Echocardiography in Advanced

Heart Failure

William F. Armstrong M.D.

University of Michigan

Disclosure: Thoratec

The Role of Echocardiography in

LVADs

• Determine suitability / need of patient

• Assess LV and RV function pre-implant

• LV thrombus

• PHTN

• Pre-implant aortic insufficiency

• Presence of PFO

LVADs General Principles

• Blood removed from LV apex via cannula

• Pump generates flow and pressure• Currently utilized LVADs are continuous flow

devices

• Pump flow is in part preload dependent

• Creates a degree of pulsatility in outflow

• Blood delivered to ascending aorta

• Variable contribution of LV to forward flow

Continuous Flow LVADs

HeartWare LVAD

Centrifugal Flow HeartMate II

Axial flow Pump

Impact of Pre-implant Findings

Echocardiographic Finding Clinical Implications

Marked RV dysfunction Inadequate LV and pump preload, low pump flow

Fixed Pulmonary hypertension Liming factor for LV and pump preload

Severe TR Worsening RV function post implant

ASD / PFO Progressive right to left shunt / hypoxia

More than mild AI LVAD inefficiency

LV apical thrombus Complicates inflow cannula placement

Ascending aortic aneurysm Complicates outflow cannula placement

“Smaller” LV (<6cm) Further decrease in size impacts RV mechanics

Impact of LVAD on RV Function

Beneficial Impact

• Reduction in LV filling

pressure alleviates

pulmonary congestion and

reduces secondary PHTN

with concurrent

improvement in RV forward

flow and reduction in

secondary TR.

Deleterious Effect

• Reduction of LV dimension

/ volume past a threshold

may shift the septum and

alter RV geometry

– Worsening TR

– Worsening RV mechanics

• Prone to adverse outcome if

significant PHTN

• Concept of the “Suction

Event” at high flows

What to Expect on Echo

• High RPMs – closed AV

• Lower RPMs - AV opens intermittently

• Usually phasic flow into apical cannula

– Magnitude of flow and velocity depends on degree of

LV “preload” and forward aortic flow

• Phasic flow into ascending aorta

• MV opens and closes

• For latest generation devices with pump at apex,

expect destructive interference with Doppler

Challenges of Evaluating LVADs

with Echocardiography

• Limited / challenging apical windows

– Parallel interrogation of inlet cannula

– Electronic artifact with devices that have pump

mechanism at apex

• Variable range of normal inlet / outlet flow

velocities

– Best to establish early baseline for comparison

– Velocities depend on pump speed and LV

preload contribution

Destructive Interference with

Doppler

LVAD

• Persistently closed AV

– Implies all flow is via

LVAD and that LV

does not generate

sufficient pressure to

open valve or produce

forward flow

– LVAD on full support

or LV severely

compromised

Normal Inlet Flow

Impact of Doppler Angle on

Inflow Cannula Velocity

Apical Window Parasternal Short Axis

Normal Outlet Cannula Flow

Multiple transthoracic windows

needed to assess outlet canula.

Right parasternal often helpful

Impact of LVAD Speed Settings

Topilsky et al. Cardiology Research and Practice 2011

Low Sub maximal Maximal

Where Can Things Go Wrong?

• Aortic dissection

• Insufficiency of AV /Clotting

of proximal aorta

• Conduit kinking / obstruction

• Progressive RV failure

• Inlet cannula thrombosis

• Pump failure

• LV Suction /overpumping

• Controller / battery failure

LVAD Provoked Aortic

Insufficiency

• If AI present pre-implant,

needs to be addressed

• Develops in ~60% with

continuous flow devices

• AI is continuous / interrupted

by LV contraction

• Usually mild

• May reach hemodynamic

relevance and necessitate

AVR or oversewing of valve

Spectral Doppler of Continuous AI

Magnitude of flow interruption is a reflector of residual LV contractility.

Can quantify as pressure generated against aortic pressure.

Development of AI in LVAD

Supported Patients

• 78 LVAD patients

– HeartMate XVE in 25

– HeartMate-II in 53

• Serial echocardiograms baseline,

1,3,6,12,18 & 24 months after implant

• AI graded none to severe

Cowger et al Circulation –HF, 2010

Development of AI in LVAD

Supported Patients

Cowger et al Circulation –HF, 2010

Correlates of worsening AI included: female gender, smaller

body size, HM-II (vs. XVE), higher LVAD flow, increasing

aortic root size, ≤ intermittent aortic valve opening.

Kinked Outlet Canula Actual kink not in field

of view.

Imply from reduced

outflow velocity

CT to directly visualize

conduit

Clot on Inlet Cannula

Peripheral embolization

Hemolysis

Elevated LDH

Reduced pump flow if

obstructive

Thrombosed Inlet Canula

Baseline

Clinical Deterioration

Reduced pump flow

Hemolysis

Clotted Aorta

Has definite embolic potential

May interrupt coronary flow

Class IV CHF

S/P LVAD 1700 RPMs

Clinical deterioration

24 hours after implant

Poor perfusion

Hypotensive

S/P LVAD 1700 RPMs

“Suction” Event

• Overly aggressive LVAD pumping

– Concurrent RV failure / PHTN

• LVAD empties the LV

– Septum shifts to the left, further worsening TR

and RV geometry / function

• Treatment: reduce LVAD flow rate

LVAD 1500 RPMs

Progressive RV Failure after

LVAD Placement

• Progressive RV failure in up to 35% post implant

– Doubles post-implant mortality

• Predicted by:

– Clinical evidence of RVF pre-implant

– “Smaller” pre-implant LV size (<63mm)

• Probably a set up for “suction event”

– Short duration TR

– RV strain

Prediction of RV Failure after

LVAD Implantation • 117 patients undergoing

LVAD implantation

• Standard echo plus VVI for

RV strain

• RV failure = need for RVAD

or >14 days inotropes

• 47 (40%) developed RVF

• RV strain -9.6% had 68%

sensitivity and 76%

specificity

Grant, ADM (Marwick CCF) JACC 2012

Conclusions: The Role of

Echocardiography in LVADs

• Determine suitability / need of patient for support

• Identify complicating factors for implant– RV function / TR / PHTN

– LV thrombus

– PFO

– Aortic Insufficiency

• Monitor function of LVAD– Impact on RV

– Development of AI

– Must integrate pump / flow settings with echo / Doppler findings

• Evaluate for possible LVAD withdrawl