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Selected Publication:
Trozic, I.
Postural Cardiovascular Variability: A Perspective on Cerebrovascular Diseases, Sex and Seasons
Doktoratsstudium der Medizinischen Wissenschaft; Humanmedizin; [ Dissertation ] Graz Medical University; 2019. pp. 81
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- Authors Med Uni Graz:
- Advisor:
- Bondarenko Oleksandr
- Fazekas Franz
- Goswami Nandu
- Altmetrics:
- Abstract:
- Purpose: The purpose of this study was to study how seasons (colder seasons and warmer seasons) affects the responses of hemodynamic mechanisms and heart rate variability during a sit-to-stand test in patients with stroke and participants without a stroke across sex and seasons. Methods: Through a sit-to-stand test (5 min of sitting followed by 5 min of standing), we examined cardiovascular responses in patients with a stroke (n= 16) and participants without a stroke (n=25), age >55 years, in two seasons. We continuously recorded via a Task Force Monitor® device beat to beat systolic blood pressure (SBP), diastolic blood pressure (DBP), heart rate (HR), stroke index (SI) and cardiac index (CI), and low frequency and high frequency of the heart rate variability (HRV). Results: During the resting phase, DBP (delta: +15.1, SE: ±3.75, [mmHg], p<0.05) and MBP (delta: +14.35, SE; ±4.18, [mmHg], p<0.05) were significantly higher in colder months compared to warmer months and SI (delta: -3.86, SE: ±1.43, [ml/beat/m2], p<0.05) and CI (delta: -0.4, SE: ±0.11, [l/min/m2], p<0.05) were lower in colder months compared to warmer months in participants without a stroke. In patients with stroke, during the resting phase, DBP (delta: +19.92, SE: ±8.03, [mmHg], p<0.05) and MBP (delta: +19.29, SE: ±8.6, [mmHg], p<0.05) were significantly higher in colder months compared to warmer months and SI (delta: -5.43, SE: ±1.96, [ml/beat/m2], p<0.05) were significantly lower in colder months compared to warmer months. After standing, there was a significant decrease in SBP in warmer months (delta: -16.84, SE: ±4.38, [mmHg], p<0.05) and decrease in DBP in warmer months (delta: -7.8, SE: ±2.30, [mmHg], p<0.05) and colder months (delta: -6.73, SE: ±1.5, [mmHg], p<0.05) in participants without a stroke and decrease in MBP in warmer months (delta: -12.5, SE: ±2.8, [mmHg], p<0.05) and colder months (delta: -8.93, SE: ±1.8, [mmHg], p<0.05) in participants without a stroke and in warmer months (delta: -14.54, SE: ±4.1, [mmHg], p<0.05) in patients with stroke. After standing hemodynamic parameters and heart rate variability responses show differences between males and females. In female participants without a stroke, high frequency (normalized) was lower in warmer months (delta: - 20.92, SE: ± 1.63, [%], p<0.05), low frequency (normalized) was higher in warmer months (delta: 20.93, SE: ± 1.63, [%], p<0.05) compared to males. In female patients with a stroke, high frequency (normalized) was lower in colder months (delta: -13.72, SE: ± 1.61, [%], p<0.05), and low frequency (normalized) was higher in colder months (delta: 17.72, SE: ± 2.370, [%], p<0.05) compared to males. Conclusions: First, our study shows that patients with stroke and older persons without stroke respond in a comparable way to orthostatic loading with greater postural blood pressure decrease in warmer months. Nonetheless, patients one-year after stroke (minor stroke) and with no disabilities show none of the signs of orthostatic hypotension despite postural blood pressure reduction in warmer months. Second, we reported that heart rate variability responses to orthostatic loading show differences between males and females. The results of our study point for a season and sex dependency of the underlying hemodynamic mechanisms during orthostatic loading.