Radiology - CVS Flashcards
What are the 3 things we look for in PE?
Is the heart big?
Is there pleural effusions?
Is there interstitial edema?
Clinical tip for CHF
- progression of CHF may be one of the only signs that a patient’s CAD is progressing
- things as insignificant as viral infections can lead to CHF
Cardiac output
Measure of the volume of blood that your heart pumps per unit of time.
Stroke volume x heart rate = cardiac output
Why is cardiac output important?
it is crucial to adequate pulmonary or peripheral perfusion
Why is ejection fraction important?
we really want to know is how well the heart is working or how much blood is being pumped?
Ejection fraction formula
(end diastolic volume - end systolic volume) / end diastolic volume = ejection fraction
Mitral stenosis
- Back pressure from an incompetent mitral valve increases the pressure in the left atrium (LAA) and that “can” be seen in a CXR
- With continued backup, the pulmonary artery would be under increased pressure (pulmonary hypertension)
Double density sign
Means you have left atrial enlargement.
–When you look at the lateral xray you’ll see posterior enlargement of the heart.
Mitral stenosis vs. regurgitation on film
- Splaying of the carina by massively enlarged atrium
- Enlarged heart favors mitral regurgitation over mitral stenosis
Why is cardiac blood supply important?
- Coronary arteries are end arteries – they have little or no anastomosis
- Cardiac tissue has a high metabolic need
- Cardiac tissue extracts nearly all oxygen available on its pass through the heart (the blood leaving the heart is completely cyanotic)
Thus, any impediment to flow, decrease in rate or suboptimal conditions leads to immediate tissue ischemia
Do cardiac arteries fill on systole or diastole?
-They are the only arteries to fill on diastole
Coronary Angiography
- Imaging of coronary arteries with fluoroscopy and contrast dyes injected directly into arteries
- Definitive test for evaluation of CAD
Indications for Coronary Angiography
Patients who have reversible ischemia and patients with unstable angina.
Important Findings on Coronary Angiography
- Narrowing of 50% is considered Hemodynamically significant
- Narrowing >70% are usually needed to produce significant ischemia/symptoms
Relative Contraindications for Angiography:
- Creatinine greater than 1.5
- Anytime measurement of Creatinine of greater than 2.0
Prevention of kidney toxicity by high molecular weight contrast dyes
- pretreat with bolus IV hydration, 2hrs before and 2 hrs after
- acetylcysteine (Mucomyst) for two days and proceed to contrast study
Coronary angiography requires
multiple separate views
Indications for Noninvasive Cardiac Testing
Confirm diagnosis of angina – stable
*requires a patient that is generally healthy because they have to be able to reach specific heart rates.
Contraindications for Exercise Stress Testing
- Patients where there is ongoing unstable angina or a suspicion of myocardial infarction!!!!!
- Treadmill tests in women are misleading (50%) and seldom done
Other Considerations for Stress Testing
-To evaluate success of non-invasive therapies (conservative treatments)
-Equivocal in asymptomatic patients
–false positive may exceed true positives
–this leads to “disability” and anxiety
used if there is a strong family history of early cardiac death or hypercholesterolemia
–used in occupations where there is high risk if undetected – airline pilot
Bruce Protocol
- Standardizes the work done by the patient during treadmill
- Multi-stage test of increasing effort while recording EKG, HR and BP
For a positive stress test…
1mm (0.1 mV) horizontal or down-sloping ST-segment depression (ischemia) 80msec (or two boxes after the J-point – end of the S-wave
Treadmill tests in women
- Take middle aged women that have no coronary artery disease and send them for testing
- Thirty to fifty percent of these women will have false positive exercise treadmill test!
Alternative to treadmill in women
You can do thallium testing or stress echocardiograms if you need to look for disease
*Some cardiologist will just go straight to catheterization
Pros of Evaluating Cardiac Function Using Echocardiograms
- gives you real time values, see the wall motion, see the heart contracting, see the heart resting.
- to evaluate for systolic vs. diastolic heart failure.
Important: you can see ejection fraction
Evaluation of Cardiac Function Using Echocardiograms
Sound waves can be used to look at a functioning heart and evaluate ventricular walls and valve functions
- Excellent for visualizing cardiac valves
- Excellent for evaluation of new cardiac mummers
- Used to evaluate the actual walls of the heart
- Intracardiac volumes can be calculated
What is Multiple Gated Acquisition?
MUGA scan (Multiple Gated Acquisition scan) is a useful noninvasive tool for assessing the function of the heart.
How is MUGA used?
MUGA scan produces a moving image of the beating heart, and from this image several important features can be determined about the health of the cardiac.
What has replaced MUGA?
Echocardiogram because it can be used at bedside.
How is the MUGA scan performed?
Radioactive label in the blood, patient placed under gamma camera, track radioactive label throughout the body to look at ejection fraction.
What population is MUGA still used in?
Cancer patients
What part of the heart are you most concerned about in nuclear studies?
Left ventricle
Coronary distribution
Anterior 2/3 – LAD
Lateral – Left circumflex A
Posterior and 1/3 of interventricular septum – RCA/PDA
Indications for Percutaneous Transluminal Coronary Angioplasty (PTCA)?
an appropriate alternative to CABG in patients with the following diseases (sometimes called balloon angioplasty):
- -Single Vessel disease
- -Two vessel disease without significant involvement (stenosis) of the proximal anterior interventricular artery
- -Patients with previous CABG, initial consideration of PTCA may be preferable to repeat CABG
- -Recent reports (COURAGE Trial) question the harms/benefit for optimized medical management versus PTCA with stent
What is CABG?
Coronary Artery Bypass Grafting (CABG) uses the patients own blood vessels to go around blockages in the coronary arteries
Indications for CABG
- Triple vessel disease (left, right, circumflex or other ventricular branches) with LV dysfunction (EF <50 or wall infarct)
- Two vessel disease with significant disease of the proximal anterior interventricular (left anterior descending)
Methods of evaluating ventricular ejection fraction:
MUGA/Nuclear > Ultrasound (TEE>TTE) > Cardiac Angiography
When would you use TEE?
if you’re going to start someone on blood thinners and you want to make sure they don’t have a thrombus in their left atrium.
What is normal ejection fraction?
45-70
What do you see on CXR in aortic tear?
- Widening of mediastinum
- Fluid tracking on the sides
Aneurysm of the aorta
- widening of the mediastinum
- there is a structure called the False Lumen that forms in an aneurism –> this is the area outside the endothelium!
Peripheral Vessels Modalities include:
- Contrast angiography
- MRA
- Duplex Ultrasonography implies the machines ability to be used for both US with Doppler - most common
Peripheral vessel considerations
- consider Arterial thrombus when there is claudication
- look for DVT in the setting where there are risk factors or pulmonary embolus
- remember ½ of DVT have no symptoms so PE may be the presenting finding
Ultrasound is Used for Evaluation of…
Bruits - flow abnormalities that can be heard by auscultation can be evaluated by US
US used to evaluate vessels
Anytime there is a stroke or embolic phenomenon, US can be used to evaluate the blood vessels
*excellent for evaluation of DVT
DVT risk factors
- -Prolonged Bed Rest
- -Immobilization of the extremity
- -Pregnancy
- -Oral contraceptives
- -Malignancy
- -Postoperative
- -Traumatic circumstances
Evaluation of DVT
- -D-Dymer*
- -US with Doppler flow study
- -Clotting Studies
*D-Dymer is not always helpful - it’s positive in a lot of cases that aren’t DVT.
Inferior Vena Cava Filter
This is a filter used in patients with chronic problem with DVT when all else fails.
Magnetic Resonance Imaging (MRI)
- High resolution of heart and great vessels
- No radiation exposure
- Good for pericardial disease, neoplasms, myocardial wall evaluation, chamber size and congenital abnormalities
- Evaluation of non-emergent aortic dissection
Magnetic Resonance Angiography (MRA)
is best for…
familial aneurysm screening.
–MRA can be used to evaluate intracranial vasculature in patients allergic to contrast dye.
Intravascular Echograms
- This will show the presence of Plaque even when the lumen seems wide, without disease!
- Useful when angiogram is equivocal
- Evaluation of angioplasty or stint placement
- Useful for left ostial lesions or coronary dissections
Multislice Computer Tomography (CT)
- Clear pictures without risks associated with regular angiography!!
- Role for everyday practice not well established
