Method
Evidence for Early Right Ventricular and Septal Mechanical Activation (Interventricular Dyssynchrony) in Pulmonary Hypertension

https://doi.org/10.1016/j.amjcard.2008.06.062Get rights and content

This study sought to characterize mechanical activation in pulmonary arterial hypertension (PAH) using 2-dimensional echocardiography with tissue Doppler imaging. Whether pathologic alterations of the right ventricle in PAH affect interventricular dyssynchrony due to changes in mechanical activation of the septum and the right ventricle is unclear. We studied 20 patients with PAH (14 women, mean age 55 ± 16 years) and 20 healthy controls (15 women, mean age 41 ± 11 years) that underwent tissue Doppler imaging between July 2006 and May 2007. PAH was associated with accelerated right ventricular (RV) (p <0.0001) and septal (p = 0.022) activation times, but no differences were found in lateral wall activation times between groups (p = 0.35). Measures of ventricular dyssynchrony indicated that patients with PAH had significantly lower RV-lateral wall delays (patients 3.2 ± 66.2 ms vs controls 56.7 ± 52.0 ms, p = 0.007), reflecting a faster activation of the right ventricle relative to the lateral wall than controls. In conclusion, PAH is associated with interventricular dyssynchrony manifested by accelerated RV free wall and septal activation times. Whether such dyssynchrony should serve as a therapeutic target remains to be determined.

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Methods

Subjects were enrolled from the pulmonary hypertension clinic and the inpatient cardiology services at the University of Maryland Medical Center. All subjects with PAH had been previously diagnosed with pulmonary hypertension at right heart catheterization. The inclusion criteria for patients with PAH were previous right heart catheterization with mean pulmonary artery pressure >25 mm Hg, age >21 years, and normal sinus rhythm. Patients were excluded for any of the following criteria:

Results

Table 1 presents characteristics of patients with PAH and controls. There were no significant differences between groups in blood pressure or heart rate. Patients with PAH were older then controls; statistical analyses were therefore adjusted for age. No patient had right bundle branch block or left bundle branch block, and the mean QRS was 89.4 ± 8.6 ms (range 76 to 102 ms). Medication use was as follows: sidenafil (n = 14), epoprostenol (n = 5), bosentan (n = 4), treprostinil (n = 2),

Discussion

The principal finding of the study is that chronic PAH is associated with accelerated RV activation in patients with evidence of RV dysfunction and a normal QRS duration. However, despite early RV activation times, the times to Doppler-assessed aortic and pulmonic valve opening were similar in patients with PAH and controls. Although there was no time difference between onset of RV and LV there was evidence of accelerated myocardial systolic activation in the basal RV free wall in patients with

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Dr. Myung H. Park is a consultant and serves on the speaker's bureau for Actelion Pharmaceuticals, Gilead, and United Therapeutics.

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