Basics of ECG- How different factors show up in ECG.

Question	Answer
P wave	atrial DEpolarization
PR interval	time required for impulse to travel from atria through conduction system to Purkinje fibers
QRS wave	ventricular DEpolarization
ST segment	beginning of ventricular REpolarization
T wave	ventricular REpolarization
QT interval	time for electrical systole
Heart Rate	# of intervals between QRS complexes in a 6-second strip multiplied by 10
Ventricular arrhythmias	originate from an ectopic focus in the ventricles (outside normal conduction system)
Ventricular fibrillation	pulseless, emergency situation requiring EMT: CPR, defibrillation, medications
Premature ventricular contractions (PVCs)	NO P wave, bizarre & wide QRS that is premature, followed by a long compensatory pulse
Serious PVCs	>6 per minute, paired or in sequential runs, multifocal, very early PVC (R on T Phenomena)
Ventricular tachycardia	3 or more PVCs occuring sequentially; very rapid rate (150-200 bpm)
Ventricular tachycardia	wide, bizarre QRS waves, NO P waves, seriously compromised cardiac output
Ventricular fibrillation	chaotic activity of ventricle originating from multiple foci; unable to determine rate
Ventricular fibrillation	bizarre, erratic activity without QRS complex
Ventricular fibrillation	No effective cardiac output; clinical death within 4-6 mins
Atrial arrhythmias (supraventricular)	Rapid & repetitive firing of 1 or more ectopic foci in the atria
Atrial arrhythmias (supraventricular)	P waves abnormal (variable in shape) or not identifiable (atrial fibrillation)
Atrial tachycardia	140-250 bpm
Atrial flutter	250-350 bpm
Atrial fibrillation	>300 bpm
Atrioventricular blocks	ab(N) delays or failure to conduct through (N) conductiong system
If ventricular rate is slowed,	Cardiac output is decreased
3rd degree AV block	life threatening, requires meds (ATROPHINE), pacemaker
ST depression	impaired coronary perfusion (ischemia or injury)
MI central zone of infarction	Ab(N) Q waves
MI zone of injury	ST elevation
MI zone of ischemia	T wave inversion
Hyperkalemia	wide QRS, flat P wave, peaked T wave
Hypokalemia	flat T wave (or inverted), produces U wave
Hypercalcemia	wide QRS, short QT interval
Hypocalcemia	prolonged QT interval
Hypothermia	ST segment elevation; slow rhythm
Digitalis	ST segment depression, flattened T wave (or inverted), shortened QT
Quinidine	long QT, T flat/inverted, QRS long
BetaBlockers (Propranolol/Inderal)	decreased heart rate, blunts HR response to exercise
Nitrates (nitoglycerin)	Inc HR
Antiarrhythmic agents	may prolong QRS & QT intervals