Sections View Full Chapter Figures Tables Videos Annotate Full Chapter Figures Tables Videos Supplementary Content + Download Section PDF Listen ++ For further information, see CMDT Part 10-39: Syncope + Key Features Download Section PDF Listen +++ ++ Transient loss of consciousness and postural tone for few seconds to few minutes with prompt recovery without resuscitative measures 30% of adults will experience ≥ 1 syncopal episode High risk features include history of structural heart disease, abnormal ECG, and age > 60 years + Clinical Findings Download Section PDF Listen +++ +++ Reflex (neurally mediated) ++ Caused by excessive vagal tone or impaired reflex control of the peripheral circulation Vasovagal syncope ("common faint") most common Often initiated by stressful situations Common premonitory symptoms Nausea Diaphoresis Tachycardia Pallor Other varieties: carotid sinus hypersensitivity, postmicturition, or cough syncope +++ Orthostatic ++ Caused by impaired vasoconstrictive response to assuming upright posture, leading to abrupt decrease in venous return Occurs in Advanced age Diabetes or other cause of autonomic neuropathy Blood loss or hypovolemia Vasodilator, diuretic, or adrenergic-blocker therapy +++ Cardiogenic ++ Caused by Rhythm disturbances (sick sinus syndrome, atrioventricular (AV) block, tachyarrhythmias) Mechanical causes (aortic or pulmonary stenosis, hypertrophic obstructive cardiomyopathy, pulmonary hypertension, atrial myxoma) Episodes are often exertional + Diagnosis Download Section PDF Listen +++ ++ Examine for orthostatic changes in BP and pulse, cardiac abnormalities, and response to carotid sinus massage Specific cause found on initial examination in only 50% Resting ECG is recommended for all patients undergoing evaluation for syncope High-risk findings include non-sinus rhythm, complete or partial left bundle branch block, and voltage criteria indicating left ventricular hypertrophy When initial evaluation suggests a possible cardiac arrhythmia, continuous ambulatory ECG (Holter or Zio" patch) monitoring, event recorder (for infrequent episodes), or an implantable cardiac monitor can be considered Do tilt-table testing before invasive studies unless clinical and ambulatory ECG evaluation suggests a cardiac cause +++ Reflex ++ Characteristic history Tilt-table testing May be useful in patients with suspected vasovagal syncope where the diagnosis is unclear after initial evaluation, especially when syncope is recurrent Hemodynamic response to tilting determines whether there is a cardioinhibitory, vasodepressor, or mixed response The overall utility of the test is improved when there is a high pretest probability of neurally mediated syncope +++ Orthostatic ++ > 20 mm Hg decline in BP immediately on standing Tilt-table testing and Valsalva maneuver are diagnostic +++ Cardiogenic ++ Echocardiography to rule out mechanical causes If rhythm disturbance suspected, ambulatory ECG monitoring indicated; may need to repeat ambulatory (Holter) monitoring several times, up to 3 days each; Zio" patch, placed once, will record for 14 days Event recorder and transtelephone ECG monitoring indicated for more infrequent presyncopal episodes Electrophysiologic studies indicated for Recurrent episodes Nondiagnostic ambulatory ECGs Ischemic cardiomyopathy + Treatment Download Section PDF Listen +++ +++ Reflex ++ Counterpressure maneuvers (squatting, leg-crossing, abdominal contraction) can be helpful in limiting or terminating episodes Medical therapy is reserved for patients with symptoms despite these measures Midodrine is an alpha-agonist that can increase the peripheral sympathetic neural outflow and decrease venous pooling during vasovagal episodes Fludrocortisone and beta-blockers have also been used but generally provide minimal benefit Selective serotonin reuptake inhibitors have shown some benefit in certain patients Permanent pacemaker implantation In general, it is not necessary in patients with vasovagal syncope However, a possible exception is patients older than age 40 years with prolonged (> 3 seconds), symptomatic episodes of asystole documented on ambulatory monitoring +++ Orthostatic ++ Discontinue offending drugs Stand up slowly Fludrocortisone rarely effective +++ Cardiogenic ++ Treat the underlying disorder Permanent pacing is indicated in patients with Syncope and documented severe pauses (> 3 seconds) Bradycardia High-degree AV block (second-degree Mobitz type II or complete heart block) Ventricular tachyarrhythmias: implantable cardioverter-defibrillator may be indicated + References Download Section PDF Listen +++ + +Goldberger ZD et al. ACC/AHA/HRS versus ESC guidelines for the diagnosis and management of syncope: JACC guideline comparison. J Am Coll Cardiol. 2019 Nov 12;74(19):2410–23. [PubMed: 31699282] + +Hale GM et al. The treatment of primary orthostatic hypotension. Ann Pharmacother. 2017 May;51(5):417–28. [PubMed: 28092986] + +iRhythm Zio Patch Cardiac Monitor (https://www.irhythmtech.com/professionals/why-zio.com" https://www.irhythmtech.com/professionals/why-zio.com) + +Martow E et al. When is syncope arrhythmic? Med Clin North Am. 2019 Sep;103(5):793–807. [PubMed: 31378326] + +Podoleanu C et al. Novel therapeutic options in the management of reflex syncope. Am J Ther. 2019 Mar/Apr;26(2):e268–e275. [PubMed: 30839375] + +Reed MJ et al. Diagnostic yield of an ambulatory patch monitor in patients with unexplained syncope after initial evaluation in the emergency department: the PATCH-ED study. Emerg Med J. 2018 Aug;35(8):477–85. [PubMed: 29921622] + +Yenikomshian M et al. Cardiac arrhythmia detection outcomes among patients monitored with the Zio patch system: a systematic literature review. Curr Med Res Opin. 2019 Oct;35(10):1659–70. [PubMed: 31045463]