MCQ 16. Coronary branches (19)

Q. In left dominant circulation, which of the following is not a branch of left circumflex artery?
A. AV nodal artery
B. Obtuse marginal artery
C. Posterolateral branches
D. Conus artery

Answer: D. Conus artery

Explanation:
In right dominant circulation, AV nodal and posterolateral branches arise from RCA whereas in left dominant circulation they arise from left circumflex artery. In codominant circulation, AV nodal artery arise from RCA and posterolateral branches arise LCx. Obtuse marginal arteries are branches of left circumflex and acute marginal arteries are branches of right coronary artery.

Origin of conus artery is not affected by dominance of cardiac circulation. It arises from RCA and supplies the right ventricular outflow tract. Sometimes, it may directly arise from left main coronary artery.

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ECG Spotter

What is the diagnosis? Click the button below to view answer: Show Answer

High heart rate

The patient contacts the doctor over phone with this report. Obviously anxious because of his high heart rate (199 beats per minute) as detected by ECG machine. Should he be worried about this and come to emergency department as soon as possible? Correct answer- ECG machine has calculated his heart rate incorrectly. Heart rate is around 100 beats per minute. Other findings in this ECG include ST segment elevation in anterior chest leads along with presence of Q waves, denoting old MI changes with possibly development of LV aneurysm. In such cases, ST segment elevation can persist for long periods. Now, should he come to emergency department? Not because of detection of high heart rate. But, if he is having symptoms such as shortness of breath or chest pain, he should visit emergency department. Otherwise, if he is asymptomatic, he can schedule a regular visit with his cardiologist.

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