demystifying cardiac assist · pdf filedemystifying cardiac assist devices 1 2014 cynthia...

DEMYSTIFYING CARDIAC ASSIST DEVICES

1

2014 Cynthia Webner DNP, RN, CCNS, CCRN-CMC

“I ATTRIBUTE MY

SUCCESS TO

THIS – I NEVER

GAVE OR TOOK

ANY EXCUSES.”

~ FLORENCE

NIGHTINGALE

2

Objectives

Discuss pacing modes utilized to minimize right

ventricular pacing and preserve normal cardiac

function.

Review cardiac pacing modalities used in the

treatment of heart failure and the prevention of

sudden cardiac death.

Identify criteria for consideration of mechanical

assist devices in acute decompensated heart failure

or shock states.

3

PACING BASICS

4

Indications for Pacing

Symptomatic

bradycardia

Sinus node

dysfunction

AV conduction system

dysfunction - #1

Drug induced

bradycardia

5

Indications for Pacing 6

Symptomatic bradycardia

Symptomatic heart blocks

Chronic bifasicular and trifasicular blocks

Sick Sinus Syndrome

Neurocardiogenic Syncope

Hypertrophic Cardiomyopathy

Cardiac support for treatment of arrhythmias requiring ablation and / or medications resulting in bradycardia

Pacing for termination of tachyarrhythmias (part of ICD therapy)

CHF (biventricular pacing)

Types of Cardiac Pacing 7

Temporary Transvenous Pacing

Transcutaneous Pacing

Epicardial Pacing

Permanent Pacing

Single chamber

Dual chamber

Biventricular

Rate adaptive pacing

Temporary Pacemakers 8

Transcutaneous Pacer 9

Epicardial Pacer 10

Permanent

Pacemakers 11

Pacer Parts

Battery / Brains Leads

12

Implantation of Permanent Pacer

13

14

What kind of Bundle Branch Block does RV

pacing mimic?

14

15

Left Bundle Branch Block

V1 = QS

V6 = wide R

QRS = .12 sec or more

V1 = rS

Pacemaker Function 16

Bipolar vs. Unipolar 17

18 Pace

• Ability of the pacemaker to send a stimulus to the myocardium

• Identified by a pacemaker spike on the ECG

Capture

• Ability of the pacing stimulus to depolarize chamber being paced

• Identified by a pacemaker spike that is immediately followed by a P wave or a QRS complex on the ECG

Sense

• Ability of the pacemaker to recognize and respond to intrinsic cardiac depolarization

• Identified by pacing when no intrinsic beats and not pacing when intrinsic beats are present

Pacing 19

Identify automatic pacing interval (pacing rate)

Two consecutive pacer spikes

Spikes should appear regularly unless pacer is

inhibited by sensed intrinsic activity

Capture 20

Pacing stimulus results in depolarization of chamber

being paced

Each spike should be followed by a QRS unless it

falls in heart’s refractory period

Sensing 21

Pacemaker sees and responds to intrinsic activity

Must be given opportunity to sense

Must be in demand mode

There must be intrinsic activity to be sensed

22

Position I Position II Position

III Position

IV Position V

Chamber(s) Paced

Chamber(s) Sensed

Response to Sensing

Rate Modulation

Multisite

O=None O=None O=None O=None O=None

A=Atrium A=Atrium T=Triggered R=Rate

modulation P=Paced

V=Ventricle V=Ventricle I=Inhibited S=Shocks

D=Dual (A+V)

D=Dual (A+V)

D=Dual (T+I)

D=Dual (P+SV)

(Bernstein et al., 2002)

Revised NASPE/BPEG Generic

Code for Antitachycardia Pacing

UNDERSTANDING PACEMAKER

FUNCTION

23

25

AAI Pacing – Atrial Inhibited

AAI

Paces the Atrium

AAI

Senses the Atrium

AAI

Atrial sensing inhibits atrial pacing

Pacing Modes AAI 26

VVI Pacing – Ventricular Inhibited 27

VVI

Paces the Ventricle

VVI

Senses the Ventricle

VVI

Ventricular sensing inhibits ventricular pacing

VVI Pacing 28

Dual Chamber Pacers 29

Provide AV synchrony Maintains atrial kick

Improves hemodynamics in those with heart blocks

Tracks atrial activity Ventricular pacing occurs in response to atrial activity

Improved hemodynamics

Decreased incidence of pacemaker syndrome

Basic Pacemaker Timing 30

AV Interval

Period of time between an atrial event (sensed “P” wave or atrial pace) and a paced ventricular event

VV Interval

Period of time from ventricular complex to ventricular complex

VA Interval

Ventricular complex to atrial activity

Also called AEI or atrial escape interval

Basic Pacemaker Timing

Refractory Period

Brief period of time when pacer is not allowed to

look for intrinsic events

Absolute Refractory Period

Nothing can be sensed

Relative Refractory Period

Allows sensing but pacer will not respond

31

Basic Pacemaker Timing 32

Low Rate

Lowest rate allowed by the pacer before a paced

beat is initiated

High Rate

Upper rate limit

Highest rate that can be achieved and still maintain

AV synchrony

DDDR Pacing 33

DDDR

Paces both Atrium and Ventricle

DDDR

Senses both Atrium and Ventricle

DDDR

1. Atrial sensing inhibits atrial pacing and triggers ventricular pacing

2. Ventricular sensing inhibits ventricular and atrial pacing

DDD Pacing:

AV Sequential Pacing State 35

DDD Pacing:

Atrial Pacing State 36

DDD Pacing:

Atrial Tracking State 37

DDD Pacing:

Atrial Sensing and Ventricular Sensing State 38

Minimizing Right Ventricular Pacing

1/9/2014

39

1/9/2014 40

41

Left Bundle Branch Block

V1 = QS

V6 = wide R

QRS = .12 sec or more

V1 = rS

V1

V6

Understanding Dyssynchrony 42

Normal function:

Septum moves towards left ventricle during ventricular

contraction

Mitral valve papillary muscles contract slightly before

LV free wall


Electrical Abnormalities with LBBB

RV depolarizes normally

Septum depolarizes after activated by the right bundle

branch and before the left ventricle

Left ventricle depolarizes late


Mechanical abnormalities with LBBB LV activation delayed Septum completes contraction before LV contracts Septum bulges into RV when LV contracts Mitral valve papillary muscle contract late allowing

leaflets to open into LA resulting in mitral regurgitation

Minimizing RV Pacing with Dual

Chamber Pacers 45

Increased hospitalizations for HF (DAVID Trial)

Increased mortality (DAVID Trial)

No improvement in mortality, HF hospitalizations or stroke free survival when compared to VVI (MOST Trial, CTOPP Trial)

AAI pacing demonstrates improved outcomes

Reducing RV pacing to less than 10% in patients with dual chamber pacemakers reduced the relative risk of developing persistent atrial fibrillation by 40% compared to conventional dual chamber pacing (SAVE PACe Trial)

Minimizing Right Ventricular Pacing 46

RV pacing results in mechanical dysynchrony (mechanical LBBB)

Similar changes occur as do with LBBB normally: LV remodeling

Systolic dysfunction

Decreased perfusion

Wall motion abnormalities

Mitral valve regurgitation

Increased risk of AF and HF


Pacer Lead Placement Options

His Bundle

RV outflow tract

RV septal sites

Dual pacers in RV

LV pacing

Biventricular pacing


Programming Options

DDIR mode

AAIR mode with mode switching

VVI mode with low rate for those being paced as

defibrillation back up only

Long AV delays

49

DDI Pacing

DDI

Paces both Atrium and Ventricle

DDI

Senses both Atrium and Ventricle

DDI

1. Atrial sensing inhibits atrial pacing and DOES NOT trigger ventricular pacing

2. Ventricular sensing inhibits ventricular and atrial pacing

DDI Pacing 50

LRI

Managed Ventricular Pacing 51

Promotes Intrinsic Conduction

Reduces unnecessary RV pacing

Risk of atrial fibrillation increases as the percentage of

ventricular pacing increases

AAI(R) pacing

Back up dual chamber system available

Medtronic Program

VIP (Ventricular Intrinsic Preference) – St. Jude

AV Search Hysteresis 54

Guidant Program

Functions in DDD/R mode and automatically searches for

intrinsic AV conduction by extending the AV delay by 10% -

100% (programmable value) to look for intrinsic conduction

If intrinsic conduction is present, AV delay remains long until

conduction fails, then pacer returns to DDD/R mode

Search AV Operation 55

• Search AV periodically measures AV intervals

• Determine the effect of Search AV delay in reducing unnecessary ventricular pacing, especially in patients with 1:1 conduction

• Encourage intrinsic conduction

Search AV extension

Cardiac Resynchronization Therapy 56


Treatment modality for heart failure not just pacing

Treatment modality in conjunction with drug therapy

Goals:

Improve hemodynamics by restoring synchrony of

ventricular contraction

Improve quality of life

Decrease mortality and morbidity


Improves ventricular systolic function with reduced metabolic

costs

Decreases functional mitral regurgitation

Induces favorable remodeling with reduction of cardiac

chamber dimensions

Mortality reduction – 24-36%

Reduction in hospitalizations - 30%

Improved 6 minute walk tests

Improvement by at least one NYHA class

Clinical improvement in quality of life

Improved ejection fraction

Improved peak oxygen consumption


•Septum contracts with LV

•Increased LA filling time – improved “atrial kick”

•Improves papillary muscle contraction - ↓ MR

•Reverse remodeling


Normal function:

Septum moves towards left ventricle during ventricular

contraction

Mitral valve papillary muscles contract slightly before

LV free wall


Electrical Abnormalities with LBBB

RV depolarizes normally

Septum depolarizes after activated by the right bundle

branch and before the left ventricle

Left ventricle depolarizes late


Mechanical abnormalities with LBBB LV activation delayed Septum completes contraction before LV contracts Septum bulges into RV when LV contracts Mitral valve papillary muscle contract late allowing

leaflets to open into LA resulting in mitral regurgitation

Indications for CRT 63

For patients who have LVEF less than or equal

to 35%

QRS duration greater than or equal to 0.12

seconds

Sinus rhythm

NYHA functional Class III or ambulatory Class IV

heart failure symptoms with optimal recommend

medical therapy

64

Lead Location

HOW DO YOU KNOW YOUR PATIENT

IS RECEIVING RESYNCHRONIZATION

THERAPY BY LOOKING AT THE

RHYTHM STRIP?

65

Internal Monitoring with CRT 69

Heart Rate Variability

Patient Activity

Night Heart Rate

Impedance

CRT 70

Goal: Force biventricular pacing

Goal: Ventricular Pacing 90% of time or greater

Causes of Loss of Bi V pacing:

Long AV Delays

Prolonged PVARP

ST with 1 degree AV Block

Lead dislodgement

Dealing with Non Responders 71

30% are “nonresponders”

Hemodynamics

Clinical Assessment

Echocardiogram

Location of lead

Programming

AUTOMATIC IMPLANTABLE

CARDIOVERTER DEFIBRILLATORS

72

Sudden Cardiac Death 73

Cardiac arrest with cessation of cardiac function

Ventricular fibrillation or pulseless VT

Pulseless electrical activity

Asystole

Occurs most often in patients with:

CAD

Cardiomyopathy

Indications for ICD

Survivors of cardiac arrest due to VF or

hemodynamically unstable sustained VT after

evaluation to define the cause of the event and to

exclude any completely reversible causes.

Structural heart disease and spontaneous sustained

VT, whether hemodynamically stable or unstable.

Syncope of undetermined origin with clinically

relevant, hemodynamically significant sustained VT

or VF induced at electrophysiological study.

74

Indications for ICD

LVEF <35% due to prior MI > 40 days old and NYHA functional Class II or III.

Nonischemic DCM, LVEF <35% and NYHA functional Class II or III.

LV dysfunction due to prior MI > 40 days old, LVEF <30%, and are in NYHA functional Class I.

Nonsustained VT due to prior MI, LVEF <40%, and inducible VF or sustained VT at electrophysiological

Other Indications 76

Patients with long QT syndrome and prior cardiac arrest, syncope, and strong family history of sudden death, or intolerance to beta blockers.

Patients with HCM with family history of sudden death, syncope, nonsustained VT, abnormal blood pressure response to exercise, left ventricular wall thickness > 30 mm.

Secondary prevention in patients with arrhythmogenic right ventricular dysplasia, but primary prevention in patients with syncope or inducible VT.

ICD Device 77

Pulse Generator

Single chamber, dual chamber, or biventricular pacing

Back up pacing

Antitachycardia pacing

Implanted subcutaneously – same as pacemaker

Defibrillator lead

Detects arrhythmias

Delivers therapy

Defibrillator lead capable of pacing and defibrillating

Placed in right ventricle

ICD Function – Rhythm Detection 78

Heart Rate

Monitors ventricular rate and delivers therapy when rate

exceeds programmed tachycardia detection rate

Defined rate boundaries

Tachycardia zones

Sudden Onset

Detects sudden shortening of cycle length

ICD Function – Rhythm Detection 79

Interval stability

Looks for variability in cycle lengths

Differentiates regular from irregular rhythms

Morphology

Measures width of electogram

Only treats if width is greater than programmed value

ICD Termination Therapies 80

ATP-Antitachycardia Pacing

Painless

“Slow” VT’s

Burst

Ramp

Decremental Scanning

Cardioversion Shock

Defibrillating Shock

ICD Function

ATP-Anti tachycardia Pacing

Tiered Antiarrhythmia Therapies

81

ICD Functions

Cardioversion Shock Delivers shocks from 0.1 to 30 joules synchronized on the R wave

82

ICD Function 83

Defibrillating Shock Delivers high energy (20-34 joules) unsynchronized shock for

VF

Other Device Features 84

Brady Pacing

Atrial Diagnostics

Differentiates between SVT and VT

Stored Electrograms

Store arrhythmia event

Noninvasive EPS

EP study through implantable leads

Care of Patient With ICD 85

Implantation

Cath Lab, EP Lab, OR

Similar to permanent pacer

General anesthesia or conscious sedation

Note Status of Device

Is device on or off

Know what therapies will be delivered for detection of ventricular arrhythmias: pacing, cardioversion, defibrillation

Care of Patient With ICD 86

Emergency Care for VT/VF

Device will deliver therapy within 10-15 seconds and will

continue to deliver therapy as programmed

DO NOT WAIT for device to deliver all its therapies if

patient is hemodynamically unstable or in VF

Defibrillate if necessary – avoid placing paddles directly

over device

Assure patient

Document rhythm

Care of the Patient with ICD 87

Inappropriate firing of ICD Device may fire with SVT’s

Notify physician to have device deactivated

All ICDs can be turned off using a programmer

A round magnet over the generator will deactivate arrhythmia detection

Removal of magnet will reactivate arrhythmia detection

Considerations when the patient requires surgery

NOTE: Magnet works differently for ICD’s than pacemakers!

Care of the Patient with ICD

Patient / Family Education

Reason for ICD, how it works, what to expect

Carry ID card always

Continue to take antiarrhythmic medications if on them

Importance of follow up visits

Every 4-6 moths

Family should learn CPR

Activities

Contact sports restricted

Driving may be restricted

Swimming and boating OK but not alone

Support groups

88

What To Do When ICD Fires 89

If patient is aware of rhythm sit or lie down

If receive only one shock – notify MD

If receive multiple shocks or feels terrible after one

shock– call 911

If device fires and patient does not wake up

immediately call 911.

Device Options

Acute Decompensated HF or Shock

States 90

0

1

4

3

2

5

20 18 16 14 12 10 8 6 4 2 32 30 28 26 24 22 34 36

Preload: PWP, lung sounds (dry or wet)

Fo

rwa

rds F

low

:

CI,

Sk

in t

em

p (

wa

rm o

r co

ld)

Normal Hemodynamics (I) No pulmonary congestion:

• PWP < 18; Dry lungs No hypoperfusion:

• CI > 2.2; Warm skin

Backwards Failure (II) Pulmonary congestion

• PWP > 18; Wet lungs No hypoperfusion

• CI > 2.2; Warm skin

Forwards Failure (III) No pulmonary congestion

• PWP < 18; Dry lungs Hypoperfusion

• CI < 2.2; Cold skin

The Shock Box (IV) Pulmonary congestion

• PWP > 18; Wet lungs Hypoperfusion

• CI < 2.2; Cold skin

91

Hemodynamic and Clinical Subsets

Treatment for Acute Decompensated

Heart Failure

Congestion with

Adequate Perfusion

Subset II

Reduce Preload

Hypoperfusion with

No Congestion Subset III

Increase contractility

Assure adequate preload

Hypoperfusion with

Congestion

Subset IV

Reduce Afterload

92

Bridge to transplant (BBT) for those who are

transplant eligible

Destination therapy (DT) for those who are not

transplant eligible.

Careful consideration for all therapies

Some patients may be too ill with multisystem issues to

benefit from MCS

Some decisions are best made in the hands of the most

experienced centers

Mechanical Circulatory Support in ADHF 93

94

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Intra Aortic Balloon Pump

Most often 1st step in cardiogenic shock treatment

Minimally invasive

The IAB is a volume displacement device

Decreases LV afterload

Increases coronary perfusion

95

Impella

Mechanical Cirulatory

Support Device

“Percutaneous VAD”

Minimally invasive

Unloads ventricle reducing

myocardial workload

Produces 2.5 liters of

cardiac output

Recommended for up to 7

days

Bridge to Recovery 96

ECMO

Extracorporeal Membrane Oxygenation

Used to treat medically refractory cardiogenic

shock with poor oxygenation

Provides biventricular support

Not good for long term durability

Used in a short term situation

Requires perfusion support

Bridge to Recovery 97

Left Ventricular Assist Devices

Profound failure Mean blood pressure < 60 mmHg,

Systolic blood pressure < 90 mmHg, Cardiac index < 2.0 L/min/m2

Temporary replacement of pumping function of the left ventricle

Blood diverted from LA and LV to the LVAD

Blood returned to the aorta

Continuous flow vs. pulsatile flow

Portability

98

Courtesy of Thoratec Heart Mate II

Left Ventricular Assist Devices

LVADs

Bridge to transplant

“Destination Therapy”

Can improve quality of life

Prolonged LVAD support may result in enough

recovery of myocardial function to allow for

life after explantation

Occurs more frequently in patients with acute CHF

and no CAD

99

100

Final Quote:

Our grand business in life

is not to see what lies

dimly at a distance,

but to do what lies clearly at hand.

Thomas Carlyle (1795-1881)

BE THE BEST THAT YOU CAN BE

EVERY DAY. YOUR PATIENTS ARE

COUNTING ON IT!

101

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