The usefulness of impedance cardiography for predicting beneficial effects of cardiac rehabilitation in patients with heart failure

Effects of early phase 1 cardiac rehabilitation on cardiac function evaluated by impedance cardiography in patients with coronary heart disease and acute heart failure

Purpose

The purpose of the study was to access the impact of phase 1 cardiac rehabilitation (CR) on cardiac function and hemodynamic changes in patients with coronary heart disease (CHD) and acute heart failure (AHF).

Materials and methods

A total of 98 patients with CHD and AHF were recruited and randomized into two groups. Control group received standard pharmacotherapy and CR group received standard pharmacotherapy combined phase 1 CR. NT-proBNP and hemodynamic parameters measured by impedance cardiography (ICG) were estimated at baseline and at the end of treatment period.

Results

Phase 1 CR combined routine medical treatment could lower NT-proBNP levels. The percentage of high-risk patients was significantly decreased in CR group, although the post-treatment NT-proBNP level between control group and CR group showed no significant differences. Similarly, most hemodynamic parameters improved in the CR group, but not in the control group, suggesting that phase 1 CR in combination with the standard pharmacotherapy improved hemodynamic characteristics by elevating cardiac output, ameliorating preload, improving systolic and diastolic function, and relieving afterload, although the post-treatment hemodynamic parameters showed no statistically significant differences between the control group and the CR group.

Conclusion

Phase 1 CR combined routine medication can improve cardiac function and hemodynamic characteristics in patients with CHD and AHF. Thus, recommendation of phase 1 CR to stable patients is necessary.

A Retrospective Study of Hemodynamic Changes in Patients After Off-Pump Coronary Artery Bypass Graft Surgery Using Impedance Cardiography

Background

This study aimed to investigate the role of impedance cardiography (ICG) to evaluate hemodynamic changes in patients after off-pump coronary artery bypass graft (OPCABG) surgery.

Material/Methods

One-hundred and sixty patients who had undergone OPCAGB were enrolled and assessed using New York Heart Association NYHA functional class (II, II, and IV). ICG was used to measure the stroke volume (SV), stroke volume index (SI), cardiac output per minute (CO/min), cardiac index (CI), end-diastolic volume (EDV), pre-ejection period (PEP), left ventricular ejection time (LVET), systolic time ratio (STR), left ventricular ejection fraction (LVEF), acceleration index (ACI), systemic vascular resistance (SVR), and thoracic fluid content (TFC). The ICG parameters were correlated with brain natriuretic peptide (BNP) and echocardiography parameters using multivariate regression analysis.

Results

The levels of CO, ACI, TFC, SVR, and BNP compared with ICG showed differences between NYHA functional class, with CO showing a significant difference (p<0.05). There were no significant differences between SV, SI, EDV, and LVEF before and after OPCAGB. Using ICG, the parameters of CI, LVEF, EDV, and TFC showed no significant correlation with BNP. SV, SI, CO, ACI, and LVET, which were negatively correlated with BNP. SVR, PEP, and STR were positively correlated with BNP (P<0.05).

Conclusions

In patients who had OPCABG, the findings from ICG were significantly correlated with BNP levels and the results from echocardiography for the evaluation of cardiac hemodynamic changes. ICG might have a role in the assessment of cardiac function in clinical practice.

Diagnostic and Outcome Prediction Value of Transthoracic Impedance Cardiography in Heart Failure Patients During Heart Failure Flare-Ups

BACKGROUND This study aimed at evaluating the diagnostic and outcome prediction value of transthoracic impedance cardiography (ICG) in heart failure (HF) patients admitted for in-hospital treatment due to flare-ups of their condition. MATERIAL AND METHODS In total, 120 patients of intensive care units who were admitted due to HF flare-ups were involved to the study. The findings of ICG were compared to data obtained by other methods used for diagnosing HF. RESULTS Statistically significant (p<0.001) results were obtained when evaluating differences in ICG data between admission and discharge from the intensive care unit. In addition, a correlation was detected between brain natriuretic peptide (BNP) and thoracic fluid content index (r=0.4, p<0.001). Differences in ICG values, and BNP data emerged after the participants were grouped according to NYHA classes (p<0.05). The evaluation of lethal outcome during 6 months after the discharge yielded statistically significant results: BNP ≥350 pg/mL (Odds Ratio (OR) 4.4), thoracic fluid content ≥34 1/kOhm (OR 4.3), and systolic time ratio ≥0.55 (OR 2.9), p<0.05. CONCLUSIONS ICG data might be applied for the diagnosis and prognosis of HF, although the links between ICG and HF need further evaluation.

Evaluation of Skeletal Muscle Function and Effects of Early Rehabilitation during Acute Heart Failure: Rationale and Study Design

Background

Acute heart failure (AHF) is associated with disturbances of the peripheral perfusion leading to the dysfunction of many organs. Consequently, an episode of AHF constitutes a “multiple organ failure” which may also affect the skeletal muscles. However, the abnormalities within skeletal muscles during AHF have not been investigated so far. The aim of this project is to comprehensively evaluate skeletal muscles (at a functional and tissue level) during AHF.

Methods

The study will include ≥63 consecutive AHF patients who will be randomized into 2 groups: ≥42 with cardiac rehabilitation group versus ≥21 with standard pharmacotherapy alone. The following tests will be conducted on the first and last day of hospitalization, at rest and after exercise, and 30 days following the discharge: clinical evaluation, medical interview, routine physical examination, echocardiography, and laboratory tests (including the assessment of NT-proBNP, inflammatory markers, and parameters reflecting the status of the kidneys and the liver); hemodynamic evaluation, noninvasive determination of cardiac output and systemic vascular resistance using the impedance cardiography; evaluation of biomarkers reflecting myocyte damage, immunochemical measurements of tissue-specific enzymatic isoforms; evaluation of skeletal muscle function, using surface electromyography (sEMG) (maximum tonus of the muscles will be determined along with the level of muscular fatigability); evaluation of muscle tissue perfusion, assessed on the basis of the oxygenation level, with noninvasive direct continuous recording of perfusion in peripheral tissues by local tissue oximetry, measured by near-infrared spectroscopy (NIRS).

Results and Conclusions

Our findings will demonstrate that the muscle tissue is another area of the body which should be taken into consideration in the course of treatment of AHF, requiring a development of targeted therapeutic strategies, such as a properly conducted rehabilitation.

Evaluation of heart function with impedance cardiography in acute myocardial infarction patients

To evaluate the capability of impedance cardiography (ICG) in reflecting the cardiac functions of acute myocardial infarction (AMI) patients.

METHODS

99 inpatients with initial AMI were recruited. Venous blood was obtained for detection of N-terminal brain-type natriuretic peptide (NT-proBNP), B-Type natriuretic peptide (BNP) and c troponin-T (cTnT) followed by ICG. Thorax fluid capacity (TFC), pre-ejection period (PEP), left ventricular ejection fraction (LVEF), cardiac output (CO), stroke volume (SV), stroke index (SI), systemic vascular resistance (SVR), systemic vascular resistance index (SVRI), cardiac index (CI), end-diastolic volume (EDV) and systolic time ratio (STR) were measured. All these patients underwent ICG and echocardiography 2 days after surgery.

RESULTS

Our results indicated NT-proBNP and BNP were associated with SVR, SVRI, PEP and STR, independently (P < 0.05). cTnT was associated with SVR and SVRI (P < 0.05). And the outcomes showed correlation between ICG and echocardiography in SV, SI, EDV, LEVT, STR, LVEF (P < 0.01), CO and CI (P < 0.05). However, no correlation was noted in PEP. In addition, changes were also found in the blood pressure and heart rate 7 days after PCI.

CONCLUSION

May be ICG data could reflect the early cardiac functions of AMI patients, but the accuracy of ICG in evaluating cardiac functions should be combined with detection of blood NT-proBNP, BNP and cTnT and echocardiography.