Conduction Disorders Part II (Exam 2)

Question 1

list the five major causes of bundle branch blocks.

Answer 1

coronary disease is the most common cause, rheumatic heart disease, trauma, cardiiomyopathy, congenial lesions

Question 2

what are the ECG characteristics of a right bundle branch block?

Answer 2

QRS complex greater than .12 seconds

RSR’ (aka rabbit ears) in V1 and V2 with STsegment depression and T wave inversion

Question 3

what are the ECG characteristics of a left bundle branch block?

Answer 3

QRS complex greater than .12 seconds, usually much greater with full block.
Broad or notched R wave with prolonged upstroke in V5, V6, I, aVL with ST segment depression and T wave inversion.

Question 4

what is the pathophysiology of Right Ventricular Hypertrophy?

Answer 4

caused by increased pressure and/or volume. occurs in pulmonary valve stenosis, COPD, status asthmaticus, pulmonary embolus, mitral valve stenosis or insufficiency. Less common than left.

Question 5

what are the ECG characteristics of Right Ventricular Hypertrophy?

Answer 5

MUST HAVE BOTH: right axis deviation of +100 or more
the R wave is larger (deeper) than the S wave in V1, where the S wave is larger (deeper) than the R wave in V6. (opposite of normal)

Question 6

what is the pathophysiology of Left Ventricular Hypertrophy?

Answer 6

caused by increased pressure and/or volume, left ventricular overlad. occurs in mitral insufficiency, systemic hypertension, acute MI, aortic Stenosis or insufficiency. Hypertrophic cardiomyopathy.

Question 7

what are the ECG characteristics of left ventricular hypertrophy?

Answer 7

axis is usually normal, but can occasionally see left axis deviation.
The tallest R wave in V5 or V6 plus the deepest S wave in V1 or V2 will be greater than or equal to 35 mm.
the R wave in aVL exceeds 13 mm.
R wave amplitude in V6 exceeds the R wave amplitude in V5.
R wave amplitude in lead I exceeds 14 mm.
Pattern is present in about 50% of patients who actually demonstrate LVH on an echocardiogram.