter. After administration of 1.5 mg midazolam, right jugular canulation was performed using sterile precautions. Dermatome level of anesthesia was found to be T9, T7, and T4 at 3, 5, and 10 min after epidural saline injection, respectively.

Non-invasive blood pressure was monitored in both the upper and the lower limbs and the pulse oximeter probe was placed on the right upper limb. A healthy baby was delivered. Intraoperatively, central venous pressure was maintained between 10 and 12 cm of H2 O. The surgical time was 45 min and the blood loss was 600 ml. The intraoperative period was uneventful and the patient was shifted to the post-operative ward for further management.

DISCUSSION

TA is a form of granulomatous pan-endarteritis resulting in occlusion and thrombosis of the aorta and pulmonary arteries.[3] It results in narrowing of the arterial lumen, with a consequent distal ischemia and loss of pulse distal to the site of the lesion; hence, the term “pulseless disease.” In Japan, an autopsy survey suggested a frequency of 1 in 3000 persons.[4] In a study conducted in USA, the incidence of Takayasu's disease was found to be 2.6 new cases/million/year.[5] Females are predominantly affected, with the overall incidence being 85% of all affected. No exact figures are available for the Indian subcontinent.

Cerebrovascular ischemia occurs in about one-third of the patients and hence maintenance of cerebral perfusion pressure is of utmost importance. Takayasu's disease was first described in 1908 by a Japanese ophthalmologist, Takayasu, who observed retinopathy occurring with absent limb pulses.[6]

The disease is of unknown origin and multiple etiological factors have been proposed, including tuberculosis, syphilis, streptococcal infection, rheumatic fever, collagen vascular disease, genetic factors, and hypersensitivity among various others, but none of these factors have proven an etiological link. Ishikawa graded TA depending on the presence of four major complications: hypertension, retinopathy, aneurysm formation, and aortic regurgitation.[2] Based on this grading, the patient discussed in this report had stage IIb disease. Table 1 summarizes the major pathological features of TA[7] according to the major systems involved along with their anesthetic significance.

Table 1

Major pathological features and important anesthetic implications

During the pre-operative visit, patients should be evaluated for clinical features suggestive of carotid involvement, like dizziness and syncope on head extension and check for carotid bruit. It is always best to keep the head in a neutral position in all cases, avoiding hyperextension of the head during laryngoscopy as it can lead to post-operative visual disturbances, vertigo, hemiparesis, and seizures.[8] These patients usually have a lower blood pressure recording in the upper limb as compared with the lower limb and, hence, it is advisable to record blood pressure from both the upper and the lower limbs during the pre-operative visit and also during the intraoperative period. The lower limb can also be used for pulse oximetry.

Perioperative steroid replacement is warranted to prevent the occurrence of Addisonian hypotensive crisis,[8] as they are usual on long-term steroid replacement and may present with Cushingoid features pre-operatively.

Hypertension in the main complication affecting the anesthetic management of these patients, with blood pressure control being of paramount importance as these patients with TA may have arterial aneurysms and cerebral dysfunction from carotid occlusion. Because of poor cardiac function, cardioprotective drugs should be kept ready during the intraoperative period. Although the use of a flow-directed pulmonary artery catheter has been recommended, we used CVP measurement, which provided adequate information about cardiac pre-load in our patient during the intraoperative period.

Literature review confirms that both regional and general anesthesia have been used successfully in these cases.[3] Regional anesthesia is as safe as an awake and communicating patient, and is the best clinical neurologic monitor. However, the associated sympathetic blockade-induced hypotension may compromise the regional circulation. The graded blockade with epidural anesthesia avoids precipitous falls in blood pressure and also lowers the rate of thrombosis. Although sympatholysis is avoided with the use of general anesthesia, sophisticated monitoring of the cerebral function is needed as it may be associated with hypertensive episode and consequent cerebral/cardiac events.

We report successful anesthetic management of an obstetric case with TA managed by a unique epidural volume extension (EVE) technique, which offers the reliability and rapidity of spinal anesthesia and the flexibility of epidural anesthesia, avoiding the degree of symapthectomy that accompanies spinal anesthesia when used alone as the dose of drug used for spinal anesthesia is very less. It also offers early sensory-motor recovery,[9] along with lower umbilical and maternal concentration of local anesthetics, leading to better neurobehavioral outcome of newborns and increased patient satisfaction. This technique avoids stress response, negative inotropy due to inhalation agents, neonatal depression, and reduction in venous return due to positive pressure ventilation.

Blumgart et al,[10] hypothesized that epidural injection of a local anesthetic or saline 5 min after spinal anesthesia in patients undergoing cesarean section produces significantly higher levels of analgesia compared with spinal anesthesia alone. Combined spinal epidural with the EVE technique was found to have a dose-sparing effect, with only 55% of the bupivacaine dose required, allowing more rapid motor recovery of the lower limbs, which may have an impact on shortening the PACU stay. Adequate pre-loading with crystalloids along with a low dose of spinal anesthetics, which was followed by epidural saline injection, helped us to attain the desired level of block for cesarean section, avoiding a precipitous decrease in blood pressure. The epidural catheter also helped provide post-operative analgesia.

Invasive monitoring was deemed unnecessary taking into account the nature of the surgical procedure and the fact that there is a theoretical risk of precipitating an occlusion and aneurysm formation in the blood vessel following cannulation.[3] If invasive monitoring is considered, it is important that the tip of the catheter be placed proximal to the area of the arteritis as there is a difference in blood pressure proximal and distal to the arteritis. We opted for non-invasive monitoring of arterial blood pressure in both the upper and the lower limbs and pulse oximeter in the right arm. However, upper limb blood pressure should be correlated with lower limb blood pressure because the lower extremity blood vessels are spared clinically in these patients.

CONCLUSION

We successfully managed a case of TA for cesarean section using the EVE technique, which offers the advantages of both spinal and epidural anesthesia as it obviates the need for neurological monitoring and avoids major changes in the blood pressure. Careful pre-loading guided by CVP and use of a low and graded dose of local anesthetic is recommended to ensure hemodynamic stability. Regional anesthesia is a safe technique as it obviates the need for neurological monitoring and avoids major changes in the blood pressure.