Systolic time ratio measured by impedance cardiography accurately screens left ventricular diastolic dysfunction in patients with arterial hypertension

Examining the haemodynamic repercussions of ventilator hyperinflation in elderly patients: An explanatory study

This study assessed the cardiovascular repercussions of two VHI (ventilation hyperinflation) protocols using the volume-controlled mode, one with an inspiratory pause (VHI-P) and the other without an inspiratory pause (VHI-NP), in mechanically ventilated elderly patients. The patients underwent both VHI protocols in a randomized order, and impedance cardiography was used to record cardiovascular variables. During VHI-P, the diastolic blood pressure was lower than during VHI-NP (Δ = 10%; p = 0.009). VHI-NP and VHI-P demonstrated a decrease in cardiac output (CO) during the first and third sets compared to baseline (p < 0.05; ES=0.23 and 0.29, respectively). Arterial oxygen delivery decreased simultaneously with CO compared to baseline values (p < 0.05; ES=0.22 and 0.23, respectively). Five minutes after the intervention, the systolic time ratio values were lower for VHI-P than VHI-NP (Δ = 10%; p = 0.01). Left ventricular ejection time values were consistently lower in VHI-NP compared to VHI-P (Δ = 2%; p = 0.02). In conclusion, our study shows that VHI in volume-controlled mode induces hemodynamic changes in mechanically ventilated elderly patients, albeit with a small effect size and within the normal range.

Improvement of hemodynamic parameters in aortic stenosis patients with transcatheter valve replacement by using impedance cardiography

Background

The hemodynamic changes of patients with aortic stenosis (AS) who underwent transcatheter valve replacement (TAVR) have not been completely investigated.

Methods and results

We enrolled 74 patients with AS who underwent TAVR and assessed cardiac function changes at 1 week post-operation by impedance cardiography (ICG) in a supine position at rest for more than 15 min. Of the 74 patients, 47 had preserved left ventricular ejection fraction (LVEF ≥ 50%; preserved-LVEF group) and 27 had reduced LVEF (LVEF <50%; reduced-LVEF group). TAVR improved the cardiac structure and function, as evidenced by the decrease in the left ventricular end-diastolic (LVED), left atrial diameter (LAD), and an increase in the LVEF. We observed a decrease in N-terminal pro-brain natriuretic peptide (NT-proBNP) level compared to that before treatment. Moreover, patients with reduced LVEF had a more significant reduction of NT-proBNP than those with preserved LVEF. Meanwhile, the blood pressure of patients had no significant differences pre- and post-operation. Based on ICG, there were no changes in the parameter of cardiac preload [thoracic fluid content (TFC)]. We observed an improvement in parameters of diastolic cardiac function [left ventricular ejection time (LVET) and pre-ejection period (PEP)]. And we detected converse results in parameters of heart systolic function [systolic time ratio (STR), cardiac output (CO), cardiac index (CI), stroke index (SI), and stroke volume (SV)] and cardiac afterload [stroke systemic vascular resistance (SSVR) and SSVR-index (SSVRI)]. In addition, TFC level was decreased in patients with thoracic volume overload after valve replacement. Subgroup analysis showed that the changes in those parameters were more noticeable in patients with reduced LVEF than that with preserved LVEF. Moreover, we observed no effects on parameters of heart systolic function and heart afterload in the LVEF ≥ 50% group before and after TAVR.

Conclusion

Our data revealed a beneficial effect of TAVR in diastolic function and preload as detected by the ICG. But the LV systolic function and cardiac afterload were not improved in patients with LVEF <50%. The result indicated that ICG could be used as an important technique to monitor the cardiac condition of patients after aortic valve replacement.

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.

Modulation of left ventricular diastolic filling during exercise in persons with cervical motor incomplete spinal cord injury

PURPOSE

To characterize left ventricular diastolic function during an exertional challenge in adults with incomplete cervical spinal cord Injury (icSCI).

METHODS

In this cross-sectional study, a two-group convenience sample was used to compare left ventricular LV diastolic performance during a 5-10 W·min-1 incremental arm ergometer exercise protocol, using bioimpedance cardiography. Subjects were eight males with cervical incomplete spinal cord injury (icSCI; C5-C7: age 39 ± 14 years) versus eight able-bodied males (CON: age 38 ± 13 years). Left ventricular (LV) diastolic indices included end-diastolic volume (EDV) and early diastolic filling ratio (EDFR). LV ejection time (LVET), inotropic index (dZ/dT2) and stroke volume (SV) were compared between the groups at peak exercise, and maximum workload for the icSCI group (isomax).

RESULTS

EDV (at peak exercise:131.4 ± 7.3 vs 188.78 ± 9.4, p < 0.001; at isomax: 131.4 ± 7.3 vs 169 ± 23, p = 0.0009) and EDFR (at peak exercise 73 ± 14% vs 119 ± 11%, p = 0.006; at isomax 94 ± 10; p = 0.009) were significantly reduced in icSCI compared to CON, respectively. Significant differences in LVET (icSCI: 273 ± 48 vs CON: 305 ± 68; p = 0.1) and dZ/dT2 (icSCI: 0.64 ± 0.11 vs CON: 0.85 ± 0.31; p = 0.1) were not observed at isomax, despite a significant decrease in SV in the subjects with icSCI (77.1 ± 6.05 mL vs 105.8 ± 9.2 mL, p < 0.00) CONCLUSION: Left ventricular filling was impaired in the subjects with icSCI as evidenced at both peak exercise and isomax. It is likely that restrictions on the skeletal muscle pump mechanized the impairment but increased left ventricular wall stiffness could not be excluded as a mediator.

Effects of the SGLT2 inhibitor dapagliflozin on cardiac function evaluated by impedance cardiography in patients with type 2 diabetes. Secondary analysis of a randomized placebo-controlled trial

BACKGROUND AND AIMS

Cardiovascular outcome trials have documented a strong benefit of sodium glucose cotransporter-2 inhibitors (SGLT2i) on the risk of hospitalization for heart failure (HF) in patients with type 2 diabetes (T2D) with or without established cardiovascular disease or prior history of HF. The mechanisms, however, are not entirely clear. We aimed to evaluate whether treatment with SGLT2i affected cardiac function using impedance cardiography (ICG) in a randomized placebo-controlled trial.

MATERIALS AND METHODS

Thirty-three patients with T2D were randomized to receive blind dapagliflozin 10 mg or matching placebo for 12-week on top of their ongoing glucose lowering medication regimen. Cardiac function was evaluated by resting ICG at baseline and at the end of the 12-week treatment period. ICG is a non-invasive technology based on the continuous measurement of thoracic electrical conductivity to process a cardiodynamic parameters related to fluid content, blood flow, cardiac function, and circulatory function. We also evaluated changes in glycaemic control, blood pressure, and body weight.

RESULTS

Thirty-one patients completed the study, 1 was excluded because ICG data was missing. Patients included in the final analysis were on average 63.4-year-old, with a known diabetes duration of 14.1 years and a baseline HbA1c of 8.2% (66 mmol/mol). 63.3% of patients had established cardiovascular disease (symptomatic or asymptomatic) and 36.7% had microangiopathy, but none had a prior history of HF. After 12 weeks, patients randomized to dapagliflozin, as compared to those randomized to placebo, showed improvements in HbA1c (- 1.2%; 13 mmol/mol), systolic blood pressure (- 3.7 mmHg), and body weight (- 3.3 kg). Based on ICG, in both groups, we detected no significant change in parameters of blood flow (stroke volume, cardiac output, cardiac index), systolic function (ejection fraction, acceleration and velocity indexes, systolic time ratio), circulatory function (systemic vascular resistance index), and fluid status (thoracic fluid content) after treatment.

CONCLUSION

This is the first study exploring cardiac effects of SGLT2i using ICG in T2D. We observed no change in cardiac function parameters estimated by ICG in T2D patients who received dapagliflozin versus placebo for 12 weeks. Trial registration ClinicalTrial.gov NCT02327039. Registered 30 December 2014.