Response of the Stroke Volume and Blood Pressure of Young Patients With Nonobstructive Hypertrophic Cardiomyopathy to Exercise

Abstract

Stroke volume (SV), cardiac output (CO) and systolic blood pressure (SBP) were measured during maximal symptom-limited bicycle exercise testing in 13 young patients (age, 11-26 years) with nonobstructive hypertrophic cardiomyopathy (HCM). SV was measured by impedance plethysmocardiography; %SVend, %COend, and %SBPend represent the ratio of the value at termination of the exercise to the respective value at rest. In all patients of HCM-I (the Cardiac Event Group, 3 patients) and 3 of HCM-II (the Non-Cardiac Event Group, 10 patients), the %SVend was less than 100%. The %SVend of HCM-I was significantly lower than the respective values of the HCM-II and Control groups. The %COend values of the HCM-I and HCM-II groups were each significantly lower than that of the Control. The %SBPend values of the HCM-I and HCM-II groups were each significantly lower than that of the Control. Among the HCM patients, the %SVend value was positively correlated with the %SBPend value. The patients who had more severe HCM had poorer exercise-induced increases in SV and SBP. These results suggest that sudden cardiac death in young HCM patients is associated with inhibition of the increase in SV upon exercise. (Jpn Circ J 2001; 65: 300 -304)

Effects of lifestyle changes and high-dose β-blocker therapy on exercise capacity in children, adolescents, and young adults with hypertrophic cardiomyopathy

“…34 , 35 They are unable to increase their stroke volume during exercise, and stroke volume might even fall secondary to a decrease of atrial contribution to preload. 36 – 39 Patients with abnormal blood pressure response to exercise have particularly marked reduction in stroke volume during exercise. 36 , 37 , 39 Exercise aggravates the relative disproportion between duration of systole versus duration of diastole with disproportionate shortening of diastolic filling time.…”

“… 36 – 39 Patients with abnormal blood pressure response to exercise have particularly marked reduction in stroke volume during exercise. 36 , 37 , 39 Exercise aggravates the relative disproportion between duration of systole versus duration of diastole with disproportionate shortening of diastolic filling time. 40 , 41 However, as therapy with propranolol has been reported to improve diastolic dysfunction in adult patients with hypertrophic cardiomyopathy, 41 , 42 and will allow longer diastolic filling time, there are potential mechanisms for β-blocker therapy to improve stroke volume on exercise in hypertrophic cardiomyopathy.…”

“…The majority of adult patients with hypertrophic cardiomyopathy have an exercise capacity that is lower than predicted 34 35 They are unable to increase their stroke volume during exercise, and stroke volume might even fall secondary to a decrease of atrial contribution to preload 36 39 Patients with abnormal blood pressure response to exercise have particularly marked reduction in stroke volume during exercise 36 …”

Exercise testing in hypertrophic cardiomyopathy

“…Because patients with HCM may not show any significant functional impairment at rest, optimal assessment requires exercise testing [7]. An abnormal blood pressure [8][9][10] and stroke volume [9] response during exercise is a risk factor for sudden cardiac death in HCM patients. Nagata et al [11] reported that abnormal blood pressure response occurred in 11% of their patients with HCM and was associated with a high prevalence of cardiac events.…”