Transcript Cardiac Resynchronization for the Implanter

Intraoperative Biventricular Pacing
Applications, Techniques, Early Results
Vincent A. Gaudiani, MD
Luis J. Castro, MD
Audrey L. Fisher, MPH
Published in The Heart Surgery Forum, Volume 6, Issue 6, 2003.
Traditional Pacing - What Is It?
Traditional Pacing
• Unipolar Pacing – requires a single dipole
from the active electrode on the heart to
the ground on the skin
• Bipolar Pacing – requires a single dipole
from the active electrode on the heart to a
ground on the heart
Biventricular Pacing - What Is It?
Biventricular Pacing
• Requires two dipoles about 180 degrees
apart on heart. A dipole from an active
electrode on the anterior RV to a ground
and a second dipole from an active
electrode on the posterolateral LV to a
ground.
Why Biventricular Pacing?
• With two dipoles far apart activating the
ventricles simultaneously, electrical
activation is quicker (90 – 110 ms) than
traditional pacing and therefore mechanical
activation is more synchronous.
Biventricular Pacing
• Another term for biventricular pacing is
cardiac resynchronization therapy (CRT).
Biventricular Pacing
What are the common clinical examples of
suboptimal ventricular synchronization?
1. LBBB
2. Pacemaker Syndrome
3. Some VT’s
4. Any QRS > 130 ms (IVCD’s)
Biventricular Pacing
Which patient groups are most likely to
suffer reduced cardiac output when poorly
synchronized?
Patients with a combination of:
• Large LVIDd’s
• QRS > 130 ms
• Low EF’s
Biventricular Pacing
What are the clinical consequences of
ventricular dyssynchrony?
• Abnormal septal wall motion
• Reduced dP/dt
• Reduced diastolic filling time
• Prolonged MR duration
Cardiac Resynchronization Therapy
• Cardiac resynchronization
in association with an
optimized AV delay
improves hemodynamic
performance by forcing
the left ventricle to
complete contraction and
begin relaxation earlier,
allowing an increase in
ventricular filling time.
ECG depicting IVCD
• Coordinated activation of
the ventricles and septum.
ECG depicting cardiac resynchronization
Achieving Cardiac Resynchronization
Mechanical Goal: Pace Right and Left Ventricles
• Transvenous Approach
– Standard pacing leads in RA and RV
– Specially designed left heart lead placed in a left ventricular cardiac
vein via the coronary sinus
Cardiac Resynchronization System
Proposed Mechanisms of
Cardiac Resynchronization
•
More synchronous left
ventricular contraction
(towards its own center
of mass)
•
Improved AV interval
optimization
•
Mitral valve closure
earlier in systole
CRT Improves Cardiac Function at
Diminished Energy Cost
MVO2/HR (Relative Units)
0.24
p< 0.05
0.22
Dobutamine
0.20
0.18
LV Pacing
0.16
0.14
500
600
700
800
dP/dtmax (mmHg/s)
Nelson et al. Circulation 2000;102:3053-3059.
900
1000
Is Cardiac Resynchronization
Pro-arrhythmic?
Sinus Rhythm Group; N=12
With CR
Without CR
P
PVC Count
1,255 ± 1,535
3,394 ± 2,970
NS
PVC Runs
1±3
76 ± 147
0.02
17 ± 20
87 ± 142
0.01
Ventricular Arrhythmia
Duration (min)
Walker, et al. Am J Cardiol 2000;86:231-3.
Randomized Clinical Trials
• MIRACLE
– Multicenter InSync® Randomized Clinical Evaluation
• MUSTIC
– Multisite Stimulation in Cardiomyopathy
Data from these trials document symptomatic improvement and
increased exercise capacity in patients who have moderate to severe
heart failure and ventricular dysynchrony when treated with cardiac
resynchronization therapy.
Measurable Outcomes
•
•
•
•
NYHA functional classification
Quality of Life
6-Minute Hall Walk Distance
Peak VO2
Comparison of Clinical Results
MUSTIC* Trial
MIRACLE** Trial
NYHA Functional
Class
Not assessed
Improvement
Quality of Life
32% improvement

6-Minute Hall Walk
Peak VO2
23% improvement
8% improvement
+ Results consistent with MUSTIC trial results
* Cazeau S, Leclercq C, Lavergne T, et al. N Engl J Med. 2001; 344:873-880.
** Abraham WT, et al. ACC/NASPE 2001 Scientific Sessions. Results not yet published.


Results of the DAVID Trial
• 506 patients on maximal medical therapy
indicated for ICD
• Randomized to ventricular back-up pacing
(40/min) or dual-chamber rate-responsive
pacing (70/min)
Results of the DAVID Trial
Endpoint:
One-year survival free composite time to death or first
hospitalization for CHF
Ventricular Backup Pacing
40/min
Dual-chamber Rate-responsive
70/min
Results:
83.9%
1-yr free of death or
CHF hospitalization
*p < 0.03
73.3%
1-yr free of death or
CHF hospitalization
Conclusion:
“Dual-chamber pacing offers no clinical advantage over ventricular
backup pacing and may be detrimental by increasing… death or
hospitalization for CHF,” for patients with standard indications for
ICD therapy, EF<40%, and no indication for bradycardic pacing.
Results of the COMPANION Trial
1600 patients with active CHF and QRS >
120 ms with maximal medical therapy
Endpoint:
Combined All-Cause Mortality and All-Cause Hospitalization
0
% Reduction
in Mortality +/Hospitalization
Medical Therapy Only
-20%
Biventricular Pacer Only
-40%
Biventricular Pacer + ICD
Biventricular Pacing
How can biventricular pacing help cardiac
surgery patients?
• Use temporary DDD biventricular pacing
in all patients with large LV’s, low EF’s +
wide QRS’s
• Implant permanent LV epicardial
electrode in those likely to benefit
How To Do Temporary BiV Pacing
1. Sew temporary electrodes to anterior
RV and posterolateral LV
2. Attach BOTH to the negative pole of the
gray cable
3. Place a skin ground in the positive pole
You have now created TWO unipolar
pacing dipoles that will activate
the RV + LV simultaneously
Temporary BiV Lead Placement
Biventricular Pacing
• Virtually all cardiac surgery patients with
poor LV function who require temporary
pacing postoperatively should have
temporary biventricular leads as well as
atrial leads.
• Who should have a permanent LV lateral
electrode placed at the time of operation?
Biventricular Pacing
The following groups may benefit from a
posterolateral LV epicardial electrode placed
at the time of cardiac operation:
• Those with pacers already in place
• Those with large, hypocontractile LV’s
who are likely to need pacing
• Some Maze patients
• Those who may need ICD’s
How To Do Permanent BiV Pacing
Sew a steroid eluting epicardial pacing wire
posterolaterally on all those with large LVIDd
and low EF:
• Who already have pacers in place
• Who are likely to need permanent pacing
• Leave it buried under clavicle
Permanent BiV Lead Placement
How To Do Permanent BiV Pacing
Where is the optimal location for the LV wire?
Outcomes
Biventricular Pacing:
Preoperative Characteristics (n=25)
Mean Age (yrs)
NYHA 3+
Previous MI
Previous Cardiac Surgery
Diabetes
Renal Failure
Cerebrovascular Disease
Peripheral Vascular Disease
75
80%
40%
32%
32%
20%
20%
20%
Biventricular Pacing:
Intraoperative Characteristics (n=25)
Average # Cardiac Procedures
Concomitant Procedures:
CAB
MVV/R
AVR/Ao Root Recon
Maze
TVV
LV Remodel
Ascending Ao Recon
Only 1 patient required IABP
2.2
56%
60%
48%
16%
8%
8%
8%
36% Double
Valves
Biventricular Pacing:
Intraoperative BiV Pacing - # of Procedures
• Excluding pacing procedures,
– (8) pts had one procedure
– (9) pts had two procedures
– (7) pts had three procedures
– (1) pt had five procedures
Pts BiV Procedure List
4 CAB
1 CAB, LVA
2 AVR
1 Redo AoRR
1 Redo AoRR, ASC Ao
1 Redo AVR, MVR
1 ARE, MVR
1 AoRR, MVV
3 AVR, MVV, CAB
1 AVR, MVR, CAB, ASC Ao, LVA
1 Redo AVR, CAB, ASC Ao
3 MVV, CAB, MAZE
1 MVV,MAZE
1 MVV, CAB
2 MVV, TVV
1 MVV
Biventricular Pacing:
Distribution of LVIDd (n=25)
8
7
# Patients
6
5
4
3
2
1
0
<5
5.0-5.5
5.6-6.0
LVIDd (cm)
6.1-7.0
> 7.0
Biventricular Pacing:
Procedural Categories (n=25)
New Pacer (13)
52%
Upgrade (7)
28%
Lead Only (5)
20%
Biventricular Pacing:
Preoperative Characteristics
Average
LVEF
Average
LVIDd
Lead Only (5)
43%
5.9
New Pacer (13)
29%
6.8
Upgrade (7)
30%
5.5
Total (25)
32%
6.3
Category
Biventricular Pacing:
Patient Characteristics: EF vs. LV Size
% Ejection Fraction (EF)
Figure 1. Ejection Fraction vs. LV Size
70
NORMAL
60
50
(EF>50% & LVID<5.7 cm )
40
30
20
10
0
0
1
2
3
4
5
6
7
8
Left Ventricular Internal Dimension (cm)
9
10
Biventricular Pacing:
Patient Characteristics: QRS vs. LV Size
Figure 2. QRS Interval vs. LV Size
QRS Interval (ms)
200
150
Paced Preop
Not Paced
Preop
100
NORMAL
50
(QRS<120 ms & LVIDd<5.7 cm)
0
0
1
2
3
4
5
6
7
8
Left Ventricular Internal Dimension (cm)
9
10
Biventricular Pacing:
Results
•
•
•
•
1 operative mortality
3 late deaths
1 patient had two postop strokes
1 patient required subsequent VT ablation
Biventricular Pacing:
Postoperative Survival (Days)
Kaplan-Meier Survival
1.0
.9
.8
.7
.6
.5
.4
.3
.2
Survival Function
.1
0.0
Censored
0
100
200
Days from Surgery
300
400
Surgical Implications of CRT - Overall
If we are to improve our knowledge of who
will benefit from permanent LV
electrodes, we must
1. Renew our interest in preoperative EKG,
for instance RBBB v. LBBB
2. Improve our knowledge about
intraoperative echo diagnosis of
dyssynchrony
3. Learn optimal LV electrode placement
Surgical Implications of CRT – Ischemic MR
• Because dyssynchrony contributes to
“ischemic” MR, we must consider it a
correctable part of the syndrome that
neither ring nor prosthetic valve placement
addresses.
• Dyssynchrony tethers the posterior leaflet.
Surgical Implications of CRT - LV Remodeling
• LV aneurysmectomy to physically remodel
the heart can no longer be complete
unless we “electrically” remodel the heart
as well.
Surgical Implications of CRT - Maze
• The maze operation in some patients will
no longer be complete unless we restore
AV synchrony and LV synchrony as well
Surgical Implications of CRT - Paced
• Chronically paced patients with large,
hypocontractile hearts who require cardiac
operations are easy to upgrade to
biventricular pacing and likely to benefit
Biventricular Pacing Conclusions
• We prefer temporary biventricular DDD
pacing for postop pacing in all patients with
large, low EF hearts
• We consider placing a permanent
epicardial lead in patients with poor LV
function and prolonged QRS who are likely
to need permanent pacing or who currently
have permanent pacers