Paroxysmal hypertension due to baroreflex failure

CASE PRESENTATION A 78-year-old Caucasian male was referred to our hypertension clinic in February 2005 for severe blood pressure (BP) lability. He had a diagnosis of hypertension for about 10 years, but had been previously well controlled. Over the preceding 14 months, he had noticed fluctuations in BP that became progressively more severe. Based on self-monitored home BP readings, he reported systolic BP peaks of 220–240 mmHg and systolic BP nadirs of 80–90 mmHg, often happening within the same day. He also described that the rise in BP was associated with significant diaphoresis of the head and palms and facial flushing, analogous to a ‘thermometer rising inside his face and head’. Occasionally he also experienced palpitations. He had erectile dysfunction but no history of urinary incontinence or retention, or any other genitourinary complaints. He had no other cardiopulmonary, digestive, neurological or psychiatric symptoms. At the time of the initial visit, his hypertension was managed with labetalol 50 mg that he took irregularly, on average once daily. In the past, he had experienced symptomatic hypotension and fatigue with diltiazem, metoprolol, and diuretics. He did not abuse alcohol or any illicit substances and did not use any over-the-counter medications or nutriceuticals. In addition to hypertension, he had a history of squamous cell carcinoma of the left pyriform sinus (treated with extensive radiation to the neck and chemotherapy in 1998), coronary artery disease (coronary artery bypass grafting in 2000), nonproteinuric chronic kidney disease stage 3 (clinically presumed to be due to hypertensive nephrosclerosis), gastroesophageal reflux, and well-controlled hypothyroidism. In addition to labetalol, his medications included aspirin, levothyroxine, lovastatin, omeprazole, and fish oil. On examination, the patient appeared well and calm. BP averaged 184/84 mmHg in the supine position, 152/ 78 mmHg when seated, and 140/74 mmHg after 5 min of orthostasis. His heart rate was 68 b.p.m. and there were no changes with posture. Fundoscopic examination revealed arteriolar narrowing and occasional abnormal arteriovenous crossings. The skin overlying his neck was taut from previous radiation exposure. There was no jugular venous distension at 30 degrees. Bilateral carotid bruits were heard; carotid pulsations were normal. Examination of the heart, lungs, abdomen, and extremities were normal. The neurological examination showed normal focused sensory and motor examination, without any Parkinsonian or cerebellar features. Laboratory tests were significant for an elevated serum creatinine (1.9 mg dl ), with an associated estimated glomerular filtration rate of 38 ml per min per 1.73 m. Relevant laboratory tests, all of which were unremarkable, are listed in Table 1. A renal sonogram was unremarkable. A renal magnetic resonance angiogram was normal. Duplex ultrasound of the carotid arteries revealed hemodynamically significant bilateral carotid stenosis, confirmed by magnetic resonance angiography. A magnetic resonance scan of his brain was remarkable only for deep white matter ischemic lesions; there was no evidence of a brain stem lesion or infarct. Owing to the patient’s history of neck irradiation and clinical presentation, bedside evaluation of baroreflex pathway integrity was performed after he had been off antihypertensive drugs for 5 days. BP averaged 158/ 72 mmHg in the supine position, 158/64 mmHg when seated, and 156/80 in standing. The heart rate was 84 b.p.m. in all positions. The RR interval was unchanged (0.63 s) during slow deep breathing and throughout the Valsalva maneuver. We did not use a beat-to-beat monitor, so we were unable to assess the BP response to the Valsalva maneuver. The cold pressor test (hand/ forearm immersion) showed an unexpected response: he had a decline in both heart rate (93–70 b.p.m.) and BP (154/78–98/60 mmHg), both of which recovered to baseline levels after 5 min of monitoring. His 24 h ambulatory BP monitoring is displayed in Figure 1, demonstrating marked BP lability. t h e r e n a l c o n s u l t http://www.kidney-international.org