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What is incidence of atrial fibrillation

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.


Common causes of atrial fibrillation

Idiopathic (primary)
Mitral valve disease (left atrial dilation)
Ichemic heart disease
Post-cardiac surgery


List risk factors for atrial fibrillation following cardiac surgery

withdrawal of beta blockers
electrolyte imbalance
pericardial effusion
infection, penumonia.


Pathophysiology of AF

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


What are surgical options for the treatment of AF

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


What are principles of maze operation

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.


Describe management of atrial flutter

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


What is Vaughn-Williams classification of anti-arrhythmic drugs

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


What is incidence of AF in persons older then 65


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


What is Cox Maze III

This is the "cut-and-sew" technique


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

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


List points of AF surgery

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


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

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


What is WPW (wolff-parkinson white syndrome)

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%


What are causes of VT

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


What is 4 letter code for International pacemaker

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


List different Demand (rate-inhibited) pacers



what is a VDD pacemakers

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


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

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


List controversial indications for cardiac pacemaker implantation

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


What is definition of first degree atrioventricular block

Prolongation of R-R interval beyond 200 milliseconds


What is second degree block

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)


What is 3rd degree block

complete atrioventricular dissociation

the atrial rate usually exceeding the ventricular rate


What are etiologies of AV block

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


What type of cardiac pacemaker is recommended for sinus node dysfunction

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


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

5 to 15% with AV synchrony

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


What is ventricular resynchronization

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


What factors influence the rate response

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


What is difference between Epicardial and endocardial leads

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


What is Lone Atrial Fibrillation indication for surgery

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


What are results of Cox-Maze III procedure

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


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

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


What are benefits of Cox IV over III

shorter cross clamp time for both lone and concomitant AF


What are indications for pacing in children

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


What is acceptable Ventricular thresholds

Pacing threshold < 0.7 volts

R wave amplitude > 5 mV

Impedence: 400 to 1000 Ohms

There should be no diaphragmatic pacing when 10mV


What is acceptable atrial threshold

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


what are complications of PPM

mortality-very rare
Lead displacement
Hemopneumothorax and tamponade < 2%
pacemaker syndrome
lead entrapment
generatory dysfunction
cross talk
exit block
lead fracture
subclavian crush
air embolism
nerve injury


What are indications for biventricular pacing

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


What is Radiofrequency

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


What is cryoablation

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


What is laser ablation

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


What is Mircowave ablation

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


What are the 5 letter codes for pacing

Chamber paced
chamber sensed
response of pacemaker to sensing
I= Inhibited; T = triggered; D = dual
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


What is dual chamber pacing algorithm

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


What to do with surgery and pacemakers

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


What is magnet mode

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


Who would you place a VVI pacer in

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


Who would you place a VDD pacer

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


Who would place a DDD

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


What does DVI indicate

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


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

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.


What pacemaker do you place in a transplant



What pacemaker do place in an atrial fibrillation pt

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


CCS definitions of AF

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

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