Arrhythmia Surgery Flashcards

1
Q

What is incidence of atrial fibrillation

A

AF 1% in the general population
increase with age with an incidence of 0.2-0.3% at 25-35. 3-4$ at 55 to 65 and 6-9% at age 65 to 90.
most commonest arrhythmia occurring in all patients with an arrhymia.

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2
Q

Common causes of atrial fibrillation

A
Idiopathic (primary) 
Mitral valve disease (left atrial dilation) 
Ichemic heart disease
Hypertension
Post-cardiac surgery
alcohol
Thyrotoxiciosis
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3
Q

List risk factors for atrial fibrillation following cardiac surgery

A
Age
withdrawal of beta blockers
electrolyte imbalance
hypoxia
ischemia
pericardial effusion
infection, penumonia.
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4
Q

Pathophysiology of AF

A

AF is induced by focal areas of automaticity (mainly around the pulmonary veins) and is maintained by multiple march re-entry circuits within both atria

Treatment of parysymal AF–requires stopped the induction pathways (focal areas of automaticity) by pulmonary vein isolation

treatment of persistent AF requires elimination the maintaing pathways (macro re-rentry) using the Cox-maze procedure

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5
Q

What are surgical options for the treatment of AF

A

1) Cut and sew–surgical incisions using the lesion set described by Cox in the maze III operation
2) Radiofrequency ablation–employs an alternating current at 350kHz-1MHz to heat tissues to 70 to 80 degree for 1 mintue, creates a 3 to 6mm lesion using unipolar or bipolar devices. Transmurality is indicated by electrical conductance and impedance monitoring
3) Microwave–uses high-frequency electromagnetic radiation to induce oscillation of water molecules
4) Cryoablation, which uses nitrous oxide as a cooling agent for 2 minutes at -60 degree C to produce a transmural lesion that can be visualised as an iceball
5) Ultrasound, which uses high-frequency sound waves (2- 20 MHz) emitted by piezoelectric cyrstals to cause thermal heating and disruption of cell membranes.
6) Laster, which uses a monchromatic, phase coherent beam to cause heating and cellular destruction

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6
Q

What are principles of maze operation

A

A “maze” is created with a set of blind alleys with one entrance and one exit fro atrial electrical activation, thereby direction the electrical impulse along one specified route from the sino-atrial node to the atrioventrical node by interrupting conduction routes and re-entrant pathways.

Left atrial appendage excision is performed to reduce the area of blood stasis and potential site for thrombus

Less likely to be associated with successful outcome in patients with large left atria (>5c) or with lonstanding AF >5 year.

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7
Q

Describe management of atrial flutter

A

Aflutter is caused by a single macro re-entry circuit
Presents in variable block (2:1; 3:1;4:1) which represents an atral rate of 300 blom and a ventricular response of 150, 100, 75)
Treatment: amiodarone, calcium channel blockers, DC cardioversion, catheter ablation or surgical ablation of the flutter isthmus
Atrial flutter isthmus runs from the inferior vena caval opening along the eustachian valve and the coronary sinus, to the tricuspid valve

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8
Q

What is Vaughn-Williams classification of anti-arrhythmic drugs

A

I) Fast Sodium channel blockade 1a quinidine; procainamide;
1b lidocaine, phenytoin
1c propafenone, flecainide
II) Beta sympathetic blockade beta blockers

III) Potassium channel blockade amiodarone, sotalol

IV) Slow calcium channel blockade verapamil, diltazem, adenosine

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9
Q

What is incidence of AF in persons older then 65

A

5.9%

The absolute number of pts in AF will rise as population ages

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10
Q

What is Cox Maze III

A

This is the “cut-and-sew” technique

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11
Q

Study by Michael Argenziano (Coloumbia NY) JTCS 2013; 145:356-63

A

Right atrial lesions do not improve the efficacy of a complete left atrial lesion set in the surgical treatment of AF, but they do increase procedural morbidity

Success rates (freedom from AF or flutter at 3 months intervals)
Pulmonary vein isolation 56.7%, 56.9, 54
PVI + Mitral, + appendage 74.5%, 72%, 72%
Biatrial-extended 79%, 74, 83

Biatrial had a higher rate of pacemaker placement 16.5% vs 7.5%!

This is a weak study because it has many selection bias and it’s outcomes are not clear

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12
Q

List points of AF surgery

A

should not get heart block because you don’t ablate across the AV node

Multiple mapping studies have shown that with paroxysmal AF activation occurs from the pulmonary vein and the right atrium, indicate the left atrium set would be enough to terminate AF.

chronic AF shows a reentrant activation in the right atrium–indicating that biatrial lesion should be necessary to eliminate AF.

Right atrial size is very important in chronic AF

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13
Q

The CURE-AF trial: A prospective multicenter trial of irrigated radiofrequency ablation for the treatment of persistent AF during comcomitant cardiac surgery

Ralph Daminao, Jr
AATS

A

150 pts in 15 US centers, pts followed for 6 to 9 months and then had 24 hour holter.

All pts underwent standardized biatrial cox-max IV lesion set using irrigated RF ablation devices

total RF time was 9 min
Freedom from AF was 66% with 47% of pts off antiarrhythmic at 6-9 months
Success rate was 82% in persistent AF as opposed to 63% in permanent AF
Increased LA diameter, shorter RF ablation time, and increasing number of concomitant procedures were associated with occurrence of AF

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14
Q

What is WPW (wolff-parkinson white syndrome)

A
Short PR interval 
Wide QRS-delta wave
Accessory pathway 
	Free wall left atrium-type A 
	Right atrium==anterior superior type B 
Atrial fibrillation can be lethal due to rapid conduction via accessory pathway--can cause VF 

Catheter ablation is very successful> 99%

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15
Q

What are causes of VT

A

Idiopathic
Non-ischemic cardiomyopathy
Right ventricular dysplasia (Uhl’s anomaly)
Ischemic ventricular tachycardia

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16
Q

What is 4 letter code for International pacemaker

A

I chamber paced
II Chamber sensed
III Pacing algorith
IV Rate modulation

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17
Q

List different Demand (rate-inhibited) pacers

A

VVI and AAI

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18
Q

what is a VDD pacemakers

A

Pace maker that paces only the ventricle but sense both atrium and ventricle

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19
Q

List accepted indications for cardiac pacemaker in symptomatic patients with chronic conditions

A
Atroventricular block 
	Complete (3rd degree) 
	Incomplete (Second-degree) 
	Incomplete with 2:1 or 3:1
Sinus node dysfunction 
	sinus bradycardia
	sinoatrial block 
	sinus arrest
	bradycardia-tachycardia syndrome
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20
Q

List controversial indications for cardiac pacemaker implantation

A

In symptomatic patients
bifascicular/trifasiciular intraventricular block
hypersensitive carotid sinus syndrome
In asymptomatic patients
Third-degree block
Mobitz II
Mobitz II atrioventricular block following myocardial infarction
congenital atrioventricular block
Sinus bradycardia < 40 with long-term necessary drug therapy
overdrive pacing for ventricular tachycardia

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21
Q

What is definition of first degree atrioventricular block

A

Prolongation of R-R interval beyond 200 milliseconds

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22
Q

What is second degree block

A
Incomplete dissociation of the atrial and ventricular rates, with increasing P-R intervals and dropped beats
	Mobitz I (usally AV nodal block) 
	Mobitz II (usually in the HIS-Purkinje system)
23
Q

What is 3rd degree block

A

complete atrioventricular dissociation

the atrial rate usually exceeding the ventricular rate

24
Q

What are etiologies of AV block

A
Ischemic injury 
Idiopathic fibrosis 
cardiomyopathy 
iatrogenic injury 
AV node ablation 
Lyme disease
bacterial endocarditis 
systemic lupus erythematosus
congenital lesions
25
Q

What type of cardiac pacemaker is recommended for sinus node dysfunction

A

Dual-chamber pacing (DDD or VDD) is favored because AV synchrony increases stroke volume and decreases symptoms

26
Q

What is increase stroke volume with AV synchrony and who benefits from this approach

A

5 to 15% with AV synchrony

Left ventricular hypertrophy, decreased diastolic compliance, and heart failure increase the importance of AV synchrony

27
Q

What is ventricular resynchronization

A

Biventricular (RV apex and coronary sinus) pacing patients with advanced cardiomyopathy and an intraventricular conduction delay improves left ventricular function by restoring simultaneous contraction of the septum and free wall

28
Q

What factors influence the rate response

A
increased ventricular contractility
venous return
heart rate
body temperature
venous oxygen saturation 
QT interval 
right ventricular systolic pressure
right ventricular stroke volume
29
Q

What is difference between Epicardial and endocardial leads

A

Epicardial leads are inferior in electrical characterisitcs and are prone to conduction
fractures

30
Q

What is Lone Atrial Fibrillation indication for surgery

A
  1. Intolerance of arrhythmia in patients who have failed medical therapy
  2. Development of tachycardia induced cardiomyopathy
  3. contraindication to longer term anticoagulation
31
Q

What are results of Cox-Maze III procedure

A

5.4 year F/U showing 97% NSR
No difference if it was done for lone AF or as a concomitant procedure
Medical therapy in lone AF is 80% in NSR at 5 years

32
Q

What are results of Cox-Maze IV- atrial incisions and cryoblate

A

6 month results show 91-96% freedom from AF –no mortality

33
Q

What are benefits of Cox IV over III

A

shorter cross clamp time for both lone and concomitant AF

34
Q

What are indications for pacing in children

A

Congenital complete heart block: due to maternal lupus antibodies attacking the myocardium. Can also lead to cardiomyopathy
symptomatic pts in CHF
post operative CHB: should wait 7 to 14 days to see if there is recovery of conduction
rate < 50 at rest
long QT
ventricular arrhythmias

35
Q

What is acceptable Ventricular thresholds

A

Pacing threshold < 0.7 volts

R wave amplitude > 5 mV

Impedence: 400 to 1000 Ohms

There should be no diaphragmatic pacing when 10mV

36
Q

What is acceptable atrial threshold

A

pacing threshold < 2 volts
sensingL if the atrial sensing is not satisfactory a DDD PM will not function
AV delay is set shorter than the patients PR interval

37
Q

what are complications of PPM

A
mortality-very rare
Lead displacement
MI 
Hemopneumothorax and tamponade < 2% 
pacemaker syndrome
lead entrapment
Infection/erosion 
generatory dysfunction 
undersensing 
oversensing
cross talk
exit block 
lead fracture
subclavian crush
air embolism 
nerve injury
38
Q

What are indications for biventricular pacing

A

NHYA III-IV, now extended to NHYA II
EF < 35%
QRS > 150 seconds, LBBB
PR interval > 200 ms

39
Q

What is Radiofrequency

A

lesions formed from local tissue heating (coagulation necrosis)
alternative current in range (0.5-1.0 MHz between 2 electrodes)
homogenous lesions that measure 5 to 6 mm in diameter and 2-3 depth
unipolar 50degree C for 60 seconds

40
Q

What is cryoablation

A
Coldest temp (prime determinant of cell death) mat range btw-50 to -150 degree 
was a nitrous-based argon but newer ones are argon and helium which allow for much cooler temps
used for endocardial
41
Q

What is laser ablation

A

lesion formed thermally thru photon absorption at surface w deeper myocardial sites hearted through passive conduction
creates a unidirectional linear ablation of 2 - 5 cm flexible configuration
mechanism is wavelength dependent by creating harmonic oscillation in water molecules with resulting kinetic energy and heat generation
used endocardial and epicardial because transmural lesions pass even through epicardial fat

42
Q

What is Mircowave ablation

A

effective and controlled heating of large tissue volume w/o charring
Frictional heating by induction of dielectric ionic movements

43
Q

What are the 5 letter codes for pacing

A
Chamber paced
chamber sensed 
response of pacemaker to sensing
I= Inhibited; T = triggered; D = dual
programmability 
O= none; P = simply programmability; M = multiprogrammability; C = communicating R = rate modult 
anti-tachycardia (position 5 is only for devices with ant-tachycardia function 
P = pacing stimuli 
S = countershock
44
Q

What is dual chamber pacing algorithm

A

calculate lower rate and upper rate and AV delay
if atrial rate lies between upper and lower limits, pacemaker will maintain 1:1 response b/w RA and RV w/o atrial pacing
if atrial rate < lower rate limit then pacemaker adds atrial pacing
if atrial rate > upper rate limit, then pacemaker maintains ventricular rate upper rate limit w loss of AV synchrony, resembling wenchebach
when atria paced, physiologic P wave may occur as much as 100ms after atrial pacing artifcat. Longer delays are needed in AV pacing

45
Q

What to do with surgery and pacemakers

A

Use of a unipolar electrocautery increases the chances of electromagnetic interference with pacemaker
If patient is pacemaker dependent, back up pacing or chronotropic agents should be available
pacemaker should be programmed to VOO, DOO, of VVT made to prevent inhibition

46
Q

What is magnet mode

A

magnet placed over pacemaker closes a switch and converts pacemaker to “magnet mode”. Initiats VOO mode making pacer insensitive to electromagnetic interference.

Older pacemakers will convert to VOO for a few beats and then revert to underlying program

47
Q

Who would you place a VVI pacer in

A

a patient with AV block with absence of reliable atrial function or sending. Sick sinus syndrom (most have intermitten AF–tachy-brady)

48
Q

Who would you place a VDD pacer

A

Patient with AV block p waves and atrial function. Allows AV synchrony with only a single lead

49
Q

Who would place a DDD

A

Patient with a AV block with functional atrium but slow atrial rate. This provides AV synchorny. Would help in HOCM, MR,
This is common in about 60% of patients

50
Q

What does DVI indicate

A

a pacer that does atrial and ventricle pacing but only only ventricular sensing

51
Q

Why does biventricular pacing even work? and what is it?

A

It’s pacing in the RV and the coronary sinus

Improves left centricular function by restoring simultaneous contraction of the septum and free wall, so called ventricular resynchoronization.

52
Q

What pacemaker do you place in a transplant

A

AAIR

53
Q

What pacemaker do place in an atrial fibrillation pt

A

VVI or VVIR is appropriate for pts with bradycardia and chronic AF

54
Q

CCS definitions of AF

A
  1. First detected AF
  2. Paroxysmal: AF is self-terminating within 7 days of onset
  3. Persistent: AF is not self-terminating within 7 days or isterminated electrically or pharmacologically or
  4. Permanent: AF in which cardioversion has failed or inwhich clinical judgment has led to a decision not topursue cardioversion