The Ship Captain’s Medical Guide – Chapter 7 – Other Diseases and Medical Problems

When the calibre of the coronary arteries becomes narrowed by degenerative change, insufficient blood is supplied to the heart and, consequently, it works less efficiently. The heart may then be unable to meet demands for extra work beyond a certain level and whenever that level is exceeded, attacks of heart pain (angina) occur. This can be compared to a ‘stitch’ of the heart muscle. Between episodes of angina the patient may feel well. Any diseased coronary artery is liable to get blocked by a blood clot. If that blockage occurs the blood supply to a localised part of the heart muscle is shut off and a heart attack (coronary thrombosis) occurs.