Topic 10: VAD Flashcards
Roller pumps aren’t good VADS
Limitations?
Tethering, Blood trauma, Adjust pump speeds due to changes in heart pressures.
1963–Spencer, et al. Reported using a roller pump to support a patient to recovery
1st successful clinical application of a true
VAD - who? when?
DeBakey, 1966
Pneumatically driven diaphragm pump Paracorporeal LA to Axillary Artery 37yo patient who could not be weaned from CPB s/p AVR/MVR Supported for 10 days Weaned and Discharged
1st used a Total Artificial Heart (TAH) to temporarily support a patient to transplant
Cooley, 1969
47yo man with failure to wean from CPB s/p LV Aneurysm repair
TAH had only been tested for up to 12 hours in an animal model
Implanted the “Liotta Heart” which was a pneumatic device
Supported the patient for 64 hours
University of Utah investigators were the first in the world to implant a permanent what? when?
TAH on 12/2/1982
Jarvik 7 TAH performed by Dr. William DeVries
Implanted into Dr. Barney Clark, 61yo dentist with end stage idiopathic dilated cardiomyopathy
Died of complications from aspiration pneumonia, Renal failure, colitis with septicemia.
Was supported for 112 days
1st planned TAH implant as a Bridge to
Transplant (BTT)
1985–Copeland at the University of Arizona
Syncardia, Cardiowest–Tucson, AZ
Drs. Olsen and Copeland revived the first TAH model
Modified and renamed–Cardiowest C70
Received FDA Approval as a BTT in 2004
Transplantation provided a stimulus for the development of what?
VADs for support until transplant
30% of patients died on the list
Became an incentive to develop devices that could be used for patients with acute cardiac decompensation while awaiting transplantation
9/1984–Stanford University
Oyer and Colleagues –Implanted the Novacor LVAD - which is what?
1st successful transplant s/p BTT with LVAD
Followed by Hill and colleagues who implanted a Pearce-Donachey pneumatic LVAD
1992–Frazier and colleagues
1st to report successful BTT with Thoratec Heartmate IP VAD (Implantable pneumatic)
Restored near normal hemodynamics.
What were its Limitations?
Devices dependent on large consoles for power and controller function
Patients confined to hospital until
transplantation despite being fully ambulatory
1991–Frazier at Texas Heart Institute
first to use what?
First to use an untethered vented electric LVAD for long term support
33 y/o patient
Battery operated Heartmate VE
500 days of support
Patient died of embolic cerebral vascular accident.
1990–Kormos at University of Pittsburg
Developed a program to do what?
transfer VAD patients to a monitored outpatient setting until transplantation
1994–What was the first FDA approved implantable device for bridge to
transplant?
Heartmate LVAD
Biological Barriers to VAD design (4)
- Blood versus Foreign surface
- Moving parts
- Changes to patients anticoagulation and immune system over time in response to the mechanical pump
- Pharmacologic modifications (Heparin, Coumadin, ASA)
Indications for VAD: Bridge to Transplant
Worsening hemodynamics despite high level
of IV inotropic support and/or vasodilator
therapy or refractor arrhythmias.
Indications for VAD: Destination Therapy
Patients who are not transplant candidates.
Have an EF less than 25% and NYHA Class IV
symptoms despite optimal therapy.
Indications for VAD two options?
Bridge to Transplant
Destination Therapy
Contraindications for VAD - tons
High surgical risk Recent/evolving stroke Neurological deficits impairing the ability to manage device Coexisting terminal condition Abdominal aortic aneurysm (greater than 5cm) Active infection Fixed pulmonary hypertension Severe pulmonary dysfunction Multisystem organ failure Inability to tolerate anticoagulation HIT Psychiatric illness Lack of social support pregnancy
Design of a VAD must take into consideration? tons
Configured for their eventual application
(Shorter term vs partial assist vs long term support vs total support)
Different uses and device requirements impact design.
Anatomically compatible (Used over large variations in body mass, chest size/ shape, abdominal girth, etc.)
Structurally stable in a corrosive saline environment
Operate continuously w/o maintenance 4years.
Cannot fail under increased stress conditions
Reduce power requirements to save battery life
Must be efficient–reduce heat waste
2 different kinds of pumps for VAD
Positive displacements (Usually pneumatic) Rotary
Flow and Pressure - Positive Displacement - how?
Change volume in the chamber
