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Left ventricular hypercontractility immediately after tilting triggers a disregulated cardioinhibitory reaction in vasovagal syncope: echocardiographic evaluation during the head-up tilt test.

 Moon J.  ;  Kim H.  ;  Kim J.-Y.  ;  Chung S.  ;  Choi E.-Y.  ;  Min P.-K.  ;  Lee B.K.  ;  Hong B.-K.  ;  Kwon H.M.  ;  Rim S.-J. 
 CARDIOLOGY, Vol.117(2) : 118-123, 2010 
Journal Title
Issue Date
Adult ; Autonomic Nervous System/physiopathology ; Cardiac Volume/physiology ; Echocardiography ; Female ; Heart/innervation ; Heart/physiology ; Humans ; Male ; Middle Aged ; Myocardial Contraction/physiology* ; Posture/physiology ; Reflex, Abnormal/physiology ; Syncope, Vasovagal/complications* ; Syncope, Vasovagal/physiopathology* ; Tilt-Table Test ; Ventricular Dysfunction, Left/diagnostic imaging ; Ventricular Dysfunction, Left/etiology* ; Ventricular Dysfunction, Left/physiopathology* ; Young Adult
OBJECTIVES: Vasovagal syncope (VVS) has been believed to occur when mechanoreceptors are discharged by vigorous ventricular contraction. However, previous investigators have reported divergent observations regarding the presence of left ventricular (LV) hypercontractility in VVS. Because the autonomic nervous system can be promptly activated after certain stimuli, we postulated that instantaneously increased LV contractility at the time of venous pooling may trigger the disregulated vasovagal reaction in VVS. METHODS: Forty-seven patients (31 males, mean age 41 ± 18 years) with unexplained syncope were enrolled. Echocardiography was performed during the head-up tilt test (HUTT) as follows: baseline, passive tilting (0 and 20 min), and tilting with isoproterenol administration (5 and 10 min). Patients were divided into 2 groups according to the results of the HUTT; group 1 (n = 12) had a positive result and group 2 had a negative response. RESULTS: LV ejection fraction (LVEF), determined immediately after tilting, increased in group 1, whereas LVEF decreased in group 2 (p = 0.032). Although left atrial and LV volumes decreased similarly during the test, group 1 showed a progressive reduction in LVEF, while LVEF progressively increased in group 2 (p = 0.007). CONCLUSION: Patients with HUTT-induced VVS presented LV hypercontractions immediately after tilting and a subsequent decrease in LV contractility. An instantaneous activation of the sympathetic nervous system at the time of venous pooling may trigger an early disregulated vasovagal reflex via an increase in LV contractility in VVS.
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1. College of Medicine (의과대학) > Dept. of Internal Medicine (내과학교실) > 1. Journal Papers
Yonsei Authors
Kwon, Hyuck Moon(권혁문) ORCID logo https://orcid.org/0000-0001-9901-5015
Kim, Jong Youn(김종윤) ORCID logo https://orcid.org/0000-0001-7040-8771
Moon, Jeong Geun(문정근)
Min, Pil Ki(민필기) ORCID logo https://orcid.org/0000-0001-7033-7651
Lee, Byoung Kwon(이병권) ORCID logo https://orcid.org/0000-0001-9259-2776
Rim, Se Joong(임세중) ORCID logo https://orcid.org/0000-0002-7631-5581
Choi, Eui Young(최의영) ORCID logo https://orcid.org/0000-0003-3732-0190
Hong, Bum Kee(홍범기) ORCID logo https://orcid.org/0000-0002-6456-0184
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