Coronary Hemodynamics and FFR

Question 1

What is CFR?

Answer 1

Coronary Flow Reserve

Question 2

What controls coronary blood flow?

Answer 2

Local metabolites such as adenosine or nitric oxide

Question 3

What is the basic principle of FFR?

Answer 3

When resistance is constant, changes in pressure are proportional to changes in flow.

Question 4

What does FFR correlate with?

Answer 4

Maximum myocardial blood flow in the presence of a stenosis divided by the theoretical maximum flow in a normal vessel.

Question 5

How is FFR obtained?

Answer 5

Simultaneously measuring the mean aortic pressure and coronary pressure distal to the stenosis at hyperemia.

Question 6

What is the FFR threshold that is used in clinical practice today?

Answer 6

0.80

Question 7

What process are myocardial cell contraction and relaxations?

Answer 7

Aerobic processes that require oxygen

Question 8

What are the determinants of myocardial oxygen demands? (5)

Answer 8

-Preload
-Afterload
-Heart rate
-Contractility
-Basal Metabolic Rate

Question 9

What percentage does systolic wall tension use for myocardial oxygen demand?

Answer 9

30%

Question 10

What affects wall tension? (4)

Answer 10

-Interventricular pressure
-Afterload
-End Diastolic Volume
-Myocardial Wall Thickness

Question 11

What vessels are the first to branch off the aorta?

Answer 11

Coronary Arteries

Question 12

What is the percentage of cardiac output when the body is at rest through the coronary arteries? (2)

Answer 12

5%
250 mL/min

Question 13

Under basal conditions, the myocardium extracts approximately what percentage of delivered oxygen?

Answer 13

75%

Question 14

The myocardium has a basal metabolic requirement that is what times that of resting skeletal muscle and what to that of skeletal muscle under sever acidotic conditions? (2)

Answer 14

-15 to 20 times
-Equal

Question 15

What is coronary blood flow controlled primarily by?

Answer 15

Changes in resistance in the small arteries and arterioles.

Question 16

When does coronary blood flow occurs?

Answer 16

During diastole

Question 17

Flow in the left coronary artery has what compared to the right coronary artery?

Answer 17

Greater diastolic predominance because of the compressive forces of the left ventricle

Question 18

What percentage of coronary flow in the left anterior descending artery occurs in diastole?

Answer 18

85%

Question 19

Right coronary artery blood flow is what in systole and diastole

Answer 19

More or less equal

Question 20

The predominance of flow during diastole does what during tachycardia?

Answer 20

Exacerbates myocardial ischemia

Question 21

With increased heart rates, oxygen supply is?

Answer 21

Reduced because diastole is shortened whereas demand increases

Question 22

What is autoregulation?

Answer 22

Hearts ability to maintain coronary blood flow in the presence of varying perfusion pressures

Question 23

Auto regulation maintains consistent coronary flow over a range of perfusion pressures from?

Answer 23

60 to 150 mm Hg

Question 24

In the setting of maximum vasodilation of coronary resistance vessels, blood flow is?

Answer 24

No longer autoregulated and varies linearly with perfusion pressure

Question 25

The ability to auto regulate to maintain flow when perfusion pressures are decreased are important in?

Answer 25

Presence of epicardial coronary stenoses

Question 26

What is the basic principle of Fractional Flow Reserve?

Answer 26

When resistance is constant, changes in pressure are proportional to changes in flow

Question 27

What enabled the introduction of the concept of pressure derived FFR?

Answer 27

A pressure transducer mounted on a 0.014 in angioplasty wire

Question 28

What does FFR correlate with?

Answer 28

Maximum myocardial blood flow in the presence of a stenosis divided by the theoretical maximum flow in a normal vessel

Question 29

FFR represents that fraction of?

Answer 29

Normal maximum flow that is achievable in the presence of epicardial coronary stenosis

Question 30

What is the measurement and clinical use of FFR depends on what two assumptions?

Answer 30

-Maximal Hyperemia in the target vessel has been obtained -Negligible coronary venous pressure

Question 31

What is iFR?

Answer 31

Instantaneous wave-free ratio

Question 32

What is instantenous wave-free ratio iFR?

Answer 32

Measurement of the hemodynamic significance of a coronary artery stenosis which relies on comparison of pressures during diastole in the absence of hyperemia.

Question 33

When is iFR measured?

Answer 33

During the wave free period of mid to late diastole when flow during the cardiac cycle is highest and microcirculatory resistance is the lowest.

Question 34

During the period of iFR, what is related?

Answer 34

Pressure and flow velocity are linearly related, which allows pressure ratios to be used to determine the limitation to flow of a lesion

Question 35

What is not required in iFR unlike FFR assessment?

Answer 35

Hyperemia (thus adenosine) is not required