Tilt Table Testing. Dr. Prateek Suri

Transcription

1 Tilt Table Testing Dr. Prateek Suri

2 Background Syncope is very commonly seen in the population Among the various causes of syncope vasovagal syncope is the most common cause There is an absence of a gold standard to diagnose vasovagal syncope A tilt table is used to duplicate a vasovagal response and induce syncope in susceptible patients

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5 ESC 2009 GUIDELINES ON SYNCOPE

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7 Historical aspects of vasovagal syncope William Harvey first described a circulatory ( vasovagal ) response during a phlebotomy in Gover first used the term vasovagal syncope 1932 Lewis descibed the classical triad of bradycardia, hypotension and syncope In the 1950 s and 60 s a lot of work was done to assess orthostatic stress in airforce pilots

8 1957 one of the pioneering works on tilt table testing was published by Weissler et al in Circulation. In this work university students were tilted at 60 degrees and vasovagal syncope induced in 20% and syncope induced in 80% of remaining by using sodium nitrite minutes before tilting

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10 Circulation 1957

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16 Freeman R. N Engl J Med 2008;358: The Baroreflex

17 Mechanism Blood pools in venous capacitance vessels Reduced venous return and cardiac output Baroreceptor mediated activity Mild in BP and HR sympathetic Paradoxical stimulation of ventricular mechanoreceptors Usually stimulated by vigorous contraction

18 Contd. Afferent pathways activated via Vagal C fibres Vasomotor center stimulated Stimulation of parasympathetic actvity (vagusnerve) Withdrawl of sympathetic activity BP and HR fall Reduced cerebral perfusion - syncope

19 Bezold-Jarisch Reflex TILT venous return HR BP Small vigorous ventricle Brain stem BP SYNCOPE chatecholamines Vasodilation

20 Bezold jarisch reflex

21 Other mechanisms postulated Central serotonergic receptors may be involved in vasovagal syncope. This is based on increased levels of prolactin and cortisol seen in patients with syncope (Centraserotonergic responsiveness in neurocardiogenic syncope: a clomipramine test challenge. Theodorakis GN; Markianos M; Livanis EG; Zarvalis E; Flevari P; Kremastinos DT Circulation 1998 Dec 15;98(24): ) Adenosine The observation that adenosine administration can provoke neurally mediated syncope raises the possibility that endogenous adenosine plays a role in the pathogenesis of neurocardiogenic syncope Role of endogenous adenosine as a modulator of syncope induced during tilt testing. Saadjian AY; Levy S; Franceschi F; Zouher I; Paganelli F; Guieu RP Circulation 2002 Jul 30;106(5): )

22 Cerebral vasoconstriction

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27 Head-up tilt, a recognised stimulus to vasovagal syncope, was used to investigate syncope that remained unexplained despite full clinical and electrophysiological assessment in fifteen patients, mean age 65 ± 10 years, who had had 15 ± 19 episodes of unexplained syncope over periods of a week to 26 years. After overnight fast systolic blood pressure and heart rate were continuously monitored during 40 head-up tilt for 60 min. Ten control subjects with no history of syncope were studied similarly. In ten patients (67%) and one control vasovagal syncope developed after 29 ± 19 min (p < 0 001). In symptomatic patients systolic blood pressure fell from 150 ± 32 to 56 ± 9 mm Hg (p < 0 001) and heart rate from 62 ± 9 to 38 ± 12 beats per min (p < 0 01). In each case symptoms during the test reproduced those previously experienced. No clinical findings predicted development of syncope during tilt. Baseline systolic blood pressure and heart rate did not differ significantly between patients and controls. Pacemakers were implanted in seven patients who have remained symptom-free since implant (follow-up 10 ± 3 mo).-lancet 14 th june 1986

28 Is there a standardised protocol? Westminister protocol This was described by a group in Westminister hospital london and involved tilting at an angle of 60 for 45 minutes and they described a sensitivity of 75% and specificity of 93%.(Fitzpatrick et al JACC 1991 ;17: ) However other authors have described a sensitivity as low as 24% Isoprenaline protocol This involved an initial phase of tilting without drug administration and then using isoprenaline infusion at various rates at to increase HR 25% above resting and sensitivity has varied from 64-87% and specificity of 88% (Alquist et al NEJM 1989 ; 320: ) Clomipramine protocol 5mg of clomipramine is infused over 5 minutes while patients are tilted at 60 for 20 minutes. A sensitivity of 83% and specificty of 86% described (Euro heart journal 2003;24: )

29 Nitroglycerine protocol (Italian protocol) This was put forth in 2000 and describes tilting at 60 for 20 minutes followed by one spray of 400 micrograms of gtn S/L followed by another 15 minutes of tilting. Initially a sensitivity of 62% and a specificity of 92% was achieved. (Eurospace 2000; 2: ). Other investigators have achieved similar results and this has become a popular protocol.

30 TTT Protocols Core element is head-upright tilt for min. Main provocative factor is prolonged orthostatic stress Variants include use of : IV isoprenaline mimics catecholamine response to stress IV clomipramine increase intracranial serotonin (neurotransmitter central to reflex) SL GTN increases venodilatation (JHH) Duration of test, tilt angle, provocative agent differs from centre to centre, hence difficulty in assessing diagnostic accuracy of TTT. Robert Sheldon, Current Opinion in Cardiology 2005, 20:38-41

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34 Optimal duration of tilt

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45 JHH Tilt Table Test protocol Patient is supposed to be fasting overnight Pt is supine for ~ 5min. Baseline measurements. Table is elevated to 70 o for 10 minutes. If Sx not reproduced and no obvious haemodynamic changes observed, GTN (400ug) is administered. Pt remains standing until Sx reproduction or 20 minutes has elapsed. Finapres is used to monitor hemodynamics on a beat to beat basis by measuring finger BP

46 Normal response

47 Vasovagal response

48 Autonomic dysfunction

49 POTS

50 Work in progress at JHH 2010 Retrospective study of self reported bloodinjection-injury phobia and asystolic response to head up tilt- Robert Blake

51 ESC 2009 guidelines

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53 ACC scientific statement on syncope 2006 Sensitivity of tilt table testing varies from 26% -80% and the specificity is 90% ESC GUDELINES ON SYNCOPE 2009 sensitivity of both isoprenaline and GTN varies from 61-69% and the specificity from 92-94%