Cardio Week 5 - Surgical Treatment Of Patients With CAD Flashcards
Graded exercise test major purposes
- Detect ischemic heart disease under controlled conditions
- Detect exercise-induced arrhythmias
- Evaluate hemodynamics during exercise
Alternatives to graded exercise test
- Pharmacologic testing
- Imaging
- Imaging combined with graded exercise test
Pharmacologic stress testing - Dipyridamole and Adenosine
Dilate healthy arteries; unhealthy arteries do not due to plaque build up on the inside
Pharmacologic Stress Testing - Dobutamine
Increases mVO2 (myocardial O2 consumption)
What are radionuclide imaging or Echocardiography used to assess?
For abnormal wall movement indicative of ischemia
Echocardiography
- Ultrasonographic imaging of the heart
- Noninvasive, real-time imaging of valve function and dimensions of the heart
- Color Doppler used to measure flow velocity and direction
- Used to detect heart motion and estimate SV and EF
What do echocardiography’s rule in/out?
- Pericardial effusion
- Cardiac tamponade
- Cardiomyopathy
- Masses in/on heart
Transesophageal Echocardiography (TEE)
Better image than ordinary echo due to fewer structures to obscure image
Imaging Techniques
- Rapid computed tomography to view early calcification of the coronary vessels
- Graded exercise test combined with radionuclide perfusion (SPECT or PET scan)
Thallium 201 - What are images examined for cold spots indicative of?
- Ischemia if they occur during exercise
- Nonviable myocardium if they occur post-exercise
Thallium 201
- Injection of thallium 201 or other radionuclides
- Taken up by metabolically active myocytes in proportion to blood flow
- Images examined for cold spots - places where the blood flow is less
Angiogram
When a dye is injected into the blood vessel and X-rays are used to determine blood flow in the coronary arteries
Ventriculography
- Performed during cardiac catheterization (determine cardiac function)
- Check for valvular dz and ventricular dysfunction
What estimates does the ventriculography make?
- Cardiac output
- Stroke volume
- Ejection fraction
- Chamber pressures
- Presence of stenosis or regurgitation
Multigated acquisition imaging (MUGA)
- Provides views throughout the cardiac cycle
- Calculate LV EF
- Measure emptying of LV with time
- Noninvasive
CABG - Coronary artery bypass graft
- Creation of bypasses around the narrowed areas using grafts
- Vein segments are sewn into (grafted) above and below the occluded areas
What veins are harvested during a CABG?
- Portions of one or both saphenous veins
- Depending on the quality of the vein and the number of bypasses required
Short term consequences of CABG Saphenous VG
- Risk of infection in both the chest and LEs - length of procedure and hematoma formation
- LE wounds can extend from ankle to groin bilaterally
- May be unwilling to move the involved LE due to pain and inflammation
Alternatives to saphenous vein graft
- Radial artery
- Internal mammary arteries (left)
LIMA to LAD
- Left internal mammary artery grafted to the LAD distal to occlusion
- RIMA may be used on occasion by some surgeons
- Use of IMAs may compromise sternal integrity
Minimally - Invasive Direct Coronary Artery Bypass (MIDCAB)
- Alternative to open CABG for some patients
- Much smaller incision
- Endoscopic surgery
Advantages of Percutaneous Coronary Intervention (PCI)
- Can combine diagnostic testing with intervention
- More rapid intervention than CABG and is less invasive
Disadvantage to percutaneous coronary intervention (PCI) or PTCA
- Long-term results are not as good as CABG
- May not work, requiring CABG after PCI is done
Percutaneous Coronary Intervention (PCI) or PTCA
Balloon-tipped catheter is inserted into the occluded vessel and inflated to restore patency of vessel by compressing the plaque and widening the lumen
Stent
- Wire device placed with balloon-tipped catheter
- Opened within the occluded vessel to maintain patency
- May be coated with material to reduce risk of re-occlusion
Cardiac diagnostic testing
- Heart rate and rhythm
- Evidence of CAD
Revascularization procedures
- CABG with SVG
- Radial artery
- LMA to LAD
- PCI
Ischemia/Reversible injury
Blood flow returns when the patient goes back to resting
Emergency management
- Receives a dose of TPA through a catheter
- Stabilized and sent for cardiac catheterization to determine what vessels are compromised and to what extent
What tests would you use to visualize metabolism of the heart?
- SPECT (single photon emission CT) or PET (positron emission tomography) scan
- Echocardiogram
SPECT or PET
- Provide 3D imaging
- Can use single photon or positron emission computed tomography
- Gamma ray detection
- Myocardial perfusion imaging
- May use Tc99 rather than Thallium
- Can calculate the L ventricular ejection fraction
Bed rest and bleeding risk
- Three hours to prevent bleeding and hematoma formation at the groin due to vascular access required for cardiac catheterization
- When pacing wires for temporary pacemaker are removed from chest
