Effect of Changes in Atrioventricular Delay on dP/dt in Patients with Dilated Cardiomyopathy

pp. 276-280

Abstract

Background

Left ventricular LV dP/dt is an index used to assess ventricular function and prognosis in dilated cardiomypathy, but it is preload and afterload-dependent. Changes in the coupling interval between atrial and ventricular contraction may influence ventricular end-diastolic load (preload) and hence modify the dP/dt.

Objective

To analyze the effects of changes in atrioventricular (AV) delay on dP/dt in patients with dilated cardiomyopathy.

Material and Methods

Twelve patients (6men and 6 women; mean age: 51 ± 13 years), with dilated cardiomypathy, programmable dual-chamber pacemakers and mitral regurgitation were studied. The dP/dt was assessed with Bargiggia’s method. In all patients, the AV delay was modified within the maximum and minimum possible values, at 50 msec decrements (3 to 6 AV delays per patient) without any change in heart rate. Thus, for different AV delays, a wide range of dP/dt values were obtained. For correlation analysis, dP/dt values and AV delays were expressed as the percent change (% D) from the minimum dP/dt value and the maximum AV delay.

Results

The minimum dP/dt was 491 ± 114 mmHg/sec with an AV delay of 246 ± 70 msec, and the maximum dP/dt was 729 ± 98 mmHg/sec with an AV delay of 75 ± 34 msec (p<0.0001). Decreases in AV delay correlated with an increase in dP/dt: r = -0.74, y = 0.59 - 28.x (p<0.001).

Conclusion

In patients with dilated cardiomyopathy, dP/dt is sensitive to change in AV delay, thus demonstrating its preload/dependece. This findings should be taken into account when measuring dP/dt to assess systolic function and prognosis in dilated cardiomyopathy.