Mechanical support as destination therapy

Mechanical support as destination therapy James Young MDHead, Heart Failure and Cardiac Transplant Medicine Cleveland Clinic Foundation Cleveland, OHMehmet Oz MDDirector, Cardiac Assist Device Program Columbia Presbyterian Medical Center New York City, NY Geetha Bhat MD PhDDirector, Heart Failure and Cardiac Transplant Center Jewish Hospital Louisville, KY

Overview of the field • Axial flow pumps are an example of the trend away from old pusher-plate technology • Micromed (DeBakey pump) • Jarvik 2000 (Jarvik Inc) • HeartMate II (Thoratec)

Challenges of axial flow pumps • It is more difficult to monitor how much blood is flowing through the pumpNo traditional blood pressureNo pulse you can measure traditionally

Jarvik 2000 solution • “We don’t care about pumping all the blood, we’ll pump less than all the blood in order to make sure we don’t suck the heart down into the device.” Oz Jarvik 2000 VAD ©Texas Heart Institute

Centrifugal flow pumps • Many groups moving to centrifugal flow pumps • HeartMate III (Thoratec) • AB 180 iVAD (CardiacAssist) • CorAide (Arrow International) • Biomedicus Biopump (Medtronic) • “These pumps are in theory more efficient than axial flow pumps.” Oz

Forgettable pumps • Major stumbling blocks to “forgettable” systems • miniaturization – especially power supply • infection control • “Patients get them, and they don’t realize they have them anymore, nor do the people around them.” Oz

Patients for the artificial heart • As we have gained more experience we realize that death in the operating room isn’t the real definition of right heart failure • who is unable to come off of inotropic support? • who has irreversible end organ injury? • who is unable to return to normal exercise capacity?

Need for total artificial heart • Over time, there are progressive changes in the native heart. • “From a medical need perspective, we will ideally want maybe ¼ of the patients to be supported with total artificial heart support.” Oz

Sizing issues • Patients must be sized very meticulously to be able to use an artificial heart. Need enough room and need to not kink off key structures • Abiomed came up with a special algorithm to determine if a patient is acceptable – AbioFit™

AbioCor

Cardiologist assessment • Patients for the AbioCor need to be assessed by a cardiologist in advance of implantation • must be non-transplantable • must be scanned and measured for sizing • limited to large men (no small men or women)

Use of the artificial heart • LVADs do an excellent job as bridge to transplant, but there would still be a role for artificial hearts in: • patients who deteriorate rapidly after placement of LVAD • patients not suitable for transplant Bhat

State of the patients Robert Tools, world's first recipient of the AbioCor Implantable Replacement Heart. • First two patients are doing as well as can be expected • “Since he’s the first patient we’re still working on how to do the discharge planning for the future.” Bhat Source: Jewish Hospital

Totally implantable • From an internal medicine perspective, total implantability is a huge step • portable • no external connections • transcutaneous power minimizes the consoles and excess baggage of the old systems

Patient selection • If they are too ill for transplant, are they too ill for mechanical therapy? • there are more sick patients than hearts to transplant • it may be better not to use a rare transplanted heart on weaker patients • if we can save more people with devices, the costs involved must be discussed • Oz

Which path to take • Moving to more complicated full support is better, or do we move to smaller, less complicated support? • equally large populations • both approaches are needed • “The way I envision this being a decade from now is […] not to bother with the coronaries and just plug in a support device that gives them 2 or 3 liters extra blood flow every minute.” Oz

Later transplantation • If a patient improves sufficiently on the artificial heart, could they be considered for a transplant? • the AbioCor trials insisted on non-transplant candidates • if the patients improve sufficiently, the trial allows for them to be considered for transplant

Patients who improve • Some patients improve drastically • score system created with Cleveland Clinic for stratifying patients • the younger patients are the ones most likely to tolerate the insult and recover • of more concern is the group that stays in the ICU with end-organ dysfunction

Three outcomes • These patients are divided into three outcomes after device implantation • they survive and do well • they die on the operating table or soon after • they linger on in the ICU - the worst outcome

The challenge • “In the early days of piggyback assist device use […] our biggest challenges were convincing patients that this was not human experimentation. That they would get the quality and dignity of life they desired, and not just be an experiment.” • Oz

Patient advocate • The AbioCor trial protocol includes a patient advocate to look out for the patient’s needs • “As these people look normal, the American public will make peace with the fact that you can have a bionic heart, and it is something that Granddad can have.” Oz

End-stage organ failure • Selection criteria has always been a problem • patients with irreversible end-organ damage are not a good subset • experience with the LVADs have shown us patients can do fairly well • Bhat

Major concern • The worry is that they go to the operating room with borderline function, but they develop less recoverable function • “If we envision these patients like planes taking off from an aircraft carrier, they dip a little bit before they actually get airborne. And if we’re too close to the water when we launch them, they hit that water.” Oz

REMATCH • Randomized Evaluation of Mechanical Assistance Therapy for Congestive Heart Failure • it will answer some questions but raise many others • we cannot rule out devices as a solution for heart failure • who should get devices, and who should not? • Oz

Cost benefit • We need an open dialogue on the cost-benefit of these systems • “[This is a dialogue] we can either have behind closed doors, by important agencies not addressing the problem, or we can have it a more public level, which is going to be painful, but is probably worth having.” Oz

Bridge to recovery? • We have not yet succeeded in providing long-term survival in bridge to recovery • about 10 out of >225 have had devices removed • most have not survived long term, and are back in the hospital with heart failure • the more we learn about why they recover even partially, the closer we will be

Explantable patients? • It’s an intriguing field, with lots of basic science questions • what happens at the cellular level? • what happens when a device is placed? • what kinds of markers might predict an explantable patient? CorCap™ cardiac support device Courtesy Acorn Cardiovascular, Inc

Source: Jewish Hospital

Mechanical support as destination therapy