Myocardial Ischemia:
- One of the most important things to evaluate on EKG
- If severe narrowing/complete blockage of a coronary artery causes blood flow to become adequate, ischemia of the heart muscle develops
- Can be transient (angina pectoris) or more severe (necrosis & MI)
Myocardial Ischemia
- LV consists of an outer layer (epicardium/sub-epicardium) and inner layer (sub-endocardium)
- Can have limit of ischemia to the inner layer or can affect the entire thickness of the ventricular wall (transmural ischemia)
Myocardial Blood Supply
- RCA supplies both inferior (diaphragmatic) portion of the heart and RV
- Left main divides into the left anterior descending artery (LAD), which supplies the ventricular septum and large part of free LV wall, and LCx (lateral wall of the LV)
ST Elevation/Transmural Ischemia
- Ischemia & ultimately necrosis of a portion of the LV free wall
- Most patients w/ acute MI have underlying atherosclerotic disease
- Occlusion of coronary artery with a ruptured plaque leads to coagulation cascade (fibrin & platelets)
ST Elevation/Transmural Ischemia
- Other factors for acute STEMI: cocaine, coronary artery dissection, coronary artery emboli
- Acute phase: ST elevations, hyper-acute T-waves in multiple leads
- Evolving phase: Hours/days later with deep T-wave inversions replacing ST elevation
ST Elevation/Transmural Ischemia
- Anterior MI: infarct of anterior/lateral wall of LV
- Inferior MI: infarct of inferior wall of LV
- ST segment (& reciprocal) changes generally seen within minutes of blood flow occlusion
- Reperfusion therapy can decrease ST elevations
Thanks to these amazing website for the wonderful graphics:
Pre-Rounding Tips 3d: How to think about Troponin? (
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Pro-Tip: If you can print out a pre-rounding sheet with the labs auto-populated, that is always helpful.
One of the most common consults from the Emergency Room to Cardiology is 'elevated troponin.'
Yes, elevated troponin can be scary, but here is the framework that I use to analyze / consider troponin.
1. Patient Presentation? 2. Patient's risk factors and prior cardiac history? 3. What is the troponin trend? 4. What does the ECG look like? 5. What are some non-cardiac reasons troponin may be elevated?
1. Patient Presentation?
In Cardiology, the clinical presentation is the most important part of the story when determining the significance of an elevated troponin! In many situations, clinical decisions (whether to pursue a LHC) may be made in the absence of having a troponin available.
Key Questions: 1. If the patient presents with chest pain, how does he/she describe it?
- Some common worrisome symptoms associated with angina. Elevated troponin in the setting of these symptoms should always be taken seriously.
a) Chest pressure, constant, sub-sternal.
b) Radiation of pain to the neck or jaw
c) Diaphoresis
d) Numbness to the left arm
e) New onset dyspnea
f) Worse with exertion, better with rest
2. What makes the pain better?
- If the patient got improvement with nitroglycerin more likely to be consistent with cardiac chest pain.
- If patient's pain improves with muscle relaxers, IV toradol, IV PPI, IV Ativan, less likely to be a cardiac etiology.
3. Has the patient had this type of pain before?
- If similar recent presentation with a negative work-up, this might be reassuring. However, you don't want to have anchor bias and should keep an open perspective.
When I was an intern, pre-rounding was one of the most stressful parts of the day. I would take too long and be inefficient. Part 1.
Now as a PGY7 (long-time, right?), here is 3 parts of my system that I use for new patients.
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Future direction will be ECG/Echo/General Cardiology Topics!
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1) Why is the patient here / chief concern?
- This seems like the most basic question that is often overlooked. What made the patient decide to leave his/her house to come to the hospital?
- When reading the overnight H&P, the abundance of clinical documentation can create confusion.
- Simplicity is key. What is the chief concern? Is it chest pain? Is it dyspnea on exertion? Knowing this information will help frame your thoughts.
2) What are the relevant past medical problems?
- Most patients will have chronic medical problems that will contribute to the current presentation.
- It is easy to get lost in the weeds of this presentation. In Cardiology, I typically focus on (but not limited to) coronary artery disease, atrial fibrillation, hypertension, hyperlipidemia, diabetes mellitus, history of CVA. Again, this is not all inclusive but it is a start.
- Although patients may present to the hospital with a new diagnosis, it is more likely that the presentation may be an exacerbation of a previous problem.