CRM13: CRT

Question 1

What is heart failure?

Answer 1

-Complex, progressive disorder in which heart function is reduced
-Heart muscles either becomes stiff or dilated

Question 2

What are the 2 types of heart failure?

Answer 2

HFpEF - diastolic dysfunction
HFrEF - systolic dysfunction

Question 3

Symptoms of heart failure

Answer 3

-SOB
-Fluid retention
-Fatigue
-Cough

Question 4

Causes of HF

Answer 4

-IHD
-Valvular disease
-Hypertension
-HCM
-DCM

Question 5

What does electrical dyssynchrony look like on ECG?

Answer 5

LBBB
-Left and right ventricle are not pumping in synchrony

Question 6

Risks of directly stimulating the LV

Answer 6

-Higher pressure in the left ventricle
-Clots

Question 6

How is LV stimulation achieved?

Answer 6

-Placing a pacing lead in a branch of the coronary sinus

Question 7

Difference between CRT-P and CRT-D

Answer 7

-CRT-D has shocking lead which goes into right ventricle (thick)

Question 8

NICE guidelines for ICD and CRT implant based on NYHA class and QRS interval

Answer 8

Question 9

Features of coronary sinus leads

Answer 9

-Coronary sinus leads are flexible to negotiate venous system
-Variety of shapes available for selected veins
-Majority do not have fixation as friction of vessel walls holds them in place
-IS-4 leads have 4 poles to pace from and can cover different vectors within ventricle

Question 10

Which area of heart is best for achieving effective CRT?

Answer 10

-Posterolateral

Question 11

Is basal or apical activation better in CRT?

Answer 11

Basal

Question 12

Risk of going for coronary sinus in CRT?

Answer 12

-AV node can be disturbed
-Patients with BBB could get complete heart block

Question 13

Which cardiac veins are most commonly gone for in CRT to target left ventricle?

Answer 13

-Lateral cardiac vein
-Postero-lateral cardiac vein

Question 14

Why should there be a distance between left and right leads?

Answer 14

-To activate the largest area possible

Question 15

Process of CRT implantation

Answer 15

-Venous access
-Place atrial and RV leads - test
-Use delivery catheter to intubate coronary sinus
-Perform venogram
-Select vein and lead shape
-Place lead
-Measure threshold and QLV
-Test of phrenic nerve stimulation

Question 16

Threshold and impedance ranges in CRT

Answer 16

-High thresholds and impedance are acceptable, especially with limited suitable veins
-Threshold 2.0V @ 0.4ms
-Impedance 300-1300ohms

Question 17

Phrenic nerve stimulation in CRT

Answer 17

-Phrenic nerve stimulation is tested at 5V and 10V
-Don’t want to cause phrenic nerve stimulation when pacing ventricle
-Place hand on stomach to see if twitching
-No fixation to vessel so leads may move

Question 18

What is QLV interval?

Answer 18

-Measurement from onset of QRS of surface ECG to first positive or negative peak of LV electrogram (EGM)
-Indicates dyssynchrony and the latest area of deactivation
-QLV>95ms is good indication of resynchronisation

Question 19

Issues with pacing in scar tissue

Answer 19

-Substrate for arrhythmias
-Delayed conduction

Question 20

Features of lead testing in CRT

Answer 20

-Multiple vector testing
-Ideal vector should be as basal as possible
-Threshold should be low
-Higher impedances can reduce current drain on battery however need for balance
-Can have unipolar pacing vectors
-Assess ECG changes during testing (Look at V1 for LBBB and RBBB)

Question 21

Complications of CRT implant

Answer 21

-CS lead displacement
-Asystole during CS cannulation
-CS dissection
-CS lead leading to arrhythmia
-High thresholds (battery drain)
-Phrenic nerve stimulation
-Long procedure time = increased risk of infection

Question 22

Why does RV lead go in first?

Answer 22

-RV lead goes in first so you can pace if left lead causes arrhythmia

Question 23

Benefits of conduction system pacing?

Answer 23

-Preservation of native activation
-Better results
-More stable lead positions
-Does not depend on venous anatomy
-Pacing along conduction system avoids cardiac remodelling

Question 24

What is WISE CRT?

Answer 24

Wireless Stimulation Endocardially:
-Delivers ultrasonic energy to LV endocardial receiver to achieve biventricular pacing
-Potential solution to patients who failed conventional CRT
-Percutaneously delivered LV endocardial electrode delivers electrical stimulus that is synchronised to RV pacing output

Question 25

CRT follow up

Answer 25

-6/12 month follow up
-Effective CRT Biventricular pacing percentage (>95%)
-Causes of reduced BiVp - lead malfunction, arrhythmia, ectopics
-Assess lead measurements
-Heart rate histograms - maintain BiVp at higher rates and rates not going too fast
-Patient symptoms - HF symptoms?
-Optimisation of ECG - narrowest ECG possible

Question 26

What device should patient get?

Answer 26

CRT-D
-NYHA 3
-LBBB with prolonged QRS

Question 27

Why were the sensing values lower at implant?

Answer 27

-Dilated ventricle
-Ischaemia (scarring)

Question 28

What has happened?

Answer 28

-LV lead has displaced
-Not capturing
-Needs to be repositioned
-Patient still has LBBB