Tools of the Trade Flashcards
What are the two standard CXR views?
PA (posterior-anterior) and Lateral
Why is Posterior-Anterior good for viewing the heart in CXR?
In posterior-anterior XR, the radiation is shot through the back and hits the film in front of the patient. Because, the heart sits more anterior in the chest cavity, there is less distance between the film and the heart in posterior-anterior than if the XR was shot anterior-posterior.
For lateral XR, which side is the film on when imaging the heart?
The film would be on the left side of the patient. You always want to have the film close to the object you’re trying to image it’s most accurate. Since the heart is on the left, the film will be on the left. The XR will be shot from right side of the patient.
Why is bone white and air black in XR?
In XR, radiation is shot at a film and the radiation is blocked by dense things. So, things like metal and bone are very dense so they block the radiation and show up as white on the film. Air is least dense and show up black
Does Echocardiogram use radiation?
No
How does Echocardiogram get its image?
It shoots ultrasound into the body, strikes objects, and returns to the transducer too form image.
What are the 4 functions/modes of Echocardiogram?
- 2-dimensional motion picture
- M-Mode
- Color Doppler map of blood flow
- Spectral Doppler map of blood or tissue velocity
Which ventricle is more anterior?
Right ventricle
Where is the esophagus in relation to the heart?
The esophagus goes behind the heart, specifically behind the left atrium.
What color is fluid in ultrasound?
Black
What is a trans-esophageal echocardiogram?
This is when you have a patient swallow the probe and you can image the heart through the esophagus.
What is an added benefit to doing the trans-esophageal echocardiogram?
Since you can get closer to the heart with the probe, you can use a higher-resolution probe to image.
What is the M-Mode echocardiogram?
This is when your probe actually shoots down in straw-like sections. (imagine if you took a straw and poked through the layers).
What is the X axis on M-Mode echocardiogram?
Time
What is the Y axis on M-Mode echocardiogram?
Movement
What was the earliest form of echocardiogram?
M-Mode
What is M-Mode good at?
M-Mode is great at observing physical dimensions or change in time. Since the M-Mode was the first echocardiogram version, many standard measurements of the heart are understood through M-Mode. It’s also great at making measurements and differences in timing comparing between structures.
For ultrasound color doppler, what colors represents towards the transducer and what colors represent away from the transducer?
Red/yellow = towards transducer, Blue/white = away from transducer
What is the diameter of a RBC?
6-8 microns
How small does something have to be to get through the pulmonary capillaries?
Less than 10 microns
How can you use agitated saline to detect shunts?
Agitated saline created micro-bubbles around 16 microns in diameter. Since these are more than 10 microns, they won’t make it through the capillaries of the pulmonary system. So, you inject agitated saline into the venous system, and you should be able to see it on the right side of the heart but not the left. If you see micro bubbles in the left side of the heart, that means that there is either an intra-cardiac shunt or intra-pulmonary shunt.
How can you tell the difference between a patent foramen ovale v.s. an atrial septal defect? (when using agitated saline)
A patent foramen ovale should have blood flowing from right atrium to left atrium because the flap only opens one way. The flap is typically held closed because the left side of the heart has higher pressure… the flap would only be open during times that the right atrium has higher pressure than left atrium.
In atrial septal defect, you have bidirectional shunt. The blood would flow from left atrium to right atrium because the left side of the heart has higher pressure. When viewing the ultrasound with agitated saline, you can see that there are black puffs coming from the left atrium into the right. These are black because the blood coming from the left atrium doesn’t have any bubbles.
What are 11 things that can be obtained from Echocardiography?
- Chamber size
- Function
- Chamber structure
- Wall motion
- Valves
- Pressure and hemodynamics
- Shunts
- Murmurs
- Intracardiac masses
- Bacterial endocarditis
- Pericardial disease
What is the purpose of a stress test?
Stress test is supposed to increase myocardial oxygen demand so that you can identify potential ischemia.
What does BP normally do with exercise?
Systolic normally goes up, and diastolic either stays the same or goes down
What happens with ECG during stress test?
ST segment depression is ischemia.
What symptoms do you watch out for during stress test?
Looking out for symptoms typical of ischemia (shortness of breath, angina, etc)
What 5 things do you monitor/observe during a stress test?
- BP
- ECG
- Symptoms typical of ischemia
- Can look at blood flow w/ perfusion imaging (to localize ischemia)
- Wall motion (echocardiography) imaging
How is stress for stress test typically induced?
With exercise on treadmill or exercise bike, or if patient cannot exercise, there are drugs that can be given to induce stress.
What are reasons for using Exercise Treadmill Test (ETT)? (name 5)
- Screening for Coronary Artery Disease (CAD)
- Evaluate chest pain (see if it’s ischemia)
- Evaluate exercise capacity
- Prognosis (Exercise duration is correlated to prognosis)
- Evaluation after revascularization
What are 9 contraindications for Exercise Treadmill Test (ETT)?
- Unstable Angina
- Untreated life-threading arrhythmias
- Uncompensated heart failure
- Advanced AV Block
- Acute myocarditis, pericarditis
- Critical aortic stenosis
- Significant HOCM
- Uncontrolled HTN
- Acute systemic illness
What is the sensitivity of ETT for diagnosing Left Main or 3 vessel CAD?
75-95%
What is the sensitivity of ETT for diagnosing 1 vessel CAD?
25-70% (LAD > RCA > CIRC). This means that there is still a great chance that if you have a single vessel CAD, you would still get a normal ETT result.
The ETT was designed using middle aged men. Does the sensitivity go up or down if you’re using ETT on a younger patient?
Sensitivity goes down. Younger patients have less likelihood for having CAD because age is a significant risk factor. So, if you have a younger patient doing ETT, the sensitivity is lower (because pre-test probability is lower)
How do you prepare a patient for ETT? (2 things)
- No PO for at least 2 hours (at least 4 hours if using nuclear imaging)
- Wear comfortable clothes
When doing ETT test, how high does the HR have to go up to know that you’re pushing the heart enough?
At least 85% of age predicted maximal heart rate for particular patient, unless the test becomes abnormal before you reach that rate.
Which leads are best to look at for stress test ECG, regardless of location of ischemia?
Lateral precordial leads (V5, V6) and inferior limb leads
In stress test ECG, which segment do you use for your isoelectric reference point?
PR interval
What are 4 pharmacologic agents that can be used for inducing stress test?
- Vasodilator (dipyridamole, adenosine, regadenoson)
2. Dobutamine
What do vasodilators do for pharmacologically induced stress test? When is this used?
Vasodilators dilate the vessels and areas where the vessel are normal will dilate where as areas where there is plaque will not dilate. This gives a redistribution of the blood flow that can be studied. This is done if the patient is on medications that prevent heart rate from going up.
What does dobutamine do for pharmacologically induced stress test? When is this used?
It increases the heart rate without requiring the patient to exercise. This is appropriate for patients who cannot exercise to do the stress test. This is also HR dependent so you need to get the HR up to at least 85% age predicted maximum.
What are 5 reasons to use imaging stress test?
- Abnormal baseline ECG, digoxin, Wolf-Parkinson-White
- To increase sensitivity (if pre-test probability is lower e.g. younger patients)
- Localization (helps bc lead location isn’t as accurate during stress test)
- Preoperative cardiac risk assessment
- Myocardial viability
How is the patient preparation different for if you’re doing imaging stress test w/ vasodilators? (2 things)
- For imaging stress test w/ vasodilators, in addition to no PO, patients should not have had caffeine, chocolate, or theophylline for at least the past 24 hours. This is because vasodilators target the adenosine receptors.
- Vasodilators can cause bronchospasm so if patient has asthma or reactive airway disease, they shouldn’t be given dipyridamole or adenosine. They should be given regadenoson.
What is a reversible perfusion defect and how is it seen with stress test radionuclide perfusion imaging?
Reversible perfusion defect is when the perfusion looks incomplete during stress but returns to normal during rest.
What is fixed perfusion defect and how is it seen with stress test radionuclide perfusion imaging?
Fixed perfusion defect is when the perfusion appears to be incomplete both during rest as well as stress.
Name an older radionuclide perfusion imaging agent and some characteristics of it.
Thallium-201. Continuously equilibrate across cells and aren’t as strong radiation emitters. You have to image right away or else you might miss the ischemia. Potassium analog.
Name a newer radionuclide perfusion imaging agent and some characteristics of it.
Technetium-99m-sestamibi. One pass. Go in and stick to myocardium. Stronger radiation emitters. Don’t have to image right away.
Between ECG and radionuclide perfusion imaging, what is taken as true if there is a discrepancy between the results of the two?
Radionuclide perfusion imaging. If the ECG shows abnormal findings but the imaging shows normal, it is assumed that the imaging is correct and that the patient is normal.
In stress echocardiography, what are you looking out for?
When there is an imbalance between supply and demand of O2, there is abnormal wall motion. Compare increased demand (stress) wall motion to decreased demand (rest) wall motion. Normally, the LV should beat faster and thicken more with exercise or dobutamine. An ischemic part of the heart wall won’t thicken.
Do MRIs use radiation?
NO
What is MRI?
Magnetic Resonance Imaging. Uses a strong magnetic field to create 3D tomographic images
What are 2 contraindications for MRI?
Metallic implants, kidney dysfunction (because of Gadolinium contrast)
What is cardiac catheterization?
A catheter is inserted into an artery or vein ad advanced to the heart or coronary arteries
What 4 things can you measure with cardiac catheterization?
- pressure
- gradients
- saturation
- intracardiac shunt
What can you inject with cardiac catheterization?
Contrast. For angiography
If you do the cardiac catheterization through the femoral vein, where do you go?
IVC, RA, RV, PA
If you do the cardiac catheterization through the femoral artery, where do you go?
Ascending Ao, Ao, Coronary arteries
If you do the cardiac catheterization through the right internal jugular vein, where do you go?
SVC, RA
Which arteries are common for catheterization?
Right radial, femoral arteries
Which veins are common for catheterization?
Internal jugular vein, femoral vein
