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New Advances in Medical Device Technologies for Treatment of Heart Failure

By Manijeh “Mani” Berenji

Heart failure (HF) is a progressive condition in which the heart is unable to pump blood out efficiently to the rest of the body. The heart tries to compensate at first by enlarging, developing more muscle mass, and increasing its pumping rate. The circulatory system also kicks in, with blood vessels narrowing to keep blood pressure up and by diverting blood flow to less important organs and structures. However, over time, the heart starts to exhaust itself. HF can be categorized based on the left ventricular ejection fraction (LVEF) into systolic and diastolic HF.

Even with major advances in medical and symptom management (with medications like angiotensin converting enzyme (ACE) inhibitors, angiotensin receptor blockers or beta blockers to lower blood pressure and reduce strain on the heart and diuretics to reduce fluid buildup in the lungs and swelling in the feet and ankles) as well as evidence-based therapies (including neurohormonal blockade and biventricular pacing), morbidity and mortality from systolic heart failure remain high (1,2). Over 6.5 million adults in the United States have been diagnosed with HF, with its incidence increasing (3,4). The prevalence of HF in the aging US population is projected to increase by 46% between 2012 and 2030 (5). Heart failure was a contributing cause of 1 in 8 deaths in the US in 2017 (4,6). Heart transplant is usually reserved for those with severe HF and there are major limitations in available donor hearts available for transplantation globally.

But over the past 2.5 decades, advances in mechanical circulatory support (in the form of durable left ventricular assist devices or LVADs), has extended survival and improved health-related quality of life for select patients with New York Heart Association (NYHA) Class IIIB and IV HF as a bridge to transplantation (7,8). LVADs are increasingly used and have been implanted in more than 16,500 patients worldwide (9). The landmark REMATCH trial (which compared LVADs with optimal medical therapy in class IV HF patients) found a 48% reduction in mortality from any cause as well as a significant increase in the survival rates for HF at one year (52% versus 25%) and two years (23% versus 8%) (10,11).

The first LVAD approved by the Food and Drug Administration was Heartmate I (developed by Thoratec, owned by St Jude Medical) in 1994. This LVAD operated primarily as a pump. Since then, there have been major improvements in their design and function. But the basic components of an LVAD remain the same: i) an inflow cannula which serves as a conduit for blood from the LV to the pump; ii) a pump with an impeller that delivers continuous blood flow; iii) an outflow graft which serves as a conduit for blood from the pump to the aorta; and iv) a tunnelled driveline that connects the pump to an external controller (7). The next wave of LVADs went from a pump to a stream, or what’s called a continuous flow. The HeartMate II generates the stream using a rotating screw. Blood comes into the chamber and twists through a device that is smaller and more comfortable than its predecessor. The HeartMate II is the most commonly used LVAD in the US. The latest concept in the 3rd generation LVAD is an improved method of continuous flow. It’s based on centrifugal force, with electromagnets spinning the blood. The HeartWare Ventricular Assist System (made by HeartWare), does this using a chamber that’s even smaller and with no mechanical bearings, attaching directly to the heart (12).

The future of LVADs? Smaller and minimally invasive are the new trends in LVAD technologies. Next generation LVADs in development are the size of an AA battery and are connected from the top chamber of the heart to one of the big blood vessels via a mini-thoracotomy. These devices promise to reduce the short- and long-term complications associated with LVADs.

References

1. Yancy CW, Jessup M, Bozkurt B, et al. ACC/AHA/HFSA focused update of the 2013 ACCF/AHA guideline for the management of heart failure: a report of the American College of Cardiology/American Heart Association Task Force on Clinical Practice guidelines and the Heart Failure Society of America

J Am Coll Cardiol. 2017;23:628–65.

2. Stehlik J, Mountis M, Haas D, Palardy M, Ambardekar AV, Estep JD, Ewald G, Russell SD, Robinson S, Jorde U, Taddei-Peters WC, Jeffries N, Richards B, Khalatbari S, Spino C, Baldwin JT, Mann D, Stewart GC, Aaronson KD; REVIVAL Investigators. Quality of life and treatment preference for ventricular assist

device therapy in ambulatory advanced heart failure: A report from the REVIVAL study. J Heart Lung Transplant. 2020;39(1):27–36.

3. Benjamin EJ, Muntner P, Alonso A, Bittencourt MS, Callaway CW, Carson AP, et al. Heart disease and stroke statistics — 2019 update: a report from the American Heart Association. Circulation. 2019;139(10):e56–528.

4. Centers for Disease Control and Prevention. Heart Failure. Available at: https://www.cdc.gov/heartdisease/heart_failure.htm. Accessed on 19 January 2020.

5. Jackson SL, Tong X, King RJ, Loustalot F, Hong Y, Ritchey MD. National Burden

of Heart Failure Events in the United States, 2006 to 2014. Circ Heart Fail. 2018;11(12):e004873.

6. Centers for Disease Control and Prevention, National Center for Health Statistics. Underlying Cause of Death, 1999–2017. Available at: https://wonder.cdc.gov/ucd-icd10.html. Accessed on 19 January 2020.

7. Kiamanesh O, Kaan A, Toma M. Medical Management of Left Ventricular Assist Device Patients: A Practical Guide for the Nonexpert Clinician. Can J Cardiol.2019;pii: S0828–282X(19)31285–1.

8. Stehlik J, Estep JD, Selzman CH, Rogers JG, Spertus JA, Shah KB, Chuang J,Farrar DJ, Starling RC; ROADMAP Study Investigators. Patient-Reported Health-Related Quality of Life Is a Predictor of Outcomes in Ambulatory Heart Failure Patients Treated With Left Ventricular Assist Device Compared With Medical Management: Results From the ROADMAP Study (Risk Assessment and Comparative Effectiveness of Left Ventricular Assist Device and Medical Management). Circ Heart Fail. 2017;10(6). pii: e003910.

9. Goldstein DJ, Meyns B, Xie R, Cowger J, Pettit S, Nakatani T, Netuka I, Shaw S, Yanase M, Kirklin JK. Third Annual Report From the ISHLT Mechanically Assisted Circulatory Support Registry: A comparison of centrifugal and axial continuous-flow left ventricular assist devices. J Heart Lung Transplant. 2019;38(4):352–363.

10. Vaidya Y, Dhamoon AS. Left Ventricular Assist Devices (LVAD) [Updated 2019 Sep 10]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2019 Jan.

11. Rose EA, Gelijns AC, Moskowitz AJ, Heitjan DF, Stevenson LW, Dembitsky W, Long JW, Ascheim DD, Tierney AR, Levitan RG, Watson JT, Meier P, Ronan NS, Shapiro PA, Lazar RM, Miller LW, Gupta L, Frazier OH, Desvigne-Nickens P, Oz MC, Poirier VL., Randomized Evaluation of Mechanical Assistance for the Treatment of Congestive Heart Failure (REMATCH) Study Group. Long-term use of a left ventricular assist device for end-stage heart failure. N. Engl. J. Med. 2001 Nov 15;345(20):1435–43.

12. American Heart Association News. The past, present and future of the device keeping alive Carew, thousands of HF patients. Available at: https://www.heart.org/en/news/2018/06/13/the-past-present-and-future-of-the-device-keeping-alive-carew-thousands-of-hf-patients. Accessed on 19 January 2020.

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Manijeh “Mani” Berenji

Manijeh “Mani” Berenji

Physician in Southern California. Interests: Workplace, Public & Global Health. Climate and environmental health advocate. @UCLA @UCSF @UMich alum.