Detection of left ventricular systolic dysfunction using a newly developed, laptop based, impedance cardiographic index

Noninvasive Hemodynamic Evaluation Following TAVI for Severe Aortic Stenosis

Background Various hemodynamic changes occur following transcatheter aortic valve implantation (TAVI) that may impact therapeutic decisions. NICaS is a noninvasive bioimpedance monitoring system aimed at hemodynamic assessment. We used the NICaS system in patients with severe aortic stenosis (AS) to evaluate short-term hemodynamic changes after TAVI. Methods and Results We performed hemodynamic analysis using NICaS on 97 patients with severe AS who underwent TAVI using either self-expandable (68%) or balloon-expandable (32%) valves. Patients were more often women (54%) and had multiple comorbidities including hypertension (83%), coronary artery disease (46%), and diabetes (37%). NICaS was performed at several time points-before TAVI, soon after TAVI, at hospital discharge, and during follow-up. Compared with baseline NICaS measurements, we observed a significant increase in systolic blood pressure and total peripheral resistance (systolic blood pressure 132±21 mm Hg at baseline versus 147±23 mm Hg after TAVI, P<0.001; total peripheral resistance 1751±512 versus 2084±762 dynes*s/cm⁵, respectively, P<0.001) concurrent with a decrease in cardiac output and stroke volume (cardiac output 4.2±1.5 versus 3.9±1.3 L/min, P=0.037; stroke volume 61.4±14.8 versus 56.2±15.9 mL, P=0.001) in the immediate post-TAVI period. At follow-up (median 59 days [interquartile range, 40.5-91]) these measurements returned to values that were not different from the baseline. A significant improvement in echocardiography-based left ventricular ejection fraction was observed from baseline to follow-up (55.6%±11.6% to 59.4%±9.4%, P<0.001). Conclusions Unique short-term adaptive hemodynamic changes were observed using NICaS in patients with AS soon after TAVI. Noninvasive hemodynamic evaluation immediately following TAVI may contribute to the understanding of complex hemodynamic changes and merits favorable consideration.

In Search of Clinical Impact: Advanced Monitoring Technologies in Daily Heart Failure Care

Despite significant advances in the management of heart failure (HF), further improvement in the outcome of this chronic and progressive disease is still considered a major unmet need. Recurrent hospitalizations due to decompensated HF frequently occur, resulting in increased morbidity and mortality rates. Past attempts at early detection of clinical deterioration were mainly based on monitoring of signs and symptoms of HF exacerbation, which have mostly given disappointing results. Extensive research of the pathophysiology of HF decompensation has indicated that hemodynamic alterations start days prior to clinical manifestation. Novel technologies aim to monitor these minute hemodynamic changes, allowing time for therapeutic interventions to prevent hemodynamic derangement and HF exacerbation. The latest noticeable advancements include assessment of lung fluid volume, wearable devices with integrated sensors, and microelectromechanical systems-based implantable devices for continuous measurement of cardiac filling pressures. This manuscript will review the rationale for monitoring HF patients and discuss previous and ongoing attempts to develop clinically meaningful monitoring devices to improve daily HF health care, with particular emphasis on the recent advances and clinical trials relevant to this evolving field.

A Noninvasive Stroke Volume Monitoring for Early Detection of Minimal Blood Loss: A Pilot Study

INTRODUCTION

Alternation in traditional vital signs can only be observed during advanced stages of hypovolemia and shortly before the hemodynamic collapse. However, even minimal blood loss induces a decrease in the cardiac preload which translates to a decrease in stroke volume, but these indices are not readily monitored. We aimed to determine whether minor hemodynamic alternations induced by controlled and standardized hypovolemia can be detected by a whole-body bio-impedance technology.

METHODS

This was a non-randomized controlled trial that enrolled healthy blood donors. Vital signs, as well as shock index and stroke volume (SV), were recorded using noninvasive cardiac system, a noninvasive whole-body impedance-based hemodynamic analysis system, during phlebotomy.

RESULTS

Sixty subjects were included in the study group and 20 in the control group. Blood loss of 450 mL resulted in a significant decrease in systolic blood pressure (5 mm Hg; 95% CI 3, 6) and SV (5.07 mL; 95% CI 3.21, 6.92), and increase in shock index (0.03 bpm/mm Hg; 95% CI 0.01, 0.05). Clinically detectable changes (≥10%) in blood pressure and shock index were detectable in 15% and 5%, respectively. SV decreased by more than 10% in 40% of blood donors. No significant changes occurred in the control group.

CONCLUSION

Continuous noninvasive monitoring of SV may be superior to conventional indices (e.g., heart rate, blood pressure, or shock index) for early identification of acute blood loss. As an operator-independent and point-of-care technology, the SV whole body bio-impedance measurement may assist in accurate monitoring of potentially bleeding patients and early identification of hemorrhage.

Non-Invasive Hemodynamic Whole-Body Bioimpedance Indices for the Early Detection of Cancer Treatment-Related Cardiotoxicity: A Retrospective Observational Study

<b><i>Introduction:</i></b> Patients undergoing chemotherapy are extremely vulnerable to cardiotoxicity. Early detection of cardiac dysfunction is of vital importance to optimize the management of these patients. <b><i>Objective:</i></b> The aim of this study was to test the effectiveness of non-invasive hemodynamic whole-body bioimpedance (WBI) technology as a modality to detect heart failure in patients undergoing chemotherapy treatment. <b><i>Methods:</i></b> This retrospective observational trial included 84 patients treated at the cardio-oncology outpatient clinic of the Rabin Medical Center. Clinical assessments were performed including biomarker testing and measurement of hemodynamic and volume status parameters as measured by WBI. <b><i>Results:</i></b> We included 84 patients with a median age of 64.8 years, and 40.5% were males. Clinical heart failure was detected in 43% of the whole group. Patients were divided into two groups according to baseline NT-proBNP levels with a cut-off of 900 pg/mL. Left ventricular ejection fraction did not differ between the groups. Those with NT-proBNP &#x3e;900 pg/mL had lower levels of stroke index, cardiac index, and Granov-Goor index (GGI; 25.9 vs. 34.0, 2.0 vs. 2.3, 8.3 vs. 11.4, respectively, with <i>p</i> &#x3c; 0.001 for all comparisons). The optimal cut-off value for the GGI to detect NT-proBNP &#x3e;900 pg/mL was 8.3. The area under the curve of a GGI cut-off &#x3c;8.3 to detect NT-proBNP &#x3e;900 pg/mL was 0.81 (positive predictive value 95% and negative predictive value 72%), with a 51% sensitivity and 98% specificity. <b><i>Conclusion:</i></b> GGI, a parameter measured by WBI, can reliably correlate to biomarker evidence of heart failure in patients after chemotherapy. Its use as a screening tool for cardiotoxicity in patients with ongoing anticancer therapy is promising.

Correlation between the left atrial low-voltage area and the cardiac function improvement after catheter ablation for paroxysmal atrial fibrillation

BACKGROUND

The impact of the left atrial low-voltage area (LVA) on the cardiac function improvement following ablation for atrial fibrillation (AF) is unclear.

METHODS

In 49 patients with paroxysmal AF who underwent ablation, the left ventricular stroke volume index (SVI) was repeatedly measured using an impedance cardiography until 6 months after ablation. We defined the cardiac function improvement as a 20% increase in the SVI. The LVA (the area with the voltage amplitude of <0.5 mV) was assessed before ablation.

RESULTS

The reduced baseline SVI (<33 mL/m2) was observed in 18 (37%) patients. The SVI increased following ablation (from 36 ± 5 to 39 ± 6 mL/m2, P < .001). We observed the cardiac function improvement in 14 (29%) patients. The LVA was smaller in patients with the improved cardiac function than in those without (8.3% ± 5.2% vs 14.0% ± 8.5%, P = .026). The multivariate analysis revealed that only the LVA was independently associated with the cardiac function improvement (odds ratio, 0.878; 95% confidence interval: 0.778-0.991, P = .036). Furthermore, LVAs of the anterior (7.9% ± 7.6% vs 18.2% ± 15.5%, P = .022), septal (12.0 ± 7.3% vs 20.7% ± 13.8%, P = .031), and roof walls (6.9% ± 6.0% vs 16.9% ± 15.2%, P = .022) were smaller in patients with the improved cardiac function than in those without.

CONCLUSIONS

The LVA was related to the cardiac function improvement following ablation in patients with paroxysmal AF.

Improvement of Hemodynamic Parameters in Patients With Preserved Left Ventricular Systolic Function by Catheter Ablation of Atrial Fibrillation - A Prospective Study Using Impedance Cardiography

BACKGROUND

The effects of catheter ablation for atrial fibrillation (AF) on hemodynamic parameters in patients with preserved left ventricular (LV) systolic function are unclear. Methods and Results: We enrolled 178 patients with AF (paroxysmal, 108; persistent, 70) with preserved LV systolic function who underwent AF ablation. The stroke volume index (SVI) was repeatedly measured using impedance cardiography. Reduced SVI (SVI, <33 mL/m²) was observed in 55% of patients before ablation. In patients with paroxysmal AF, the SVI did not change immediately after ablation (from 35±6 mL/m²to 35±5 mL/m²; P=0.652); however, it increased 1 month after ablation and further increased 6 months after ablation (1 month, 37±6 mL/m², P<0.001; 6 months, 38±6 mL/m², P<0.001). In patients with persistent AF, the SVI increased immediately after ablation (from 30±5 mL/m²to 36±6 mL/m²; P<0.001) and further increased until 6 months after ablation (1 month, 37±6 mL, P<0.001; 6 months, 38±5 mL/m², P<0.001). The baseline SVI was the strongest predictor of the cardiac function improvement with an area under the curve of 0.828.

CONCLUSIONS

The restoration and maintenance of sinus rhythm using catheter ablation increased the SVI in patients with preserved LV systolic function.