Basic Cardiology Physiology

Question 1

S3 vs S4

Answer 1

S3:

• occurs during early diastole
• Atrial blood reverberating against poorly functioning ventricular walls
• “Systolic Heart failure”
• associated strongly with Major Adverse Cardiac Event (MACE)
• According to guidelines a patient wil HF would qualify for preop ECHO if has worsening clinical status or other signs (NEW S3)

S4:

• Due to non compliant LV
• Late diastolie during active LV filling

Question 2

What is the largest component to myocardial oxygen demand?

Answer 2

Wall tension described by LaPlace’s Law: T = Pr/2h. P=ventricular pressure, r=radius, h = wall thickness

Question 3

What is the equation for SVR?

Answer 3

SVR = [(MAP-CVP)/CO] x 80

Question 4

What are some of the effects of beta blockers?

Answer 4

1. Decrease inotropy, chronotropy, dromotropy and lusitropy
2. Bronchospasm (blockade of Beta 2)
3. Antinociceptive (can decrease opioid doses
4. Glycogenolysis –> lower glucose levels
5. Decrease aqueous humor production
6. Decrease peripherial conversion of T4 to T3

Question 5

Up to what HR will cardiac index be maximized in an otherwise healthy individual? And down to what HR would you see a drop off?

Answer 5

Up to 120 bpm. Then it falls precipitously afterwards as SV decreases due to decreased LVEDV (preload). At that rate, the decreases in SV outweight the increases in HR.

At rest CI is 3.5 l/min/m2. At HR 120 raises to 5.5

Below 40 CI drops quickly as increases SV are outweighted by decreases in HR

Question 6

Which organs at rest receive the most, middle and least cardiac output?

Answer 6

High: Liver (19%), Muscle (19%), Heart and lungs (19%), Kidneys (16%)

Medium: Brain (10%), Intestines (6%)

Question 7

What is the von Bezold Jarisch reflex

Answer 7

Receptor in the LV will fire in the setting of low pressures. These are wired to vagal afferents –> bradycardia and hypotension

1) Hypovolemic patient has sudden further decrease in preload or spinal anesthesia
2) following MI or coronary reperfusion

Question 8

What is the barorecptor reflex?

Effects due to anesthesia?

Answer 8

KNOW THIS!!!!

Increase BP –> increased firing from baroreceptors in carotid sinus -> carried by Hering nerve (CN IX) to cardiovascular centers in medulla –> inhibition of sympathetic and increased parasympathetic –> decreased chronotrophy, inotropy and vascular tone

Anesthesia decreases this reflex.

Question 9

Perioperative use of ACE inhibitors is associated with?

Answer 9

Increased intraoperative hypotension

No increase or reduction of MI, Stroke or mortality

Question 10

In which equation do you find the starling equation

Answer 10

Q=kA x {(Pc-Pi) - sigma(pi c - pi i)}

Q= net fluid filtration
k= capillary filtration coefficient (of water)
A= area of the membrane
sigma= reflection coefficient (of albumin)
Pc= capillary hydrostatic pressure
Pi=interstitial hydrostatic pressure
pi i= interstitial colloid osmotic pressure
pi c: capillary colloid osmotic pressure

Question 11

What are normal reference ranges for CVP, Wedge, Cardiac Output and Stroke Volume?

Answer 11

CVP: 6
Wedge: 10
CO: 5 L/min
Stroke Vol: 70cc