CARDIOVASCULAR SYSTEM

Question 1

MAJOR AREAS OF INTEREST

Answer 1

• CORONARY ARTERY DISEASE
• LEFT VENTRICULAR FUNCTION
• CARDIAC SHUNTS

Question 2

Name the cardiac shunts

Answer 2

• VSD : VENTRICULAR SEPTAL DEFECT
• PDA: PATENT DUCTUS ARTERIOSUS
• ASD: ATRIAL SEPTAL DEFECT

Question 3

What radiopharmaceutical is used in myocardial perfusion imaging for coronary artery disease (CAD)?

Answer 3

A: 99mTc Sestamibi.

Question 4

Q: How does 99mTc Sestamibi uptake occur in myocardial cells?

Answer 4

A: Uptake depends on blood flow and the negative electrical potential created by mitochondria in heart muscle cells.

Question 5

: When are patients injected with 99mTc Sestamibi during myocardial perfusion imaging?

Answer 5

:
A: Patients are injected at stress and at rest.

Question 6

: What is the detection accuracy of myocardial perfusion imaging for CAD compared to ECG?

Answer 6

:
A: It detects 90% of patients with CAD, while ECG detects 60%.

Question 7

Q: How does coronary vascular reserve affect myocardial perfusion during resting and stress periods?

Answer 7

A: - Resting: Stenotic vessels may appear normal due to coronary vascular reserve (autoregulation).

Stress: Stenotic vessels cannot dilate further due to the exhaustion of coronary vascular reserve, leading to ischemia.

Question 8

: What radiopharmaceutical is used in a MUGA scan to assess left ventricular ejection fraction?

Answer 8

:
A: 99mTc-labelled red blood cells

Question 9

: What radiopharmaceuticals are used for heart flow studies to evaluate cardiac shunts?

Answer 9

:
A: Any radiopharmaceutical that is not trapped in the lungs, such as 99mTc pertechnetate.

Question 10

Why is 99mTc MAA not used in cardiac shunt evaluation?

Answer 10

A: 99mTc MAA gets trapped in the lungs and is used for perfusion lung scans.

Question 11

Q: What ensures the binding of 99mTc to hemoglobin in RBCs during heart flow studies?

Answer 11

A: Pyrophosphate.

Question 12

What are the potential impacts of chemotherapy, hormonal therapy, and radiation therapy on the heart?

Answer 12

A: They can depress ejection fraction, leading to left ventricular systolic dysfunction.

Question 13

List some clinical uses of nuclear medicine in cardiovascular studies.
A:

Answer 13

Diagnosis of coronary artery disease (CAD).
Determining the extent and severity of CAD.
Identifying viable myocardium for revascularization.
Assessing left ventricular ejection fraction.
Evaluating cardiac shunts.

Question 14

What does an abnormal stress study but a normal rest study indicate in myocardial perfusion imaging?

Answer 14

A: Myocardial ischemia.

Question 15

Give one example of a cardiac shunt.

Answer 15

A: Patent ductus arteriosus (PDA).

Question 16

What is the normal ejection fraction?

Answer 16

A: Approximately 60% or 50-70%.