Atrial Abnormalities Case Studies

Home » MEDCLIN530 » EKG » 12-Lead EKG Confidence » VI. The Nonischemic Disorders: Hypertrophy » 16. Atrial Abnormalities » Atrial Abnormalities Case Studies
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Kevin Hodges
Vice Chair, Emergency Medicine
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Chris Anderson
Vice Chair, Pediatrics
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Table of Contents

Case 1: Mitral stenosis

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The mitral valve separates the left atrium from the left ventricle. When the valve is stenosed, it becomes constricted and narrows. This interferes with the flow of blood from the left atrium into the left ventricle. This increases the workload of the heart and eventually causes the left atrium to become enlarged. As the pressure backs up to the lungs, the right ventricle and right atrium also enlarge. Mitral stenosis is almost always a result of acute rheumatic fever. LAA, RVH, and RAA can be seen in mitral stenosis. The left ventricle is not involved. Treatment is surgical and is aimed at reducing the resistance to flow through the mitral valve.
Mitral stenosis causes blood to back up into the left atrium. It backs up from the left atrium into the lungs, causing shortness of breath (dyspnea). Eventually the blood backs up into the right ventricle and right atrium. The results are dilated left atrium, right ventricular hypertrophy, and right atrial hypertrophy.

Meanwhile, the left ventricle does not see any problem. There is no extra work for the left ventricle. Mitral stenosis does not affect the left ventricle!

Case 2: Mitral regurgitation

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Mitral regurgitation is most commonly caused by mitral valve prolapse, or rheumatic heart disease. Mitral regurgitation occurs when the mitral valve allows the backflow of blood from the left ventricle into the left atrium. The left atrium and left ventricle become dilated and hypertrophied trying to accommodate the extra blood volume. The EKG can demonstrate LAA and LVH.
Mitral regurgitation allows for a backward movement of blood between the left ventricle and left atrium during ventricular systole. The left atrium dilates to accommodate the extra blood volume. The left atrium fills from blood pumped from the right ventricle, but has no extra room to accommodate the regurgitant volume from the left ventricle. As a result, it dilates to compensate. The left ventricle dilates to accommodate the extra blood volume. The left ventricle fills with blood pumped from the right ventricle, but has no extra room to accommodate the regurgitant volume, and so it also dilates to compensate.

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