Fast arrhythmias come in two primary flavors: increased automaticity of tissue or re-entry of tissue.

	Increased automaticity	Re-entry	Notes
SA node	Sinoatrial tachycardia (ST) - can be physiologic (ie. exercise) or pathologic (inappropriate sinus atrial tachycardia, ca clock dysregulation	Sinoatrial node re-entry	differentiate the 2: they both appear as sinus rhythm, but ST starts and stops gradually, but re-entrant rhythms start and stops immediately
Atrial tissue	Atrial tachcardia (another focus in atria) - faster than sinus, necessarily, because if it were slower it’d be suppressed by sinus rhythm	Aflutter. Maybe a-fib - macro re-entrant rhythm, so there’s no electroneutral baseline, as something is always depolarizing - limb leads The precordial leads will not show bc they show a small window of myocardium	Will not stop with AV nodal block - if you apply adenosine the flutter will still go on, but there will be complete block
AV node	Junctional tach (more common in kids— in adults usually due to dig toxicity) - P & QRS waves will be separated  - like complete block, but there will be more QRS than P	AVNRT	should break with AV nodal block (ie vagal maneurver, adenosine)
Pathways		AVRT (circuit involves ventricles)

Bradyarrythmias in STEMI: 

Sinus brady

- revasc first (cath lab asap)

- if that fails or can't be done, then try atropine (full dose - half may have paradoxial reaction)

- if that fails, then temporary pacing 

AV block 

- First degree- usually due to meds ; PR <0.24

- Mobitz 1: manage with atropine 

- Mobitz 2: concerning b/c can progress to CHB. usually below bundle of his. tx with pacing 

- CHB

anterior or inferior infarct 

anterior (LAD) - massive septal necrosis - unstable escape rhythm (wide QRS, slow) - progresses to asystole, pump failure, shock 

Interior infarct - intranodal or supranodal - usually stable escape rhythm - narrow QRS, ok speed 

- Intraventricular block

RBB - lad and rca

LAF - LAD

LPF - LAD and RCA

Indications for temporary pacing in acute MI

- ventricular asystole 

- symptomatic brady 2//2 node dysfunction

- mobitiz I unresponsive to atropine

- mobitz 2 

- CHB

- bilateral or alternating BBB - indicates low level of block, unstable escape rhythm 

- new BBB with First deg AV block - suggesting concomitant disorders 

- old RBBB with first deg av block and new fasicular block - too many pathways compromised. 

Other temporary pacing indications

- bradyarrhythmia sufficient to cause hemodynamic instab

- injury to either node or his-purkinje 2/2 surgery

- lyme

- OHT

- trauma

- toxins, metabolites 

Temporary Pacing options: 

medical: b1 agonists - ie. isoproternol 

epicardial: surgeons  leave the leads on

transcutaneous: direct puncture to heart

esophageal: only paces atria - high current, painful

external: pacer pads

transvenous pacing: 

access:

RIJ is good for emergency, straight shot, easy 

subclavian if more permanent

femoral if in cath lab 

types: 

balloon, pacing swan ganz

pacemaker paramaters: 

rate - set rate 10-20 above baseline HR, then dial down, backup at 60 rate

current - set at max output, dial down until you get capture 

external/transthoracic pacing: 

- asystolic arrest

- prophylaxis during catheterization in someone with LBB - in case you bump RB with catheter and cause CHB 

- overdrive pacing to terminate tachyarrhythmias

- brady with unstable hemodynamics

pacemaker complications

- lead dislodgement or disconnection

- tamponade

- catheter knotting

- air embolli

- ptx

- more arrhythmias