R-wave amplitude changes during exercise in adolescents with left ventricular pressure and volume overload

To determine the diagnostic value of exerciseinduced R-wave changes in adolescents with congenital heart disease, the responses of 50 adolescents without significant heart disease were compared with those of 72 patients with either a left ventricular (LV) pressure or volume overload lesion. Among the pressure overload group, 24 patients had valvular aortic stenosis (AS) and 27 had coarctation of the aorta. The volume overload group included 12 patients with mitral regurgitation (MR) and 9 with aortic regurgitation (AR). Severity of the cardiac lesion was assessed using cardiac catheterization in patients with AS, physical examination in patients with coarctation of the aorta and clinical or angiographiec criteria, or both, in patients with valvular regurgitation. The R wave was measured in 10 consecutive QRS complexes in leads II, aVF and V₅ at rest, maximal exercise and 1-minute recovery. At maximal exercise, control subjects had a mean decrease in amplitude (ΔR) of ?3.6 mm (p < 0.0001). Compared with the control group, the AS group had a similar decrease of ?3.5 mm, but the coarctation group had a ΔR of ?1.4 (p < 0.005) and the volume overload group a ΔR of ?1.1 mm (p < 0.003). Patients with AS and ischemic ST-segment changes during exercise (n = 12) had greater decreases in R-wave amplitude than did those with no ST changes (n = 12) (p < 0.04). In patients with AS and an LV end-diastolic pressure ? 12 mm Hg (n = 7), the decrease in ΔR was also greater than that in patients with LV end-diastolic pressure ≤ 12 mm Hg (n = 14) (p < 0.006). Among patients with volume overload, more severe valvular regurgitation was associated with a smaller ΔR (p < 0.03). In patients with AS an increased ΔR reflects ischemia or diminished LV compliance, or both, whereas in patients with volume overload a decrease in ΔR is an indicator of the severity of regurgitation.