Medicine Poster Session
Materials and Methods
One hundred sixteen patients with LV dysfunction caused by ischemic heart disease or idiopathic dilated cardiomyopathy were studied. Patients with either symptomatic or asymptomatic LV dysfunction as defined by echocardiographic ejection fraction < 40% and sinus rhythm were eligible for the study. The following exclusion criteria were applied: structural valvular heart disease; atrial fibrillation; myocardial infarction within 6 months. All patients provided informed consent to participate in the study.
Each patient underwent an assessment of clinical status according to the classification of the New York Heart Association. The 6 MW test was performed to assess exercise capacity as described by Guyatt et al. (8).Complete M-mode, B-mode echocardiography and Doppler cardiac studies were performed in all patients. Measurements of LV end-diastolic volume, end-systolic volume were made using the biplane area-length method. Ejection fraction was calculated with the standard formula. Pulsed Doppler studies were performed by using apical windows. Recordings of mitral inflow velocity were made from an apical four-chamber view with the sample volume positioned adjacent to the tip of mitral leaflets in diastole. The following Doppler-derived parameters were calculated: peak velocity of early filling (PE), peak velocity of atrial filling (PA), ratio of early wave to atrial wave peak velocity (PE/PA ratio), and deceleration time of early filling, defined as the interval between PE and the termination of early filling. Isovolumic relaxation time was calculated as the interval between the beginning of the aortic valve closure signal and mitral valve opening signal in the Doppler spectrum. All measurements were made in at least five cardiac cycles and analyzed off-line by two independent observers. The data were averaged.
All values are expressed as mean +/- SD. Correlation between NYHA class and 6 MW test distance was performed by the Spearman rank correlation test. The relation between echocardiographic, Doppler-derived parameters, and 6 MW test distance was assessed by univariate linear regression analysis. A multivariate forward stepwise regression analysis was subsequently performed to determine which parameters were independently related. The p value was considered to be statistically significant when it was less than 0.05.
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|Nikitin, NP.; (1998). Determinants Of Exercise Capacity In Patients With Left Ventricular Dysfunction As Assessed By Six-Minute Walk Test. Presented at INABIS '98 - 5th Internet World Congress on Biomedical Sciences at McMaster University, Canada, Dec 7-16th. Available at URL http://www.mcmaster.ca/inabis98/medicine/nikitin0578/index.html|
|© 1998 Author(s) Hold Copyright|