| Question |
Answer |
| In the ventricular action potential, what causes the Phase 0 rapid upswing? |
opening of voltage gated Na channels |
| In the phase 2 plateau, Ca++ influx triggers Ca++ release from the SR causing …. |
myocyte contraction |
| What effect does Ach have on HR? |
decrease |
| What effect do catecholamines have on HR |
increase |
| Name 4 things that increase contractility: |
catecholamines, digitalis, an increase in intracellular Ca++, or a decrease in extracellular Na+ |
| What effect does increased afterload have on myocardial oxygen demand? |
increased |
| how do catecholamines increase contractility? |
increase the activity of Ca++ pump in the SR |
| What effect will and MI have on contractile state of the heart? |
decrease |
| what does S1 correspond to? |
mitral and tricuspid valve closure |
| what does S2 correspond to? |
aortic and pulmonary valve closure |
| what does S3 correspond to? |
the end of rapid ventricular filling |
| what is S3 associated with? |
dilated CHF |
| what is S4 and what does it indicate? |
an atrial kick associated with a hyptertrophic ventricle (high atrial pressure/stiff ventricle) |
| what is the a wave? |
atrial contraction |
| what is the c wave? |
RV contraction when the tricuspid valve bulges into atrium |
| what is the v wave? |
increase in atrial pressure due to filling against a closed tricuspid valve |
| what is physiologic S2 splitting |
aortic valve closes just before the pulmonic - the difference is increased on inspiration |
| what is paradoxical splitting |
when the split is heard on expiration instead of inspiration … associated with aortic stenosis |
| what is meant by "HIZ" shrinkage |
the H, I, and Z band decrease in length on muscle contraction, the A band (myosin) stays the same length |
| describe the pathway of smooth muscle contraction |
ap - > sm muslce depolarization - > open Ca++ channels -> increase in cytosol Ca++ -> Ca++ bind Calmodulin -> activates MLCK -> relaxation ->MLCP forms a cross bridge and contraction by binding myosin to actin - > MLCK relaxes … cycle continues while Ca |
| in an EKG, what does the P wave represent? |
atrial depolarization |
| in an EKG, what does the PR segment represent? |
conduction delay through the AV (200 msec) |
| in an EKG, what does the QRS complex represent? |
ventricular depolarization(120 msec) |
| in an EKG, what does the QT interval represent? |
mechanical contraction of the ventricle |
| in and EKG, what does the T wave represent? |
ventricular repolarization |
| do you see atrial repolarization on an EKG? |
no, it is masked by the QRS complex |
| in an EKG, what does the ST segment represent? |
isoelectric, ventricles are depolarized |
| on an EKG, what is a U wave? |
caused by hypokalemia |
| what is Wolff-Parkinson-White syndrome |
when an accessory conduction pathway exists from atria to ventricle (bundle of Kent) - bypasses the AV node and ventricles partially depoliarize earlier giving rise to a delta wave. WPW syndrome may lead to recurrent entry and SVTs. |
| What do you see on and EKG with atrial fibrillation? |
chaotic erratic baseline with no disrete P waves in between iregularly spaced QRS complexes |
| What do you see on an EKG with atrial flutter? |
sawtooth, identical back to back P waves |
| How many kinds of AV block are there? |
4: 1st degree, mobitz I, mobitz II, complete |
| What is 1st degree AV block? |
asymptomatic - PR interval longer than 200 msec |
| What is mobitz II AV block? |
driooed beats not proceeded by a progressively lengthening PR interval. Pathological … can progress to complete block |
| What is mobitz I AV block? |
progressive PR lengthening until a beat is dropped … usually asymptomatic |
| what is a 3rd degree AV block |
complete AV block, atria and ventricles beat independently … rx with pacemaker |
| what is v-fib |
completely erradic rhythm with no identifiable waves, fatal without immediate defibrillation |
| what is the normal right atrial pressure? |
5 |
| what is the normal left atrial pressure |
12 (approx with pcwp - swan-ganz) |
| what is the normal right ventricular blood pressure? |
25/5 |
| what is the normal pulmonary artery pressure? |
25/10 |
| what is the normal left ventricular pressure? |
130/10 |
| what is a normal aortic blood pressure? |
130/90 |
Cardio Block2anatomy
