Special Tests and Procedures
Terms
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- List the major branches of the Coronary Arteries
-
1. Left main coronary artery:
Gives rise to left anterior descending (LAD) and circumflex arteries
--> Left anterior descending gives rise to septal perforators and diagonal branches
--> Circumflex Artery gives rise to obtuse marginal branches
2. Right coronary artery gives rise to posterior descending artery (90% dominant) - Describe the anatomy of the specialized conduction system
-
- Sinus node
- Atrioventricular node
- Left bundle branch has two hemifascicles
- Right bundle branch -
12-lead ECG
How does it work?
Time segment recorded?
Associated with?
Used to assess what? -
1. Standard limb and chest leads
2. Recorded over about 10 seconds
3. Usually associated with computer reading
4. Good for many insights – chamber size, conduction patterns, acute or old MI -
Exercise ECG
Used to asses what?
12-lead ECG is recorded at what time points?
ST-depression means what? -
1. Used to assess for the presence of coronary artery disease
2. 12-lead ECG recorded at rest and after graded stress on a treadmill
3. ST segment depression during stress is correlated to myocardial ischemia -
Holter Monitor
How does it work?
Used to examine what?
Has what disadvantage? -
1. Long term (24, 48 hour) recording of cardiac rhythm –useful for surveillance when trying to identify intermittent abnormal rhythms and to correlate them to symptoms
2. Patient wears monitor, keeps diary
3. Strips are printed out and checked against symptoms.
Holter page may show:
1. Periods of regular rhythm and irregularities of rhythm.
--> This allows physician to link symptoms to rhythm.
--> It is useful for both positive and negative outcomes
--> BUT may miss rarely occurring problems!! -
Chest X-ray
What views are routine?
Disadvantage of portable CXR?
Visualizes what?
Useful to assess what?
What disadvantage in general? -
1. Routinely there is a PA and lateral film
2. Portable CXR is usually AP – less useful for chamber size
3. A silhouette of the radiopaque structures in the chest – bones, heart, aorta
4. Useful to assess for chamber size, presence of pulmonary infiltrates, aortic dissection
5. Nonspecific in nature -
Echocardiography
How does it work? -
1. Sound is bounced off cardiac structures and transit time is used to define anatomy
2. M-mode is a plot of distance versus time
3. 2-d is a composite of many M-mode images to provide a moving picture of the heart and its structures
4. The Doppler effect can be used to define velocity of blood flow
5. New approaches include use of contrast bubbles, improved technologies -
Radionuclide studies
How does it work?
Blood pool scans provide info on what?
Myocardial scans provide info on what? -
1. Use of energy emitting particles to make images of the heart
2. Blood pool scans provide information on pump performance: gated acquisition
3. Myocardial scans provide
information on distribution of coronary blood flow
Ex: R-R interval is divided into 28-32 frames for resting gated blood pool scan.
--> Each image segment is summed of all counts acquired during that specific portion of the cardiac cycle.
--> Complete set of image segements represents composit of all the beats ocurring during acquisitions -
Cardiac Catheterization
How does it work?
Contrast injection allows definition of what? -
1. Small tubes passed into the arteries and ventricles to measure pressures
2. Contrast injection allows definition of chamber size and function
3. Contrast injection allows definition of coronary anatomy, and presence of plaque -
Interventional Cath
What 5 techniques does it involve? -
1. Balloons used to dilate stenotic coronary arteries
2. Stent implantation improves long term success
3. Various devices for removing plaques
4. Implantation of drugs/genetic material
5. May be used to open stenotic mitral valves -
Electrophysiological Study
Used to assess/map what?
How is it used to reproduce pathological electrical conditions?
How is it used to eliminate abnormal rhythems? -
1. Study to assess abnormal rhythm patterns
2. Mapping of unusual conducting tracts
3. Efforts to initiate pathological tachycardia
4. Ablation is used to alter electrical substrate, to eliminate abnormal rhythms