Bidirectional ventricular tachycardia unmasked by beta-blockade in pheochromocytoma presenting as hypertensive optic neuropathy: a case report and literature review.

Abstract

Background: Pheochromocytoma is a catecholamine-secreting neuroendocrine tumor that can produce life-threatening cardiovascular complications. Bidirectional ventricular tachycardia (BVT) is a rare arrhythmia with a narrow differential diagnosis, classically associated with digitalis toxicity and catecholaminergic polymorphic ventricular tachycardia, and only exceptionally reported as the presenting feature of pheochromocytoma.

Case presentation: A 51-year-old woman presented with acute visual impairment secondary to hypertensive optic neuropathy; her blood pressure was 220/138 mmHg. Within 24 h of initiating sodium nitroprusside and metoprolol, she developed bidirectional ventricular tachycardia followed by torsades de pointes. Marked blood-pressure lability, dramatically elevated plasma free metanephrines and catecholamines, and a left adrenal mass on computed tomography established the diagnosis of pheochromocytoma. After alpha-adrenergic blockade with phenoxybenzamine, laparoscopic adrenalectomy was performed, and histopathology confirmed the diagnosis. No ventricular arrhythmia recurred, and blood pressure normalized without antihypertensive medication.

Conclusion: Bidirectional ventricular tachycardia may be the initial manifestation of pheochromocytoma and may be unmasked by beta-blockade administered before alpha-blockade. Unexplained BVT accompanied by blood-pressure fluctuations should prompt biochemical screening and adrenal imaging. Etiologic treatment is curative, whereas antiarrhythmic therapy alone is insufficient. We review the previously published cases to contextualize this rare phenotype.