Flashcards in VADs- Exam 2 Deck (109):
History: VAD 1930s - Carrell and Lindbergh and Demikhov
Experimented with mechanical support in animal models
History: 1953- Gibbon
1st use of CPB
Inability to wean fuelest interested in prolonged mechanical suport in order to promote myocardial recovery
History: 1963- Spencer, et. al
Reported using a roller pump to support a patient to recovery
Roller pumps aren't good VADS
What are the limitations of roller pumps as VADs?
Tethering, Blood trauma, Adjust pump speeds due to changes in heart pressures
History: 1966- DeBakey
1st successful clinical application of a true VAD
Pneumatically driven diaphragm pump
Describe the paracorporeal setup of DeBakey in 1966?
LA to Axillary ARtery
Describe DeBakey's patient and the use of the VAD
37 y/o patient who could not be weaned from CPB s/p AVR/ MVR
Supported for 10 days
Weaned and Discharged
History: 1960's Klaus, et al.
Introduced the concept of atrial counter pulsation
Rapid systolic unloading of the ventricle with diastolic augmentation
What did 1960's Klaus development lead to?
Development of the balloon pump which was developed in 1963 and applied clinically in 1967
When was the total artificial heart used in dog model? How long was it supported?
1962: TAH Reported survival for how long?
Up to 24 hours
1969: Cooley TAH
1st used a TAH to temporarily support a patient to transplant
47 y/o man failure to wean from CPB s/p LV Aneurysm repair
TAH had only been tested for up to 12 hours in animal model
Implanted the "Liotta Heart" which was a pneumatic device
Supported the patient for 64 hours
History: TAH: Research continued into the ________.
Who were the first investigators in the world to implant a permanent TAH on 12/2/1982.
University of Utah
Describe the first patient to receive a permanent TAH (University of Utah)
Jarvik 7 TAH performed by Dr. William DeVries
Implanted into Dr. Barney Clark, 61 y/o dentist with end stage idiopathic dilated cardiomyopathy
Died of complications from aspiration pneumonia, renal failure, colitis with septicemia
Was supported for 112 days
When 5 patients received permanent TAH under FDA trial, what was the longest survival?
1985: Where was the first planned TAH implant as a Bridge to Transplant?
Copeland at the University of Arizona
bridge to transplant
TAH: Device implanted in __________ had issues with the manufacturer so the FDA withdrew the FDA exemption for implantation. Describe the device.
Tuscon; Syncardia, Cardiowest
Who revived the Syncardia, Cardiowest model?
Drs. Olsen and Copeland (Tuscon, AZ)
Syncardia was modified and renamed what?
Cardiowest 70 received FDA approval as a BTT in _______.
____________ provided a stimulus for the development of VADs for support until transplant.
1978- Norman (VAD as a BTT)
Device used for 5 days of support
Intracorporeal pneumatic device
patient died of multi-organ system failure s/p transplant
Early 1980's- what happened with transplantation?
Transplanation became a widely applied therapy
What percent of patients died on the list in the early 1980's?
30%; became an incentive to develop devices that could be used for patients with acute cardiac decompensation while awaiting transplantation
1980: NIH sent out request for proposals to develop what?
"Implantable, integrated, electrically powered left heart assist system" that could be used on a long term basis and allow extensive patient mobility
9/1984 - Standford University: Oyer and Colleagues implanted what?
1st successful transplant s/p BTT with LVAD
Follow 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
restored near normal hemodynamics
containing or operative by air or gas under pressure
What are some limitations of Thoratec Heartmate IP VAD?
devices dependent on large consoles for power and controller function
patients confined to hospital until transplantation despite being fully ambulatory
1990- Kormos at University of Pittsburg
developed a program to transfer VAD patients to a monitored outpatient setting until transplantation
1991-Frazier at Texas Heart Institute
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
1994: _________ LVAD was the first FDA approved implantable device for BTT.
What are some biological barriers to VAD design?
Blood versus foreign surface
changes to patient's anticoagulation and immune system over time in response to the mechanical pump
Pharmacologic modifications (heparin, coumadin, asa)
VADS: Blood vs. Foreign Surface
blood contact surface cannot harm the patient
minimum generation of blood clots
VADS: changes to patient's anticoagulation over time
coagulopathy immediately after implantation because of bypass; period of hypercoagulability, returning to baseline
What are some indications for VAD?
Bridge to Transplant
Bridge to Transplant
Worsening hemodynamics despite high level of IV inotropic support and/or vasodilator therapy or refractor arrhythmias
patients who are not transplant candidates
have an EF less than 25% and NYHA Class IV symptoms despite optimal Therapy
What are the contraindications for VADs?
High surgical risk
Neurological deficits impairing ability to manage device
Coexisting terminal condition
Abdominal aortic aneurysm (greater than 5cm)
fixed pulmonary htn
severe pulmonary dysfunction
multisystem organ failure
inability to tolerate anticoagulation
lack of social support
Devices need to be configured for their eventual application. Describe configuration types.
Shorter term vs. partial assist vs. long term support vs total support. Different uses and device requirements impact design
What can impact the design of the VAD?
different uses and device requirements
VADs: Anatomically compatible
used over large variations in body mass, chest size/shape, abdominal girth, etc.
What else is important regarding the design of a VAD?
structurally stable in a corrosive saline environment
operate continuously w/o regular maintenance for yrs
cannot fail under increased stress conditions
reduce power requirements to save battery life
must be efficient-reduce heat waste
What are the two different types of VAD pumps?
Positive displacement (usually pneumatic)
Comparison of pumps: Flow and Pressure
Positive displacement: change volume in the chamber
Rotary: Rotating Impellar
Comparison of Pumps: Source of Energy
Positive Displacement: Air pressure/electricity
Comparison of Pumps: Size
Rotary is smaller with a smaller cannula
Comparison of Pumps: Prime Volume
Positive Displacement: Large prime volume
Rotary: Smaller prime vol
Comparison of Pumps: Flow Ranges
both plagued with thrombosis with decreased flow and hemolysis with increased flow
Comparison of Pumps: Afterload
positive displacement: unaffected by changes in afterload
rotary: flow drops with increased svr
Comparison of Pumps: preload
Positive displacement: passive filling, output follows venous return
Rotary: flow increases with increased VR, but no active suction applied
How do positive displacement pumps propel fluid?
Changing the internal volume of a pumping chamber; compression of a sac/membrane, etc.
What type of flow do positive displacement pumps provide?
What do positive displacement pumps require to produce forward flow?
1 way valves
What is the flow in positive displacement pumps?
Mean BP in positive displacement pumps
Rate in positive displacement pumps
Mean filling pressure in positive displacement pumps
Thoratec PVAD/IVAD has been FDA approved as a BTT since when?
Thoratec PVAD/IVAD provides support for what?
right, left, or both ventricles
BiVAD: ____% of LVADs will need an RVAD
_________ is common after transplant failure, postpartum cardiomyopathy, acute MI, myocardities.
BiVad is used least with what conditions?
idiotpathic CM and ischemic CM
According to the Thoratec Registry, ____% received BiVad support with hybrid RVAD and LVAD or Thoratec BiVAD.
BiVAD has increased ____% since 2000.
What are some preop risk factors for right heart failure?
Hemodynamics- low CI with inc RA pressure not necessarily an idicator of Right heart failure; may improve when LV is unloaded with LVAD
Ability of RV to generate pressure
low pulse pressure with high CVP- indicator of BiVAd
Indicators of BiVAD: Higher prep lab values
Creatinine (normalize within 2-3 weeks after implant of VAD)
Greater transfusion requirements increases ___________ and promotes the development of ________.
PVR; right heart failure
What is common for BiVAD patients? What is it related to?
Post-op bleeding; related to severity of hepatic failure
What is the stroke volume pump chamber?
What is the pump chamber in the Thoratec PVAD/IVAD made of?
How many mechanical valves does the Thoratec PVAD/IVAD use?
2 mechanical valves
What alternates in a thoratec PVAD and IVAD?
positive and negative air pressure by console/ portable driver
How many beats per minute does the thoratec pvad/ivad?
What is the flow in the thoratec pvad/ivad?
1.3- 7.2 L/min
Where is the thoratec pvad/ivad placed?
anterior abdominal wall with cannulas crossing into the chest wall to connect the VAD to the heart and great vessels
External location of Thoratec PVAD/IVAD is suitable for use in smaller patients. What BSA?
> 0.73 m2
Dual Drive Console
TCII approved what year.
Thoratec PVAD/IVAD ideally uses what type of cannulation?
Thoratec Pump considerations
w/o cardioplegia or XC
De-aired via LV apex cannula before conntecting to the VAD
Ultrafiltrate to keep hematocrit greater than 30% (in case clotting factors are needed to assist coagulation)
Describe Anticoagulation for Thoratec.
Chronic Warfarin Anticoagulation
INR= 2.5- 3.5
Starts with heparin- PTT 1.5x baseline until GI function is stable and show low bleeding risk (10-14 days)
Switch to warfarin and ASA
Can a PVAD be used in pediatrics?
When is an IVAD used?
When longer term support is anticipated
When was IVAD approved?
Approved in 2004 by the FDA as a BTT or BTR
IVAD BSA requirement ; Why?
>1.3 m2 b/c of intracorporeal position
How is IVAD different from PVAD?
Polished titanium body- makes it implantable
reduced weight (339 gms vs 417 gms)
Narrower percutaneous leads
9mm vs. 20mm
Heartmate XVE placed in how many patients worldwide?
What type of anticoagulation is needed with the Heartmate XVE?
None, except an antiplatelet agent
What limits thrombogenesis in the Heartmate XVE?
Texture inner surface promotes pseudointimal layer
What's a con of the Heartmate XVE?
Immunologically active; limits transplant candidacy due to increase in immunologic reactivity
What type of pump does the Heartmate XVe use?
Positive displacement pump
What is the Heartmate XVE made out of?
Made of titanium with a polyurethane diaphragm and a pusher plate actuator (which is responsible for producing mechanical energy)
How is the Heartmate XVE powered?
Pneumatically (emergency) or electrically
What do you cannulate in the Heartmate XVE? What type of valve?
LV apex (apical cannula) (dacron conduit with 25 mm porcine valve)
and descending aorta (dacron conduit outflow graft with porcine valve)
How heavy is the driver console in the Heartmate XVE?
9kg driver console
How is the Heartmate XVE powered?
2 batteries (4-7 hours of use)
What is the stroke volume in the Heartmate XVE?
What types of modes does the Heartmate XVE use?
Fixed and Auto
Heartmate XVE: Auto Mode
SV maintained at 97 % full
Flow 4-10 L/min
Heartmate XVE: Fixed Mode
SV depends on filling
Rate is adjusted manually to keep stroke volume between 70-80mL
When do the bearings wear out in the Heartmate XVE?
18-24 months; requires replacement
Heartmate XVE: What percent survival transplant/recovery?
Heartmate XVE: If they survive the first month, they have what percent chance of a successful outcome?
How is the Micromed -Debakey VAD anticoagulated?