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A 52 year old woman with a 10 year history of arterial hypertension was referred to the outpatient hypertensive clinic because of episodes of palpitations and high blood pressure. These episodes had deteriorated during the last few months (systolic blood pressure up to 240 mm Hg), although she was receiving antihypertensive treatment (angiotensin converting enzyme inhibitor, β blocker, diuretic). The ECG revealed significant diffuse repolarisation abnormalities (below left, upper panel), suggestive of severe ischaemia or hypertrophic cardiomyopathy. Chest x ray, echocardiogram, and biochemistry tests, including urine VMA and metanephrines, were normal. An adrenal mass of 5.6 cm diameter was visualised by renal ultrasound and computed tomography. An MIBG scan established the diagnosis of left adrenal pheochromocytoma (below right). The patient was treated with oral phenoxybenzamine (10 mg three times a day) and a β blocker during the preoperative management and her ECG became normal (below left lower panel). The latter event is uncommon and proves the effect catecholamines have on myocardial repolarisation.
Adrenergic hormone effects are responsible for a functional coronary insufficiency with an imbalance of supply and demand of oxygen, which may cause myocardial damage. Also, acute heart failure and transient low voltage in the ECG after massive catecholamine release from a pheochromocytoma have been previously described. Blockade with phenoxybenzamine in pheochromocytoma, apart from its well defined effects on vagal activity and the occurrence of ventricular arrhythmias, also contributes to an improvement in myocardial repolarisation. The patient underwent an operation where the tumour was excised and histological examination revealed it to be a left adrenal pheochromocytoma. The patient's blood pressure returned to normal without any further medical treatment.