1. Correct Answer: D. LV apical aneurysm

Rationale: All LVAD candidates should be screened for structural and functional abnormalities that preclude LVAD implantation. Optimal candidate selection is one of the determinants for operative and long-term success of an LVAD. A TTE is generally the first-line imaging modality used to screen for structural and functional abnormalities. However, in some situations, a patient may require an urgent or emergent surgical LVAD placement. In these situations, a TEE can be used. In addition to performing a comprehensive examination, the ASE suggests to focus on high-risk or “red-flag” findings that may impact successful LVAD implantation.

1. Stainback RF, Estep JD, Agler DA, et al. Echocardiography in the management of patients with left ventricular assist devices: recommendations from the American Society of Echocardiography. J Am Soc Echocardiogra. 2015;28(8):853-909.

2. Correct Answer: D. Use of microbubble contrast agents to improve precision of LV ejection fraction measurement before LVAD implantation is strongly recommended.

Rationale/Critique: According to the Centers for Medicare and Medicaid, qualifying conditions for LVAD implantation as a destination therapy include an LV ejection fraction of <25% (A). While LV ejection fraction is a component of clinical risk scoring tools (Seattle Heart Failure Model, Heart Failure Survival Score) that can be used to calculate a patient’s expected survival times and suitability for LVAD, it is not the only clinical parameter used to determine whether a patient gets referred for an LVAD (B and C). Calculating an accurate ejection fraction can be difficult among LVAD candidates. The ASE recommends either the biplane method of disk (modified Simpson’s rule) from two-dimensional images or three-dimensional assessment for determining LV ejection fraction. The ASE also recommends using microbubble contrast agents when indicated to improve endocardial definition and precision of LV ejection fraction measurement (D).

1. Aaronson KD, Schwartz JS, Chen TM, Wong KL, Goin JE, Mancini DM. Development and prospective validation of a clinical index to predict survival in ambulatory patients referred for cardiac transplant evaluation. Circulation. 1997;95(12):2660-2667.1.

2. Patel CB, Cowger JA, Zuckermann A. A contemporary review of mechanical circulatory support. J Heart Lung Transplant. 2014;33(7):667-674.

3. Correct Answer: A. Comparison of the preoperative LVIDd to the postoperative LVIDd is the primary clinical measure of the degree of LVAD-mediated left ventricle unloading

Rationale: LVIDd is an important parameter for LVAD candidates and patients who have undergone LVAD implantation. The LVIDd is best measured from parasternal long-axis TTE images (B). Prior to LVAD implantation, LVAD candidates often have increased LVIDd (C). Special consideration should be focused on patients whose preoperative LVIDd is small (<63 mm) as data suggest that it is associated with increased 30-day morbidity and mortality after LVAD implantation (D). Comparison of the preoperative LVIDd to the postoperative LVIDd is the primary clinical measure of the degree of LVAD-mediated LV unloading (A).

1. Topilsky Y, Oh JK, Shah DK, et al. Echocardiographic predictors of adverse outcomes after continuous left ventricular assist device implantation. JACC Cardiovasc Imaging. 2011;4(3):211-222.

4. Correct Answer: D. Mild tricuspid regurgitation

Rationale: It is important to assess RV function when evaluating patients for LVAD. Failure of the right ventricle in the perioperative period is the leading cause of morbidity and mortality following placement of an LVAD. Preoperative clinically severe RV dysfunction may prompt biventricular mechanical support devices as this may lead to better outcomes in this population. Echocardiographic signs of RV dysfunction include TAPSE <17 mm, RV FAC <35%, RV dilatation, and moderate or greater tricuspid regurgitation.

1. Rudski LG, Lai WW, Afilalo J, et al. Guidelines for the echocardiographic assessment of the right heart in adults: a report from the American Society of Echocardiography: endorsed by the European Association of Echocardiography, a registered branch of the European Society of Cardiology, and the Canadian Society of Echocardiography. J Am Soc Echocardiogr. 2010;23(7):685-713.

2. Slaughter MS, Pagani FD, Rogers JG, et al. Clinical management of continuous-flow left ventricular assist devices in advanced heart failure. J Heart Lung Transplant. 2010 Apr;29(4 suppl):S1-S39.

5. Correct Answer: C. Presence of a mechanical AV

Rationale/Critique: According to the manufacturer, Abiomed, the Impella is contraindicated for use in patients with a mural thrombus in the left ventricle, mechanical AV or heart constrictive device, AV stenosis/calcification (equivalent to an orifice area of 0.6 cm² or less), moderate-to-severe aortic insufficiency (echocardiographic assessment graded as ≥+2), severe peripheral arterial disease precluding placement of the Impella System, significant right heart failure, combined cardiorespiratory failure, presence of an atrial or ventricular septal defect, LV rupture, and cardiac tamponade.

1. Impella® left-side devices indication & safety information. Accessed February 29, 2020. http://www.abiomed.com/important-safety-information.

6. Correct Answer: D. When present at HeartMate III implantation, AR can enable a “blind” loop of flow between LVAD, ascending aorta, and back into the left ventricle.

Rationale: LVADs, including CF-LVADs such as the HeartMate III, lead to a reduction in LV diastolic filling pressure and an increase in central aortic pressure. This physiologic change worsens AR. It is estimated that AR occurs in 25% to 30% of patients with continuous-flow LVAD. Significant AR can lead to ineffective LVAD output due to the recycling of regurgitant blood from the outflow graft in the proximal aorta back into the LV inflow cannulas (D).

Among patients with preexisting AR, AR generally worsens after LVAD implantation. As a result, moderate or severe AR is a contraindication for continuous-flow LVAD (A). Vena contracta width, and jet width/LV outflow tract width are recommended to assess AR severity (C). While surgical closure of the AV can eliminate AR after LVAD implantation, this can leave the patient with no means of LV ejection in the event of LVAD failure (B).

1. Bouabdallaoui N, El-Hamamsy I, Pham M, et al. Aortic regurgitation in patients with a left ventricular assist device: a contemporary review. J Heart Lung Transplant. 2018;37(11):1289-1297.

7. Correct Answer: D. The patient may benefit from starting an inhaled pulmonary vasodilator.

Rationale: After LVAD implantation, the preload to the right ventricle increases secondary to an increase in LV cardiac output. As a result, the output of the right ventricle has to increase to match the LVAD work. Unfortunately, early RV dysfunction after LVAD initiation is not uncommon. Rapid increases in RV preload, cardiopulmonary bypass, and underlying RV dysfunction can all contribute to RV dysfunction after LVAD initiation. Furthermore, LVAD implantation can lead to a leftward IVS shift that alters RV geometry and further exacerbates RV dysfunction. The echo image demonstrates RV dysfunction, which echocardiographically presents as an enlarged right ventricle, a left shifted IVS, small left ventricle, and RV hypokinesis (A). Due to a decrease in RV cardiac output and small left ventricle, the LV filling pressure is decreased (B). Increasing LVAD pump speed can result in a “suction event,” a condition in which a segment of the LV myocardium partially occludes the inflow cannula and reduces pump inflow, further worsening the patient’s hemodynamics (C). Often, post-LVAD implantation RV dysfunction can be treated with RV afterload reduction by using agents such as inhaled pulmonary vasodilators (D, Video 48.5).

1. Flores AS, Essandoh M, Yerington GC, et al. Echocardiographic assessment for ventricular assist device placement. J Thorac Dis. 2015;7(12):2139.

8. Correct Answer: A. There is no evidence of mechanical obstruction.

Rationale: Traditionally, perioperative echocardiographic assessment of LVAD patients includes assessment of flow around the inflow and outflow cannula. Utilizing color flow Doppler can assist in determining the presence or absence of a mechanical obstruction (A) based on turbulence of flow (notice the lack of mosaicism near the inflow cannula in Figure 48.2) (C). The blue noted on color Doppler indicates flow away from the probe and there is no bidirectional flow noted near the inflow cannula (B). This color Doppler flow allows for the assessment of flow direction, flow velocity, and mechanical obstruction (D).

1. Stainback RF, Estep JD, Agler DA, et al. Echocardiography in the management of patients with left ventricular assist devices: recommendations from the American Society of Echocardiography. J Am Soc Echocardiogra. 2015;28(8):853-909.

9. Correct Answer: C. Continuous-wave Doppler interrogation of a properly aligned inflow cannula should reveal low-velocity (<1.5 m/s) flow.

Rationale: In HeartMate and HeartWare devices, appropriately positioned inflow cannulas should lie near or within the LV apex and are directed toward the mitral valve. Significant angulation of the inflow cannula can cause direct contact between the inflow cannula and the septum, which can cause ventricular arrhythmias and/or cannula obstruction and may necessitate surgical revision. Inflow cannula velocity can be assessed using pulsed-wave and continuous-wave spectral Doppler. Spectral Doppler profile should yield low-velocity (<1.5 m/s) and unidirectional laminar flow. In some cases, blood flow from normal mitral valve inflow or AR can contaminate spectral Doppler assessment of the inflow cannula.

1. Chivukula VK, Beckman JA, Prisco AR, et al. Left ventricular assist device inflow cannula angle and thrombosis risk. Circ Heart Fail. 2018;11(4):e004325.1.

2. Rasalingam R, Johnson SN, Bilhorn KR, et al. Transthoracic echocardiographic assessment of continuous-flow left ventricular assist devices. J Am Soc Echocardiogr. 2011;24(2):135-148.

10. Correct Answer: B. Doppler interrogation of the outflow graft should be performed coaxially to the direction of flow.

Rationale: Outflow cannulas can be visualized by both TTE and TEE. Whereas the proximal outflow graft is not visible with TEE, the distal portion of the outflow cannula attached to the aorta can be visualized in the majority of patients. For optimal assessment of outflow graft velocity, spectral Doppler interrogation should be performed coaxially to the direction of flow. Both pulsed-wave Doppler and continuous-wave Doppler can be used to assess outflow graft flow. Outflow graft peak systolic velocity should be <2 m/s. Velocity >2 m/s should warrant further investigation as it may suggest possible obstruction.

1. Rasalingam R, Johnson SN, Bilhorn KR, et al. Transthoracic echocardiographic assessment of continuous-flow left ventricular assist devices. J Am Soc Echocardiogr. 2011;24(2):135-148.

2. Stainback RF, Estep JD, Agler DA, et al. Echocardiography in the management of patients with left ventricular assist devices: recommendations from the American Society of Echocardiography. J Am Soc Echocardiogra. 2015;28(8):853-909.

11. Correct Answer: C. Decrease in mitral regurgitation

Rationale: Placement of a CF-LVAD increases LV cardiac output, which decreases LV size, LV pressure, and mitral regurgitation. One should be aware that a malpositioned LVAD can worsen mitral regurgitation. This decrease in LV pressure coupled with an increased ascending aorta pressure from the LVAD outflow cannula can lead to worsening aortic insufficiency. After initiation of the LVAD, particular attention should be focused on the interatrial septum as the decrease in left-sided pressure coupled with an increase in right-sided pressure can unmask a PFO with right-to-left shunt. This can present clinically as a decrease in arterial oxygen saturation.

1. Kapur NK, Conte JV, Resar JR. Percutaneous closure of patent foramen ovale for refractory hypoxemia after HeartMate II left ventricular assist device placement. J Invasive Cardiol. 2007;19(9):E268-E270.

2. Stainback RF, Estep JD, Agler DA, et al. Echocardiography in the management of patients with left ventricular assist devices: recommendations from the American Society of Echocardiography. J Am Soc Echocardiogra. 2015;28(8):853-909.