Quiz 9

Question 1

major branches of the coronary arteries

Answer 1

RCA to PDA

Left Main to LAD, L Circ, Ramus (37%)

Question 2

What is the Ramus Intermedius? In what percentage of the population does it exist?

Answer 2

37% of ppl have trifurcation of left main

Question 3

Do the major epicardial arteries contribute significantly to coronary vascular resistance?

Answer 3

no, myocardial vessels do

Question 4

What is capillary density? Is capillary density increased or decreased in the myocardium?

Answer 4

Increased

Question 5

What are the major determinants of myocardial oxygen demand?

Answer 5

HR
Contractility
Systolic wall tension

Question 6

What are the major determinants of myocardial oxygen supply?

Answer 6

Coronary blood flow

O2 carrying capacity

Question 7

Is resting oxygen consumption of the heart high or low relative to other organs in the body?

Answer 7

Its the highest at 9.7 ml/100 g/min

Question 8

What is the formula for coronary perfusion pressure?

Answer 8

Diastolic BP – LVEDP (or PCWP)

Question 9

Is oxygen highly extracted from blood flowing through the heart?

Answer 9

yes, higher than any other organ

Question 10

Does the majority of coronary blood flow occur during systole or diastole in the left ventricle? Why?

Answer 10

Diastole

Extravascular compression during systole markedly affects coronary flow

Question 11

Which layer of the myocardium is at greatest risk for ischemia? Why?

Answer 11

subendocardium

Epicardial coronary stenoses are associated with reductions in the subendocardial to subepicardial flow ratio

Question 12

What is coronary flow reserve? how much max vs resting?

Answer 12

Difference between resting/baseline blood flow and maximal flow

maximal flow is 4 – 5 times as great as at rest

Question 13

Which of the following places a greater oxygen cost on the heart? Pressure work versus volume work.

Answer 13

Pressures work

increasing arterial pressure at a constant cardiac output harder on heart

Question 14

How stenotic do coronary vessels have to be before there is a significant decrease in flow?

Answer 14

60% occluded or 40% max Radius

Question 15

What is the final intracellular ion disturbance that leads to impaired myocardial contraction and cell death?

Answer 15

Intracellular Ca++ Overload

Question 16

What are the effects of myocardial ischemia on systolic function?

Answer 16

Normal myocardium thickens and shortens during systole

minimal impairment to absence of movement (akinesis) to systolic lengthening and post- systolic shortening (dyskinesis)

May have compensation by surrounding areas of normal muscle

Question 17

What are the effects of myocardial ischemia on diastolic dysfunction?

Answer 17

LVEDP rises
Impaired Relaxation
decreased compliance

Question 18

The point After a brief episode severe ischemia, prolonged myocardial dysfunction with gradual return of contractile activity occurs

Answer 18

myocardial stunning

Question 19

Presence of impaired resting LV function, owing to reduced CBF that can be restored toward normal by revascularization.

Answer 19

myocardial hibernation

Question 20

What are some of the consequences of myocardial ischemia?

Answer 20

Myocardial Infarction
Angina
Death
Systolic and diastolic dysfunction
Ventricular Rupture or VSD
Arrythmias
CHF or Pulmonary Edema
Cardiogenic Shock

Question 21

What are some of the drugs used for the treatment of ischemia?

Answer 21

Antiplatelet/Anticoagulant Drugs
Analgesics
Beta-Blockers
Oxygen 
Nitrates
Calcium-Channel Blockers

Question 22

What are some of the interventions used in the treatment of ischemia?

Answer 22

Coronary artery bypass surgery (CABG)

Percutaneous Coronary Interventions

• Coronary Balloon Angioplasty
• Bare-metal Coronary Stents
• Drug-eluting Stents

Question 23

How long should you wait before doing elective surgery on a patient who has had a drug-eluting stent inserted?

Answer 23

> 6 months to 1 year

bare metal stent 90 days

Question 24

What are some of the drugs that are used to reduce cardiac ischemic events during surgery?

Answer 24

• Volatile anesthetic agents may be preferred
• Anesthetic Preconditioning
• Beta-blockers
• Statins
• Alpha-2-agonists (good in ppl who cant take B.Blockers)
• Calcium channel blockers

Question 25

Is isoflurane an appropriate anesthetic agent to use during cardiac surgery? Why or why not?

Answer 25

Isoflurane has been associated with Coronary Steal (shunting blood from poorly perfused areas to better perfused) causing worsening ischemia.
In reality, coronary steal is not that big a deal - don’t use Iso if pt has severe hypotension.

Question 26

What are collateral blood vessels in the heart? How are they formed?

Answer 26

• develop between branches of occluded and non-occluded arteries and can contribute a significant amount of blood flow
• They originate from pre-existing arterioles that undergo proliferative changes of the endothelium and smooth muscle

Question 27

What is ischemic preconditioning in the heart?

Answer 27

single or multiple brief periods of ischemia can be protective against a subsequent prolonged ischemic insult. The brief periods of ischemia appear to “precondition” myocardium against reversible or irreversible tissue injury, including stunning, infarction, and the development of malignant ventricular arrhythmias

Question 28

What is anesthetic preconditioning in the heart?

Answer 28

effects that mimic IPC

K+ATP channels play an important role

Question 29

which part of heart supplies diagonal branches?

Answer 29

LAD

Question 30

which part of heart supplies obtuse marginals?

Answer 30

Left Circumflex

Question 31

What controls coronary blood flow?

Answer 31

Vascular resistance

Question 32

What controls vascular resistance?

Answer 32

Neural control
Metabolic control
Endothelial control
Autoregulation
Extravascular compressive forces

Question 33

Blood flow through thecoronarysystem is regulated mostly by __________ ?

Answer 33

local arteriolar vasodilation

Question 34

What 2 things help create collateral blood flow?

Answer 34

Monocyte chemoattractant protein-1 (MCP-1)

Vascular endothelial growth factor (VEGF)

Question 35

normal coronary blood flow?

Answer 35

• 70 ml/min/100 g of heart weight,
• 225 ml/min
• 4 to 5 percent of the total cardiac output

Question 36

What of the heart is the most important physiological mechanism regulating coronary vascular resistance

Answer 36

Metabolic activity

Question 37

what mechanisms are responsible for metabolic control?

Answer 37

Nitric oxide
Adenosine
Prostaglandins
K+ATP channels

(causes increased blood flow and vasodilation)