3 COMMENT
A pheochromocytoma is a catecholamine-secreting tumor that arises from chromaffin cells of the adrenal medulla. Patients with unrecognized pheochromocytoma who undergo anesthesia for unrelated surgery have significantly high risk for a hypertensive crisis. Five previous reports of cardiac surgeries completed despite complications encountered due to unsuspected pheochromocytoma are known, including coronary artery bypass grafting (CABG),2 AVR,3 concurrent AVR and CABG,4 mitral valve replacement,5 and even a heart transplant operation,6 each an elective procedure. As noted in a study of cases of aortic dissection complicated by unsuspected pheochromocytoma,7 reports of emergency cardiac surgery for patients with unsuspected pheochromocytoma are limited. Generally, while the incidence of pheochromocytoma is infrequent, it can be encountered during various emergency as well as elective cardiac procedures. Identification of such a situation is an unsolved issue, though a systematic diagnosis and treatment strategy is necessary, because surgeons sometimes must continue the operation for various reasons, such as heart failure or neurological complications. Our case provides valuable detailed information for establishment of appropriate management of a hypertensive crisis in a case of unsuspected pheochromocytoma.
Cardiac surgery requires precise control of hemodynamics to permit bypass, and myocardial and organ protection procedures, as well as return to a normal loaded heart as circulatory support is withdrawn. Therefore, appropriate BP control is important when a hypertensive crisis emerges during cardiac surgery. For precise management of BP in patients with a pheochromocytoma, a combined alpha- and beta-adrenergic blockade is the most commonly implemented strategy. In a previous case with a pheochromocytoma suspected during the operation, an alpha-adrenergic blockade such as phentolamine and beta-adrenergic blockade such as propranolol were used in combination with nitroprusside for BP management.5 Our patient suffered from an unpredicted hypertensive crisis that occurred after induction of anesthesia. Before we suspected a pheochromocytoma, nicardipine and nitroglycerin were used, then when the condition was revealed, those were promptly replaced by phentolamine, which was effective for lowering BP. While there were various differential diagnoses for the cause of the hypertensive crisis, including neurological injury, preoperative CT imaging helped to confirm the diagnosis of pheochromocytoma in this case, which resulted in adequate BP management using a combined alpha-adrenergic blockade. Refractory or persistent hypertension may sometimes be associated with a serious disease in cases of cardiac surgery, thus it is important to consider a differential diagnosis, including pheochromocytoma, with early intervention needed to overcome this critical situation.
During cardiovascular surgery, once CPB is established, it is expected that hemodynamics will stabilize due to hemodilution. However, Brown et al. reported that CPB itself may contribute to the severity of hypertension, while exposure to cold can increase catecholamine secretion from a pheochromocytoma.8 In this case, it was difficult to control BP even after starting CPB. Careful hemodynamic management of a hypertensive crisis caused by a pheochromocytoma is necessary even after CPB is established. It is also important to note that vasopressor use was needed to maintain adequate BP during and after our operation, though that can potentially make management difficult. To overcome such complications, findings in our case provide useful detailed information of this rare situation from a pharmacological management point of view.