Effects of failure of the right side of the heart and increased pulmonary resistance on mechanical circulatory support with use of the miniaturized HIA-VAD displacement pump system

Development and Initial in Vivo Testing of a New Hydraulic Drive System (Paedipump) for Circulatory Support in Infants

The main limitation in the use of circulatory support in children is the lack of an adequate system with regard to size and pumping capacity Recently, two pneumatically driven ventricular support systems with low volume chambers for use in a pediatric population became available. We have developed a hydraulic drive system with an advantageous exact control of the stroke volume. The system enables two different modes of operation: the full-empty and the filled-empty modes. In both cases the ventricle is empty at the end of systole.

This new system was tested in experimental animals (6 pigs, body weight 9.5–14.0 kg) with normal and reduced left ventricular function (MAP<45 mmHg). A 25 ml ventricle (HIA-Medos) was implanted. The full-empty and the filled-empty mode used led to a significant load reduction, both in animals with normal and impaired cardiac function. Plasma lactate levels, pH-values and total body 0 2 consumption were in the normal range during circulatory support indicating adequate organ perfusion.

Results showed that sufficient ventricular support was achieved during all pumping modes due to the possibility of controlling and modifying the stroke volume of the hydraulically driven support system employed according to necessity. This is a promising feature for its future application in infants with congenital or acquired heart diseases.

[Noncardiological surgical procedure for patients implanted with a ventricular assist device. Anesthesiological management concepts]

BACKGROUND

The implantation of a ventricular assist device (VAD) is more frequently used as destination therapy of end-stage heart failure compared to the use of the device as bridge-to-transplantation, this results in an increasing number of noncardiac surgical procedures for patients implanted with a VAD.

OBJECTIVE

For these procedures, the anesthesia provider faces various device-related complications, such as an increased risk for bleeding complications, thromboembolism, hypotension, infections, mechanical device limitations, and right heart failure. Anesthesia care is challenging in this high-risk patient population and has significant implications on patient outcome.

CONCLUSION

More research is needed to determine specific guidelines for the anesthesiological management of VAD patients undergoing noncardiac surgical procedures. In this manuscript, device-related perioperative complications and concepts of anesthesia care for noncardiac procedures in patients implanted with a VAD are briefly reviewed.

Recurrent orthostatic syncope due to left atrial and left ventricular collapse after a continuous-flow left ventricular assist device implantation

Left ventricular assist devices (LVADs) have become an established treatment for patients with advanced heart failure as a bridge to transplantation or for permanent support as an alternative to heart transplantation. Continuous-flow LVADs have been shown to improve outcomes, including survival, and reduce device failure compared with pulsatile devices. Although LVADs have been shown to be a good option for patients with end-stage heart failure, unanticipated complications may occur. We describe dynamic left atrial and left ventricular chamber collapse related to postural changes in a patient with a recent continuous-flow LVAD implantation.

The ABCs of left ventricular assist device echocardiography: a systematic approach

Echocardiography is an important imaging modality used to determine the indication of left ventricular assist device (LVAD) implantation for patients with advanced heart failure (HF) and for serial follow-up to make management decisions in patient care post-implant. Continuous axial-flow LVAD therapy provides effective haemodynamic support for the failing left ventricle, improving both the clinical functional status and quality of life. Echocardiographers must develop a systematic approach to echocardiographic assessment of LVAD implantation and post-LVAD implant cardiac morphology and physiology. This approach must include the evaluation of left and right heart chamber morphology and physiology and the anatomy and physiology of the inflow and outflow cannulas and the rotor pump, and the determination of the degree of tricuspid regurgitation and the presence of interatrial shunts and aortic regurgitation. Collaboration among the echocardiography and HF/transplant teams is essential to obtain this comprehensive evaluation. We outline a systematic approach to evaluating patients with HF who have failed conventional therapy and require LVAD therapy as a bridge to cardiac transplantation or destination therapy.

Preimplant transthoracic echocardiographic assessment of continuous flow left ventricular assist device

For many patients with end-stage heart failure, heart transplantation is the only remaining option to prolong survival and provide symptom relief. Transthoracic echo is the modality of choice in assessing a patient for potential left ventricular assist device (LVAD) insertion. There are currently no guidelines available, and assessing this specific patient population can prove extremely challenging. As such, an understanding of LVAD mechanism, the important physiological consequences of device implantation together with the related echocardiographic examination is vital to accurately and effectively gauge correct patient selection and also improve implantation success. This review aims to highlight the common devices implanted, how these devices affect cardiac physiology and hemodynamics, and therefore discuss the major echocardiographic variables that should be assessed predevice implantation. (Echocardiography 2012;29:52-58).

Prolonged biventricular assist device support as a bridge to heart transplantation

We report a case in which long-term biventricular assist device (BiVAD) support enabled successful heart transplantation. The patient was diagnosed with dilated cardiomyopathy at age 11. She underwent implantation of a Toyobo LVAD, tricuspid valvuloplasty and annuloplasty at age 15. Right heart bypass (RHB) was established using a centrifugal pump. Right ventricular function showed no improvement during a ten-day period, and RHB was switched to a Toyobo RVAD on postoperative day (POD) 11. Because of poor oxygenation, veno-venous extracorporeal membrane oxygenation (V-V ECMO) was instituted. She was weaned from V-V ECMO on POD 14. She was brought to the United States on POD 189 under BiVAD support, and underwent heart transplantation on POD 199. She was discharged 4 months later. Two years after heart transplantation, she remained in New York Heart Association class one without rejection.

Focused review on transthoracic echocardiographic assessment of patients with continuous axial left ventricular assist devices

Left ventricular assist devices (LVADs) are systems for mechanical support for patients with end-stage heart failure. Preoperative, postoperative and comprehensive followup with transthoracic echocardiography has a major role in LVAD patient management. In this paper, we will present briefly the hemodynamics of axial-flow LVAD, the rationale, and available data for a complete and organized echocardiographic assessment in these patients including preoperative assessment, postoperative and long-term evaluation.

Differential response of the right and left ventricle to beta-adrenergic stimulation: an echo planar MR study in intact animals

PURPOSE

The purpose of this study was to compare the response in contractility of the right (RV) and left (LV) ventricle of the heart to beta-adrenergic stimulation using an echo planar MR technique.

METHOD

In six sheep, RV and LV pressure-volume (P-V) relationships were constructed simultaneously using intraventricular pressures and volumes measured with echo planar MRI at rest and during dobutamine stress. Contractility changes were quantified by assessment of the end-systolic P-V relationship (ESPVR) and the preload recruitable stroke work (PRSW).

RESULTS

Both the ESPVR the the PRSW showed a significant increase in contractility for both ventricles after dobutamine administration. The increase in contractility was significantly larger for the LV than for the RV, both measured wit the ESPVR (p < 0.0003) and the PRSW (p < 0.007).

CONCLUSION

This study shows the usefulness of echo planar MRI to assess myocardial contractility of both ventricles simultaneously. Furthermore, the study shows that beta-adrenergic stimulation has a significantly greater positive inotropic effect on LV contractility than on RV contractility.