Coronary Circulation - Quiz 9 🫀

Question 1

What are the Major Coronary Arteries? (4)

Answer 1

Right Coronary Artery (RCA) - 85%

Left Main Coronary Artery (LM)

Left Anterior Descending (LAD)

Circumflex Artery (CX)

Question 2

What is the Ramus Intermedius?

Answer 2

Additional Branch in people who have Trifurcation of the Left Main

37%

Question 3

Do the Epicardial Arteries contribute significantly to Coronary Vascular Resistance?

Answer 3

No - Intramyocardial Vessels (Arterioles) contribute the most to resistance

Question 4

What is Capillary Density and is it increased or decreased in the Myocardium? (2)

Answer 4

Number of capillaries per unit cross sectional area.

Capillary Density is increased in the Heart

Question 5

What are the major Metabolic determinants of Myocardial Oxygen Demand (3)

Answer 5

HR, Contractility, Systolic Wall Tension

Question 6

What are the major determinants of Myocardial Oxygen Supply? (3)

Answer 6

Coronary Blood FLow

O2- Carrying Capacity

Vascular Resistance

Question 7

Is O2 Consumption of the Heart at rest higher or lower than other organs?

Answer 7

Higher

Heart > Kidneys > Brain > Liver

Question 8

Coronary Perfusion Pressure Formula?

Answer 8

CPP = DBP - LVEDP (or PCWP)

Question 9

Is Oxygen highly extracted from blood flowing through the heart?

Answer 9

Yes, more than any other organ

Question 10

What factors control Coronary Blood Flow? (5)

Answer 10

Metabolic Control

Autoregulation

Endothelial Control of Tone

Extravascular Compression

Neural Control

Question 11

Which stage of the heart cycle does the majority of coronary blood flow occur in the left ventricle?

Answer 11

Most blood flow during Distole b/c the muscles relax & no longer obstructs blood flow

During Systole, there’s strong compression of vessels by LV muscle

Question 12

Which Layer of the Myocardium is at the greatest risk for ischemia?

Answer 12

Endocardium

Question 13

What is Coronary Flow Reserve?

Answer 13

The Max increase of blood flow through Coronary Arteries above normal resting volume

4-5x more than at rest

Question 14

Does Pressure Work or Volume Work cause more Heart O2 Consumption?

Answer 14

Pressure Work is much more costly

Question 15

A significant decrease in flow happens at what degree of coronary vessel stenosis?

Answer 15

Critical Stenosis

60-75% Reduction

Question 16

What is the final Intracellular Ion Disturbance that leads to impaired heart contraction & cell death?

Answer 16

Intracellular Calcium Overload

Question 17

How does Myocardial Ischemia affect Systolic Function? (2)

Answer 17

Akinesis - No Movement

Dyskinesis - Systolic lengthening & Post-Systolic Shortening

Question 18

How does Myocardial Ischemia affect Diastolic Function? (3)

Answer 18

↑LVEDP

Impaired Relaxation

↓Compliance

Question 19

What is Myocardia Stunning?

Answer 19

Prolonged Heart Dysfunction after episode of severe Ischemia with gradual return of activity

Stunning is Completely Reversible

Question 20

What is Myocardial Hibernation?

Answer 20

When heart function is depressed from chronic ishemia

Function can return to normal if blood flow is returned to normal in time

Question 21

What are some consequences of Myocardial Ischemia? (8)

Answer 21

• Systolic/Diastolic Dysfunction
• Angina
• CHF
• Pulmonary Edema
• MI
• Ventricular Rupture/VSD
• Cardiogenic Shock
• Death

Question 22

What are some drugs used to treat cardiac ischemia? (6)

Answer 22

Oxygen
B-Blockers
Calcium Channel Blockers
Nitrates
Antiplatelet/Anticoagulant
Analgesic

Question 23

What are some Interventions used to treat cardiac ischemia? (5)

Answer 23

• CABG
• Percutaneous Coronary Intervention (PCI)
  
  • Balloon Angioplasty
  • Bare-Metal Stents
  • Drug-Eluding Stents

Question 24

How Long should you wait before doing elective surgery for patients w/ Drug-Eluting Stents or Bare-Metal Stents?

Answer 24

Drug-Eluting: 1 Year

Bare-Metal: 90 days

Question 25

What are some Drugs used to reduce cardiac ischemic events during surgery? (6)

Answer 25

Anesthetic Gas B-Blockers CC-Blockers Statins Alpha 2 Agonist NTG

Question 26

Should Isoflurane be used for Cardiac Surgery?

Answer 26

No because it causes Coronary Steal

Question 27

What are Collateral Blood Vessels in the Heart? How are they formed?

Answer 27

New vessels that form in response to impaired coronary blood flow. Form from pre-existing arterioles that branches b/t occluded & non-occluded arteries

Question 28

What is Ischemic Preconditioning in the Heart? (3)

Answer 28

Brief periods of Ischemia can be protective against subsequent prolonged ischemic injury Anesthetic Gas: Mimics IPC K⁺_ATP channels play important role

Question 29

What is the main way that the heart compensates for underperfusion?

Answer 29

Increase Coronary Blood Flow - cant extract much more Oxygen

Question 30

What is Cardiac Autoregulation?

Answer 30

Ability of vascular network to maintain constant blood flow Tightly coupled to Demand and is location-dependent

Question 31

What serves as complimentary control of Coronary Blood Flow?

Answer 31

Neural Control

Question 32

What are the Direct effects of Neural Control of Coronary Blood Flow?

Answer 32

Sympathetic Stimulation - Release norepi & Epi

Question 33

What are the Indirect Effects of Neural Control of Coronary Blood Flow?

Answer 33

Increased metabolism activates local blood flow regulatory mechanisms to dilate vessels

Question 34

What is Parasympathetic control of Coronary Blood Flow?

Answer 34

Releases Acetylcholine

Question 35

Define Myocardial Oxygen Consumption

Answer 35

Volume of Oxygen consumed per minute

Question 36

What anesthetic agents are know as anesthetic preconditioning?

Answer 36

Volatile Anesthetics

Question 37

What is myocardial preconditioning?

Answer 37

Describes the experimentally observed phenomenon that an intervention or trigger that results in a reduction of infarcted area in subsequent ischemia.