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Noninvasive hemodynamic profiles in hypertensive subjects
Abdelhammed I Abdelhammed1, Ronald D Smith, Pavel Levy
1Hypertension and Vascular Disease Center, Wake Forest University School of Medicine, Winston-Salem, North Carolina 27157-1032, USA.
Insights
Noninvasive impedance cardiography reveals distinct hemodynamic profiles in hypertensive individuals, showing altered cardiac index and systemic vascular resistance. Despite group differences, significant individual variations in hemodynamic status highlight the need for personalized assessment in hypertension management.
Area of Science:
- Cardiovascular Physiology
- Biomedical Engineering
Background:
- Hypertension is characterized by elevated blood pressure (BP) and abnormal hemodynamics, including increased systemic vascular resistance index (SVRI) and altered cardiac index (CI).
- Noninvasive impedance cardiography (ICG) offers a method to evaluate these hemodynamic characteristics.
Purpose of the Study:
- To utilize ICG to assess and compare hemodynamic profiles of individuals with and without hypertension.
- To identify specific hemodynamic parameters that differentiate hypertensive from nonhypertensive subjects.
Main Methods:
- Retrospective analysis of 19 healthy nonhypertensive and 136 hypertensive subjects.
- ICG measurements included cardiac index (CI), systemic vascular resistance index (SVRI), total arterial compliance index (TACI), and thoracic fluid content (TFC).
- Hemodynamic parameters were compared based on hypertension status, BP levels, demographics, and medication use.
Main Results:
- Hypertensive subjects exhibited significantly lower CI, TACI, and thoracic fluid content (TFC), and higher SVRI compared to nonhypertensive individuals.
- Stage 2 hypertension was associated with higher SVRI and lower TACI than stage 1 hypertension.
- Significant correlations were observed between TACI, SVRI, and CI with systolic blood pressure (SBP), though individual variations in SVRI were noted even within controlled BP ranges.
Conclusions:
- ICG-derived hemodynamic parameters effectively differentiate between hypertensive and nonhypertensive subjects.
- Despite group trends, substantial individual variability in hemodynamic status exists.
- ICG measurements can aid in the diagnosis, prognosis, and treatment decisions for hypertensive patients.
Background:
Hypertension is a disease state characterized by increased blood pressure (BP) associated with hemodynamic abnormalities, including elevated systemic vascular resistance index (SVRI); and altered cardiac index (CI). The objective of this study was to use noninvasive impedance cardiography (ICG) to evaluate hemodynamic characteristics of subjects with and without hypertension.
Methods:
A total of 19 healthy nonhypertensive and 136 hypertensive subjects were retrospectively evaluated. Hemodynamic parameters were measured with ICG and included CI, SVRI, total arterial compliance index (TACI), and thoracic fluid content (TFC); these were compared with subject type, blood pressure value, demographics, and medications.
Results:
The BP levels of healthy and hypertensive subjects were 117/71 and 154/90 mm Hg, respectively (P < .0001). Subjects with prehypertension had a lower TACI (0.97 v 1.21, P < .05) compared with those with a normal BP, ie, <120/80 mm Hg. Hypertensive subjects had significantly lower SI, CI, TACI, and TFC and significantly higher SVRI. Subjects with stage 2 hypertension had higher SVRI (4149 v 3418 dyne.sec(2).cm(-5).m(2), P < .01) and lower TACI (0.61 v 0.53 mm Hg/mL/m(2), P < .05) than those with stage 1 hypertension. Compared with subjects with controlled hypertension, normal subjects had significantly lower SVRI (1996 v 2746 dyne.sec(2).cm(-5).m(2), P < .0001) and significantly higher CI (3.23 v 2.63 L/min/m(2), P < .001), SI (48.2 v 37.4 mL/m(2), P < .0001), TACI (1.08 v 0.85 mm Hg/mL/m(2), P < .01), and TFC (29.1 v 24.1/kOhm, P < .0001). The parameters of TACI, SVRI, and CI demonstrated modest correlation (-0.75, 0.62, and -0.30), respectively, with SBP. In the 54 subjects with BP <140/90 mm Hg, SVRI values varied significantly, with 32 subjects (39.2%) with SVRI values in the high range (>2483 dyne.sec(2).cm(-5).m(2)).
Conclusions:
Hemodynamic parameters from ICG displayed significantly different hemodynamic profiles between hypertensive and nonhypertensive subjects. However, significant individual variation of hemodynamic status exists. Hemodynamic measurements with ICG characterize hemodynamic status and may be helpful in diagnostic, prognostic, and therapeutic decision making in hypertensive subjects.
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