Document Detail

Dobutamine-inducible left ventricular obstruction: head-up tilt and autonomic balance.
MedLine Citation:
PMID:  12559546     Owner:  NLM     Status:  MEDLINE    
BACKGROUND: Dobutamine-inducible left ventricular obstruction lacks a sound clinical meaning. This phenomenon may be related to an abnormal response of the heart to the sympathetic stimulation, and head-up tilt would elicit intraventricular obstruction in patients known to develop it during dobutamine administration, through the synergistic effects of reduced preload, hypercontractility, and reflex increase in the cardiac sympathetic tone. METHODS: Twenty-one patients with normal coronaries and available dobutamine stress-echocardiography underwent 60 degrees -head-up tilt on echocardiographic and electrocardiographic monitoring in drug-free and nitroglycerin infusion (0.3 mcg/kg/min) protocols. Twelve patients had (group 1: 7 males, aged 61+/-7 years), and nine had not (group 2: 3 males, aged 60+/-9 years) developed left ventricular obstruction during dobutamine stress-echocardiography. Doppler echocardiographic measurements of left ventricular diameters, function and outflow tract flow velocity were performed; power heart rate variability was analysed on short electrocardiographic recordings (low/high frequency ratio); plasma catecholamines were determined at baseline and during the tilt manoeuvres. RESULTS: Intraventricular obstruction did not develop in group 1. There were baseline differences in ventricular dimensions and mitral early-to-late velocity ratio between group 1 and 2, but hemodynamic behaviour during either tilt manoeuvre was similar. Low/high frequency ratio, that was similar at baseline and similarly increased on head-up tilt, increased significantly less on nitroglycerin-tilt in group 1. No difference in plasma catecholamines was found. CONCLUSIONS: Reflex cardiovascular adaptive responses as those elicited by passive tilt are not involved in dynamic intraventricular obstruction in dobutamine-inducible obstruction patients, data indicating that left ventricular geometry and hypercontractility are not sufficient pathophysiological determinants.
Giuseppe Barletta
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Publication Detail:
Type:  Journal Article    
Journal Detail:
Title:  International journal of cardiology     Volume:  87     ISSN:  0167-5273     ISO Abbreviation:  Int. J. Cardiol.     Publication Date:  2003 Feb 
Date Detail:
Created Date:  2003-01-31     Completed Date:  2003-05-29     Revised Date:  2007-11-15    
Medline Journal Info:
Nlm Unique ID:  8200291     Medline TA:  Int J Cardiol     Country:  Ireland    
Other Details:
Languages:  eng     Pagination:  245-52     Citation Subset:  IM    
A.O. Careggi, Cardiovascular Medicine, Florence, Italy.
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MeSH Terms
Adaptation, Physiological
Case-Control Studies
Dobutamine / diagnostic use*
Echocardiography, Doppler / methods*
Epinephrine / blood
Exercise Test
Heart Rate / physiology
Hemodynamics / physiology
Hypotension / physiopathology
Middle Aged
Multivariate Analysis
Norepinephrine / blood
Reference Values
Sampling Studies
Sensitivity and Specificity
Stroke Volume
Tilt-Table Test
Ventricular Outflow Obstruction / physiopathology,  ultrasonography*
Reg. No./Substance:
34368-04-2/Dobutamine; 51-41-2/Norepinephrine; 51-43-4/Epinephrine

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