Initial Evaluation and Management of Complex Cardiac Patients

Educational Objectives

The goal of this program is to improve the initial evaluation and management of complex cardiac patients. After hearing and assimilating this program, the clinician will be better able to:

1. Select patients who require a left ventricular assist device (LVAD) who are not eligible for transplantation.
2. Identify the common clinical presentations and complications associated with LVADs.
3. Implement the emergency management steps for suspected transplant rejection.

Summary

Left ventricular assist device (LVAD): indicated in patients with advanced or end-stage left-sided heart failure (HF) to improve symptoms, quality of life, and longevity; unlike heart transplant patients, LVAD recipients still have HF; LVAD supports only the left side of the heart, often exacerbating right ventricular (RV) dysfunction; 2 main categories of LVAD patients include those receiving destination therapy (will have the LVAD for life as they are not candidates for transplantation) and those using it as a bridge to transplantation while waiting to become eligible; patients with peripartum cardiomyopathy also receive an LVAD with hope of recovery and eventual device removal

The pump: the HeartMate 3 is the only current LVAD model on the market, praised for its improvements over earlier devices; while the HeartMate 2 and HeartWare VAD are still in use, other pumps have been withdrawn due to complications

Pump design: the pump is installed by creating a small hole in the LV apex to insert an inflow cannula; blood is drawn from the LV, spun within the magnetically levitated motor to prevent clots, and then pumped through an outflow graft into the aorta

Power source: the pump relies on external power supply; a driveline connects the internal pump to an external controller and batteries; this driveline, which passes through the skin, must be kept sterile to prevent infection; the external controller, which includes a backup battery, requires continuous power from 2 external batteries that typically last ≈12 hr but can extend to 15 to 17 hr; patients should carry spare batteries and ensure their caregiver brings the mobile power unit; battery exchanges should be done one at a time to avoid triggering alarms

Controller: provides key information about the device’s status and history; interaction with the controller does not pose a risk for harm or data loss; to check battery levels, press the battery button; illuminated bars show remaining charge, yellow diamond indicates <15 min, and a battery icon indicates <5 min; red heart symbol indicates serious issues, and a wrench symbol indicates mechanical problems

Initial evaluation: continuous flow from the pump eliminates a detectable pulse; for a lightheaded patient, use the Doppler pulse method to measure blood pressure by placing the Doppler on the brachial artery, inflating the cuff until flow is inaudible, and then slowly deflating it until flow is heard again; this point indicates the mean arterial pressure (MAP), which ideally should be 65 to 90 mm Hg; for an unstable patient, consider an arterial line but expect the tracing to resemble a flatline with small dips due to the HeartMate 3's intrinsic pulsatility; monitoring MAP (≈71 mm Hg) is crucial; pulse oximetry may be unreliable (use arterial blood gas analysis if necessary); physical examination is usually normal, but auscultation may reveal a mechanical VAD hum; ensure sterility of the driveline site

Contacting patient’s LVAD center: if the patient is conscious, they likely will know the phone number to call; if the patient is unconscious but accompanied by caregivers or family, call the center where the LVAD was implanted; these centers typically offer 24/7 support; if the patient is alone and unconscious, check their backup bag for a contact card

Diagnostic Tests

Electrocardiography: may show significant interference from the pump, making it challenging to detect subtle ischemic changes; primarily identifies the patient's rhythm

Imaging: magnetic resonance imaging is not feasible due to the metallic pump, but computed tomography (CT), including CT angiography, is useful for evaluating graft patency and identifying any issues with the pump; chest and pelvic CT with contrast helps to assess the driveline and investigate potential infections

Echocardiography (ECHO): the 2 most useful views are the parasternal long axis and apical 4-chamber; direct visualization of the LVAD is challenging; size of the LV and RV provides insight into LVAD performance; an enlarged LV with the septum bowing toward the right side indicates inadequate unloading by the LVAD, whereas a dilated RV with the septum bowing toward the left side suggests RV failure and insufficient blood flow to the LVAD; a well-functioning LVAD should reduce mitral regurgitation (MR); significant MR might indicate pump issues; the aortic valve should open approximately once every 3 heartbeats to avoid calcification and severe aortic regurgitation

Laboratory tests: include comprehensive metabolic panel and complete blood cell count; since most LVAD patients are anticoagulated with warfarin, monitoring the international normalized ratio (INR) is crucial (typical target is 2-3, can vary); elevated lactate dehydrogenase levels indicate hemolysis, which may occur if there is thrombosis or clotting within the pump

Common Presentations

Lightheadedness, syncope, fatigue, or worsening HF: can stem from issues related to preload, the pump, or afterload; dehydration or bleeding can lower preload, which is crucial for LVAD function; administering fluids or blood is essential; if preload is adequate but symptoms persist, the problem may be due to pump or heart issues, eg, RV failure, which can be managed with inotropes (eg, milrinone, dobutamine) or epinephrine for hypotension; complications, eg, clot formation, arrhythmias, or cardiac tamponade, can affect LVAD performance and may be detected via ECHO; high blood pressure can increase resistance against the pump, potentially leading to low flow, which requires antihypertensives; outflow graft obstructions (identifiable through CT scans) can obstruct blood flow

Bleeding complications: LVAD patients on anticoagulation with warfarin are at high risk for bleeding complications, particularly gastrointestinal bleeds, due to acquired von Willebrand syndrome and arteriovenous malformations; recent findings suggest aspirin may no longer be necessary; for hemodynamically unstable patients with significant bleeding, reversing anticoagulation is crucial to maintain pump function; however, for stable patients with minor bleeding, immediate reversal might not be required

Clots: LVAD patients are at risk for strokes, although newer pumps have reduced this risk; stroke management depends on whether it is hemorrhagic or ischemic; clotting can also occur within the pump or its outflow graft; while adjusting the INR goal may help manage these issues, severe cases might require surgery or pump replacement

Arrhythmias: in LVAD patients, atrial arrhythmias are generally well tolerated since the pump maintains blood flow regardless of electrical activity; ventricular tachycardia (VT) and ventricular fibrillation (VF) can be managed initially, but persistent cases may lead to RV fatigue and reduced blood flow; prompt treatment is necessary; cardioversion is acceptable but avoid placing pads over the pump; for stable patients, amiodarone and other cardiac medications, including vasopressors and inotropes, can be used as needed

Unconscious LVAD patient with weak pulse: first check the pump's controller for a green circle indicating the pump is running; if the light is off, the pump may not be working; the primary focus should be on fixing the pump, ie, try to restart it and contact the LVAD center immediately; initiate chest compressions only if the pump cannot be restarted, as the LVAD is more effective at maintaining blood flow; if chest compressions are initiated, success is unlikely, and the patient may need to be moved to other mechanical support and transported to a transplant center; closed aortic valve reduces the effectiveness of chest compressions

Transplant patients: generally have normal cardiac function with a new heart, though some may show mild HF with preserved ejection fraction; high immunosuppression increases risk for infections; they often have a resting tachycardia due to denervated hearts, with heart rates typically in the 100s or 110s; right bundle branch block or incomplete right bundle branch block is common post-surgery; early contact with the transplant center is crucial for proper management

Rejection: often presents with new HF symptoms, eg, volume overload, shortness of breath, edema, orthopnea, and decreased LV and RV function; even if function appears normal, presence of symptoms warrants attention; arrhythmias (eg, atrial fibrillation, atrial flutter, supraventricular tachycardias, complete heart block, VT/VF) are also red flags; in suspected cases of rejection, promptly administer 1 g methylprednisolone (a crucial and low-risk intervention) until contact with the transplant center is established; for acute rejection, the dosage is 1 g daily for 3 days

Readings

Abu Akel M, Shaul AA, Goldenberg GR, et al. Combined mechanical circulatory support for ventricular fibrillation in left ventricular assist device patient. ESC Heart Fail. 2022 Oct;9(5):3593-3596. doi: 10.1002/ehf2.13980; Andersen M, Videbaek R, Boesgaard S, et al. Incidence of ventricular arrhythmias in patients on long-term support with a continuous-flow assist device (HeartMate II). J Heart Lung Transplant. 2009 Jul;28(7):733-5. doi: 10.1016/j.healun.2009.03.011; Chamberlain R, Edwards NFA, Doyle SN, et al. Prognostic value of left and right ventricular deformation strain analysis on acute cellular rejection in heart transplant recipients: A 6-year outcome study. Int J Cardiovasc Imaging. 2022 Nov;38(11):2271-2281. doi: 10.1007/s10554-022-02586-z; Dar O, Dulay MS, Riesgo-Gil F, et al. Cardiac transplant rejection assessment with 18F-FDG PET-CT: Initial single-centre experience for diagnosis and management. EJNMMI Rep. 2024 Apr 19;8(1):9. doi: 10.1186/s41824-024-00191-y; Hayek S, Sims DB, Markham DW, et al. Assessment of right ventricular function in left ventricular assist device candidates. Circ Cardiovasc Imaging. 2014 Mar;7(2):379-89. doi: 10.1161/CIRCIMAGING.113.001127. PMID: 24642920; PMCID: PMC3961845; Mehra MR, Naka Y, Uriel N, et al; MOMENTUM 3 investigators. a fully magnetically levitated circulatory pump for advanced heart failure. N Engl J Med. 2017 Feb 2;376(5):440-450. doi: 10.1056/NEJMoa1610426; Mehra MR, Goldstein DJ, Uriel N, et al; MOMENTUM 3 Investigators. Two-year outcomes with a magnetically levitated cardiac pump in heart failure. N Engl J Med. 2018 Apr 12;378(15):1386-1395. doi: 10.1056/NEJMoa1800866; Mena C, Wencker D, Krumholz HM, et al. Detection of heart transplant rejection in adults by echocardiographic diastolic indices: A systematic review of the literature. J Am Soc Echocardiogr. 2006 Oct;19(10):1295-300. doi: 10.1016/j.echo.2006.04.029; Wilson SI, Ingram KE, Oh A, et al. The role of innovative modeling and imaging techniques in improving outcomes in patients with LVAD. Front Cardiovasc Med. 2023 Aug 24;10:1248300. doi: 10.3389/fcvm.2023.1248300.

Disclosures

For this program, members of the faculty and planning committee reported nothing relevant to disclose.

Acknowledgements

Dr. Manning was recorded at the CREST Symposium, held on November 15, 2023, in Lebanon, NH, and presented by Dartmouth-Hitchcock Medical Center. For information on upcoming CME activities from this presenter, please visit dh.cloud-cme.com. Audio Digest thanks the speakers and presenters for their cooperation in the production of this program.

CME/CE INFO

Accreditation:

The Audio- Digest Foundation is accredited by the Accreditation Council for Continuing Medical Education to provide continuing medical education for physicians.

The Audio- Digest Foundation designates this enduring material for a maximum of 1.00 AMA PRA Category 1 Credits™. Physicians should claim only the credit commensurate with the extent of their participation in the activity.

Audio Digest Foundation is accredited as a provider of continuing nursing education by the American Nurses Credentialing Center's (ANCC's) Commission on Accreditation. Audio Digest Foundation designates this activity for 1.00 CE contact hours.

Lecture ID:

EM411902

Expiration:

This CME course qualifies for AMA PRA Category 1 Credits™ for 3 years from the date of publication.

Instructions:

To earn CME/CE credit for this course, you must complete all the following components in the order recommended: (1) Review introductory course content, including Educational Objectives and Faculty/Planner Disclosures; (2) Listen to the audio program and review accompanying learning materials; (3) Complete posttest (only after completing Step 2) and earn a passing score of at least 80%. Taking the course Pretest and completing the Evaluation Survey are strongly recommended (but not mandatory) components of completing this CME/CE course.

Estimated time to complete this CME/CE course:

Approximately 2x the length of the recorded lecture to account for time spent studying accompanying learning materials and completing tests.

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