14 - Arrhythmias

ARRHYTHMIA ALGORITHM

A: Narrow QRS --> Check P:Q ratio 

 -You might not see P wave if buried in QRS during a Short RP tachycardia. 

 -Look for subtle changes in QRS/T to find a P wave or you might mistakenly call it sinus tachy if you don't realize there's another, hidden, P wave

        - P>Q

                 -A fib

                -A flutter

                -Atrial tachycardia (e.g. multifocal atrial tachycardia)

                A-fib, A-flutter w variable block & MAT will have an irregular rhythm.

         - P=Q --> Check RP

                -Long RP (> 1/2 RR interval) = P in front or QRS

                        -Sinus Tachycardia

                        -Reentrant Tachycardia (some)

                                -PJRT (Permanent Junctional Reciprocating Tachycardia)

                                    -atria, AV node/HPS, ventricles, then serpiginous post-septal AP that delays

                                      retrograde conduction enough to --> long RP (unlike AVRT)

                                    -Often incessant, in kids/teens, +/-CM bc incessant

                                    -c/s PJRT if pt has retro (down) P wave before QRS in inf leads (II, III, F)

                                                -DDx low RA rhythm may also be retrograde P wave but not in all...

                        -Atypical AVNRT

                                -Goes down fast and up slow, so --> long RP (takes a while to get to atria)

                -Short RP (<1/2 RR interval)  = looks like P follows QRS 

                        -AVRT (AV reentrant tachy = orthodromic accessory pathway)

                              -Orthodromic: Down AV node, up accessory pathway - P wave often retrograde & 

                                embedded in ST-T bc it takes time to get up the slow AP to the atria

                              -Antidromic: Down accessory, up AV node--> wide QRS

                            -WPW (see delta wave when out of SVT)

                           -Concealed pathway (don't see delta wave when out of SVT)

                            -AVNRT (AV nodal RT=2 paths w/in AV node, usually P:Q 1:1, but sometimes not)

                             -Go down slow and up fast, so there's a short RP bc the P came 2nd and is just p R

                                    "Slow Down!"

                    Reentry Tachy - usually abrupt on/off, unlike Sinus Tachy which is more gradual on/off.

 B: Wide QRS

        -Ventricular Rhythm

                -Accelerated Ventricular Rhythm ( if <20% more than the upper limit of Nl HR)

                -Ventricular Tachycardia

                        -If P>R, like atrial with BBB, but if R>P then likely VT

                         -If there is a-v dissociation ("P's are marching through") then it's VT

                         -Fusion beats (atrial beat + ventricular) prove it's VT (bc they came fr diff places...)

                         -Capture beats (Nl, narrow atrial beat in between  wider beats) prove it's VT (av dissoc)

                -Ventricular Fibrillation

        -Atrial Rhythm

                -Atrial Fibrillation with WPW (DON'T GIVE ADENOSINE)

                                 -won't see delta wave w AF+WPW bc it's ~all going down AP, not AV node

                 -Sinus Tachy with Aberrant Conduction *

                                -c/s if wide complex w P before each QRS

                -Sinus Tachy with BBB*

                                -c/s if wide complex w P before each QRS

*Aberrancy = 2y to sudden incr Rate w diff in bundle propagation, but BBB is bc of a fundamental xx of the branch

                 -DDx VT vs SVT+BBB bc w SVT the morph will be the same as when pt was in sinus

Response to Adenosine to Aid in DDx:

-A-fib, flutter, and sinus tachycardia occur above AV node so likely won't respond to Adenosine

-With termination of the tachy w Adenosine- check for delta wave- if + then +WPW, otherwise AVRT/AVNRT/PJRT

-Ventricular rhythms are below the AV node so they are not likely to respond either

-A transient response, with return to tachyarrhythmia is still a response (see pic below)

 Adenosine Complications:

VT/VF/a-fib

bronchospasm if asthmatic

AV block, esp if transplanted heart = use a lesser dose at 1/2 to 1/5 

NEVER GIVE to pt w A-fib + WPW bc it will block the AV node and so heart can only conduct via the AP which is very slippery, allowing for very fast conduction to ventricles... (cardiovert (w sync) instead, if unstable)

 Sinus Capture Beat:

If you see a sinus capture beat (wide complex and then a p-QRS narrow complex, then it must have been a ventricular rhythm w/ an a-v dissociation...

WPW

-The signal goes down both AV nd and AP, but bc AP is slower, --> delta wave till the signal gets from AV node to His Bundle (when QRS is made...)

-Increased Automaticity

    -Sinus tachy 

            -check for cause; 

            -P wave axis same as sinus & faster; long RP

            -if u give adenosine, see P waves march thru, be prepared for HB and need for compressions if pt is d/o C.O....

    -focal atrial tachycardia

            -long RP; P axis will be different than Nl, warm up/down

    -multifocal atrial tachy

    -JET

  -A-fib - similar spectrum to MAT, not really incr automaticity, but similar enough...

-Reentry

    -AVNRT

        -Typical 

        -Atypical

    -AVRT

        -PJRT

        -Concealed accessory connection

        -WPW

        -Mahaim fibers

   -a-flutter

   -IART