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return to a normal loaded heart as circulatory support is withdrawn.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.