Microcardia

Definition of Microcardia from the PharmacyDictionary.in

Microcardia

Microcardia refers to a condition where the heart is abnormally small.

This is typically diagnosed based on a cardiothoracic ratio (CTR) on a chest X-ray. A CTR is the ratio of the width of the heart to the width of the chest cavity. In adults, a CTR of less than 0.42 (or 42%) is generally considered indicative of microcardia.

There are two main categories of microcardia:

  1. Microcardia with cardiac atrophy: In this case, the heart muscle itself is wasted or shrunk. This can be caused by various factors, including:

    • Chronic wasting diseases: Conditions like malnutrition, severe anorexia nervosa, or advanced stages of cancer can lead to overall muscle wasting, including the heart muscle.
    • Undernutrition: Long-term lack of proper nutrition can deprive the heart muscle of essential nutrients for growth and function.
    • Adrenal insufficiency: This condition, also known as Addison’s disease, affects the adrenal glands and their hormone production. Without enough cortisol, a key hormone, the heart muscle can weaken.
  2. Microcardia without cardiac atrophy: Here, the heart size is small, but the heart muscle itself is not necessarily wasted. This can be caused by:

    • Dehydration: Severe dehydration can lead to a decrease in blood volume, making the heart appear smaller on X-ray.
    • Pneumothorax: This is a collapsed lung, which can push on the heart and make it appear smaller.
    • Constrictive pericarditis: This is inflammation of the pericardium, the sac surrounding the heart. Scarring from this inflammation can constrict the heart and limit its ability to expand.

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