**Introduction/Hypothesis:**
Left-ventricular assist devices (LVAD) are often used as a bridge to heart transplantation. They can develop complications, however. One such complication is extrinsic occlusion of the outflow graft. Patients can present with non-specific symptoms include sequelae of heart and renal failure. The LVAD can log multiple low-flow alerts. A high index of suspicion should be maintained to look for outflow graft obstruction, as this can be a life-threatening adverse effect. As the LVAD is increasingly being used, it is essential for radiologists to understand their normal appearance, as well as complications.

**Methods**
LVADs are frequently used as a bridge to cardiac transplantation. They are prone to several complications, however, which can be life-threatening. Imaging is often the first step in diagnosing these complications. One such complication is outflow graft obstruction, which cardiac CT angiography plays a crucial role in diagnosing. CT angiography can demonstrate the presence of a thrombus in the lumen of the outflow graft. It is also important to assess for other imaging features associated with outflow graft obstruction, such as kinking and stenosis at the aortic anastomosis.

**Results**
Outflow graft obstruction is thought to be due to acellular debris accumulating in the outflow graft, at a specific area called the bend relief. Cardiac CT angiography is an essential tool in making the diagnosis, and is considered the gold-standard. On imaging, outflow graft obstruction can be demonstrated as thrombus, which can lead to narrowing of the cross-sectional area on CT. A filling defect may be seen on CT angiogram. Other imaging features include areas of external compression, kinking of the graft, and stenosis at the anastomosis with the aorta. Three-dimensional reconstruction can aid in the diagnosis.
Echocardiography may demonstrate elevated peak gradients. Intravascular ultrasound and angiography can subsequently can also demonstrate critical narrowing.
Other complications of LVAD that may be evaluated on imaging include driveline infection, thromboembolism, tearing at the attachment to the aorta, and aortic stenosis or insufficiency.

**Conclusion**
Recently, the Heartmate II and III LVAD were recalled for this reason, highlighting the importance of recognizing outflow graft occlusion. Certain factors can contribute to this complication, including a lower aspirin dose.
Outflow graft obstruction can be treated medically. An endovascular stent can also be a treatment option. Finally, it can be treated surgically, via explantation of LVAD with subsequent heart transplantation.
In summary, outflow graft obstruction is a potentially fatal complication of LVADs. Imaging, particularly in the form of cardiac CT angiography, plays a crucial role in its diagnosis. The Heartmate II and III were recently recalled due to this complication, highlighting the growing acknowledgement and recognition of this phenomenon. Knowledge of this complication, as well as other complications of LVADs, allow radiologists to play a central role in preventing patient morbidity and mortality.



Outflow Graft Obstruction of the Left Ventricular Assist Device: A Review of Imaging Findings

This course will explore basic and cutting-edge imaging techniques to improve patient care and hone individual skills in performance and interpretation of echocardiography, nuclear cardiology, cardiac computed tomography, and cardiovascular magnetic resonance imaging. Days will reinforce how cardiovascular imaging may improve comprehension in ischemic heart disease, structural heart disease, cardiomyopathies, and heart failure. Experts will utilize novel techniques to reinforce key topics including taped interventional cases and a strong emphasis on case presentations.