This EKG comes courtesy of Dr. Ahad Anjum.
A 67 year old male with a history of end stage renal disease on dialysis, presented complaining of substernal crushing chest pain and bilateral shoulder pain, 5/10, associated with shortness of breath. Onset at rest.
Vital signs: Pulse – 62, BP 103/56, Respirations 20, O2 sat 98%.
His first EKG (EKG a) is below.
A second EKG (EKG b) was performed with right sided leads.
1. What does EKG a show?
2. What does EKG b show?
3. What medication is contraindicated in this patient?
4. How would you manage this patient?
EKG a shows an infero-posterior STEMI with a 2nd degree type I AV block
EKG b shows ST elevations in V3R and V4R.
Nitroglycerin is contraindicated.
The patient should be managed as an acute STEMI with antiplatelets, anticoagulation and urgent revascularization. Nitroglycerin should not be given.
EKG a shows ST elevations in leads II, III and aVF. There are reciprocal depressions in lead V5, V6, I and aVL. This suggests an inferior wall STEMI. There are also R waves with ST depressions in lead V2. This suggests posterior involvement as well.
The EKG also shows a 2nd degree type I AV block. The PR intervals get progressively longer and ultimately there is a dropped P wave. This type of AV block often occurs in the setting of an inferior wall MI. As the ischemia is corrected, the AV block goes away as well.
The inferior wall is typically supplied by the right coronary artery (RCA). If there is a distal occlusion of the RCA, you will get an inferior wall MI. If there is more proximal occlusion of the RCA, you will get an inferior wall MI as well as a right ventricular MI. This is important to recognize because a right ventricular MI is a contraindication to nitroglycerin. So, any time you see an inferior wall STEMI, you must do right sided leads to exclude right ventricular MI prior to giving the patient nitroglycerin.
In our patient, the right sided leads showed ST elevations in V3R and V4R consistent with right ventricular MI. Patients with inferior wall MI and right ventricular MI have decreased cardiac output as well as decreased preload. If nitroglycerin is given, venous return to the heart decreased, preload to the left ventricle will decrease and cardiac output will decrease even more. Blood pressure will plummet. So, nitroglycerin is contraindicated in right ventricular MI’s.
Our patient was sent to the cath lab and was found to have a 100% proximal RCA occlusion and an EF of 25%. A stent was placed.