Electrocardiography Flashcards
Represents Ventricular Repolarization
ST-T-U complex
Junction between the end of the QRS complex and beginning of the ST segment
J point
Rapid upstroke of action potential and corresponds to onset of QRS
Phase 0
Plateau/isoelectric ST segment
Phase 2
Active repolarization / inscription of T waves
Phase 3
Decrease the slope of phase 0–> inc QRS duration
Impairment of influx of Na
If you prolong phase 2 what will happen
Increase QT interval
if you shorten phase 2
Lessens the ST segment
Normal P wave
positive in lead II and negative in avR
Precordial lead where R and S waves are of approximately equal amplitude
Transition zone ( usually V3 or V4)
Normal axis `
-30 to 100
Left axis deviation
More negative than -30
Right axis deviation
More positive than +100
Right axis deviation may also be seen in the ff conditio
Reversal of the left and right arm electrodes, right ventricular overload, infarction of the lateral wall of the left ventricle, dextrocardia, left pneumothorax, left posterior fascicular block
Right atrial overload
P pulmonale
Increase in P-wave amplitude (> or = 2.5 mm)
Left atrial overload
P mitrale
biphasic P wave in V1 with a broad negative component or a broad (>=120 ms) often notched Pwave
Right ventricular hypertrophy
R wave in lead V1 (R >= S wave) usually with right axis deviation
qR pattern in V1 or V3R
ST depression and T wave inversion in the right to mid precordial leads
Prominent S waves may occur in the left lateral precordial leads
Left ventricular Hypertrophy
SV1 + (RV5 or RV6) > 35mm
Repolarization abnormalities
Left ventricular strain pattern
ST depression with T wave inversions
Left Ventricular Hypertrophy
increase limb lead voltage with or without increased precordial voltage
(RavL + SV3 > 20 mm in women
> 28 in men)
Right Bundle Branch Block
Terminal QRS vector is oriented to the right and anteriorly (rSR’ in V1 and qRS in V6 typically)
Left Bundle Branch Block
wide predominantly negative QS complexes in lead v1 and entirely positive (R complexes in lead V6
Often a marker of one of four underlying conditions associated with inc risk of cardiovascular morbidity and mortality
(Coronary Heart Disease, Hypertensive heart disease, Aortic valve disease, Cardiomyopathy)
Left Bundle Branch Block
Left anterior fascicular block (QRS axis more negative than -45)
Most common cause of marked left axis deviation in adults
Left Posterior Fascicular block
QRS more rightward than +110-120
Extremely rare
Diagnostic triad of WPW
Wide QRS complex associated with relatively short PR interval and slurring of the initial part of the QRS (delta wave)
