Left ventricular dysfunction after long-term right ventricular apical pacing in the young
M. Victoria T. Tantengco, MD, FAAC*,
Ronald L. Thomas, PhD and
Peter P. Karpawich, MD, FAAC*
* Division of Cardiology, Department of Pediatrics, Children’s Hospital of Michigan, Wayne State University School of Medicine, Detroit, Michigan, USA
Children’s Research Center of Michigan, Department of Pediatrics, Children’s Hospital of Michigan, Wayne State University School of Medicine, Detroit, Michigan, USA
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Figure 1 Image of on-line derivation of beat-to-beat changes in the left ventricle area throughout the cardiac cycle, obtained from the parasternal short-axis view using automated border detection by echocardiography. The inherent computer software algorithm allows instantaneous calculation of the fractional area of change (FAC), as well as the maximal rate of rise of LV pressure (+dA/dt) and –dA/dt normalized to the LV end-diastolic area. EDA = end-diastolic area; ESA = end-systolic area; PER = peak emptying rate; PFR = peak filling rate; TPFR = time to peak filling rate.
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Figure 2 This box plot diagram depicts the difference in automated border detection-derived left ventricular (LV) parasternal short-axis fractional area of change between the patients (pts) (n = 24) and control subjects (n = 33). Data contained within the box represents the 25th to 75th percentile values, with the thick line depicting the median value. The bars represent the maximal and minimal data points, excluding outliers. The LV area shortening appears diminished in the young patients who had long-term right ventricle apical pacing (mean age 19.5 years, mean follow-up 9.5 years) versus the age- and body surface area-matched control subjects (52 ± 10 vs. 60 ± 6, p = 0.002).
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Figure 3 This box plot diagram shows reduced global left ventricular (LV) function, expressed as the Doppler flow-derived myocardial performace index (MPI), in the paced patient (pts) group versus the control group. Data contained within the box represents the 25th to 75th percentile values, with the thick line depicting the median value. The bars represent the maximal and minimal data points, excluding outliers. A higher Doppler MPI value correlates with reduced combined (systolic and diastolic) ventricular function. The Doppler MPI was increased in the pacemaker group versus the control group (46 ± 13 vs. 34 ± 8, p = 0.005).
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Figure 4 Linear regression analysis depicting the negative inverse relationship between left ventricular (LV) parasternal short-axis fractional area of change (FAC) (%) and paced QRS duration (ms) in 24 young patients who had long-term right ventricle apical pacing, including the mean regression line and regression coefficient (with 95% confidence interval [CI]) of the QRS interval. The slope of the regression line was –0.2 (95% CI of –0.34 to –0.04), p < 0.05, r2 = 0.24, Y = –0.2X + 78.4. Therefore, for every 1-ms increase in QRS duration, the LV FAC decreases by 0.2%.
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