Influence of Slippery Pacemaker Leads on Lead-Induced Venous Occlusion

Introduction

Introduction

! Pacemakers are used to treat arrhythmias.! Pacemaker implantation: between 1993-2009, 2.9 M patients in US! Complications: Infection, haemothorax, lead dislodgement, lead

failure, venous occlusion...! Venous occlusion: 15-30% for adults and 20% for children

! Symptomatic: 1-3%! Challenges arise with system revision or upgrade.

http://www.nhlbi.nih.gov

Stanford University Introduction 2 / 9

Introduction

! Does lead size matter? Maybe.

! Small-diameter lead: increased rate of lead failure

! Simulations show flow stasis is concentrated around leads.! What if slippery?

! Pitcher plant inspired omniphobic surface coating (SLIPS)

Leslie et al., Nature Biotechnology, 2014

Stanford University Introduction 3 / 9

Computational Approach

r · u = 0

uk = �n · � · (I� nn)/µ

@⌧

@t+ u ·r⌧ �r · r⌧ = H

⇢

✓@u

@t+ u ·ru

◆= r · �

Methods

! Navier-Stokes equations:

ρ(u,t + u · ∇u) − ∇ · σ = 0, (1)

∇ · u = 0, (2)

where σ = −pI + µ(∇u + ∇(u)T ).! Slip boundary conditions:

n · u = 0 on Γslip, (3)

t · σ(u, p) · n = βt · u on Γslip, (4)

b · σ(u, p) · n = βb · u on Γslip (5)

! Slip length: Lslip = µβ .

! Implemented in Simvascular package! Stabilized finite element formulation (SUPG),! Linear finite element for space discretization! Generalized α method for time integration

Stanford University Methods 4 / 9

Validation

Eccentric Cylinders

Eccentric lead

! Three positions are simulated: h = 0.55, 0.41 and 0.26 cm.

! Slippery coating reduces flow stasis between lead and vessel wall.

h

Stanford University Results 7 / 9

Eccentric lead

! Three positions are simulated: h = 0.55, 0.41 and 0.26 cm.

! Slippery coating reduces flow stasis between lead and vessel wall.

h

Stanford University Results 7 / 9

Eccentric lead

! Three positions are simulated: h = 0.55, 0.41 and 0.26 cm.

! Slippery coating reduces flow stasis between lead and vessel wall.

h

Stanford University Results 7 / 9

Eccentric lead

! Three positions are simulated: h = 0.55, 0.41 and 0.26 cm.

! Slippery coating reduces flow stasis between lead and vessel wall.

h

Stanford University Results 7 / 9

Eccentric lead

! Three positions are simulated: h = 0.55, 0.41 and 0.26 cm.

! Slippery coating reduces flow stasis between lead and vessel wall.

h

Stanford University Results 7 / 9

Patient-specific Simulation

Conclusions �

�

Leslie et al., Nature Biotechnology, 2014

1. Slippery surfaces 2. Lead-induced occulsions

3. Simulation and comparison 4. Patient specific modeling

Stanford University Conclusions 9 / 9

Conclusions �

�

Leslie et al., Nature Biotechnology, 2014

1. Slippery surfaces 2. Lead-induced occulsions

3. Simulation and comparison 4. Patient specific modeling

Stanford University Conclusions 9 / 9

Anatomy realistic cases

! A 3-4 year old patient (pulsatile inflow, resistance outlet)! Residence time: ∂τ

∂t + u · ∇τ − ∇ · κ∇τ = H (Esmaily Moghadamet al.,Phys Fluids, 2013)

AB

C

noslip slip

noslip slipnoslip slip

Vel

RT

Vel

RT

Vel

RT

Stanford University Results 8 / 9

Anatomy realistic cases

! A 3-4 year old patient (pulsatile inflow, resistance outlet)! Residence time: ∂τ

∂t + u · ∇τ − ∇ · κ∇τ = H (Esmaily Moghadamet al.,Phys Fluids, 2013)

AB

C

noslip slip

noslip slipnoslip slip

Vel

RT

Vel

RT

Vel

RT

Stanford University Results 8 / 9

Anatomy realistic cases

! A 3-4 year old patient (pulsatile inflow, resistance outlet)! Residence time: ∂τ

∂t + u · ∇τ − ∇ · κ∇τ = H (Esmaily Moghadamet al.,Phys Fluids, 2013)

AB

C

noslip slip

noslip slipnoslip slip

Vel

RT

Vel

RT

Vel

RT

Stanford University Results 8 / 9

Concentric lead

! Analytical solution is given by

v(r) = Q(R2

0−R2

i)π

×1+4c ln(r/R0)−(r/R0)2

1−4c[1/2+b2 ln b/(1−b2)]−(1+b2)/2 , where

b = Ri/Ro, c = b(1−b2+2bλ)4(λ−b ln b) , λ =

Lslip

Ro.

! Simulation setting: Q = 16cc/s, Ro = 0.55cm, Ri = 0.117cm

Stanford University Results 6 / 9

Concentric lead

! Analytical solution is given by

v(r) = Q(R2

0−R2

i)π

×1+4c ln(r/R0)−(r/R0)2

1−4c[1/2+b2 ln b/(1−b2)]−(1+b2)/2 , where

b = Ri/Ro, c = b(1−b2+2bλ)4(λ−b ln b) , λ =

Lslip

Ro.

! Simulation setting: Q = 16cc/s, Ro = 0.55cm, Ri = 0.117cm

Stanford University Results 6 / 9

Concentric lead

! Analytical solution is given by

v(r) = Q(R2

0−R2

i)π

×1+4c ln(r/R0)−(r/R0)2

1−4c[1/2+b2 ln b/(1−b2)]−(1+b2)/2 , where

b = Ri/Ro, c = b(1−b2+2bλ)4(λ−b ln b) , λ =

Lslip

Ro.

! Simulation setting: Q = 16cc/s, Ro = 0.55cm, Ri = 0.117cm

Stanford University Results 6 / 9

�/R0 = 10

�/R0 = 1

�/R0 = 0.1�/R0 = 0

V [cm/s]

S. Bhatia, D. Obenauf, O. S. Pak Department of Mechanical Engineering

Santa Clara University

W. Yang, M. Esmaily-Moghadam, J. Feinstein Department of Pediatric Cardiology and Mechanical Engineering

Stanford University

Introduction

! Pacemakers are used to treat arrhythmias.! Pacemaker implantation: between 1993-2009, 2.9 M patients in US! Complications: Infection, haemothorax, lead dislodgement, lead

failure, venous occlusion...! Venous occlusion: 15-30% for adults and 20% for children

! Symptomatic: 1-3%! Challenges arise with system revision or upgrade.

http://www.nhlbi.nih.gov

Stanford University Introduction 2 / 9

Introduction

! Pacemakers are used to treat arrhythmias.! Pacemaker implantation: between 1993-2009, 2.9 M patients in US! Complications: Infection, haemothorax, lead dislodgement, lead

failure, venous occlusion...! Venous occlusion: 15-30% for adults and 20% for children

! Symptomatic: 1-3%! Challenges arise with system revision or upgrade.

http://www.nhlbi.nih.gov

Stanford University Introduction 2 / 9

Introduction

! Pacemakers are used to treat arrhythmias.! Pacemaker implantation: between 1993-2009, 2.9 M patients in US! Complications: Infection, haemothorax, lead dislodgement, lead

failure, venous occlusion...! Venous occlusion: 15-30% for adults and 20% for children

! Symptomatic: 1-3%! Challenges arise with system revision or upgrade.

http://www.nhlbi.nih.gov

Stanford University Introduction 2 / 9

Introduction

! Pacemakers are used to treat arrhythmias.! Pacemaker implantation: between 1993-2009, 2.9 M patients in US! Complications: Infection, haemothorax, lead dislodgement, lead

failure, venous occlusion...! Venous occlusion: 15-30% for adults and 20% for children

! Symptomatic: 1-3%! Challenges arise with system revision or upgrade.

http://www.nhlbi.nih.gov

Stanford University Introduction 2 / 9

Introduction

! Pacemakers are used to treat arrhythmias.! Pacemaker implantation: between 1993-2009, 2.9 M patients in US! Complications: Infection, haemothorax, lead dislodgement, lead

failure, venous occlusion...! Venous occlusion: 15-30% for adults and 20% for children

! Symptomatic: 1-3%! Challenges arise with system revision or upgrade.

http://www.nhlbi.nih.gov

Stanford University Introduction 2 / 9

Methods

! Navier-Stokes equations:

ρ(u,t + u · ∇u) − ∇ · σ = 0, (1)

∇ · u = 0, (2)

where σ = −pI + µ(∇u + ∇(u)T ).! Slip boundary conditions:

n · u = 0 on Γslip, (3)

t · σ(u, p) · n = βt · u on Γslip, (4)

b · σ(u, p) · n = βb · u on Γslip (5)

! Slip length: Lslip = µβ .

! Implemented in Simvascular package! Stabilized finite element formulation (SUPG),! Linear finite element for space discretization! Generalized α method for time integration

Stanford University Methods 4 / 9

Methods

! Navier-Stokes equations:

ρ(u,t + u · ∇u) − ∇ · σ = 0, (1)

∇ · u = 0, (2)

where σ = −pI + µ(∇u + ∇(u)T ).! Slip boundary conditions:

n · u = 0 on Γslip, (3)

t · σ(u, p) · n = βt · u on Γslip, (4)

b · σ(u, p) · n = βb · u on Γslip (5)

! Slip length: Lslip = µβ .

! Implemented in Simvascular package! Stabilized finite element formulation (SUPG),! Linear finite element for space discretization! Generalized α method for time integration

Stanford University Methods 4 / 9

Methods

! Navier-Stokes equations:

ρ(u,t + u · ∇u) − ∇ · σ = 0, (1)

∇ · u = 0, (2)

where σ = −pI + µ(∇u + ∇(u)T ).! Slip boundary conditions:

n · u = 0 on Γslip, (3)

t · σ(u, p) · n = βt · u on Γslip, (4)

b · σ(u, p) · n = βb · u on Γslip (5)

! Slip length: Lslip = µβ .

! Implemented in Simvascular package! Stabilized finite element formulation (SUPG),! Linear finite element for space discretization! Generalized α method for time integration

Stanford University Methods 4 / 9

Anatomy realistic cases

! A 3-4 year old patient (pulsatile inflow, resistance outlet)! Residence time: ∂τ

∂t + u · ∇τ − ∇ · κ∇τ = H (Esmaily Moghadamet al.,Phys Fluids, 2013)

AB

C

noslip slip

noslip slipnoslip slip

Vel

RT

Vel

RT

Vel

RT

Stanford University Results 8 / 9

Concentric lead

! Analytical solution is given by

v(r) = Q(R2

0−R2

i)π

×1+4c ln(r/R0)−(r/R0)2

1−4c[1/2+b2 ln b/(1−b2)]−(1+b2)/2 , where

b = Ri/Ro, c = b(1−b2+2bλ)4(λ−b ln b) , λ =

Lslip

Ro.

! Simulation setting: Q = 16cc/s, Ro = 0.55cm, Ri = 0.117cm

Stanford University Results 6 / 9

�/R0 = 0

�/R0 = 0.2

�/R0 = 1

No-slip Slippery

Anatomy realistic cases

! A 3-4 year old patient (pulsatile inflow, resistance outlet)! Residence time: ∂τ

∂t + u · ∇τ − ∇ · κ∇τ = H (Esmaily Moghadamet al.,Phys Fluids, 2013)

AB

C

noslip slip

noslip slipnoslip slip

Vel

RT

Vel

RT

Vel

RT

Stanford University Results 8 / 9

Anatomy realistic cases

! A 3-4 year old patient (pulsatile inflow, resistance outlet)! Residence time: ∂τ

∂t + u · ∇τ − ∇ · κ∇τ = H (Esmaily Moghadamet al.,Phys Fluids, 2013)

AB

C

noslip slip

noslip slipnoslip slip

Vel

RT

Vel

RT

Vel

RT

Stanford University Results 8 / 9

The influence of a slippery hydrodynamic condition on pacemaker lead surface is evaluated in idealized and patient-specific scenarios.

The slippery surface condition reduces the residence time in close proximity of the lead, suggesting its possibility of mitigating risks of lead-induced thrombosis.

References:

Introduction

! Does lead size matter? Maybe.

! Small-diameter lead: increased rate of lead failure

! Simulations show flow stasis is concentrated around leads.! What if slippery?

! Pitcher plant inspired omniphobic surface coating (SLIPS)

Leslie et al., Nature Biotechnology, 2014

Stanford University Introduction 3 / 9

1. National Heart, Lung, and Blood Institute, NIH2 Leslie et al. (2014).Nature Biotechnol. 32,1134-1140.

Image: NHLB, NIH

Leslie et al. (2014).Nature Biotechnol.

[cm/s]