“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