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One of the hypotheses put forward concerning the mechanism of vasovagal syncope is that the vagal afferent fibres are activated during vigorous contractions against a partly empty left ventricle. The aim of the study was to confirm this hypothesis by using 2D echocardiography during a head-up tilt test. The study was carried out on 39 patients (17 male, 22 female, age range 21–64 years), all with a history of recurrent syncope. The patients were examined using a 2D echo to measure the end-diastolic and end-systolic volume before the head-up tilt test after the Westminster protocol (45min/60 grade) and every five minutes after tilting. T patients during head-up tilt test had a positive response and 32 proved negative. A reduction of both the end-diastolic and end-systolic volumes of the left ventricle was noticed. There was no significant difference in the degree of ejection fraction reduction. The difference in ejection fraction reduction between the two groups was similarly non-significant. It was also noticed that the patients with a positive response had more vigorous contractions than those with a negative test. The decision was therefore taken to use a different parameter for the left ventricle contraction, namely the LV posterior wall slope. As this parameter is partly dependent on time, its use in confirming the extremely vigorous nature of the contractions was considered appropriate. Only 6 patients were tested using this parameter. A tendency towards greater left ventricle posterior wall slope values, both before and during tilting was noticed in the group of patients with vasovagal reaction. Our data shows that vigorous contraction is probably less responsible for vasovagal syncope release than left ventricle volume reduction.
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175-178
Opis fizyczny
p.175-178,fig.,ref.
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autor
- Medical University of Gdansk, Kieturakisa 1, 80-742 Gdansk, Poland
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Bibliografia
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- 3. Deharo JC, Peyre JP, Chalvidan T, Thirion X, Valli M, Ritter P, Djiane P (2000) Continuous monitoring of an endocardial index of myocardial contractility during head-up tilt test. Am Heart J, 139: 1022–1030.
- 4. Fitzpatrick AP, Theodorakis G, Vardas P, Sutton R (1991) Methodology of head-up tilt testing in patients with unexplained syncope. J Am Coll Cardiol, 17: 125–130.
- 5. Mark AL (1983) The Bezold-Jarish reflex revisited: clinical implications of inhibitory reflexes originating in the heart. J Am Coll Cardiol, 1: 90–102.
- 6. Lee TM, Chen MF, Su SF, Chao CL, Liau CS, Lee YT (1996) Excessive myocardial contraction in vasovagal syncope demonstrated by echocardiography during head-up tilt test. Clin Cardiol, 19: 137–140.
- 7. Liu JE, Hahn RT, Stein KM, Markowitz SM (2000) Left ventricle geometry and function preeceding neurally mediated syncope. Circulation, 101: 777–783.
- 8. Shalev Y, Gal R, Tchou PJ, Anderson AJ, Avitall B, Akhtar M., Jazayeri MR (1991) Echocardiographic demonstration of decereased left ventricle dimensions. J Am Coll Cardiol, 18: 746–751.
- 9. Yamanouchi Y, Jaalouk S, Shehadeh AA, Jaeger F, Goren H, Fouad-Tarazi FM (1998) Changes in left ventricular volume during head-up tilt in patients with vasovagal syncope: an echocardiographic study. Am Heart J, 131: 73–80.
- 10. White CM, Tsikouris JP (2000) A review of pathophysiology and therapy of patients with vasovagal syncope. Pharmacotherapy, 20: 158–165.
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Bibliografia
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