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“Development of an Axial Flow Left Ventricular Assist Device (LVAD) from Inception
to Clinical Application”
George P. Noon, MD
Professor of Surgery
Chief, Division of Transplant & Assist Devices
Meyer-DeBakey Chair of Investigative Surgery
Pumps & Pipes
0
100,000
200,000
300,000
400,000
500,000
600,000
Dis
char
ges
Women
Men
The number of heart failure hospitalizations is increasing in both men and women
Heart Failure Hospitalizations
CDC/NCHS: Hospital discharges include patients both living and dead.AHA Heart and Stroke Statistical Update 2001
CIRCULATORY ASSIST DEVICESThe Methodist Hospital/Baylor College of Medicine
IABP (1971-2001) 2880Roller Pump (1971-1988) 94DeBakey VAD (1963-1966) 6Liotta, Hall, Crawford (1963) 1Symbion/Jarvik (1987-1989) 4Novacor® LVAS (1987-2005) 53BioMedicus® (1986-2005) 274MicroMed DeBakey-Noon VAD® (2000-2005) 36 Thoratec® LVAD (1998-2005) 31 HeartMate® VAD (2001-2005) 17Abiomed® BVS 5000 (2002-2004) 7Abiomed® AB 5000 (2003-2004) 1
Biomedical Engineering
Role in Development of
Total Artificial Heart and Assist Pumps
Biomedical Engineering
• Pump Design
• Blood Contact Surface
• Controller
• Power Source
Biomedical EngineeringBlood trauma and clotting
• Blood contacting surface• Duration of contact• Stasis• Cavitation• Heat• Shear
Biomedical Engineering
Pump Testing•Mock Loop
•Animal
•Human
First NASA Axial Flow PrototypeTwo rotating components
NASA - Ames Research Center
Flow Field inside impeller
· Minimize hemolysis
· Increase efficiency
· Provide effective washout
Geometry from Johnson Space Center
Licensed NASA Blood Pump(1996)
Hemolysis Test Setup
Red Cells
Hemolyzed Red Cells
2½ year bench study demonstrated no significant bearing wear
35 clinical pumps returned for evaluation - no evidence of bearing wear
Bearing Wear Studies performed by Marconi
2. Titanium construction: 95 Grams
4. Speed: 7,500 - 12,500 RPM
1. Continuous, axial flow pump
3. Flow rates: 10+ liters/minute
5. Technology licensed from NASA
The DeBakey-Noon VAD
Schematic Illustration of the DeBakey VAD
Bovine tests at Baylor College of Medicine, Texas A&M
Ex-Vivo
In-Vivo
Novacor
HeartMate
DeBakey-Noon VAD
Device Comparison
DeBakey VAD® and DeBakey VAD Child
ControllerControllerPumpPump
Patient Patient Home Home Support Support SystemSystem
Data Data Acquisition Acquisition SystemSystem
Result: MicroMed DeBakey VAD® System
DeBakey-Noon VAD®
Patient Ergonomics
Comparative VAD Space Requirements
HeartMate® XVE LVAD
Adult Male
DeBakey VAD ®
6 year old girl
DeBakey VAD® ImplantationsMore than 110 years of cumulative patient experience
Total Patients – 437• Average support duration – 106 days
• 61 patients > 180 days
• Longest support duration – 841+ days
International• 286 Patients implanted
As of October 2007
United States• 151 Patients implanted
Physiologic Blood FlowSystemic Pulmonary
Textbook of Medical Physiology, Arthur C. Guyton
0
30
60
90
120
150
180
-4 -2 0 2 4 6 8 10
Flow (L/min)
De
lta
Pre
ss
ure
(m
mH
g)
7.5 kRPM
10.0 kRPM
12.5 kRPM
Speed, Flow and Delta Pressure
0
1
2
3
4
5
6
7
8
7.5 8.5 9.5 10.5 11.5 12.5
Speed, kRPM
Flo
w,
L/m
in
Hypoperfusion
Operating Range
Potential for Suction
Flow Characteristics
Arterial Pressure - Green VAD Flow - Yellow
10
0-40
140
Pump speed VAD flow (kRPM) (L/min)
OFF -2.0
7600 2.3
8900 4.5
10,800 5.6
10
0-40
140
10
0-40
140
10
0-40
140
MilanMilan
Smaller Patients PossibleMiniaturization benefits large and small patients.
MilaMilann
ZurichZurich
MuensteMuensterr
Continuous Flow Provides Adequate Circulatory Support
1. Resuscitation 2. Rehabilitation3. Maintenance
Results - CFD
Baseline Rear Hub Washout Final Rear Hub Washout
Increase gap shows an improved circulation pattern in the rear hub
Results - CFD
Baseline Diffuser Inlet Angle Final Diffuser Inlet Angle
Flow is entering the diffuser correctly on the pressure side of the blade indicating a small “angle of attack.”
EU Pediatric Device• Required CFD of the inflow cannula
• Results demonstrated pediatric inflow cannula with 2 L/min washed at least as good as adult cannula with 4 L/min
Results – Flow VisualizationResults from increased gap:
Less turbulence in the diffuser
Baseline Design 2.0x Gap
Results – Hemolysis at 4 L/min
INCREASING THE GAP WITHOUT MODIFYING THE DIFFUSER INLET ANGLE DEMONSTRATES A TREND TO SLIGHLY HIGHER HEMOLYSIS
2.0X gapBaseline
Baseline 2.0X gap, 32°
TUNING THE DIFFUSER INLET ANGLE WITH THE LARGER GAP DEMONSTRATES A TREND OF HEMOLYSIS LOWER THAN THE BASELINE VALUE; HOWEVER, THERE IS NO STATISTICAL DIFFERENCE IN HEMOLYSIS BETWEEN THE BASELINE AND FINAL DESIGN
N.I.H. = 0.006 N.I.H. = 0.014
N.I.H. = 0.009 N.I.H. = 0.006
X2 Pump Design
½ cm shorter intra-ventricular and 1cm shorter extra-ventricular length for improved anatomical fitting
Smoother inlet flare for improved blood flow into the pump
Seamless connection to pump housing for improved blood flow
Smaller flow probe cover
Titanium ring integral to gelatin sealed graft for easy, leak-free assembly
On the horizon…
Clinical Benefits of theMicroMed DeBakey-Noon VAD
Size Surgeon Patient
Implant Less Awareness Explant Drive Line Smaller Patients
NoiselessDevice Infection 5%Adequate Circulatory SupportLess Expensive
Conclusion
1. Increasing incidence of heart failure2. Transplantation limited by donor
supply3. Cardiac assist devices increasingly
used as Bridge to Transplant Bridge to Recovery Destination Therapy