Assessment of the Vasodepressor Reflex in Carotid Sinus Syndrome

Abstract

Background-Assessment of the vasodepressor reflex in carotid sinus syndrome is influenced by the method of execution of the carotid sinus massage and the coexistence of the cardioinhibitory reflex. Methods and Results-Carotid sinus massage reproduced spontaneous symptoms in 164 patients in the presence of hypotension or bradycardia (method of symptoms). When an asystolic pause was induced, the vasodepressor reflex was reassessed after suppression of the asystolic reflex by means of 0.02 mg/kg IV atropine. An isolated vasodepressor form was found in 32 (20%) patients, who had lowest systolic blood pressure (SBP) of 65±15 mm Hg. Of these, only 21 (66%) patients had an SBP fall ≥50 mm Hg, which is the universally accepted cut-off value for the diagnosis of the vasodepressor form. Conversely, a lowest SBP value of ≤85 mm Hg (corresponding to the fifth percentile) detected 97% of vasodepressor patients, but was also present in 84% of the 132 patients with an asystolic reflex. These latter patients had both asystole ≥3 s (mean 7.6±2.2 s) and SBP fall to 63±22 mm Hg: in 46 (28%) patients, symptoms persisted after atropine (mixed form), in the remaining 86 (52%) patients, symptoms did not (cardioinhibitory form) persist. Conclusions-The current definition of ≥50 mm Hg SBP fall failed to identify one third of patients with isolated vasodepressor form. A cut-off value of symptomatic SBP of ≤85 mm Hg seems more appropriate, but it is unable to identify cardioinhibitory forms. In asystolic forms, atropine testing is able to distinguish a cardioinhibitory form from a mixed form. (Circ Arrhythm Electrophysiol. 2014;7:505-510.)

Pacing for neurally-mediated syncope: How to decide?

“…The prevalence of mixed forms was higher in those studies in which the massage was prolonged ≥ 10 s and performed in standing position, and also when the magnitude of the vasodepressor component was assessed after suppression of the cardioinhibitory component by i.v. atropine [14,[18][19][20][21]. For patients who had positive TT (bradycardia and hypotension), there was a 2.7-fold greater syncope recurrence probability after dual chamber pacing than in those with negative TT [21].…”

Qual o Significado Clínico Real da Hipersensibilidade do Seio Carotídeo na Prática Clínica? Um Dilema Ainda a Espera de Respostas

“…Tentativas de refinamento ou modificação da definição da resposta positiva foram propostas para possibilitar acurácia no diagnóstico da SSC como o valor de corte da pressão arterial sistólica ≤ 85 mmHg aliado aos sintomas sugerido por Solari e colaboradores. 5 Os autores concluíram que um terço dos 164 pacientes avaliados com forma vasodepressora isolada não puderam ser identificados com o critério vigente (queda da pressão arterial sistólica ≥ 50 mmHg) quando comparado com o valor de corte de ≤ 85mmHg da pressão arterial sistólica. Krediet e colaboradores 6 também questionaram os critérios atuais para HSC, considerando como sendo muito sensíveis, resultando na alta prevalência observada na população idosa.…”

2018 ESC Guidelines for the diagnosis and management of syncope

“…In such circumstances, CSM usually shows a period of asystole >6 s. 91 The prevalence of CSS, as defined here, was 8.8% when CSM was performed after the initial evaluation in 1855 consecutive patients >40 years of age with syncope compatible with a reflex mechanism. 92,93 In a multicentre study 94 aimed at validation of the 2009 ESC Guidelines, CSM was indicated after initial evaluation in 73% of 700 patients and was diagnostic in 12%. The precise methodology and results of CSM are shown in section 5 of the Web Practical Instructions.…”

“…92 • History of syncope and its reproduction by CSM defines CSS; positive CSM without a history of syncope defines carotid sinus hypersensitivity. 89,90,92,93 Carotid sinus hypersensitivity in patients with unexplained syncope may be a non-specific finding because it is present in < _40% of older populations and should be used with caution for diagnosis of the mechanism of syncope.…”

“…40,[63][64][65]77 I B CSM CSM is indicated in patients >40 years of age with syncope of unknown origin compatible with a reflex mechanism. [92][93][94] I B…”