Correlation Between Impedance Cardiography and B-Type Natriuretic Peptide Levels in Dyspneic Patients

Complex assessment of patients with decompensated heart failure: The clinical value of impedance cardiography and N-terminal pro-brain natriuretic peptide

BACKGROUND

Acute decompensated heart failure (ADHF) is a serious clinical problem and a condition requiring immediate diagnostics, supporting the therapeutic decision adequate to the specific ADHF mechanism. N-terminal pro-brain natriuretic peptide (NT-proBNP) is an established biochemical marker of heart failure, strongly related to hemodynamic status. Impedance cardiography (ICG) provides non-invasive hemodynamic assessment that can be performed immediately at the bedside and revealed to be useful diagnostic tool in some clinical settings in cardiology.

OBJECTIVES

The aim of this study was to evaluate the usefulness of ICG in the admission diagnostics and monitoring the effects of treatment in patients hospitalized due to ADHF, with special emphasis on its relation to NT-proBNP.

METHODS

This study enrolled 102 patients, aged over 18 years, hospitalized due to ADHF. The subjects underwent detailed clinical assessment, including ICG and NT-proBNP at admission and at discharge day.

RESULTS

Among all analyzed ICG parameters thoracic fluid content (TFC), a marker of chest overload, was the most significantly correlated with NT-proBNP level (R = 0.46; p = 0.000001). In comparison with patients with low thoracic fluid content (TFC ≤ 35/kΩ), those with higher TFC values (>35/kΩ) exhibited a greater severity of symptoms (NYHA functional class); higher NT-proBNP levels; lower left ventricular ejection fraction (LVEF), stroke index (SI), and cardiac index (CI); as well as significantly higher systemic vascular resistance index (SVRI). These TFC-based subgroups showed no significant differences in terms of heart rate (HR), systolic blood pressure (SBP), or diastolic blood pressure (DBP).

CONCLUSIONS

The evaluation of hemodynamic parameters, especially TFC, seems to be a worthwhile addition to standard diagnostics, both at the stage of hospital admission and while monitoring the effects of treatment. Impedance cardiography is a useful method in evaluating individual hemodynamic profiles in patients with ADHF.

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.

[Usefulness of natriuretic peptide testing and Doppler echocardiography at bedside in the diagnosis of acute heart failure]

Acute heart failure is a common condition that leads to hospital admission, with important mortality and readmission rates. A prompt and accurate diagnosis of this condition by hospitalists is essential for an early and tailored medical management. The use of natriuretic peptide testing (BNP and NT-proBNP) through a two cut-point strategy is currently recommended as the first-line diagnostic complement to the initial clinical evaluation in the acute care setting. Transthoracic Doppler echocardiography is an other noninvasive method that can be used at bedside, especially in patients with intermediate, inconclusive natriuretic peptides levels. In this regard, left ventricular ejection fraction and several simple Doppler indexes (restrictive mitral filling pattern, spectral tissue Doppler E/e' ratio), have been validated in the emergency diagnosis of acute heart failure. The aim of the present review is to overview the respective contribution of natriuretic peptides and Doppler echocardiography at bedside to the diagnosis of acute heart failure in the acute care setting.

Applicability of Impedance Cardiography During Heart Failure Flare-Ups

BACKGROUND Heart failure (HF) accounts for about 5% of all causes of urgent hospital admissions, and the overall mortality of HF patients within 1 year after hospitalization is 17-45%. Transthoracic impedance cardiography (ICG) is a safe, non-invasive diagnostic technique that helps to detect various parameters that define different cardiac functions. The aim of this study was to investigate the value of ICG parameters in patients hospitalized due to HF flare-ups. MATERIAL AND METHODS The study included 60 patients (24 women and 36 men) who were admitted to intensive care units because of an acute episode of HF without signs of myocardial infarction. The diagnosis of HF as the main reason for hospitalization was verified according to the universally accepted techniques. ICG data were compared to those obtained via other HF diagnostic techniques. RESULTS A moderately strong relationship was found between the ejection fraction (EF) and the systolic time ratio (STR) r=-0.4 (p=0.002). Findings for STR and thoracic fluid content index (TFCI) differed after dividing the subjects into groups according to the EF (p<0.05). A moderately strong relationship was found between brain natriuretic peptide and TFCI r=0.425 (p=0.001), left cardiac work index (LCWI) r=-0.414 (p=0.001). Findings for TFCI, LCWI, and cardiac output differed after dividing the subjects into groups according to HF NYHA classes (p<0.05). CONCLUSIONS Transthoracic impedance cardiography parameters could be applied for the diagnostics and monitoring of HF, but further studies are required to evaluate the associations between ICG findings and HF.

Correlation between impedance cardiography and 6 min walk distance in atrial fibrillation patients

Background

The correlation between impedance cardiography (ICG) and 6 min walk distance (6MWD) in atrial fibrillation (AF) patients remains unknown.

Methods

We recruited 49 subjects in the study (21 AF patients and 28 patients without AF) and estimated hemodynamic parameters: cardiac output (CO), stroke volume (SV), stroke volume index (SVI), left stroke work (LSW), left stroke work index (LSWI), stroke systemic vascular resistance (SSVR), stroke systemic vascular resistance index (SSVRI); 6MWD, left ventricle ejection fraction (LVEF), NT-pro brain natriuretic peptide (NT-pro BNP) for the two groups.

Results

The AF group have apparently lower CO (2.26 ± 0.14 VS 4.11 ± 0.20 L/min, p = 0.039) and distinctly higher SVR (677.60 ± 69.10 VS 344.41 ± 22.98 dynes/cm⁵, p = 0.001), SSVRI (396.97 ± 36.80 VS 199.01 ± 11.72 dynes/cm⁵/m², p < 0.001) than the control group. NT-pro BNP (1409.48 ± 239.90 VS 332.59 ± 68.85 pg/ml, p = 0.001) in the AF group was significantly higher than the control group and 6MWD (264.33 ± 14.55 VS 428.79 ± 29.98 m, p < 0.001) in the AF group was lower than the control group. There was no significant difference in LVEF between the two groups (62.67 ± 7.62 % VS 63.93 ± 5.03 %, p = 0.470). Pearson correlation analysis revealed that CO (R = 0.494, p = 0.023), SV (R = 0.633, p = 0.002), LSW (R = 0.615, p = 0.003) and LSWI (R = 0.491, p = 0.024) significantly correlated positively with 6MWD in AF patients.

Conclusions

AF patients had lower cardiac output, shorter 6MWD and higher NT-pro BNP than patients with sinus rhythm. The cardiac output measured by impedance cardiography significantly correlated positively with 6MWD in AF patients.

Association of N-terminal pro-brain natriuretic peptide and hemodynamic parameters measured by impedance cardiography in patients with essential hypertension

The aim of this study was to evaluate the association of NT-proBNP with clinical and hemodynamic assessment in 156 patients with arterial hypertension. NT-proBNP correlated positively with, i.e. age (r=0.310, p=0.00008), mean blood pressure (MBP; r=0.199, p=0.0136), Heather index (HI; r=0.375, p<0.00001) and negatively with thoracic fluid content (TFC; r=-0.300, p=0.0002). The patients with higher NT-proBNP were older (46.1 versus 40.6 years, p=0.001), with higher MBP (102.6 versus 98.5 mm Hg, p=0.0043), HI (14.54 versus 11.93 Ohm s2, p=0.009) and lower TFC (27.5 versus 29.4 1/kOhm, p=0.0032). The independent predictors of higher NT-proBNP were: age, MBP and HI.