Hemodynamic differences among hypertensive patients with and without heart failure using impedance cardiography

Background:

Impedance cardiography is a reliable, well-tolerated, and non-invasive method used to obtain hemodynamic measurements and could potentially be useful in heart failure (HF) diagnosis, hemodynamic monitoring of critically ill patients, and help in the choice of antihypertensive therapy. The objective of this study was to determine the differences between hemodynamic parameters in a study population of hypertensive patients with and without HF, using impedance cardiography.

Methods:

A case-control study was designed and named the TARGET study. Participants were enrolled in two study groups: control group C, hypertensive patients without HF and the HF group, hypertensive patients with HF. A descriptive analysis was carried out to characterize the sample and differences in continuous variables were tested for statistical significance by independent sample t test.

Results:

The study included 102 hypertensive outpatients. The control group consisted of 77 individuals (58.4% males; mean age 63.9 ± 12.5 years old) and the HF group consisted of 25 individuals (44.0% males; mean age 74.2 ± 8.7 years old). The mean Cardiac Index (CI) was 2.70 ± 1.02 L.min.m⁻² (2.89 ± 1.04 versus 2.12 ± 0.70; p < 0.001), mean Stroke Index (SI) was 35.5 ± 14.7 mL.m⁻² (37.7 ± 15.2 versus 28.5 ± 10.8; p = 0.006), mean Ejection Phase Contractility Index (EPCI) was 33.7 ± 12.7 1000 s⁻² (35.8 ± 13.1 versus 27.2 ± 9.2; p = 0.003), mean Inotropic State Index (ISI) was 74.3 ± 28.2 100 s⁻² (78.8 ± 28.9 versus 60.6 ± 20.7; p = 0.005), and mean Left Stroke Work Index (LSWI) was 51.3 ± 23.1 g.min.m⁻² (55.4 ± 23.5 versus 38.9 ± 16.6; p = 0.002).

Conclusions:

In this study, hypertensive patients with HF had significantly lower values of blood flow parameters, contractility, and left work indices compared with hypertensive patients without HF. These differences reflected the incorrect hemodynamic pattern (mostly hypodynamic) of these patients. Impedance cardiography (ICG) seems to be an adequate method to reflect these differences.

Hemodynamic and hormonal patterns of untreated essential hypertension in men and women

BACKGROUND

Knowledge of hemodynamic factors accounting for the development of hypertension should help to tailor therapeutic approaches and improve blood pressure control. Few data exist regarding sex differences of hemodynamic factors contributing to hypertension progression among patients with untreated nondiabetic stage I and II prehypertension (PreHyp) as defined by the Joint National Committee-7 guidelines (JNC-7).

METHODS

We utilized noninvasive impedance cardiography, applanation tonometry and plasma measures of angiotensin II, angiotensin (1-7), serum aldosterone, high-sensitivity C-reactive protein (hs-CRP) and cytokine biomarkers of inflammation to characterize the hemodynamic and hormonal profile of 100 patients with untreated hypertension (39 women).

RESULTS

Despite there being no differences between women and men in terms of office blood pressure, heart rate and body mass index, men demonstrated lower values of pulse pressure, systemic vascular resistance, brachial artery pulse wave velocity and augmentation index. In each of the three hypertension categories, the increased blood pressure in men was associated with significant augmentations in stroke volume and cardiac output compared with women. Sex-related hemodynamic differences were associated in women with higher plasma levels of leptin, hs-CRP, plasma angiotensin II and serum aldosterone, and no differences in the serum concentrations of cytokinins. In women but not men, hs-CRP correlated with plasma concentrations of transforming growth factor β1 (TGFβ1) and body weight; in addition, plasma TGFβ1 correlated with levels of serum vascular cell adhesion molecule 1.

CONCLUSION

The impact of sex differences in the hemodynamic factors accounting for the elevation in arterial pressure in subjects with essential hypertension has been poorly characterized or this information is not available. We suggest that this gap in knowledge may adversely influence choices of drug treatment since our study shows for the first time significant differences in the hemodynamic and hormonal mechanisms accounting for the increased blood pressure in women compared to men.

Using impedance cardiography with postural change to stratify patients with hypertension

Background: Early detection of cardiovascular disease in patients with hypertension could initiate appropriate treatment to control blood pressure and prevent the progression of cardiovascular disease.

Objective: The goal of this study was to show how impedance cardiography waveform analysis with postural change can be used to detect subclinical cardiovascular disease in patients with high blood pressure.

Methods: Patients with high blood pressure had impedance cardiography data obtained in two positions, standing upright and supine.

Results: In 50 adults, impedance cardiography indicated that all patients had abnormal data, with 44 (88%) having multiple abnormalities. Impedance cardiography showed 32 (64%) had ventricular dysfunction, 48 (96%) had vascular load abnormalities, 34 (68%) had hemodynamic abnormalities, 2 (4%) had hypovolemia, and 3 (6%) had hypervolemia.

Conclusions: Hypertensive patients have diverse cardiovascular abnormalities that can be quantified by impedance cardiography. By stratifying patients with ventricular, vascular, and hemodynamic abnormalities, treatment could be customized based on the abnormal underlying mechanisms with the potential to rapidly control blood pressure, prevent progression of cardiovascular disease, and possibly reverse remodeling.

Individualizing hypertension treatment with impedance cardiography: a meta-analysis of published trials

Objective: Hypertension affects 73 million Americans and costs the US healthcare system over $73 billion annually. Despite increasing awareness of the consequences of uncontrolled hypertension, numerous antihypertensive pharmacologic clinical studies and consistent updates to hypertension guidelines, control rates are suboptimal and have not met national goals. Among treated hypertensives, only 45% of women and 51% of men have reached blood pressure (BP) levels below 140/90 mmHg. Individualization of antihypertensive regimens with hemodynamic information from impedance cardiography (ICG) has been advocated to further improve hypertension control rates. We therefore undertook a quantitative analysis of the trials evaluating the role of ICG as an adjunct to therapeutic decision-making in the treatment of hypertension and the attainment of BP control.

Methods: Five studies comprising a total population of 759 patients met the inclusion criteria. Two randomized controlled trials (RCTs) involving a total of 268 patients and three single-arm prospective trials with 491 patients were evaluated using ICG data to guide therapeutic decision-making in the treatment of hypertensive patients.

Results: Significant benefit was found in both RCTs for ICG-guided BP treatment. The combined odds ratio for the two trials was 2.41 (95% CI = 1.44-4.05, p = 0.0008), in favor of ICG treatment, meaning that it was more than twice as likely to achieve BP success when using ICG than if ICG was not used. Success attainment of goal BP of <140/90 mmHg was 67% in the ICG-guided arms of the combined randomized trials. Overall success in the single-arm prospective trials of ICG-guided BP treatment was a similar 68%.

Conclusion: The results of this meta-analysis confirm the value of using ICG-derived hemodynamic data as an adjunct to therapeutic decision-making in the treatment of hypertension. The data reviewed here demonstrate that ICG-based approaches are in keeping with previously advocated strategies incorporating patient-individualized drug regimens, evidence-based medicine, and practical, easy to apply, cost-effective principles to further improve hypertension control rates.