Aortic Valve Durability : What’s Predictable Before … Valve...10/8/2019 3 Prosthetic Heart...
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10/8/2019 1 Aortic Valve Durability : What’s Predictable Before The Implant? 1 Lakshmi Prasad Dasi, PhD Department of Biomedical Engineering The Ohio State University September 20 2019 Disclosures Dr. Dasi ▪ Grants: NHLBI; NIBIB; NCAI; AHA; Ohio Patents: Prosthetic Heart valves 2
Transcript of Aortic Valve Durability : What’s Predictable Before … Valve...10/8/2019 3 Prosthetic Heart...
10/8/2019
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Aortic Valve Durability : What’s Predictable Before The Implant?
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Lakshmi Prasad Dasi, PhDDepartment of Biomedical Engineering
The Ohio State University
September 20 2019
Disclosures
Dr. Dasi
▪ Grants: NHLBI; NIBIB; NCAI; AHA; Ohio
Patents: Prosthetic Heart valves
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Today’s Talk Outline• Background and Motivation
– Aortic Valve, TAVR, and durability
• Hypothesis – Careful patient specific planning and predictive modeling may be key to long term durability!
• Learning Goals:– Valve Durability definitions and FDA/ISO standards– Structural valve degeneration, thrombosis and changes in pressure gradient
– Identify patient specific factors bearing on durability
• Summary
Heart Valve Basics• Heart valves regulate flow• Prosthetic heart valves treat native valve
disease– Stenosis or Regurgitation
• Over 280,000 valves implanted world wide• More than 50 valve designs• Heart valve replacement
– ~50% with mechanical heart valves – ~50% with bioprosthetic heart valves including
Trans‐catheter valves
• Complications include• Hemolysis • Platelet activation• Calcification• Thromboembolic events
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Prosthetic Heart Valves• 90,000 valve replacements are implanted in the United States per
year• Approximately half are mechanical valves and half are biological
valves• Exponential growth of TAVI and TMVR valves• Large Market (about 1.4 Billion Dollar / year industry)
1. Pibarot, Phillip, and Jean Dumesnil. "Prosthetic Heart Disease: Changing Concepts in Disease Management." Circulation. 119. (2009): 1034‐1048..
Trans CatheterValves
Prosthetic Heart Valves
• Expanding new technologies
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FDA and ISO Standards• Bioprosthetic Heart Valves
– 200 million cycles or more
• Mechanical Heart Valves
– 600 million cycles or more
Accelerated Wear Testing• 10 to 15 beats per second• Peak back pressure of 100mmHg
Drawbacks of Bioprosthetic Heart Valves
• Lack durability! • Leaflets Calcify over time
1. Pibarot, Phillip, and Jean Dumesnil. "Prosthetic Heart Disease: Changing Concepts in Disease Management." Circulation. 119. (2009): 1034‐1048..
Need reoperation or a valve in valve
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Presented by Danny Dvir EuroPCR 2016
Drawbacks of Bioprosthetic Heart Valves
Aortic Valve Durability
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Freedom from Structural Valve Deterioration: Surgical AVR
Bourguinion et al. Ann Thorac Surg 2015
10-15 years
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So What is Important?• Recognize that TAVI is different compared to SAVR
How predictable is the valve deployment compared to surgical implantation?
The Fluid Mechanics of Transcatheter Heart Valve Leaflet Thrombosis in the Neosinus, Volume: 136, Issue: 17, Pages: 1598-1609, DOI: (10.1161/CIRCULATIONAHA.117.029479)
Angle, commissural alignment, stent interactions
Factors impacting Durability in TAVI• Calcification
– Immune driven
– rate dependent on patient (kidney status), local hemodynamics / shear stresses
– structural stresses
• Thrombosis– Washout driven
– Dependent on hemodynamic and anatomic factors
• How to even detect early degeneration in TAVI?– Carefully monitor Pressure Gradients
– Valve dependent
– Invasive catheterization vs Doppler echo
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Thrombosis
• ‐ How does sinus flow depend on patient and valve specific factors?
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Sinus Washout Neo-Sinus WashoutSinus Vortex
Sinus washout controllable
• Valve dependent sinus flows
• Currently can predict sinus washout, but..
– Patient specific
– 3D modeling required
• Good news: its controllable
• Lacerating open the neo‐sinus can improve washout
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Pressure Gradient – Pressure Recovery
• Accurate gradient assessment key to assess durability in TAVI
• Impact on valve choice!
• Detect stiffening of leaflets from calcification or thrombosis
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Pressure Gradient – Pressure Recovery
• Accurate gradient assessment key to assess durability in TAVI
• Valve and anatomy dependent
• Important for detecting stiffening of leaflets from calcification or thrombosis
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Why is Pressure Gradient and Recovery Valve dependent?
- Leaflet commissural design (flat vs arched)
- Varying tendency to pinwheel if not fully expanded
- Potential implication on durability
- Shear layer dynamics• Concentrated vs
diffused / detached
Hatoum et al. 2018 (JTCVS)
Hatoum et al. 2018 (JTCVS)
Recovery depends on how turbulence dissipates energy
- Curved stent diffuses high Reynolds stresses, but enhances mixing
- No significant difference in energy loss or pressure gradient
- Reynolds stress is the additional and significant stress that arise when blood flow turns turbulent
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Summary
TAVI Durability is
Related to calcification and thrombosis
Important to accurately detect stiffening of leaflets
TAVI Durability is different from SAVR durability because
TAVI deployment is not as controlled as in SAVR
Potential for asymmetry, canting, and presence of neo-sinus
Pressure recovery should be accurately accounted for
Impact on valve choice
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heartvalve.osu.edu
Thank you!!
