QT Dispersion And The Relationship Between QT Dispersion And The Mass Of Left Ventricle In Hypertrophic Cardiomyopathy

QT dispersion, QTd is defined as the difference between the maximum QT (QTmax) and the minimum QT (QTmin) by measurement of recording 12-lead-system electrocardiogram. It reflects un-synchronization and electrical instability of ventricular repolarization. The characteristics of hypertrophic cardiomyopathy ( HCM) are hypertrophy of ventricular muscle and increase of cardiac weight. The main causes of death of HCM patients are heart failure and sudden cardiac death, which the main mechanism is ventricular tachycardia.According to the investigation in existence, the increase of QTd may be the electrophysiological basis of inducing ventricular arrhythmia. The bigger QTd is, the more feasibility of ventricular arrhythmia occurrence. Through the research of the relationship between QT dispersion and the mass of left ventricle in hyper-trophic cardiomyopathy, following results have been looking forward to finding whether the HCM paitents have the sensitivity to electrical instability of ventricular repolarization and the chief reasons.Materrials and methods1. Materrials64 cases of in-patients with HCM are selected in case group from August, 1998 to December,2003 in Iiaoning Provincial Peoples Hospital, who all accordwith the diagnostic standard of WHO. Then they are divided into two groups; 33 cases in obstructive cardiomyopathy group and 31eases in non-obstructive cardio-myopathy group. 32 cases of healthy person are selected in our hospital in comparative group with method of comparison and equilibrium. The 3 groups of cases all exclude valvular heart disease, coronary heart disease, hypertension, e-lectrolytes disturbance and other systemic disease and are without any administration of antiarrhythmic drugs in 24 hours.2. InstrumentsJapanese photoelectrical type 8340K 12-lead-system electrocardiograph. HP type SONOS2500 ultrasonics. Qinghua purple light A600 scanner. Pentium III PC.3. Methods3. 1 Data collection(1) General data; Gather and record the general instance and brief history of illness of this 3 groups.(2)Research data: Collect 12-lead-system electrocardiogram and ultrasonic cardiogram respectively with paper speed of 25mm/s, voltage of 1.0mv/cm.3. 2 Data measurement(1) QTd measurement: experimental assistants are familiar with the instruments and principles used and the measurements are repeated blindly with the same instruments. Special person is charge of measurement of the 3 groups of 12-lead-system electrocardiogram in the whole experiment. Scan all the electrocardiograms into the PC by 2 times of the primary size and measure the variables by the CorelDRAW9.0 software, (measure after multiple blowing up and copying electrocardiogram, take the average of measurement of 3 continuous cardiac cycles) . The content of measurement and record include QT period, RR period , number of lead ( at least 7 ) and it get QTd ( QTd = QTmax-QTmin ) , QTcd (QTcd=QTd/(R-R)1/2).(2) Ultrasonic data record and calculatingMeasure the left ventricular endo-diameter in diastolic phase ( LVEDD), interventricular septum thickness ( IVST) and left ventricular posterior wall thickness ( LVPWT) of HCM patients according to Perm way. The average isgained after 3 times of continuous calculate the left ventricular mass (LVM) by Devereux formula LVM ( g) = 1. 04 [ ( LVEDD ± IVST ± LVPWT) 3-( LVEDD) 3]-13.6.3. 3 Data disposeAll the measurement data are figured by mean standard difference, checked up by one-way ANOVA,while the enumeration data are checked up by X2. The relationship between QTd and LVM, QTd and IVST analyze by linear correlation. P<0.05 has static ?significance.Results1. HCM group ( including obstructive group and non-obstructive group) LVM, QTd, QTcd enhance obviously comparing to the comparison group ( P < 0. 05 ) and have no difference in statistics in the obstructive cardiomyopathy group and non-obstructive cardiomyopathy group ( P > 0. 05 ) . The LVM ( g) value of normal group, obstructive group and non-obstructive group is respectiv...