Electrocardiogram Flashcards
P wave
Atrial depolarization
Atrial repolarization is masked by QRS complex
PR interval
conduction delay through AV node (normally <200 msec)
QRS complex
ventricular depolarization (normally <120 msec)
QT interval
mechanical contraction of the ventricles
T wave
ventricular repolarization
inversion may indicate recent MI
ST segment
isoelectric, ventricles depolarized
U wave
caused by hypokalemia, bradycardia
Speed of conduction from fastest to slowest
Purkinje > atria > ventricle > AV node
Pacemakers
SA > AV > bundle of His/Purkinje/ventricles
Conduction pathway
SA node –> atria –> AV node –> common bundle –> bundle branches –> Purkinje fibers –> ventricles
Inherent pacemaker
SA node “pacemaker” inherent dominance with slow phase of upstroke
Pacemaker with delay
AV node has 100 msec delay - AV delay to allow time for ventricular filling
Torsades de pointes - what?
What can cause?
Tx?
VT characterized by shifting sinusoidal waveform of ECG - can progress to Vfib
Anything that prolongs QT interval can predispose
Tx with magnesium sulfate
Congenital long QT syndromes
Torsades de pointes
Due to defects in cardiac sodium or potassium channels
Can present with severe congenital sensorinerual deafness (Jervell and Lange-Nielsen syndrome)
Atrial fibrillation ECG looks like?
Can result in?
Tx?
Chaotic and erratic baselines (irregularly irregular) with no discrete P waves in between irregularly spaced QRS complexes
Can result in atrial stasis –> stroke
Tx: rate control, anticoag, possible cardioversion
http://www.learnekgs.com/atrialfibrillation.htm
Atrial flutter ECG looks like?
Tx?
A rapid succession of identical back to back atrial depolarizations waves (saw tooth appearance of flutter waves). Tx: pharm conversion to sinus with class IA, IC, or III antiarrhythmics and Beta blocker or CCB for rate control
http://www.learnekgs.com/atrialflutter.htm
Ventricular fibrillation ECG looks like?
Can result in?
Tx?
Completely erratic rhythm with no identifiable waves.
Fatal arrhythmia without immediate CPR and defibrillation.
http://www.learnekgs.com/ventricularfibrillation.htm
1st degree AV block ECG looks like?
Presents with?
The PR interval is prolonged (>200 msec)
Asymptomatic
http://www.12leads.com/firstdegreeblock.htm
2nd degree AV block type 1 ECG looks like?
Other name?
Presents with?
Progressive lenthening of the PR interval until a beat is “dropped” (= p wave not followed by a QRS complex)
Wenckebach (Mobitz type I)
Usually asymptomatic
http://www.12leads.com/seconddegreetype1.htm
2nd degree AV block type 2 ECG looks like?
Other name?
Presents with?
Tx with?
Dropped beats that are not preceded by a change in the length of the PR interval.
Mobitz type II
These non-conducted p waves result in a pathological condition. Often a 2:1 block where there are 2 or more P waves to 1 QRS. May progress to 3rd degree.
Often treated with pacemaker.
http://www.12leads.com/seconddegreetype2.htm
3rd degree AV block ECG looks like?
Due to?
Tx with?
Both P waves and QRS complexes are present although the P waves bear no relation to the QRS complexes.
The atria and ventricle beat independently of each other. Atrial rate is faster than the ventricular rate. Lyme disease can cause.
Tx with pacemaker
http://www.12leads.com/thirddegree.htm
Atrial natriuretic peptide Release from? Causes - vascular and renal? Mechanism? Overall effect?
ANP released from atrial myocytes in response to increased blood volume and atrial pressure.
Causes generalized vascular relaxation and decrease Na+ reabsorption at the medullary collecting tubule
Constricts EFFERENT renal arterioles and dilates AFFERENT arteriole (cGMP mediates) –> promotes diuresis and contributes to the “escape from aldosterone” mechanism.
Ventricular fibrillation ECG looks like?
Can result in?
Tx?
Completely erratic rhythm with no identifiable waves.
Fatal arrhythmia without immediate CPR and defibrillation.
http://www.learnekgs.com/ventricularfibrillation.htm
1st degree AV block ECG looks like?
Presents with?
The PR interval is prolonged (>200 msec)
Asymptomatic
http://www.12leads.com/firstdegreeblock.htm
2nd degree AV block type 1 ECG looks like?
Other name?
Presents with?
Progressive lenthening of the PR interval until a beat is “dropped” (= p wave not followed by a QRS complex)
Wenckebach (Mobitz type I)
Usually asymptomatic
http://www.12leads.com/seconddegreetype1.htm
2nd degree AV block type 2 ECG looks like?
Other name?
Presents with?
Tx with?
Dropped beats that are not preceded by a change in the length of the PR interval.
Mobitz type II
These non-conducted p waves result in a pathological condition. Often a 2:1 block where there are 2 or more P waves to 1 QRS. May progress to 3rd degree.
Often treated with pacemaker.
http://www.12leads.com/seconddegreetype2.htm
3rd degree AV block ECG looks like?
Due to?
Tx with?
Both P waves and QRS complexes are present although the P waves bear no relation to the QRS complexes.
The atria and ventricle beat independently of each other. Atrial rate is faster than the ventricular rate. Lyme disease can cause.
Tx with pacemaker
http://www.12leads.com/thirddegree.htm
Atrial natriuretic peptide Release from? Causes - vascular and renal? Mechanism? Overall effect?
ANP released from atrial myocytes in response to increased blood volume and atrial pressure.
Causes generalized vascular relaxation and decrease Na+ reabsorption at the medullary collecting tubule
Constricts EFFERENT renal arterioles and dilates AFFERENT arteriole (cGMP mediates) –> promotes diuresis and contributes to the “escape from aldosterone” mechanism.
