Causes of shortness of breath with normal heart and lung tests

Shortness of breath, or dyspnea, can persist even when standard heart and lung tests, such as chest X-rays, CT scans, and echocardiograms, return normal results. This occurs because many routine tests are performed while a patient is at rest, whereas some physiological issues only manifest during physical exertion, prolonged standing, or increased metabolic demand.

Potential causes for breathlessness include both cardiac and non-cardiac factors. Non-cardiac causes may involve asthma, chronic lung conditions, respiratory infections, anemia, obesity, or reduced physical conditioning. Cardiovascular causes can include issues with heart muscle, valves, rhythm, or the heart's ability to pump and fill with blood.

Medical professionals suggest evaluating specific patterns to determine the cause. Symptoms that may warrant closer investigation include breathlessness that occurs during routine activities, appears when lying flat, wakes a person from sleep, or is accompanied by palpitations, chest discomfort, dizziness, or swelling in the ankles and legs.