Pheochromocytoma Presenting as the Alternation of Hypertension and Hypotension

We reported a rare case of pheochromocytoma presenting as the alternation of
hypertension and hypotension, which highlighted the rare event of an extreme and
cyclical blood pressure pattern in a pheochromocytoma hypertensive crisis. Early
recognition is critical for selection of the appropriate treatment to terminate the effects
of catecholamine storm, which prepares for surgical resection of the tumor.


Introduction
A 50-year-old woman presented to the emergency department and complained of chest tightness, palpitation and frequent episodes of nausea, vomiting, and headache for the past 2 hours. She had a 1-year history of type 2 diabetes mellitus and was treated with diet therapy (1500 kcal/day) and oral hypoglycemic agents' metformin (250 mg/ twice/ day). Subsequently she had fair glycemic control with a mean glycated hemoglobin (HbA1c) of 6.0 % (reference range: 4.6-6.2 %). She had never had a history of hypertension and any other notable conditions. On physical examination, she was pale, in distress, and sweating profusely; Her blood pressure (BP) was 300/180 mmHg; pulse, 180 beats/ min; respiratory rate, 38 breaths/min; and oxyhemoglobin saturation, 94% while inhaling 100% oxygen concentration with face mask; Lung auscultation revealed clear breath sounds without crepitations; the abdomen was soft on palpation and no unusual mass was detected. Electrocardiography showed sinus tachycardia, 168 beats/min; chest X-ray was normal. Her systolic BP abruptly dropped to 60 mmHg before phentolamine was administered.
She was immediately treated with fluid expansion and dopamine hydrochloride (12 μg/kg/min) to maintain BP levels between 70/40 mm Hg and 90/50 mm Hg. After 5 minutes BP rose sharply to 210/150 mmHg and complained of chest pain, palpitation and headache. Intravenous phentolamine (5 mg bolus, followed by continuous infusion) was administered promptly to eradicate blood pressure. β-blocker propmnolol (10 mg/three times/day) was initiated to control tachycardia. Her systolic blood pressure dropped to 50mmHg again.

Discussion
Hypertension is the most frequent finding in pheochromocytoma. intensively increase, leading to decreased cardiac output [2], which results in a reduction in BP. Hypotension can also be caused by a complicating cardiovascular emergency, such as heart failure due to toxic cardiomyopathy, myocardial infarction, cardiac arrhythmias, or a dissecting aortic aneurysm [3,4]. A reduction in blood volume and cardiac output would, in turn, stimulate excessive reflex catecholamine release, causing paroxysmal hypertension [5,6].
The increase in BP would stimulate baroreceptors in the blood vessel walls and activate a negative feedback loop, mediated by sympathetic and parasympathetic nervous systems, which would respond by decreasing peripheral vascular resistance and lowering cardiac output, causing a subsequent reduction in BP. Baroreceptors are tonically active and can respond quickly to changes in BP, which could explain the rapid alternation between hypertension and hypotension seen in this patient [7].
In gernal, pheochromocytoma is treated with a-blockers, usually combined with a b-blocker, prior to tumor removal decreases mortality associated with surgery [8]. Treatment with an α-adrenergic receptor blocker should precede β-blockade for the treatment of Tachycardia to prevent a paradoxical increase in BP that can occur when α-adrenergic receptors are stimulated, and This patient mainly secreted norepinephrine along with amounts of epinephrine but did not produce dopamine and/or levodopa, which led to hypertension. So, we choose phentolamine to control BP. In this case, hypertension alternating with hypotension is not associated with abrupt cessation of catecholamine secretion bacause this patient's pathologic tissue was low malignant Pheochromocytoma without necrosis. The cause of hypotension is due to hypovolemia or desensitisation of adrenergic receptors. Her BP rose sharply to hypertensive crisis owing to stimulating baroreceptors in the blood vessel walls and activating a negative feedback loop. Intravenous phentolamine (5 mg bolus, followed by continuous infusion) was administered promptly and β-blocker propmnolol (10 mg/ three times/day) was initiated after phentolamine. When SBP dropped to below 90mmHg, it is more helpful for this patient to maintain SBP between 90 mm Hg and 100 mm Hg by the treatment with fluid expansion and dopamine hydrochloride. The dose of intravenous medications was regulated monentarily by continuous intra-arterial pressure monitor. I got some benifit from this case.
Typical pheochromocytomas mainly secrete norepinephrine along with smaller amounts of epinephrine but, in rare cases, can also produce dopamine and/or levodopa. So, we should first choose fluid expansion and dopamine to maintain BP, especially in patients with Pheochromocytoma without necrosis. BP might rise sharply to hypertensive crisis if treated with norepinephrine or epinephrine. The case presented here was an unusual, lifethreatening Pheochromocytoma. The selection of the appropriate treatment is critical to terminate the effects of catecholamine storm and to prepare for surgical resection of the tumor.