A proportion of patients with carotid sinus elision (CSS) remain symptomatic even after pacemaker implantation because of persistence of a vasodepressor composing We report a patient with CS whose syncopal episodes could be reproduc at carotid sinus massage and were owing to profound hypotension associated with unexpected sympathetic withdrawal.

A proportion of patients with carotid sinus elision (CSS) remain symptomatic even after pacemaker implantation because of persistence of a vasodepressor composing We report a patient with CS whose syncopal episodes could be reproduc at carotid sinus massage and were owing to profound hypotension associated with unexpected sympathetic withdrawal, based on direct measurements of sympathetic resolution traffic. A double-blind trial with inhaled ergotamine provided significant symptomatic relief.

Transient bradycardia is a normal replication to carotid sinus massage. This normal bent back is exaggerated in patients with carotid sinus hypersensitivity who can evolve profound bradycardia, asystole, and fainting fit during light stimulation of the carotid sinus. Carotid sinus massage, therefore, is an integral diagnostic experiment in patients with unexplained elision The interpretation of this standard often relies solely on heart rate measurements. It is now well recognized, however, that carotid sinus elision may occur in the absence of significant bradycardia, owed to a sudden lowering of progeny pressure. While the bradycardic component part of this syncope is explained on an increase in parasympathetic tone, the pathophysiology of the vasodepressor component part is not fully understood. It has been postulated that it may eventuate from inhibition of sympathetic constrictor steadinesss or activation of cholinergic vasodilator fibers.[1,2] Treatment of patients with vasodepressor episodes remains problematic, as they do not rejoin to parasympathetic blockade or pacemaker implantation.

In this report, we explore the possibility that this vasodepressor constituting is due to sympathetic withdrawal using direct measurements of sympathetic fortitude activity in a patient with carotid sinus swoon We also explore the effectiveness of inhaled ergotamine in its treatment.

Case Report

A 65-year-old man had a 10-year history of syncopal episodes with a progressive course. Nine month prior to hospital admission, he was diagnosed as having sick sinus syndrome based forward episodes of "spontaneous" brachardia, and a ventricular demand (VVI) pacemaker was implanted. He also received lisinopril, 5 mg each day, for mild systolic hypertension. There was mild improvement of symptoms after pacemaker placement, further he continued having syncopal episodes for which he was referred

Methods

Treatment with all medication was withheld for 72 h before evaluation and the patient was given a controll diet containing 150 mEq of sodium daily. issues of physical examination and routine laboratory evaluation were unremarkable. Surface ECG was normal. M-mode and two-dimensional echocardiogram revealed mild left ventricular hypertrophy normal wall motion, and normal ejection fraction. During cardiovascular steps ECG was monitored continuously (Biotach amplifier, Gould Inc, Cleveland). posterity pressure was measured continuously either with an automated device (Finapres, Ohmeda 2300 Englewood Colo) or end a catheter placed in a radial artery joined to a pressure transducer (Gould Carrier Amplifier). Central venous press was monitored through a catheter placed in an antecubital vein. Forearm venous capacitance was measured with aircuff plethysmography.[3] Briefly, the latex monitoring blow is placed around the forearm and inflated to 4 cm [Hsub2]O compressing A proximal cuff is inflated to 30 mm Hg to blockade venous return while monitoring influence inside the monitoring cuff. buffet pressure reaches a plateau in approximately 3 min. The magnitude of this increase muses venous capacitance.[3]

Multiunit recordings of postganglionic sympathetic might activity were obtained with an electrode inserted selectively into muscle-nerve fascicles of the peroneal nerve[4] The neural signals were amplified (by 4 x [10sup5]) filtered (700 to 2000 Hz) and integrated (time constant 01 s) to obtain a mean voltage neurogram (Nerve Traffic Analyzer order 662C-3, University of Iowa Bioengineering, Iowa City). Muscle sympathetic resolution activity (MSNA) was expressed in arbitrary units.[4]

Autonomic function proofs included cardiovascular and hormonal drift of posture, Valsalva maneuver, handgrip, and the chill pressor test.[5] Baroreceptor sensitivity was determined by means of correlating the changes in heart rate and kin pressure produced by the Valsalva maneuver, or intravenous bolus injections of nitroprusside or phenvlephrine.[6] Carotid sinus massage was done through manual stimulation of the carotid artery at its highest horizontal in the neck for 6 s at a time.

Results

relations pressure and heart rate were 138/78 mm Hg and 70 bpm in the supine position, and 132/80 mm Hg and 90 bpm in the upright situation There was an exaggerated plasma norepinephrine and renin activity rejoinder to 30-min upright posture (from 378 to 1296 pg/ml and from 08 to 30 ng Al/ml/h). vital current pressure overshoot during phase 4 of the Valsalva maneuver was ready Pressor responses to handgrip (30 percent of maximal voluntary contraction for 3 min) and to the chilly pressor test (immersion of a hand in ice-water for 1 min) were normal (increase in systolic/diastolic family pressure of 6/15 mm Hg and 16/8 mm Hg respectively).

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