PREVENtion of HeartMate II Pump Thrombosis Through Clinical Management (PREVENT)

Current status and future directions in the development and optimization of thoracic and abdominal artificial organs

INTRODUCTION

Artificial organs are engineered devices with the capacity to be implanted or integrated into a living body to replace a failing organ, or to duplicate or augment one or multiple functions of the diseased organ.

AREAS COVERED

We evaluate the present landscape and future possibilities of artificial organ engineering by exploring the spectrum of four distinguishable device features: mobility, compatibility, functionality, and material composition. These mechanical and functional differences provide the framework through which we examine the current status and future possibilities of the abdominal and thoracic artificial organs.

EXPERT OPINION

Transforming the artificial organs landscape in ways that expand the scope of existing device capabilities and improve the clinical utility of artificial organs will require making improvements upon existing technologies and multidisciplinary cooperation to create and discover new capacities.

Role of computed tomography angiography for HeartMate II left ventricular assist device thrombosis

INTRODUCTION

Device thrombosis is one of the most devastating complications of HeartMate II left ventricular assist devices. The purpose of this study is to assess the anatomical properties that the inflow and outflow computed tomography angiography provides in assessing for left ventricular assist device thrombosis, as well as their impact on clinical management and postoperative outcomes.

METHODS

Between April 2010 and December 2016, 22 patients who received a HeartMate II left ventricular assist device implantation were readmitted for suspected device thrombosis and underwent a computed tomography angiography for workup. Left ventricular assist device-associated anatomy was assessed, including outflow abnormality on computed tomography angiography (contrast filling defect), inflow abnormalities on computed tomography angiography (space at inflow, M-I angle), and inflow abnormalities on chest X-ray (inflow angulation, pump pocket depth).

RESULTS

Computed tomography angiography revealed an outflow filling defect in three patients (14%) resulting in change in surgical approach from subcostal pump exchange to resternotomy pump and outflow graft exchange. Inflow graft malpositioning was identified in four patients, with the inflow abutting the left ventricular wall and obstructing the cannula opening. On computed tomography angiography assessment, mean space at inflow was 5.3 ± 1.6 mL and M-I angle was 35.6° ± 6.6°. Chest X-ray evaluation revealed mean inflow angle and pump pocket depth of 75.7° ± 13.4° and 110.2 ± 26.6 mm, respectively.

CONCLUSION

Computed tomography angiography provides a noninvasive assessment of the outflow graft and inflow cannulas in left ventricular assist device patients. Findings on computed tomography angiography reveal possible mechanical etiologies of thrombosis and may be useful for determining the surgical management of device thrombosis patients.

Improved Approach With Subcostal Exchange of the HeartMate II Left Ventricular Assist Device: Difference in On and Off Pump?

BACKGROUND

The HeartMate II (St. Jude Medical, Inc, St. Paul, MN [previously Thoratec]) left ventricular assist device (LVAD) exchange has traditionally involved a redo sternotomy. Alternate minimally invasive subcostal approaches have the advantage of avoiding sternal reentry, excessive bleeding, and prolonged recovery.

METHODS

This retrospective review included patients who underwent an exchange from May 2009 to March 2016. The patients were divided into three cohorts: (1) redo sternotomy, (2) subcostal approach involving cardiopulmonary bypass (CPB) (ON-CPB SC), and (3) subcostal approach off the CPB pump (OFF-CPB SC). Data pertaining to patients' baseline characteristics and outcomes were collected and analyzed.

RESULTS

From May 1, 2009 to July 31, 2016, 33 HeartMate II LVAD exchanges were performed. There were 11 redo sternotomies and 22 subcostal exchanges, 12 of which were in the OFF-CPB SC group. There was no significant difference among the groups in terms of age (p = 0.75), sex (p = 0.95), and indication for exchange (p = 0.94). There was a higher red blood cell transfusion requirement within the sternotomy cohort (p < 0.001). The median time to extubation and the intensive care unit length of stay were significantly shorter in the OFF-CPB SC group (1 and 2.5 days, respectively) than in the sternotomy (2.5 and 21 day, respectively) and ON-CPB SC groups (1.5 and 5 days, respectively). The 30-day and 90-day survival rates were equivalent among the cohorts.

CONCLUSIONS

Exchange of the HeartMate II LVAD can be accomplished with significantly improved recovery time and transfusion requirement through a less invasive subcostal approach when compared with sternotomy. The subcostal approach can be performed safely both on and off cardiopulmonary bypass.