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Flashcards in VADs- Exam 2 Deck (109):
1

History: VAD 1930s - Carrell and Lindbergh and Demikhov

Experimented with mechanical support in animal models

2

History: 1953- Gibbon

1st use of CPB
Inability to wean fuelest interested in prolonged mechanical suport in order to promote myocardial recovery

3

History: 1963- Spencer, et. al

Reported using a roller pump to support a patient to recovery
Roller pumps aren't good VADS

4

What are the limitations of roller pumps as VADs?

Tethering, Blood trauma, Adjust pump speeds due to changes in heart pressures

5

History: 1966- DeBakey

1st successful clinical application of a true VAD
Pneumatically driven diaphragm pump
Paracorporeal

6

Describe the paracorporeal setup of DeBakey in 1966?

LA to Axillary ARtery

7

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

8

History: 1960's Klaus, et al.

Introduced the concept of atrial counter pulsation
Rapid systolic unloading of the ventricle with diastolic augmentation

9

What did 1960's Klaus development lead to?

Development of the balloon pump which was developed in 1963 and applied clinically in 1967

10

When was the total artificial heart used in dog model? How long was it supported?

1958
90 minutes

11

1962: TAH Reported survival for how long?

Up to 24 hours

12

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

13

History: TAH: Research continued into the ________.

1980's

14

Who were the first investigators in the world to implant a permanent TAH on 12/2/1982.

University of Utah

15

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

16

When 5 patients received permanent TAH under FDA trial, what was the longest survival?

620 days

17

1985: Where was the first planned TAH implant as a Bridge to Transplant?

Copeland at the University of Arizona

18

BTT

bridge to transplant

19

TAH: Device implanted in __________ had issues with the manufacturer so the FDA withdrew the FDA exemption for implantation. Describe the device.

Tuscon; Syncardia, Cardiowest

20

Who revived the Syncardia, Cardiowest model?

Drs. Olsen and Copeland (Tuscon, AZ)

21

Syncardia was modified and renamed what?

Cardiowest C70

22

Cardiowest 70 received FDA approval as a BTT in _______.

2004

23

____________ provided a stimulus for the development of VADs for support until transplant.

Transplantation

24

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

25

Early 1980's- what happened with transplantation?

Transplanation became a widely applied therapy

26

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

27

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

28

9/1984 - Standford University: Oyer and Colleagues implanted what?

Novacor LVAD

29

Novacor LVAD

1st successful transplant s/p BTT with LVAD
Follow by Hill and colleagues who implanted a Pearce- Donachey pneumatic LVAD

30

1992- Frazier and colleagues

1st to report successful BTT with Thoratec Heartmate IP VAD
(implantable, pneumatic)
restored near normal hemodynamics

31

Pneumatic

containing or operative by air or gas under pressure

32

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

33

1990- Kormos at University of Pittsburg

developed a program to transfer VAD patients to a monitored outpatient setting until transplantation

34

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

35

1994: _________ LVAD was the first FDA approved implantable device for BTT.

Heartmate

36

What are some biological barriers to VAD design?

Blood versus foreign surface
Moving parts
changes to patient's anticoagulation and immune system over time in response to the mechanical pump
Pharmacologic modifications (heparin, coumadin, asa)

37

VADS: Blood vs. Foreign Surface

blood contact surface cannot harm the patient
minimum generation of blood clots

38

VADS: changes to patient's anticoagulation over time

coagulopathy immediately after implantation because of bypass; period of hypercoagulability, returning to baseline

39

What are some indications for VAD?

Bridge to Transplant
Destination Therapy

40

Bridge to Transplant

Worsening hemodynamics despite high level of IV inotropic support and/or vasodilator therapy or refractor arrhythmias

41

Destination Therapy

patients who are not transplant candidates
have an EF less than 25% and NYHA Class IV symptoms despite optimal Therapy

42

What are the contraindications for VADs?

High surgical risk
Recent/evolving stroke
Neurological deficits impairing ability to manage device
Coexisting terminal condition
Abdominal aortic aneurysm (greater than 5cm)
active infection
fixed pulmonary htn
severe pulmonary dysfunction
multisystem organ failure
inability to tolerate anticoagulation
HIT
psychiatric illness
lack of social support
prengancy

43

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

44

What can impact the design of the VAD?

different uses and device requirements

45

VADs: Anatomically compatible

used over large variations in body mass, chest size/shape, abdominal girth, etc.

46

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

47

What are the two different types of VAD pumps?

Positive displacement (usually pneumatic)
Rotary

48

Comparison of pumps: Flow and Pressure

Positive displacement: change volume in the chamber
Rotary: Rotating Impellar

49

Comparison of Pumps: Source of Energy

Positive Displacement: Air pressure/electricity
Rotary: Electricity

50

Comparison of Pumps: Size

Rotary is smaller with a smaller cannula

51

Comparison of Pumps: Prime Volume

Positive Displacement: Large prime volume
Rotary: Smaller prime vol

52

Comparison of Pumps: Flow Ranges

both plagued with thrombosis with decreased flow and hemolysis with increased flow

53

Comparison of Pumps: Afterload

positive displacement: unaffected by changes in afterload
rotary: flow drops with increased svr

54

Comparison of Pumps: preload

Positive displacement: passive filling, output follows venous return
Rotary: flow increases with increased VR, but no active suction applied

55

How do positive displacement pumps propel fluid?

Changing the internal volume of a pumping chamber; compression of a sac/membrane, etc.

56

What type of flow do positive displacement pumps provide?

Pulsatile flow

57

What do positive displacement pumps require to produce forward flow?

1 way valves

58

What is the flow in positive displacement pumps?

5-10 L/min

59

Mean BP in positive displacement pumps

100-150 mmHg

60

Rate in positive displacement pumps

<120 bpm

61

Mean filling pressure in positive displacement pumps

20 mmHg

62

Thoratec PVAD/IVAD has been FDA approved as a BTT since when?

1995

63

Thoratec PVAD/IVAD provides support for what?

right, left, or both ventricles

64

BiVAD: ____% of LVADs will need an RVAD

10

65

_________ is common after transplant failure, postpartum cardiomyopathy, acute MI, myocardities.

BiVAD

66

BiVad is used least with what conditions?

idiotpathic CM and ischemic CM

67

According to the Thoratec Registry, ____% received BiVad support with hybrid RVAD and LVAD or Thoratec BiVAD.

25%

68

BiVAD has increased ____% since 2000.

18%

69

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

70

Indicators of BiVAD: Higher prep lab values

Bilibrubin
Creatinine (normalize within 2-3 weeks after implant of VAD)

71

Greater transfusion requirements increases ___________ and promotes the development of ________.

PVR; right heart failure

72

What is common for BiVAD patients? What is it related to?

Post-op bleeding; related to severity of hepatic failure

73

What is the stroke volume pump chamber?

65 mL

74

What is the pump chamber in the Thoratec PVAD/IVAD made of?

Thoralon polyurethane

75

How many mechanical valves does the Thoratec PVAD/IVAD use?

2 mechanical valves

76

What alternates in a thoratec PVAD and IVAD?

positive and negative air pressure by console/ portable driver

77

How many beats per minute does the thoratec pvad/ivad?

40-110 bpm

78

What is the flow in the thoratec pvad/ivad?

1.3- 7.2 L/min

79

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

80

External location of Thoratec PVAD/IVAD is suitable for use in smaller patients. What BSA?

> 0.73 m2

81

DDC

Dual Drive Console

82

TCII approved what year.

2003

83

Thoratec PVAD/IVAD ideally uses what type of cannulation?

Bicaval

84

Thoratec Pump considerations

Normothermic
w/o cardioplegia or XC
LV vented
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)

85

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

86

Can a PVAD be used in pediatrics?

yes.

87

When is an IVAD used?

When longer term support is anticipated

88

When was IVAD approved?

Approved in 2004 by the FDA as a BTT or BTR

89

IVAD BSA requirement ; Why?

>1.3 m2 b/c of intracorporeal position

90

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

91

Heartmate XVE placed in how many patients worldwide?

5000 patients

92

What type of anticoagulation is needed with the Heartmate XVE?

None, except an antiplatelet agent

93

What limits thrombogenesis in the Heartmate XVE?

Texture inner surface promotes pseudointimal layer

94

What's a con of the Heartmate XVE?

Immunologically active; limits transplant candidacy due to increase in immunologic reactivity

95

What type of pump does the Heartmate XVe use?

Positive displacement pump

96

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)

97

How is the Heartmate XVE powered?

Pneumatically (emergency) or electrically

98

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)

99

How heavy is the driver console in the Heartmate XVE?

9kg driver console

100

How is the Heartmate XVE powered?

2 batteries (4-7 hours of use)
External controller

101

What is the stroke volume in the Heartmate XVE?

83 mL

102

What types of modes does the Heartmate XVE use?

Fixed and Auto

103

Heartmate XVE: Auto Mode

SV maintained at 97 % full
Flow 4-10 L/min

104

Heartmate XVE: Fixed Mode

SV depends on filling
Rate is adjusted manually to keep stroke volume between 70-80mL

105

When do the bearings wear out in the Heartmate XVE?

18-24 months; requires replacement

106

Heartmate XVE: What percent survival transplant/recovery?

65%

107

Heartmate XVE: If they survive the first month, they have what percent chance of a successful outcome?

85%

108

How is the Micromed -Debakey VAD anticoagulated?

Coumadin

109

Heartmate II: Flow is an estimate that is not accurate when flow is less than what?

3 L/min