Cardiac Didactic/Oral

What is ischemia?

an inadequate blood supply to an organ or part of the body, especially the heart muscles.

What is a myocardial infarction (heart attack)?

near to complete occlusion of blood flow causing tissue death

What does the RCA supply?

right ventricle wall, posterior interventricular septum, and inferior left ventricle wall

What does the LAD supply?

anterior right and left ventricles

What does the circumflex supply?

Lateral wall and inferior surface of the left ventricle

Clinical indication for a MPI stress test?

Detection of CAD, assess degree of stenosis and impact of regional perfusion, viability assessment, risk assessment pre-op or post MI, monitoring effect of treatment

What percentage can we start to see stress induced alteration in blood flow/perfusion?

70% stenosis

What is a bruce protocol?

treadmill test where incline and speed are increased at 3 minute intervals.

How do we figure out what heart rate a patient needs to reach on the treadmill in order to inject the RPx?

(220-age) x 85%

What happens if the patient does not reach the target heart rate?

It can severely decrease the diagnostic ability of our test

Types of pharmaceuticals used to stress?

vasodiliators and ino/chrono tropic drugs

What is the vasodilator we use most in nuclear medicine and it's dose?

Lexiscan and 0.4mg in 5 mL

Absolute contraindications for exercise stress testing?

Acute MI <4 days, severe angina, poorly controlled CHF, uncontrolled HTN, uncontrolled arrhythmias, acute PE, acute aortic dissection

Relative contraindications for exercise stress testing?

known left main CAD, moderate angina, high degree AV block, abnormal electrolytes, pacemakers

How to do a treadmill stress test?

Hook up patient to 12 lead ekg, have isotope ready, wait until the patient has reach 85% of MPHR and then inject, have patient run for an extra minute or 2 and then stop the treadmill and instruct patient to walk until treadmill is at a complete stop

Why would you terminate exercise?

Pt complains of sever chest pain, fatigue/dysnpenia, near syncope, signs of poor perfusion, Pt request, ST elevation

When do we do pharmalogic stress testing instead of exercise?

Unable to achieve target heart rate, baseline EKG abnormalities, or contraindicated

What are the 2 types of drugs we use for pharmalogic stress testing?

Vasodilators and Ino/chronotropic drugs

What are the 3 vasodilators we use in nuclear MPI?

Adenosine, Dipyridamole, and Lexiscan

MOA for adenosine?

Acts on A2a receptors in the outer part of the endothelium and smooth muscles of the cell membranes

Dose of adenosine?

140 ug/kg/min over 6 minutes

When do you inject the RPx for adenosine infusion?

About halfway through the injection of the stressor

What is the half life of adenosine? When can you image?

2-10 seconds and you can image 45-60 minutes after infusion

Side effects of adenosine (or other vasodilators)

Flushing, nausea, chest pain, AV block, dyspnea, dizziness

Early termination of adenosine (and other vasodilators)

Severe hypotension, development of AV block, wheezing, severe chest pain w/ ST depression, signs of poor perfusion

Benefits of low level stress with pharmalogical intervention?

Decrease of side effects, improves quality of images, and can image earlier (30 minutes)

Contraindications for vasodilators?

Asthma with ongoing wheezing, greater than 1st degree AV block, hypotension with a bp lower than 90, use of methylxanthines or caffeine, bradycardia

MOA of dipyridamole?

Indirect vasodilator that blocks uptake of adenosine causing vasodilation

Dose of dipyridamole?

0.142 mg/kg/min over 4 minutes or a total dose of 0.57 mg/kg

When do you inject RPx for dipyridamole stress?

3-5 minutes after completion of infusion

What drug do you give to counteract dipyridamole?

1-2 mg/kg of aminophylline at 10-12 minutes post completion of infusion

Lexiscan MOA?

Only activates the A2a receptors

Standard dose of lexiscan?

0.4 mg in 5 mL infused over 10-15 seconds followed by saline and followed by RPx

Benefit of lexiscan?

The side effects are much less severe than the other 2 vasodilators

Dobutamine MOA

Affects the B1 and B2 receptors causing an increase in heart rate, blood pressure, and contractility

Why would we use dobutamine over exercise and vasodilators?

If the patient cannot do exercise and cannot use vasodilators

Contraindications for dobutamine?

MI in less than a week, unstable angina, significant LV outflow obstruction, severe AS, Hx of V-tach, uncontrolled hypertension, beta-blockers

Dose of dobutamine?

10 ug/kg/min infusion and increase the dose by 10 every 3 minutes

When do you inject the RPx for dobutamine?

Inject once 85% of MPHR is achieved or 1 minute into highest dose and continue infusion for 2 minutes (most likely need atropine)

Side effects for dobutamine?

palpitations, headache, dizziness, CP, dyspnea

What is the counter attacking drug for dobutamine side effects?

Esmolol which is a short acting beta blocker 0.5 mg/kg over a minute

RPx for MPI in general nuc med?

Thallium, Sesta, and Myoview

RPx for PET MPI?

Rb-82, N-13, O-15, and F-18 FDG

Half life of thallium-201

73 hours

Analog of thallium?

potassium and taking up through active transport using sodium potassium pump

Thallium critical organ?

Kidney

Dose of thallium

3 mCi for rest and 4 mCi for stress

When should imaging begin for thallium?

Must begin within 10 minutes do to washout

What does normal myocardium look like on thallium redistribution?

Even distribution of RPx on both rest and stress images

What does ischemia look like on thallium redistribution?

Hypoperfusion on stress images and filling of that tissue on rest images

What does infarct tissue look like on thallium redistribution?

Both rest and stress images show hypoperfusion

What does stunned or hibernating myocardium look like on thallium images?

Hypoperfused images that fill on 24 hour delays

Benefits of Tc99m based agents over thallium

optimal imaging characteristics

What do we see more of with myoview over sesta?

more bowel uptake with myoview and less liver so you can image sooner

What is the critical organ for the Tc99m heart agents?

Large intestine

How do the Tc99m heart agents get excreted?

biliary tract

Patient pre reqs for MPI?

NPO 4-6hrs, no contrast studies, no caffeine at least 12 hrs prior (24hrs better), review meds (nitros, beta blockers, asthma meds, etc)

Thallium stress first procedure?

Inject 2-5 mCi of thallium at peak exercise or at peak vasodilation, begin SPECT images 10-15 min post inject, 2-4 hours later acquire rest images

Advantages of thallium protocol?

redistribution advantage

Disadvantage of thallium protocol?

Scheduling problems, poor imaging characteristics

What can you do with thallium to get better images of viability?

Image at 24 hours or reinject 1-2 mCi of thallium at 20-60 minutes after original images are done

Two day Tc99m protocol?

Reserved for patient with high BMI, can do either rest or stress first, doses can be higher 25-30 mCi for both doses, stress can be done first to avoid coming back

One day stress/rest protocol for Tc99m?

Inject 8-12 mCi of Tc99m agent, wait allotted time for the drug to circulate, start SPECT imaging, attach EKG leads/BP/pulse ox, do treadmill/pharmacologic stress, inject 25-30 mCi at peak stress, wait, image with leads

Advantages of Tc99m imaging over thallium?

better images, more flexible scheduling times, can do gated analysis

Dual isotope protocol?

Inject 3-4 mCi of thallium, wait 10-15 min to SPECT, stress patient and inject 20-30 mCi of Tc99m, image at 15-60 minutes

Disadvantages of dual isotope?

expensive, higher radiation dose, must do rest first with thallium

What is planar imaging used for in MPI studies?

Imaging bedside of acutely ill patients by portable cameras or obese patients who are too heavy

SPECT positioning?

supine with arms above their heads

Seconds per stop for SPECT imaging?

20-25 seconds per stop for 60-64 projections

What is the orbit for SPECT imaging?

180 degrees from RAO 45 to LPO 45

2 orbit types for heart imaging?

noncircular which gets cameras closer to patient and circular which causes cameras to be farther away

2 acquisition types for heart imaging?

Step and shoot (most common) and continuous imaging

What does gating allow us to do?

increases specificity of test, allows the calculation of EF/wall motion data

Common types of artifacts with heart imaging?

Patient motion, cardiac creep, LBBB, volume averaging, attenuation (fat), and low heart rate

Advantages of PET imaging?

High spatial and temporal resolution, excellent sensitivity, high contrast resolution, quantitative studies

Dose of Rb-82

40-60 mCi per injection

Clinical indications for a MUGA scan?

regional wall motion, evaluate cardiac function in chemo patients, stroke volume ratios, CAD

What RPx do we use for a MUGA

Tc99m labeled RBCs using ultra tag or cold PYP

How to do a PYP MUGA?

Inject patient with 1-3 mL of a cold PYP kit wait 15 minutes and inject 15-30 mCi of TcO4-

Advantage of PYP MUGA

Easiest RBC method to perform and no blood handling

Disadvantage of PYP MUGA

Not a good labeling efficiency and requires 2 injections

How to do ultratag kit MUGA

Draw 2-5 mL of blood with heparin, put into vial given with kit and wait 15 minutes, inject needle 1 into vial and agitate, then inject needle 2 and agitate, then inject Tc04- and wait for labeling to occur

Advantages of ultra tag kit

highest labeling efficiency

Disadvantage of ultra tag kit

expensive and handling of blood

What are the views for a MUGA scan?

Ant, LAO, Llat or LAO 70

When processing what ROIs do we draw for a MUGA?

Around the left ventricle and a background

What is a normal LVEF?

50-65%

What does First Pass RNA evaluate?

right ventricle

What views do we get for a RNA study?

fast dynamic flow image from RAO to Ant view

What is I-123 MIBG used for?

Checking innervation of the heart

What is I-123 MIBG a analog of?

Norepinephrine which is taken up at sympathetic nerve terminals

Dose of I-123

3-5 mCi

When do you image for a MIBG study?

15-30 minutes post injection and 3-5 hours post injections

When performing a gated equilibrium cardiac study, which of the following anatomical views best separates the right and left ventricles?

A) left lateral

B) left anterior oblique

C) left posterior oblique

D) anterior

E) posterior

B) left anterior oblique

In preparation for a Tl-201 stress test, patients are instructed to fast to:

A) prevent gastrointestinal upset during exercise

B) minimize tracer uptake in the gastrointestinal tract

C) enhance myocardial tracer uptake

D) standardized test conditions among patients

E) prevent redistribution of the tracer

B) minimize tracer uptake in the gastrointestinal tract

Which of the following agents used for pharmacologic stress testing remain in the plasma for the greatest length of time?

A) dobutamine

B) adenosine

C) nitroglycerin

D) dipyridamole

E) regadenoson

D) dipyridamole (35-45 min)

Reconstituted "cold" pyrophosphate is administered to the patient in which red blood cell labeling method(s)?

A) in vitro method

B) both the in vivo method, and the modified in vivo method

C) modified in vivo method

D) both the in vitro method, and the in vivo method

E) in vivo method

B) both the in vivo method, and the modified in vivo method

Which radiopharmaceutical is used to label red blood cells with 99mTc ?

A) 99mTc albumin

B) 99mTc pertechnetate

C) 99mTc sulfur colloid

D) 99mTc pyrophosphate

E) 99mTc exametazime

B) 99mTc pertechnetate

When positioning a patient for a LAO view of a gated equilibrium ventricular function study, tilting the camera detector torward the patient's feet separates which two structures?

A) left ventricle and aorta

B) right ventricle and aorta

C) left ventricle and left atrium

D) left and right ventricles

E) left and right atria

C) left ventricle and left atrium

A cardiac stress test requires the placement of how many electrodes on the patient's body?

A) 3

B) 6

C) 10

D) 12

E) 15

C) 10