Exam 1: Perfusion Flashcards
What is the normal conduction pathway? What are each point’s intrinsic rate?
begins at the sinoatrial node (60-100) in the right atrium then moves down to the atriventricular bundle (40-60) found in the septum and travels down the purkinje fibers (20-40)
What does the normal waveform waves, segments, and intervals indicate?
P: atrial contraction (depolarization)
Upright, constant, rounded
QRS: ventricular contraction (depolarization)
Atrial repolarization also occurs here but is masked
T: wave ventricular relaxation (repolarization)
Isoelectric line: return to baseline during waveform
PR interval is beginning of P wave to beginning of QRS: Important for blocks
QRS complex: begins at Q and ends when it goes back to isoelectric line: indicates how long it take for ventricle electrical activity
QT interval is beginning of QRS and ends where T returns to isoelectric line: If prolonged could lead to ventricular dysrhythmias
What are the steps for interpreting an EKG? What are the normal parameters? What does it indicate if it is outside the normal paramters?
Rate: count # of R waves in a six second strip
NSR=60-100
Regularity: measure distance between R to R
Assess for P waves
If upright and rounded = rhythm starts in SA node
Measure PR interval
Should be: 0.12-0.20
If greater than 0.2 think AV block
QRS duration
Should be: 0.06-0.12
If greater than 0.12 think of BBB
What is supraventricular tachycardia? Examples? Common causes?
narrow QRS complex with a rate >100
signal originates at or above AV node
atrial fibrillation
atrial flutter
HTN, DM, HF, ischemic heart disease, hyperthyroidism, moderate to heavy alcohol usage, heart valve disease, congenital heart disease, heart surgery
What is atrial fibrillation? What does the EKG look like? What are complications of it? Types?
electrical signal scrambled within the atria causing an atrial rate of 300-600bpm
no distinct p wave, wavy isoelectric line with irregular QRS complexes
blood pooling, blood clots, pulse deficit
controlled: rate<100bpm and usually well tolerated
uncontrolled: rate>100bpm, aka: rapid ventricular response, typically symptomatic and need intervention
What is atrial flutter? What does the EKG look like? What is the atrial and ventriclar rate?
ectopic foci sending irregular signals to atria causing them to circulate within the atria (causes the saw tooth pattern in EKG)
multiple p waves, QRS complexes are usually regular with saw tooth pattern between
atrial: 200-350
ventricular: 150
What are treatment for atrial fibrillation/flutter?
rate control: beta blockers, calcium channel blockers
anticoagulation: to reduce risk of stroke includes warfarin, non-vitamin k anticoagulants (apixaban, rivaroxaban)
synchronized cardioversion
radiofrequency ablation
What are heart blocks?
delay in conduction between AV node and ventricles
What are the EKG characteristics of first degree heart block? What are the symptoms?
PR interval is constantly greater than 0.20 with one P for every QRS (slow conduction but reach ventricles)
mild, typically no symptoms
What are the EKG characteristics of second degree heart block? What are the symptoms?
Type 1: Wenckebach - there are more P waves than QRS, PR interval gets longer until the QRS is dropped; benign that rarely causes hemodynamic instability but symptomatic patients will require a pacemaker (longer, longer, longer, drop, then you have a wenckebach)
Type 2: there are more P waves than QRS (no conduction to ventricles), PR interval is constant (if the PR stays normal and QRS quits then you have a type 2 mobitz)
What are the EKG characteristics of 3rd degree heart block? Cause?
there are more P waves than QRS complexes, PR interval is always changing (If P and QRS beat independently then it must be a complete third degree)
there are no electrical signals reaching the ventricles, THIS IS A LETHAL RHYTHM, the perfusing rhythm is maintained by junctional (QRS narrow 40-60bpm) or ventricular escape rhythm (QRS broad, 20-40bpm)
What are ventrical rhythms conduction sequence? Hallmark EKG characteristics? Examples?
abnormal ventricular depolarization and retrograde conduction through the system
wide, bizarre QRS complexes
ventricular tachycardia, ventricular fibrillation
What are the EKG characteristics for ventricular fibrillation? Treatment?
no P waves, no consistent QRS complexes, ventricular rate is accelerated at 150-250bpm
THIS IS A LETHAL RHYTHM
continue with CPR until defibrillator arrives
What are the EKG characteristics for ventricular tachycardia? Treatment?
no P waves, QRS complexes are wide and bizarre (may start with “runs” of 2 ro3 wide QRS periodically), ventricular rate is accelerated 150-200bpm
THIS IS A LETHAL RHYTHM
if w/ pulse and stable: synchronized cardioversion
if pulseless: early defibrillation
if good bp: IV adenosine
What are common medications used to treat dysrhythmias? What do they treat? MOA?Examples?
potassium channel blockers/class III anti arrhythmic: treats VT/VF Afib/SVT; inhibits adrenergic stimulation to prolong action potential and repolarization and decreases AV conduction and sinus node function; amiodarone, dofetilide
calcium channel blockers: Afib/flutter/SVT; inhibits extracellular calcium influx across membrane of myocardial cells and vascular smooth muscle resulting in inhibitory effects on cardiac conduction system and acts on AV and sinus node; diltiazem
adenosine: SVT; slows conduction through AV node and interrupts AV reentry pathways to restore normal sinus rhythm (chemical cardioversion) [pt needs to be educated on brief asystole, chest pain, tightness, and flushing]
beta blockers: Afib; decreases automaticity of SA node to reduce atrial and ventricular contractility
atropine: for symptomatic bradycardia; blocks effect of vagus nerve on heart [NOT effective for mobitz type 2 or third degree AVB or if pt has had a heart transplant]
What is cardiac resynchronization therapy? Indication? Examples?
sends signals to upper and lower chambers of heart to help beat in a more synchronized pattern
HF with LVEF<35%
pacemaker (CRT-P), defibrillator (CRT-D)
What are indications for a pacemaker?
bradycardia, AV block, MI, cardiomyopathy, HF
What will pacing look like on telemetry?
atrial pacing: spike before P wave
ventricle pacing: spike before QRS complex
What is failure to capture? What could cause this?
when a pacing stimulus is generated but fails to deliver to myocardial depolarization
could be d/t electrolyte imbalance?
What are indications for ICD?
ventricular tachyarrhythmias
