Cardiac Physiology

Question 1

Effect of volatile agents and opioids on automaticity of SA node and AV node

Answer 1

• volatiles depress SA node more than AV node (junctional rhythms under inhaled anesthesia)
• opioids increase AV nodal conduction but have less effect on SA node

Question 2

How do volatiles depress myocardial contractility?

Answer 2

-indirectly decreasing release of calcium from SR

Question 3

Sidedness of heart innervation

Answer 3

SA node- right vagus and sympathetic chain
AV node- left vagus and sympathetic chain

*during SVT, right carotid massage more likely inhibits sinus discharge and left carotid massage slows AV node

Question 4

E to A ratio of

Answer 4

Impaired relaxation

E=early diastolic flow
A=peak atrial flow

A>E in diastolic dysfunction

Question 5

Baroreceptor Reflex

Answer 5

Drop in BP sensed by carotid sinus and aortic arch–>decreased discharge–>less inhibition of SNS and increased inhibition of vagal tone

Increase in BP–>increase baroreceptor discharge–>increased inhibition of SNS

Question 6

Baroreceptor Reflex

Answer 6

Drop in BP sensed by carotid sinus and aortic arch–>decreased discharge–>less inhibition of SNS and increased inhibition of vagal tone

Increase in BP–>increase baroreceptor discharge–>increased inhibition of SNS

Question 7

Sensitivity of epicardium versus endocardium to ischemia

Answer 7

• endocardium is more sensitive to ischemia than the epicardium (ST depressions)
• epicardium ischemia (and therefore endocardial ischemia as well) usually has ST elevations

Question 8

Sensitivity of epicardium versus endocardium to ischemia

Answer 8

• endocardium is more sensitive to ischemia than the epicardium (ST depressions)
• epicardium ischemia (and therefore endocardial ischemia as well) usually has ST elevations

Question 9

Treatment for unstable a fib

Answer 9

Cardioversion with biphasic 120 J

Question 10

Treatment for AV nodal re-entry

Answer 10

Adenosine 6 mg, then 12 mg, then 12 mg, then cardioversion

Question 11

Most sensitive and specific monitor for intraoperative MI

Answer 11

TEE, then EKG

Question 12

Tetralogy of Fallot

Answer 12

1. RV obstruction
2. RVH
3. VSD
4. Over-riding aorta

Question 13

Cardiac Tamponade

Answer 13

-during inspiration, RV filling is enhanced, moving the septum towards the left, decreasing LV stroke volume (pulses paradoxus)
-“y” descent is absent on CVP tracing
-due to external pressure in ventricles, ventricular filling and SV are fixed, making CO heart rate dependent
-

Question 14

1st line treatment for aortic dissection

Answer 14

Beta blockers, eg. esmolol gtt

• BBs reduce HR and contractility
• nicardipine or nitroprusside can be added later, but when used alone can increase both HR and CO, increasing shear forces on aorta

Question 15

Most common location of traumatic aortic dissection in blunt trauma

Answer 15

Aortic isthmus- just distal to left SCA at location of ductus arteriosis

Question 16

Active Cardiac Conditions

Answer 16

• acute/recent MI
• unstable or severe angina
• high grade AV block (Mobitz II or complete)
• symptomatic ventricular arrhythmias
• SVTs with uncontrolled ventricular rate
• severe valvular disease
• decompensated or new heart failure

Question 17

Clinical Risk Factors for Cardiovascular Risk

Answer 17

• ischemic heart disease
• compensated CHF
• mild angina
• diabetes
• CVA
• renal insufficiency