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Heartbeat – November 2001
Destination therapy
Mechanical support as destination therapy
James Young MDHead, Heart Failure and Cardiac Transplant Medicine
Cleveland Clinic FoundationCleveland, OH
Mehmet Oz MDDirector, Cardiac Assist Device ProgramColumbia Presbyterian Medical CenterNew York City, NY
Geetha Bhat MD PhDDirector, Heart Failure and Cardiac Transplant CenterJewish HospitalLouisville, KY
Heartbeat – November 2001
Destination therapy
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)
Heartbeat – November 2001
Destination therapy
Challenges of axial flow pumps
It is more difficult to monitor how much blood is flowing through the pump
No traditional blood pressure
No pulse you can measure traditionally
Heartbeat – November 2001
Destination therapy
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
Heartbeat – November 2001
Destination therapy
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
Heartbeat – November 2001
Destination therapy
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
Heartbeat – November 2001
Destination therapy
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?
Heartbeat – November 2001
Destination therapy
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
Heartbeat – November 2001
Destination therapy
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™
Heartbeat – November 2001
Destination therapy
AbioCor
Heartbeat – November 2001
Destination therapy
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)
Heartbeat – November 2001
Destination therapy
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
Heartbeat – November 2001
Destination therapy
State of the patients
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
Robert Tools, world's first recipient of the AbioCor Implantable Replacement Heart.
Source: Jewish Hospital
Heartbeat – November 2001
Destination therapy
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
Heartbeat – November 2001
Destination therapy
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
Heartbeat – November 2001
Destination therapy
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
Heartbeat – November 2001
Destination therapy
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
Heartbeat – November 2001
Destination therapy
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
Heartbeat – November 2001
Destination therapy
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
Heartbeat – November 2001
Destination therapy
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
Heartbeat – November 2001
Destination therapy
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
Heartbeat – November 2001
Destination therapy
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
Heartbeat – November 2001
Destination therapy
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
Heartbeat – November 2001
Destination therapy
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
Heartbeat – November 2001
Destination therapy
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
Heartbeat – November 2001
Destination therapy
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
Heartbeat – November 2001
Destination therapy
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
Heartbeat – November 2001
Destination therapy
Source: Jewish Hospital