15 EKG Others

AFIB

Pathogenesis

• small depolarization occuring in atrium irregularly, some reach AV and generate QRS, others reach AV during refractory

• result: random QRS

• bottom: normal

• top: AFIB, bumps before QRS but not organized regular bumps. QRS at irregularly irregular (irregular and no pattern to the irregularity)

• bumps are actually T waves, not P

Types and Symptoms

• young pts: healthy AV node, fast

• aortic stenosis: need preload to generate enough output to get past stenosis

• stiff ventricles: need atrial kick to fill the stiff ventricles

• can see cardiogenic shock during Afib

• arrhythmia itself usually not life threatening, thrombus is

• blood flow slower during afib

• splenic infarct

• when both mitral stenosis and afib, refractory to treatment

• many drugs only test with pts with non-valvular afib

• HR has to be rapid to cause cardiomyopathy

• untreated afib for weeks: EF decline

Risks

• HF: high pressures in RA and RV

• echocardiogram: key test, determine if enlarged heart

• elderly with PNA

• pain after trauma

Treatment

• echo: exclude structural heart disease

• rate control first

• surgery last resort

Rate

• 1st thing to do after pt present with afib and fast HR: decrease HR

• will still have irregular rhythm, but good HR

• pt will feel much better with slower HR

• for elderly, usually all that's done

• Irregularly irregular static: beta blockers are useful in atrial fibrillation and flutter

• Metronome: beta blockers prevent rapid ventricular response in atrial fibrillation and flutter ("rate control") (increase AV node refractory period, slow ventricular response rate)

• Illuminated top: non-dihydropyridine CCBs treat supraventricular arrhythmias (e.g. atrial fibrillation with RVR)

• Irregularly irregular signal: non-dihydropyridine CCBs are useful in atrial fibrillation (and flutter)

• Metronome: non-dihydropyridines prevent rapid ventricular response in atrial fibrillation and flutter ("rate control")

• DJ foxglove: digoxin has antiarrhythmic properties

• Vegas: digoxin exerts direct parasympathomimetic effects via direct stimulation of the vagus nerve -> (more at) AV nodal inhibition

• Irregularly irregular signal: digoxin is useful in atrial fibrillation (and flutter) (1st goal is rate not rhythm)

• Metronome: digoxin prevents rapid ventricular response in atrial fibrillation and flutter ("rate control")

Rhythm

• if still symptoms after slow rate

• synchronized shock, if not can land on T wave = VFIB

• reduced risk of converting back

• Amigo: amiodarone (class III antiarrhythmic)

• "till I die": -tilide suffix shared by dofetilide and ibutilide (class III antiarrhythmics)

• Soda: sotalol (class III antiarrhythmic)

• Muted bugle: sotalol is also a beta blocker (-lol suffix)

• Heart illuminated on top and bottom: class III antiarrhythmics treat both supraventricular arrhythmias and ventricular arrhythmias

• Irregularly irregular signal: class III antiarrhythmics treat atrial fibrillation (and flutter)

• Converting the signal: class III antiarrhythmics can restore and maintain normal sinus rhythm in atrial fibrillation and flutter

• Class IC antiarrhythmics: propafenone, flecainide

• Flakes: flecainide (class IC antiarrhythmic)

• purple phone: propafenone (class IC antiarrhythmic)

• Illuminated top and bottom of heart: class IC antiarrhythmics treat supraventricular and ventricular arrhythmias

• Irregularly irregular signal: class IC antiarrhythmics treat atrial fibrillation (and flutter)

• Converting the signal: class IC antiarrhythmics can restore and maintain normal sinus rhythm in atrial fibrillation and flutter

• spontaneous back to sinus

• if pt has hypotension/shock with afib: emergent cardioversion

Anticoagulation

• Big GATOR: arGATROban and dabiGATRAN are direct thrombin inhibitors

• Banned foXes: direct factor Xa inhibitors rivaroXaBAN and apiXaBAN

• Directly grabbing foX: factor Xa inhibitors bind directly

• Open mouth: factor Xa inhibitors are oral medications

• Irregularly irregular TV signal: direct Xa inhibitors are used for long term anticoagulation in atrial fibrillation

• Irregularly irregular signal: warfarin is used for long term anticoagulation in atrial fibrillation. Abnormal heart can increase thrombus formation

• even in sinus rhythm, not completely normal atria, some risk of stroke

• can have short asymptomatic afib

Surgery

• aka afib ablation

• in many cases afib initiated by PA travel to atria

• treat afib by catheters that burn myocyte around PA, create small area of nonconducting scar

AFLUT

• circuit in RA going around and around, each time generate sawtooth pattern, some are conducted to V

• sawtooth EKG

• special catheter, burn line of myocyte in atrium, disrupt electrical signal

• much easier than AFIB ablation

AVNRT

• normally: single speed at AV

• AVNRT: dual pathways

• people develop tissues in AV that conduct at different speed

• activity comes from SA, splits into slow and fast pathway

• fast pathway sends signal down AV and also another one back to slow pathway, cancel out with slow pathway

• sinus rhythm: signals cancel out, person asymptomatic

• dual pathway and PAC

• signal down dual pathway at time when fast pathway is refractory (long RF period)

• slow pathway recover quickly

• activity go down slow pathway, once reach bottom, fast pathway recovered, so go back up fast and down from slow

• result: reentrant circuit, tachycardic rhythm

• AV nodal reentry tachycardia

• no p waves: rhythm generated by AV node

• when it comes back up, sends retrograde up to atrium = P wave

• narrow QRS: still using AV

• fast HR

• feel heart pounding

• conduction in slow pathway is already slow, if slow down more = block

• vagal maneuver: hold breath, slow down heart with increased parasympathetic

• adenosine: very flushed and chest discomfort

• recurrent: BB, CCB, slow AV

• if med fail, surgical

• Swing dancing: adenosine (a purine nucleoside with antiarrhythmic properties)

• Purine shaped gate: adenosine is a purine nucleotide

• A1 Swing: adenosine activates inhibitory A1 receptors on the myocardium and at the SA and AV nodes

• Falling calci-yum ice cream: activation of A1 receptors suppresses inward Ca2+ current (hyperpolarization, suppressed Ca2+ dependent AP

• Banana flying out of cup: activation of A1 receptors increases outward K+ current (hyperpolarization, suppressed Ca2+ dependent AP)

• Note shaped dance floor: adenosine inhibits the AV nodes (decreased AV conduction, prolonged AV refractory period)

• Disconnected bottom of heart: adenosine decreases atrioventricular conduction

• Dilated coronary crown: adenosine causes coronary dilation (mediated by A2 receptors)

• Illuminated #1 top of heart: adenosine is a first line agent for acute treatment of supraventricular arrhythmias (e.g. PSVT)

WPW

• pt: extra piece of tissue (bypass track, white cursor) capable of conducting electricity between atria/ventricles in both directions

• electric current will go down AV node but also through atrium to bypass track = early deflection, delta wave

• P before every QRS, but QRS begins as soon as P ends

• very short PR

• inferior lead deep Q

• portion at different angle

• early activation of ventricle via bypass track

img

• different from AV nodal re-entrant tachycardia

• ortho: "correct"

• antidromic: go down bypass tract, initiate ventricles abnormally, wide QRS

• pattern: asymptomatic

• syndrome: symptoms

• Illuminated top and bottom of heart: class IA antiarrhythmics treat supraventricular and ventricular arrhythmias

• White wolf pack: class IA antiarrhythmics treat Wolff-Parkinson-White (WPW) syndrome (a type of SVT) (extra pathway stopped)

• AFIB, if slow conduction through AV node, more impulse sent through bypass tract

• highly complex management (electric cardioversion or ibutilide/procainamide). Not important