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Augmented exercise plasma noradrenaline with impaired chronotropic responsiveness in patients with hypertrophic
H Omodani1, T Kinugawa, K Ogino
11st Department of Internal Medicine, Tottori University School of Medicine, Yonago, Japan.
Insights
Patients with hypertrophic cardiomyopathy (HCM) show higher plasma noradrenaline levels during exercise and impaired chronotropic sympathetic responsiveness. This study investigated cardiovascular and catecholamine responses to exercise in HCM patients.
Area of Science:
- Cardiovascular Physiology
- Exercise Science
- Endocrinology
Background:
- Controversy exists regarding plasma catecholamine levels in hypertrophic cardiomyopathy (HCM).
- Limited data are available on serial plasma catecholamine measurements during exercise in HCM.
- Understanding exercise responses in HCM is crucial for patient management.
Purpose of the Study:
- To determine if cardiovascular and plasma catecholamine responses to exercise are altered in patients with non-obstructive HCM.
- To assess chronotropic sympathetic responsiveness during exercise in HCM.
Main Methods:
- 15 patients with non-obstructive HCM and 15 age/sex-matched controls underwent submaximal treadmill exercise.
- Plasma noradrenaline (NA) and adrenaline levels were measured at rest, during exercise stages, and post-exercise.
- Chronotropic sympathetic responsiveness was indexed by the ratio of increment in heart rate to increment in plasma NA (delta HR/delta NA).
Main Results:
- HCM patients exhibited higher plasma NA levels at early stages of exercise compared to controls.
- Diastolic blood pressure was significantly higher in HCM patients during early exercise stages.
- The delta HR/delta NA ratio was significantly lower in HCM patients, indicating impaired chronotropic sympathetic responsiveness.
Conclusions:
- Patients with HCM demonstrate augmented plasma noradrenaline levels and altered blood pressure responses during submaximal exercise.
- Chronotropic sympathetic responsiveness to exercise is impaired in the early stages of exercise in HCM patients.
- These findings highlight potential autonomic dysfunction during exercise in HCM.
Abstract:
1. There is controversy regarding plasma catecholamine levels in patients with hypertrophic cardiomyopathy (HCM) and few data exist on serial plasma catecholamine measurements during exercise. The present study determined whether cardiovascular and plasma catecholamine responses to exercise were altered in patients with HCM. 2. Plasma noradrenaline (NA) and adrenaline were measured at rest, at the end of each stage during exercise and immediately and 5 min after submaximal treadmill exercise in 15 patients with non-obstructive HCM (13 males, two females; mean (+/- SEM) age 54 +/- 3 years) and in 15 age- and sex-matched controls. The ratio of the increment in heart rate (HR) divided by the increment in plasma NA during exercise (delta HR/delta NA) was used as an index of chronotropic sympathetic responsiveness to exercise. 3. Exercise duration was shorter (11.2 +/- 0.6 vs 8.7 +/- 0.6 min for control vs HCM, respectively; P < 0.01) and diastolic blood pressure was significantly higher at stages I and II of modified Bruce protocol HCM. 4. Resting plasma NA levels (149 +/- 17 vs 167 +/- 28 pg/mL for control vs HCM, respectively; NS) were not different, but plasma NA levels at stages I and II were significantly higher in HCM than in controls (243 +/- 26 vs 399 +/- 69 pg/mL (P < 0.05) and 308 +/- 30 vs 548 +/- 110 pg/mL (P < 0.05), respectively). 5. Peak plasma NA levels were not significantly higher in HCM than in controls (578 +/- 59 vs 918 +/- 184 pg/mL, respectively; NS). 6. The ratio delta HR/delta NA was significantly lower in HCM compared with control at stages I and II (0.49 +/- 0.10 vs 0.21 +/- 0.05 (P < 0.05) and 0.38 +/- 0.06 vs 0.20 +/- 0.05 (P < 0.05), respectively). There were no differences in plasma adrenaline responses during exercise between the two groups. 7. Patients with HCM had augmented plasma NA levels during submaximal exercise with a higher diastolic blood pressure response. Chronotropic sympathetic responsiveness was impaired during the early stages of exercise in patients with HCM.