Changes in Spirometry After Left Ventricular Assist Device Implantation

Pulmonary Capillary Recruitment Is Attenuated Post Left Ventricular Assist Device Implantation

There is limited knowledge of pulmonary physiology and pulmonary function after continuous flow-left ventricular assist device (CF-LVAD) implantation. Therefore, this study investigated whether CF-LVAD influenced pulmonary circulation by assessing pulmonary capillary blood volume and alveolar-capillary conductance in addition to pulmonary function in patients with heart failure. Seventeen patients with severe heart failure who were scheduled for CF-LVAD implantation (HeartMate II, III, Abbott, Abbott Park, IL or Heart Ware, Medtronic, Minneapolis, MN) participated in the study. They underwent pulmonary function testing (measures of lung volumes and flow rates) and unique measures of pulmonary physiology using a rebreathe technique that quantified the diffusing capacity of the lungs for carbon monoxide (DLCO) and diffusing capacity of the lungs for nitric oxide before and 3 months after CF-LVAD implantation. After CF-LVAD, pulmonary function was not significantly changed (p >0.05). For lung diffusing capacity, alveolar volume (VA) was not changed (p = 0.47), but DLCO was significantly reduced (p = 0.04). After correcting for VA, DLCO/VA showed a trend toward reduction (p = 0.08). For the alveolar-capillary component, capillary blood volume (Vc) was significantly reduced (p = 0.04), and alveolar-capillary membrane conductance trended toward a reduction (p = 0.06). However, alveolar-capillary membrane conductance/Vc was not altered (p = 0.92). In conclusion, soon after CF-LVAD implantation, Vc is reduced likely because of pulmonary capillary derecruitment, which contributes to the decrease in lung diffusing capacity.

How to select a patient for LVAD

Left ventricular assist device (LVAD) implantation leads to improvement in symptoms and survival in patients with advanced heart failure. An important factor in improving outcomes post-LVAD implantation is optimal preoperative patient selection and optimization. In this review, we highlight the latest on the evaluation of patients with advanced heart failure for LVAD candidacy, including discussion of patient selection, implantation timing, laboratory and other testing considerations, and the importance of psychosocial evaluation. Such thorough evaluation by multidisciplinary team can serve to improve the outcomes of a complex group of patients with advanced heart failure being evaluated for LVAD.

Hyoid Bone Syndrome in a Patient Undergoing Left Ventricular Assist Device Implantation

The clinical case describes the presence of hyoid bone syndrome (HBS) in a patient with a left ventricular assist device (LVAD) implantation, and the resolution of painful symptoms through an osteopathic manual technique (unwinding) applied to the tongue. To the knowledge of the authors, it is the first case report involving an LVAD patient with HBS treated with an osteopathic approach. The article briefly reviews the data relating to surgical therapy for patients with a clinical history of end-stage heart failure and symptoms related to HBS and posits some hypotheses on the presence of pain radiating from the hyoid bone to other areas of the body. The text reminds us to place greater clinical emphasis on the palpatory evaluation of the hyoid in the presence of non-specific painful symptoms.

Effects of left ventricular assist device on pulmonary functions and pulmonary hemodynamics: A meta-analysis

BACKGROUND

Given current evidence, the effect of left ventricular assist device (LVAD) implantation on pulmonary function tests remains controversial.

AIM

To better understand the factors contributing to the changes seen on pulmonary function testing and the correlation with pulmonary hemodynamics after LVAD implantation.

METHODS

Electronic databases were queried to identify relevant articles. The summary effect size was estimated as a difference of overall means and standard deviation on a random-effects model.

RESULTS

A total of four studies comprising 219 patients were included. The overall mean forced expiratory volume in one second (FEV1), forced vital capacity (FVC) and diffusion lung capacity of carbon monoxide (DLCO) after LVAD implantation were significantly lower by 0.23 L (95%CI: 0.11-0.34, P = 00002), 0.18 L (95%CI: 0.03-0.34, P = 0.02), and 3.16 mmol/min (95%CI: 2.17-4.14, P < 0.00001), respectively. The net post-LVAD mean value of the cardiac index was significantly higher by 0.49 L/min/m² (95%CI: 0.31-0.66, P < 0.00001) compared to pre-LVAD value. The pulmonary capillary wedge pressure and pulmonary vascular resistance were significantly reduced after LVAD implantation by 8.56 mmHg (95%CI: 3.78-13.35, P = 0.0004), and 0.83 Woods U (95%CI: 0.11-1.55, P = 0.02), respectively. There was no significant difference observed in the right atrial pressure after LVAD implantation (0.61 mmHg, 95%CI: -2.00 to 3.32, P = 0.65). Overall findings appear to be driven by studies using HeartMateII devices.

CONCLUSION

LVAD implantation might be associated with a significant reduction of the spirometric measures, including FEV1, FVC, and DLCO, and an overall improvement of pulmonary hemodynamics.

Association between the low percentage of forced vital capacity and increased mortality after left ventricular assist device implantation

Background

This study aims to investigate the effect of low percentage of forced vital capacity measured in the preoperative period on the 28-day mortality in patients undergoing left ventricular assist device implantation.

Methods

A total of 131 patients (111 males, 20 females; median age 54 years; range, 47 to 59 years) who underwent left ventricular assist device implantation with HeartWare™ between December 2010 and January 2016 were retrospectively analyzed. The patients were divided into two groups according to the results of pulmonary function test as a forced vital capacity percentage of ≥60% (n=113) and <60% (n=18). Both groups were compared in terms of laboratory and clinical characteristics, and postoperative complications. Risk factors for postoperative 28-day mortality were analyzed.

Results

Pre- and intraoperative characteristics were similar in both groups, except for left ventricular end-diastolic diameter. The ventilator-free days up to 28 days was shorter (p=0.046) and the length of intensive care unit stay was longer (p=0.011) in the low percentage of forced vital capacity group. The 28-day mortality rate was also higher (22.2% vs. 9.7%, respectively; p=0.12) in this group. The history of prior cardiac operation (odds ratio: 4.40; 95% confidence interval 1.19-16.20, p=0.026) and tricuspid valve repair at the time of device implantation (odds ratio: 5.30; 95% confidence interval 1.33-21.00, p=0.018) were found to be independent risk factors for mortality. Multivariate analysis showed that a forced vital capacity of <60% was not associated with mortality (odds ratio: 3.96; 95% confidence interval 0.95-16.43, p=0.058).

Conclusion

The length of intensive care unit stay and duration of mechanical ventilation may be longer in patients with a low percentage of forced vital capacity. Although the association between 28-day mortality and low percentage of forced vital capacity is not significant, the risk of 28-day mortality is higher in this group. Therefore, the patients should be assessed carefully before the left ventricular assist device operation.

Limiting factors of peak and submaximal exercise capacity in LVAD patients

AIMS

Although patients supported with a Continuous-Flow Left Ventricular Assist Device (CF-LVAD) are hemodynamically stable, their exercise capacity is limited. Hence, the aim of this work was to investigate the underlying factors that lead to peak and submaximal exercise intolerance of CF-LVAD supported patients.

METHODS

Seven months after CF-LVAD implantation, eighty three patients performed a maximal cardiopulmonary exercise test and a six minute walk test. Peak oxygen uptake and the distance walked were measured and expressed as a percentage of the predicted value (%VO2p and %6MWD, respectively). Preoperative conditions, echocardiography, laboratory results and pharmacological therapy data were collected and a correlation analysis against %VO2p and %6MWD was performed.

RESULTS

CF-LVAD patients showed a relatively higher submaximal exercise capacity (%6MWD = 64±16%) compared to their peak exertion (%VO2p = 51±14%). The variables that correlated with %VO2p were CF-LVAD parameters, chronotropic response, opening of the aortic valve at rest, tricuspid insufficiency, NT-proBNP and the presence of a cardiac implantable electronic device. On the other hand, the variables that correlated with %6MWD were diabetes, creatinine, urea, ventilation efficiency and CF-LVAD pulsatility index. Additionally, both %6MWD and %VO2p were influenced by the CF-LVAD implantation timing, calculated from the occurrence of the cardiac disease.

CONCLUSION

Overall, both %6MWD and %VO2p depend on the duration of heart failure prior to CF-LVAD implantation. %6MWD is primarily determined by parameters underlying the patient's general condition, while %VO2p mostly relies on the residual function and chronotropic response of the heart. Moreover, since %VO2p was relatively lower compared to %6MWD, we might infer that CF-LVAD can support submaximal exercise but is not sufficient during peak exertion. Hence concluding that the contribution of the ventricle is crucial in sustaining hemodynamics at peak exercise.

Non-invasive assessment of arterial pulsatility in patients with continuous-flow left ventricular assist devices

INTRODUCTION

Long-term use of continuous-flow left ventricular assist devices may have negative consequences for autonomic, cardiovascular and gastrointestinal function. It has thus been suggested that non-invasive monitoring of arterial pulsatility in patients with a left ventricular assist device is highly important for ensuring patient safety and longevity. We have developed a novel, semi-automated frequency-domain-based index of arterial pulsatility that is obtained during suprasystolic occlusions of the upper arm: the 'cuff pulsatility index'.

PURPOSE

The purpose of this study was to evaluate the relationship between the cuff pulsatility index and invasively determined arterial pulsatility in patients with a left ventricular assist device.

METHODS

Twenty-three patients with a left ventricular assist device with end-stage heart failure (six females: age = 65 ± 9 years; body mass index = 30.5 ± 3.7 kg m^-2) were recruited for this study. Suprasystolic occlusions were performed on the upper arm of the patient's dominant side, from which the cuff pressure waveform was obtained. Arterial blood pressure was obtained from the radial artery on the contralateral arm. Measurements were obtained in triplicate. The relationship between the cuff pressure and arterial blood pressure waveforms was assessed in the frequency-domain using coherence analysis. A mixed-effects approach was used to assess the relationship between cuff pulsatility index and invasively determined arterial pulsatility (i.e. pulse pressure).

RESULTS

The cuff pressure and arterial blood pressure waveforms demonstrated a high coherence up to the fifth harmonic of the cardiac frequency (heart rate). The cuff pulsatility index accurately tracked changes in arterial pulse pressure within a given patient across repeated measurements.

CONCLUSIONS

The cuff pulsatility index shows promise as a non-invasive index for monitoring residual arterial pulsatility in patients with a left ventricular assist device across time.

Pulmonary function assessment post-left ventricular assist device implantation

Aim

The lungs—and particularly the alveolar‐capillary membrane—may be sensitive to continuous flow (CF) and pulmonary pressure alterations in heart failure (HF). We aimed to investigate long‐term effects of CF pumps on respiratory function.

Methods and results

We conducted a retrospective study of patients with end‐stage HF at our institution. We analysed pulmonary function tests [e.g. forced vital capacity (FVC) and forced expiratory volume in 1 s (FEV₁)] and diffusing capacity of the lung for carbon monoxide (D_LCO) from before and after left ventricular assist device (LVAD) implantation and compared them with invasive haemodynamic studies. Of the 274 patients screened, final study analysis involved 44 patients with end‐stage HF who had CF LVAD implantation between 1 February 2007 and 31 December 2015 at our institution. These patients [mean (standard deviation, SD) age, 50 (9) years; male sex, n = 33, 75%] received either the HeartMate II (Thoratec Corp.) pump (77%) or the HeartWare (HeartWare International Inc.) pump. The mean (SD) left ventricular ejection fraction was 21% (13%). At a median of 237 days post‐LVAD implantation, we observed significant D_LCO decrease (−23%) since pre‐implantation (P < 0.001). ΔD_LCO had an inverse relationship with changes in pulmonary capillary wedge pressure (PCWP) and right atrial pressure (RAP) from pre‐LVAD to post‐LVAD implantation: ΔD_LCO to ΔPCWP (r = 0.50, P < 0.01) and ΔD_LCO to ΔRAP (r = 0.39, P < 0.05). We observed other reductions in FEV₁, FVC, and FEV₁/FVC between pre‐LVAD and post‐LVAD implantation. In mean (SD) values, FEV₁ changed from 2.3 (0.7) to 2.1 (0.7) (P = 0.005); FVC decreased from 3.2 (0.8) to 2.9 (0.9) (P = 0.01); and FEV₁/FVC went from 0.72 (0.1) to 0.72 (0.1) (P = 0.50). Landmark survival analysis revealed that ΔD_LCO from 6 months after LVAD implantation was predictive of death for HF patients [hazard ratio (95% confidence interval), 0.60 (0.28–0.98); P = 0.03].

Conclusions

Pulmonary function did not improve after LVAD implantation. The degree of D_LCO deterioration is related to haemodynamic status post‐LVAD implantation. The ΔD_LCO within 6 months post‐operative was associated with survival.

Artificial Organs 2015: A Year in Review

In this Editor's Review, articles published in 2015 are organized by category and briefly summarized. We aim to provide a brief reflection of the currently available worldwide knowledge that is intended to advance and better human life while providing insight for continued application of technologies and methods of organ Replacement, Recovery, and Regeneration. As the official journal of The International Federation for Artificial Organs, The International Faculty for Artificial Organs, the International Society for Rotary Blood Pumps, the International Society for Pediatric Mechanical Cardiopulmonary Support, and the Vienna International Workshop on Functional Electrical Stimulation, Artificial Organs continues in the original mission of its founders "to foster communications in the field of artificial organs on an international level." Artificial Organs continues to publish developments and clinical applications of artificial organ technologies in this broad and expanding field of organ Replacement, Recovery, and Regeneration from all over the world. We take this time also to express our gratitude to our authors for providing their work to this journal. We offer our very special thanks to our reviewers who give so generously of their time and expertise to review, critique, and especially provide meaningful suggestions to the author's work whether eventually accepted or rejected. Without these excellent and dedicated reviewers, the quality expected from such a journal could not be possible. We also express our special thanks to our Publisher, John Wiley & Sons for their expert attention and support in the production and marketing of Artificial Organs. We look forward to reporting further advances in the coming years.

Reversible decline in pulmonary function during left ventricular assist device therapy

Cardiac replacement therapy, consisting of left ventricular assist device (LVAD) implant surgery and heart transplantation, has considerably reduced the mortality and morbidity of patients with stage D heart failure. However, its impact on pulmonary function remains unclear. We retrospectively evaluated 22 consecutive patients (16 men; 42 ± 13 years old) who had undergone pulmonary function tests during the heart failure, LVAD, and heart transplantation periods. The LVAD therapy lasted an average of 871 ± 267 days. The % vital capacity and forced expiratory volume in 1 s decreased significantly after LVAD implantation and returned to baseline levels after heart transplantation. Correlation analysis indicated that a shorter duration of LVAD support was associated with a more significant improvement in % vital capacity in heart transplantation recipients, compared to the pre-LVAD period and the LVAD period. In conclusion, we provide evidence that a decrease in pulmonary function occurs during LVAD support but it may be reversible. Limited LVAD duration may be a key for the recovery of pulmonary dysfunction.