Welcome back! Today, we’re diving into posterior and right ventricular myocardial infarctions (MIs) – two often overlooked but crucial variations of STEMI. Recognizing these can be life-saving! 🚑
Learning Objectives 🎯
- Identify ECG changes indicative of posterior MI. 💡
- Recognize ECG changes indicative of right ventricular MI. 📝
- Understand the importance of obtaining right-sided ECGs. ➡️
- Describe the clinical presentation of posterior and right ventricular MIs. 🩺
- Explain the treatment considerations for these types of MIs. ❤️🩹
Posterior MI 📝
While a “true” posterior STEMI doesn’t exist because we don’t directly look at the posterior heart electrically with standard ECG leads, we can infer its presence based on reciprocal changes. Think of it like looking at a shadow to determine the shape of the object casting it. 👤
ECG Findings in Posterior MI 🔍
- ST-segment depression in anterior leads (V1-V4): This is the KEY reciprocal change.
- Tall, broad R waves in anterior leads (V1-V4): This is often referred to as “dominant R waves”.
- Upright T waves in anterior leads (V1-V4): Typically T waves are inverted in these leads.
To confirm a posterior MI, you can obtain posterior leads (V7-V9). These leads are placed on the back, approximately at the same horizontal level as V6. ST elevation in V7-V9 is diagnostic.
Why is it important to recognize posterior MI? 🤔
Because it often occurs in conjunction with inferior or lateral MIs. Missing a posterior component can lead to incomplete treatment. Also, patients may be experiencing symptoms which are often overlooked for different diagnosis.
Right Ventricular MI 📝
Right ventricular MI (RVMI) usually occurs in conjunction with inferior MI. It’s crucial to recognize because it significantly impacts management.
ECG Findings in Right Ventricular MI 🔍
- ST-segment elevation in V1: This is often the most prominent finding.
- ST-segment elevation in V4R: This is a right-sided ECG lead. Place the V4 electrode at the same level as V4 but on the right side of the chest. ST elevation of ≥1 mm in V4R is diagnostic.
- ST-segment depression in V1-V3: May also be present.
Important Note: Always consider obtaining right-sided ECG leads (V3R, V4R, V5R) in patients with inferior STEMI to rule out RV involvement. ➡️
Clinical Significance and Treatment of RVMI ❤️🩹
RVMI is preload-dependent. This means the right ventricle needs adequate blood volume to function properly. Therefore, avoid nitrates and diuretics in patients with RVMI, as these drugs reduce preload and can cause significant hypotension. Fluid boluses are often necessary.
Key Treatment Considerations:
- Avoid nitrates and diuretics. 🚫
- Administer IV fluids. 💧
- Consider inotropic support (e.g., dobutamine) if hypotension persists. 💪
Summary ✍️
Posterior MI is diagnosed by reciprocal changes in anterior leads and confirmed by posterior leads (V7-V9). RVMI is diagnosed by ST elevation in V1 and V4R. Both require specific management considerations. Early recognition can significantly improve patient outcomes! 👍
Review and Practice 🧐
Review ECGs of inferior STEMIs and look for clues of posterior or right ventricular involvement. Practice identifying the reciprocal changes in anterior leads for posterior MI and the ST elevation in V1 and V4R for RVMI. Consider searching for ECG examples online that demonstrate these findings.
Next Day Preview 🚀
Tomorrow, we will explore bundle branch blocks and their impact on ECG interpretation. Get ready to decipher wide QRS complexes! 🤓
Quiz Time ❓
- Which of the following ECG findings is MOST suggestive of a posterior MI?
A. ST-segment elevation in V1-V4.
B. ST-segment depression in V1-V4 (Correct).
C. Q waves in inferior leads. - What is the most important ECG lead to examine for right ventricular MI?
A. V6.
B. V4R (Correct).
C. aVL. - Which medication should be AVOIDED in a patient with right ventricular MI?
A. Aspirin.
B. Nitrates (Correct).
C. Heparin. - Where are posterior ECG leads (V7-V9) placed?
A. On the anterior chest, mirroring V1-V3.
B. On the back, at the same horizontal level as V6 (Correct).
C. On the right side of the chest, mirroring V3R-V5R. - Why is it important to recognize RVMI in inferior STEMIs?
A. It changes the thrombolytic therapy used.
B. It affects management, particularly concerning preload (Correct).
C. It is not clinically significant.
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