Cardiothoracic Flashcards
When might CKMB and troponin have increased half lives, thinking the patient is having another MI when they are not?
Kidney disease
What is most common coronary artery in which to have MI?
LAD
What is the optimal timing of revascularization of the heart after MI?
W/in 90 minutes, but some benefit up to 6 hours after onset
What is the workup for suspected MI?
- ECG
- Cardiac enzymes Q8 hours x 24 hours (troponin-I, CKMB)
- CXR to rule out aortic dissection
- Echo to rule out wall motion abnormalities and decreased EF
What is the initial treatment/management for MI?
Meds: aspirin, clopidogrel, platelet glycoprotein IIb/IIIa antagonist, heparin, beta blocker, nitro, statin and morphine
What is the definitive treatment for STEMI?
PCI w/in 90 minutes or systemic thrombosis if PCI not available
What is the definitive treatment for NSTEMI?
usually do not require PCI, elective cardiac catheterization on a selective basis
When is an emergent CABG indicated for MI? (3)
- cardiogenic shock
- failed PCI
- presenting >12 hours after initial insult
When is elective CABG indicated?
- Left main coronary artery disease (>50%)
- Multivessel disease of other coronaries (LAD + 1 more, or 3 others)
- Failed PCI or not amenable to PCI (e.g. at bifurcations)
What is the preferred graft for CABG?
Internal mammary artery from L subclavian
What meds do we discontinue before CABG?
Clopidogrel or other similar category drugs should be discontinued
Should more than one coronary artery be bypassed during CABG?
Yes: long term survival is superior in patients receiving 2 or more coronary bypass grafts vs. one
What is the most concerning symptom in patients with aortic stenosis?
Dyspnea, because those patients with evidence of CHF will succumb to the disease w/in 2 years w/o valve replacement
What imaging is recommended for acute chest pain?
- CXR: look for CHF, aortic dissection
- Echo: look for ventricular dysfunction
- CT angiography if PE/aortic dissection suspected
What is the treatment for aortic stenosis with heart failure?
Aortic valve replacement: reduces afterload
What are the indications for surgery for aortic stenosis?
Symptomatic aortic stenosis
What drugs do we avoid in aortic stenosis, and why?
Diuretics, beta blockers and vasodilators due to risk of hypotension
What are risks/benefits of bioprosthetic valve vs. mechanical valve? Which is preferred?
Bioprosthetic: Degraded by dystrophic calcification and possible chronic antigenicity and don’t last as long
Mechanical valves: require lifetime anticoagulation
Use mechanical as long as patient doesn’t have contraindication to anticoagulation
When is percutaneous balloon valvuloplasty appropriate in aortic stenosis?
Bridge to surgery in hemodynamically stable patient. Transient benefit + smaller hemodynamic benefit vs. surgical valve replacement
When is percutaneous aortic valve replacement indicated?
Only for aortic stenosis patients who are too high risk for conventional surgical valve replacement. May not be durable and has increased risk of stroke perioperatively
What are the risk factors for aortic dissection?
Hypertension CT disease Advanced age atherosclerosis Pregnancy cocaine use bicuspid aortic valve aortic coarctation
What is significance of uneven pulses in patients with aortic dissection?
Blood supply to one of extremities is affected - suggests location of dissection!
Why are Marfan’s patients at increased risk of aortic dissection?
Misfolded fibrillin proteins can result in cystic medial necrosis of large vessels
How we we classify aortic dissection?
Stanford A: involving ascending aorta (can involve descending, too)
Stanford B: involves descending distal to subclavian artery only
How do aortic dissections cause complications?
False lumen can interfere with blood flow and compromise perfusion to branching vessels = malperfusion syndrome
What are the life threatening complications of Stanford A aortic dissection?
Dissect into and obstruct coronary arteries –> MI
Disrupt blood flow in carotid arteries –> ischemic stroke
Dissect into pericardial sac –> acute tamponade
Dissect aortic valve –> acute aortic insufficiency
What is first imaging modality recommended for a patient who presents with acute chest pain?
CXR
What is the next step for a patient who is hemodynamically unstable and aortic dissection is highly suspected?
Go to OR immediately. Perform TEE into OR and if confirmatory, proceed with surgery.
What is first step in management of aortic dissection?
Maintain low blood pressure: 100-110 systolic to decrease shear forces on the aorta. Usually with IV beta blocker.
What do we do after reducing blood pressure in Stanford A vs. B aortic dissection?
A: go to OR for repair via median sternotomy
B: admitted to ICU and BP closely monitored
When do Type B dissections undergo surgical repair?
Develop complications (e.g. malperfusion syndrome) secondary to compromised perfusion to branches of descending thoracic or abdominal aorta (limb or visceral ischemia)
If type B dissection needs surgical intervention, what are options?
1 Open repair via thoracotomy
2 Endovascular repair via a stent graft
Why are beta blockers contraindicated in patients with aortic dissection complicated by cardiac tamponade or severe AR?
Worsen hypotension and may precipitate cardiac arrest.
What are diagnostic steps for aortic dissection?
1 CXR: widened mediastinum, but 15-20% won’t show that
2 CT chest with IV contrast if mediastinum wide or suspicion is high
3 unstable patient: directly to OR with transesophageal echo
