Abnormal shortened diastolic time length at increasing heart rates in patients with abnormal exercise-induced increase in pulmonary artery pressure

Abstract

Background: The degree of pulmonary hypertension is not independently related to the severity of left ventricular systolic dysfunction but is frequently associated with diastolic filling abnormalities. The aim of this study was to assess diastolic times at increasing heart rates in normal and in patients with and without abnormal exercise-induced increase in pulmonary artery pressure (PASP).

Methods: We enrolled 109 patients (78 males, age 62 ± 13 years) referred for exercise stress echocardiography and 16 controls. The PASP was derived from the tricuspid Doppler tracing. A cut-off value of PASP ≥ 50 mmHg at peak stress was considered as indicative of abnormal increase in PASP. Diastolic times and the diastolic/systolic time ratio were recorded by a precordial cutaneous force sensor based on a linear accelerometer.

Results: At baseline, PASP was 30 ± 5 mmHg in patients and 25 ± 4 in controls. At peak stress the PASP was normal in 95 patients (Group 1); 14 patients (Group 2) showed an abnormal increase in PASP (from 35 ± 4 to 62 ± 12 mmHg; P < 0.01). At 100 bpm, an abnormal (< 1) diastolic/systolic time ratio was found in 0/16 (0%) controls, in 12/93 (13%) Group 1 and 7/14 (50%) Group 2 patients (p < 0.05 between groups).

Conclusion: The first and second heart sound vibrations non-invasively monitored by a force sensor are useful for continuously assessing diastolic time during exercise. Exercise-induced abnormal PASP was associated with reduced diastolic time at heart rates beyond 100 beats per minute.

Figure 1

Boxplots of diastolic/systolic time ratios at increasing heart rates (HR, bpm) in patients with (left panel) vs patients without (middle panel) exercise-induced increase in pulmonary artery systolic pressure. Right panel, controls. At intermediate (100 bpm) heart rates an abnormal (< 1) diastolic/systolic time ratio was found in 0/16 (0%) controls, in 7/14 (50%) patients with and 12/93 (13%) patients without abnormal exercise-induced increase in pulmonary artery pressure, p < 0.05 between groups.

Figure 2

Correlation between diastolic time (mesc) during exercise and peak stress HR (bpm) in controls (triangles), in patients with (full circles) and without (empty circles) abnormal exercise-induced increase in pulmonary artery systolic pressure. The total cardiac cycle duration is algebraically dependent on the heart rate [= 60,000 msec/heart rate] with fixed values totally independent from the increasing heart rate stress type. At 100 bpm heart rate the cardiac cycle duration is = 600 msec. A longer diastolic time fraction improves ventricular filling and coronary perfusion time.