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The stroke volume in juvenile borderline hypertension
Insights
Borderline hypertension involves distinct hemodynamic patterns. Elevated heart rate or stroke volume impacts exercise adaptation and plasma volume, revealing specific patient subgroups with unique cardiovascular responses.
Area of Science:
- Cardiovascular Physiology
- Hypertension Research
- Clinical Hemodynamics
Background:
- Borderline hypertension is characterized by elevated blood pressure not yet meeting diagnostic criteria for sustained hypertension.
- Understanding the underlying hemodynamic alterations in borderline hypertension is crucial for early intervention and risk stratification.
- Previous studies suggest heterogeneous hemodynamic profiles within this patient group.
Purpose of the Study:
- To investigate and classify hemodynamic changes in men with borderline hypertension across different body positions and during exercise.
- To identify distinct hemodynamic patterns associated with varying basal heart rate and stroke index levels in borderline hypertension.
- To elucidate the adaptive responses of cardiovascular parameters during postural changes and physical exertion in different subgroups of borderline hypertensive patients.
Main Methods:
- Studied 144 men (37 normal, 107 borderline hypertensive) assessing hemodynamic parameters (heart rate, stroke index, total peripheral resistance, plasma volume, cardiac index, diastolic arterial pressure).
- Evaluated hemodynamic responses in supine, upright (tilt test), and exercise conditions.
- Classified borderline hypertensive patients into four groups based on basal heart rate and stroke index.
Main Results:
- Patients with normal stroke index and elevated heart rate (Group II) showed impaired cardiac and stroke index adaptation during exercise.
- Patients with elevated stroke index (Groups III & IV) exhibited reduced plasma volume and total peripheral resistance, with abnormal responses during tilt test.
- Group IV (elevated stroke index and heart rate) displayed a specific pattern: reduced plasma volume, impaired exercise adaptation of cardiac index and total peripheral resistance, and abnormal tilt responses.
Conclusions:
- High basal stroke volume in borderline hypertension correlates with reduced plasma volume and impaired total peripheral resistance adaptation during postural changes.
- Elevated basal heart rate is linked to compromised cardiac output adaptation during exercise.
- A specific hemodynamic profile, including reduced plasma volume and impaired adaptation during exercise and tilt, is observed in borderline hypertensive patients with concurrent increases in both heart rate and stroke volume.
Abstract:
Hemodynamic changes in supine and upright position and during exercise were studied in 144 men including 37 normal subjects and 107 patients with borderline hypertension. Borderline hypertensives were classified in 4 groups, according to the basal level of heart rate and stroke index. In the first two groups, stroke index was normal, but heart rate was either decreased (Group I) or elevated (Group II): supine total peripheral resistance was superior (Group I; p less than 0.02) or equal (Group II) to normal values; plasma volume was normal or slightly decreased; hemodynamic response to tilt test closely approximated the normal; impaired adaptation of cardiac index and stroke index to exercise was observed in Group II (p less than 0.001). In the other two groups, stroke index was significantly elevated (p less than 0.0001) but heart rate was either decreased (Group III) or increased (Group IV); supine total peripheral resistance values were decreased (p less than 0.001); plasma volume was equally reduced (p less than 0.001); abnormal percentile increase in diastolic arterial pressure (p less than 0.02; p less than 0.001) and total peripheral resistance during tilt test were observed; during exercise, only the patients of Group IV had an impaired adaptation of cardiac index (p less than 0.001) and total peripheral resistance (p less than 0.02). The study provide evidence that in boderline hypertension i) a high basal level of stroke volume is associated with a reduced plasma volume and an imparied adaptation of total peripheral resistance during tilt, ii) a high basal level of heart rate is associated with an impaired adapatation of cardiac output during exercise, and iii) only patients having an increase in both heart rate and stroke volume exhibited a specific hemodynamic pattern including: reduction of plasma volume, impaired adaptation of cardiac output during exercise, impaired adaptation of total peripheral resistance during tilt and exercise.