If the heart is damaged or overloaded by a valve not working or by beating too fast for too long then it may not pump out all the blood returning to it efficiently this is heart failure. There is then a build-up of blood waiting to be pumped, firstly in the lungs causing shortness of breath and then in the legs causing swelling oedema. The presence of heart failure and often its cause is first assessed with an ultrasound scan of the heart, an echocardiogram- please see section on tests
Shortness of breath can also be caused by a decrease in the oxygen carrying capacity in the blood, caused by anaemia. This can be detected by a simple blood test ͞full blood count.
Coronary artery disease causing a shortage of blood to parts of the heart may not be felt as chest discomfort but as shortness of breath. Most diseases of the lungs can cause shortness of breath-for instance COPD (chronic obstructive pulmonary disease) or clots on the lung (pulmonary embolus). There are many diseases of the lungs that can cause shortness of breath and not all of them show up on a chest X-ray.
Chest X-ray and CT scan of thorax in a 55 year old lady who had just had shoulder surgery. She had had some shortness of breath, the CXR was normal and I was asked to see her by her surgeon. I was suspicious that she had had a clot that had formed in the veins and had travelled to the lungs, although very uncommon after shoulder surgery I had diagnosed a case 15 years before. So I requested a CT scan of her thorax with a contrast injection timed to show up the arteries in the lungs-this confirmed the diagnosis of clots blocking the arteries in the lungs. This is a potentially fatal condition if undiagnosed but easily treated. Her shoulder surgeon who had had more than 30 years experience had never seen this complication and was rather surprised!