9. VADs- Exam 2 Flashcards
year?
Carrell and Lindbergh and Demikhov
-Experimented with mechanical support in animal models
1930s
Year?
Gibbon
-1st use of CPB
-Inability to wean fueled interest in prolonged mechanical support in order to promote myocardial recovery
1953
year?
Spencer, et al.
-Reported using a roller pump to support a patient to recovery
-Roller pumps aren’t good VADS
1963
why are roller pumps not good VADs
Tethering
Blood trauma
Adjust pump speeds due to changes in heart pressures
year?
DeBakey
-1st successful clinical application of a true VAD
-Pneumatically driven diaphragm pump
-Paracorporeal= LA to Axillary Artery
-Supported for 10 days, weaned and discharged
1966
year?
Klaus, et al.
-Introduced the concept of atrial counter pulsation
–Rapid systolic unloading of the ventricle with diastolic augmentation
1960s
what did the introduction of atrial counter pulsation by Klaus in the 1960s lead to
Lead to the development of the balloon pump which was developed in 1963 and applied clinically in 1967
year?
Total artificial heart was used in a dog model
-Supported for 90 min
1958
year?
Reporting survival up to 24 hours with TAH
1962
year?
Cooley
-1st used a TAH to temporarily support a patient to transplant
-Implanted the “Liotta Heart” which was a pneumatic device
-Supported the patient for 64 hours
1969
who was the first in the world to implant a permanent TAH on 12/2/1982.
University of Utah investigators
for the 1st implanted TAH by the university of utah: what was the name of the device? what doctor performed the procedure? name of the patient and their condition? how long did it support the patient?
- Jarvik 7 TAH
- performed by Dr. William DeVries
- Implanted into Dr. Barney Clark, 61 yo dentist with end stage idiopathic dilated cardiomyopathy. Died of complications from aspiration pneumonia, Renal failure, colitis with septicemia.
- Was supported for 112 days.
how many patients received permanent TAH under FDA trial and what was the Longest survival
5 patients
620 days
who did the 1st planned TAH implant as a Bridge to Transplant (BTT)? year?
1985 – Copeland at the University of Arizona
what happened to the Syncardia, Cardiowest TAH from Tucson, AZ?
Device implanted in Tucson had issues with the manufacturer, so the FDA withdrew the FDA exemption for implantation
after the FDA withdrew the FDA exemption for implantation of the Syncardia, Cardiowest TAH, what happened to it
Drs. Olsen and Copeland revived the model
Modified and renamed – Cardiowest C70
Received FDA Approval as a BTT in 2004
year? Norman -Device used for 5 days of support -Intracorporeal pneumatic device -Patient died of multi-organ system failure s/p transplant
1978
when did Transplantation became a widely applied therapy.
early 1980s
in the earlt 1980s when Transplantation became a widely applied therapy–how many patients died on the list
30%
year?
NIH sent out request for proposals
-To develop an “implantable, integrated, electrically powered left heart assist system” that could be used on a long term basis and allow extensive patient mobility
1980
year?
Stanford University
-Oyer and Colleagues – Implanted the Novacor LVAD
-1st successful transplant s/p BTT with LVAD
9/1984
who followed Stanford University’s 1st successful transplant s/p BTT with LVAD
Followed by Hill and colleagues who implanted a Pearce-Donachey pneumatic LVAD
year? Frazier and colleagues -1st to report successful BTT with Thoratec Heartmate IP VAD -Implantable pneumatic -Restored near normal hemodynamics
1992
what were the limitations to frazier and colleagues BTT with Thoratec Heartmate IP VAD
- Devices dependent on large consoles for power and controller function
- Patients confined to hospital until transplantation despite being fully ambulatory
year?
Kormos at University of Pittsburg
-Developed a program to transfer VAD patients to a monitored outpatient setting until transplantation
1990
year?
Frazier at Texas Heart Institute
-First to use an untethered vented electric LVAD for long term support
1991
describe the untethered vented electric LVAD Frazier did at Texas Heart Institute in 1991
Battery operated Heartmate VE
500 days of support
Patient died of embolic cerebral vascular accident
year?
FDA sponsored several multi-institution trials of assist devices as bridge to transplant and bridge to recovery
1990s
year?
Heartmate LVAD was the first FDA approved implantable device for bridge to transplant
1994
what are some
- Blood versus Foreign surface
- Moving parts
- Changes to patients anticoagulation and immune system over time in response to the mechanical pump
- Pharmacologic modifications
why is Blood versus Foreign surface a Biological Barriers to VAD design
Blood contact surface cannot harm the patient
Minimum generation of blood clots
why is Changes to patients anticoagulation and immune system over time in response to the mechanical pump a Biological Barriers to VAD design
Coagulopathy immediately after implantation b/c of CPB
Period of hypercoagulability
Returning to baseline
why is Pharmacologic modifications a Biological Barriers to VAD design
(Heparin, Coumadin, ASA)
Need to anticoagulate on some level
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
name 5 contraindications for VADs
there are 14 on slide 17
- Neurological deficits impairing the ability to manage device
- Coexisting terminal condition
- Abdominal aortic aneurysm (greater than 5 cm)
- Active infection
- Inability to tolerate anticoagulation
name 5 design musts
there are more on slide 18
- Structurally stable in a corrosive saline environment
- Operate continuously w/o regular maintenance for years.
- Cannot fail under increased stress conditions
- Reduce power requirements to save battery life
- Must be efficient – reduce heat waste.
Positive Displacement VS Rotary Pump:
Flow and Pressure
Positive Displacement: Change volume in the chamber
Rotary: Rotating Impeller
Positive Displacement VS Rotary Pump:
Source of Energy
Positive Displacement: Air pressure/ Electricity
Rotary: Electricity
Positive Displacement VS Rotary Pump:
Size
Rotary is smaller with a smaller cannula
Positive Displacement VS Rotary Pump:
Prime Volume
Positive Displacement: Large Prime Volume
Rotary: Smaller Prime Volume
Positive Displacement VS Rotary Pump:
Flow Ranges
Both plagued with thrombosis with decreased flow and hemolysis with increased flow
Positive Displacement VS Rotary Pump:
Afterload
Positive Displacement: Unaffected by changes in afterload
Rotary: Flow drops with increased SVR
Positive Displacement VS Rotary Pump:
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 work
- Propels fluid by changing the internal volume of a pumping chamber. (Compression of a sac/membrane_
- Provides pulsatile flow
- Requires 1 way valves to produce forward flow
Positive Displacement pumps: flow
5-10 liters per minute
Positive Displacement pumps: mean BP
100-150 mmHg
Positive Displacement pumps: rate (bpm)
<120 bpm
Positive Displacement pumps: Mean filling pressure
appx 20mmHg
Thoratec PVAD/IVAD has been approved by the FDA for a BTT device since what year
1995
Thoratec PVAD/IVAD provides support for what
Provides support for the right, left or both ventricles
what % of of LVADs will need an RVAD
10%
a BiVAD is common after what?
transplant failure postpartum Cardiomyopathy Acute MI Myocarditis Used least with idiopathic CM and Ischemic CM
According to the Thoratec Registry, __% received BiVAD support with hybrid RVAD and LVAD or Thoratec BiVAD
25%
BiVAD use has increased __% since 2000
18%
Preop risk factors for Right Heart Failure include?
- Hemodynamics – Low CI with inc. RA pressure not necessarily an indicator of Rt. 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 include what 6 things
- Early insertion of LVAD before significant major organ dysfunction
- Higher pre-op bilirubin
- Higher pre-op creatinine
- Emergent Implant
- Intraop Bleeding
- Greater transfusion requirements increases pulmonary vascular resistance and promotes the development of right heart failure.
why is Early insertion of LVAD before significant major organ dysfunction an indicator for a BiVAD
Less likely to need RVAD too
why is Higher pre-op creatinine an indicator for a BiVAD
Normalize w/in 2-3 weeks after implant of VAD
why is Post op bleeding is common for BiVAD patients
Related to the severity of hepatic failure
Thoratec PVAD/IVAD: internal mechanics
- 65 mL Stroke volume pump chamber
- Made of Thoralon Polyurethane
- 2 mechanical valves
- Alternate positive and negative air pressure by console/ Portable driver
Thoratec PVAD/IVAD: bpm and lpm
Beats 40-110 bpm
Flow is 1.3-7.2 Lpm
Thoratec PVAD/IVAD: is placed where?
- Placed in the anterior abdominal wall with cannulas crossing into the chest wall to connect the VAD to the heart and great vessels.
- External location is suitable for use in smaller patients
- BSA >0.73m2
what are the 6 Pump considerations for Implant: Thoratec PVAD/IVAD
- Ideally use bicaval cannulation
- Normothermic
- 0w/o cardioplegia or XC
- LV Vented
- De-aired via LV Apex cannula before connecting to the VAD
- Ultrafiltrate to keep hematocrit greater than 30% (in case clotting factors are needed to assist coagulation)
describe the Anticoagulation for Thoratec PVAD/IVAD
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
Worldwide survival from implant to transplant/ recovery:
RVADs %
BIVADs %
LVADs %
- 2% of RVADs
- 6% of BIVADs
- 8% of LVADs
why can the PVAD be used in pediatrics
due to being paracorporeal
how many peds patients as of 1/2005 have received a PVAD
150
what are the adverse events to the PVAD
Thromboembolism
Hemorrhage (more common than in adults)
what is the % survival rate for PVADs
68.4%
Intracorporeal VAD (or Implantable VAD)=
Used when longer term support is anticipated
Approved in 2004 by the FDA as a BTT or BTR
BSA >1.3m2 b/c of intracorporeal position
how are IVADs different from PVADs
Polished Titanium Body – makes it implantable Reduced weight 339gms vs. 417 gms Narrower Percutaneous leads 9mm vs. 20mm
the Heartmate XVE has been placed in how many patients world wide
5000
benefits of the Heartmate XVE
- Textured inner surface
- Circulatory assistance without anticoagulation except an antiplatelet agent
- Promotes pseudointimal layer= Limits thrombogenesis
cons of the Heartmate XVE
Immunologically active
-Limit transplant candidacy due to increase in immunologic reactivity.
describe the mechanics of the Heartmate XVE
- Positive displacement pump
- Made of titanium with a polyurethane diaphragm and a pusher plate actuator (which is responsible for producing mechanical energy).
- Powered pneumatically: 9kg driver console, batteries (4-7hours of use)
where is the Heartmate XVE cannulated
- Cannulate LV Apex (apical cannula)
- Dacron conduit with 25mm porcine valve - Cannulate ascending aorta
- 20mm Dacron outflow graft with porcine valve
Heartmate XVE: stroke volume
83 ml
Heartmate XVE: fixed vs auto mode
- Auto - SV maintained at 97% full. Flow – 4-10 Lpm
2. Fixed – stroke volume depends upon filling. Rate is adjusted manually to keep stroke volume between 70-80mL
describe the pseudointima promoted by the Heartmate XVE
- Thin layer of biologic matrix that resists thrombogenesis
- Composed of cellular elements, collagen, and cells derived from circulating progenitor cells.
- Immunologically active microenvironment
- Heightened susceptibility to opportunistic infections
describe the implantation of Heartmate XVE (6)
- Dacron grafts must be pre-clotted
- Placed intraperitoneal or in peritoneal pocket in left upper quadrant. Must go through diaphragm with cannulas
- AI, MS and PFOs must be corrected at implantation
- Requires CPB, No cardioplegia or cooling
- BSA: >1.5m2
- Anticoagulation – ASA only
when do the bearing wear out on the Heartmate XVE
18-24 months
with the Heartmate XVE, Vent filters are changed regularly and sent to Thoratec for evaluation. Why?
- Test for signs of motor dust
- Excessive motor dust is an indication of bearing wear
Heartmate XVE: BTT Survival
__% survive to transplant/ recovery. If they survive the first month, they have an __% chance of a successful outcome.
65%
85%
- DeBakey and Noon developed a small axial flow LVAD that went into clinical trials in ____
- Followed by Jarvik 2000 in ____
- Nimbus/ HMII axial flow pump in ____
1998
1999
2000
how do Rotary pumps work
Uses rotating impellers to propel blood forward
Supported with bearings
Powered by spinning shaft/ magnetic forces
describe the Micromed
- Mini electromagnetically actuated titanium pump with ball and cup bearings weighing less than 93 grams
- Has Elbow shaped inflow cannula, pump housing unit, dacro outflow, ultrasonic flow probe encircling outflow graft, flexible drive line to controller
describe the development of the Micromed by Debakey
- Collaboration between NASA engineers and Dr. DeBakey and Dr. George Noon
- Established in 6/1996 with NASA license
- Implanted in 1998 in Europe
what is used for anti-coagulation for the micromed
coumadin
what are some management issues of micromed
- Fibrin deposition on Impellar leading to thrombus formation=Could lead to pump stoppage or Back flow
- Treatment is TPA and Heparin
- Possible device change out
when was the Heartmate II developed? describe the collaboration
early 1990s
Collaboration between engineers at Nimbus, Inc and Univeristy of Pittsburg
Initially developed thru NIH grant
Heartmate II=
Axial flow device (2nd generation VAD)
Reduced size/ weight compared to XVE
describe the internal mechanics of the heartmate II
- Electric Motor
- Rotor spins within magnetic field on inlet and outlet of bearings-Only moving part of pump
- Dacron grafts may require pre-clotting
with the heartmate II, Flow is an ESTIMATE and is not accurate under what floe
3 lpm
where is the heartmate II implanted
Implant is below the L. Costal Margin under the rectus abdominus muscle
Leave LV Apex to diaphragm to pump
when was the heartmate II approved as a Destination Therapy device.
1/20/2010
heartmate II 1 and 2 year survival %
Survival to 1 year was 68%
Survival to 2 years was 58%
what the longest duration of use for the heartmate II
6+ years (patient still on device)
bsa range for the heartmate II
BSA: 1.14-3.16m2
heartmate II: ___% have either been transplanted, recovered or supported to 6 months
90%
when did the Randomized Evolution of Mechanical Assistance for the Treatment of Congestive Heart Failure (REMATCH) Trial start
1996
REAMATCH trial=
- Provided evidence for FDA to approve the device for Destination Therapy in 2002
- Medicare approved device for permanent implantation in 2003
- Set the stage for multiple clinical trials of other devices as permanent therapy for heart failure
VentrAssist=
3rd generation device (from Australia)
device development stopped due to lack of company funds
Heartware HVAD=
Small continuous flow rotary pump with a centrifugal and non-contact bearing design
- First human implant – 2006
- Approved November 20, 2012
where is the heartware HVAD implanted
Placed within the pericardial cavity at the apex of the LV
-No need for abdominal pocket
DuraHeart LVAS=
By Terumo Heart, Inc.: 2nd gen
Continuous-flow rotary pump
DuraHeart LVAS flow rate and motor speed
Flow rates of 2-8lpm
motor speeds of 1200-2400rpm
Levacor VAD=
By WorldHeart Corp.
-Bearingless centrifugal pump with an impeller competely magnetically levitated
where is the Levacor VAD implanted
Implanted in small subcostal, pre-peritoneal space
Abiomed Impella 2.5/5.0=
Intracatheter VAD
Can pump 2.5/5.0 Lpm
Pulls blood from the LV tip to the aorta.
First completely self-contained replacement heart=
Abiomed Abiocor
VAD Capable of pumping 12 liters per minute=
Abiomed Abiocor
Tandem Heart=
10cc hydrodynamic centrifugal pump
- Integrated motor
- 21 pounds
- 1 hour backup battery
Tandem Heart flows
8LPM flow
Cannula dependent
-Tandem Heart transeptal cannula and 17fr arterial cannula = 5LPM
Syncardia TAH=
- After implant and stable, patient is moved to 1A , top of the list
- 6 moving parts – inflow and outflow valves, and the diaphragm
- All electronics outside the body
- Utilizes a pneumatic driver
syncardia TAH flows
9.5 liters per minute through both ventricles
Berlin Heart=
December 16, 2011 – FDA approved Berlin Heart (Excor Pediatric System)