SAT-090 Autonomic Dysfunction and Hypoaldosteronism Before and After CABG: Case Report and Literature Review

Abstract

INTRODUCTION: The sympathetic nervous system and the renin-angiotensin-aldosterone system (RAAS) are the cornerstones of cardiovascular adaptation.Autonomic dysfunction produces symptoms that overlap with hypofunction of the RAAS, namely hypoaldosteronism. The simultaneous presence of both disorders is not uncommon, especially in patients with CAD undergoing CABG surgery. Objective: This is the case of a patient with recurrent episodes of syncope and severe bradycardia, found to have both hyporeninemic hypoaldosteronism and carotid sinus hypersensitivity. We describe those interrelated phenomena and their association with CAD and CABG surgery. Case presentation: Our patient is a 63-year-old male with a history of hypertension (On Bisoprolol, Valsartan and Hydrochlorothiazide) and hyperlipidemia presenting for coronary artery bypass grafting for triple vessel disease. On the day of admission, the patient lost consciousness briefly and was transiently hypotensive (60/30 mm Hg) with a heart rate of 65 bpm. He reported having had similar self resolving episodes in the past at times of emotional stress. The next day, the patient underwent CABG surgery that was uneventful. Four hours later he developed another episode of unprovoked hypotension that resolved with the administration of neosynephrine. On postoperative day 3, while removing the central line from the right IJ vein, he lost consciousness and had a cardiac pause of 5 seconds. His blood pressure was 70/45 mm Hg. He regained consciousness immediately afterwards upon leg elevation. A carotid massage resulted in a 7 seconds cardiac pause, confirming the presence of carotid sinus hypersensitivity, necessitating the insertion of a pacemaker. However the patient lost consciousness again the next morning despite a normal functioning device. Endocrinology work up was initiated to rule out adrenal insufficiency. It revealed an undetectable aldosterone level with a low-normal renin level, ie hyporeninemic hypoaldosteronism.No hyponatremia, hyperkalemia, renal insufficiency or hypocortisolism were noted. Patient was started on fludrocortisone 0.1 mg daily, and his hemodynamics improved.He remained free of symptoms with normal electrolytes and vital signs on follow up since then. Conclusion: This case describes coexistence of hyporeninemic hypoaldosteronism and carotid sinus hypersensitivity. Although both entities might seem unrelated, a review of the literature and the physiology of cardiovascular hemodynamics revealed that CAD leads to autonomic dysfunction, which can present as carotid sinus hypersensitivity as in our case. In turn, the impaired adrenergic function blocks the activation of renin, leading to hypoaldosteronism and hypofunctioning RAAS. CABG surgery unmasked those interrelated entities. Patient was treated successfully with pacemaker placement and fludrocortisone replacement.