Possible reasons for the symptoms of shortness of breath but no abnormality on cardiac ultrasound include: the primary disease is not related to the heart, and the heart disease does not cause structural changes. 1. Primary diseases not related to the heart: In addition to heart diseases that cause shortness of breath and fatigue, some infectious diseases of the lungs also cause such symptoms, such as interstitial pneumonitis, lobar pneumonia, tuberculosis, etc. In addition, pulmonary vascular diseases also cause such symptoms, such as primary pneumonitis and tuberculosis. In addition, pulmonary vascular disease will also appear such symptoms, such as primary pulmonary hypertension. 2. Heart disease does not cause structural changes: any disease has a certain stage of compensation, which is a dynamic process. Early compensation is often only functional changes without structural changes, so although shortness of breath and fatigue but ultrasound did not see abnormalities. In addition, cardiac diseases such as arrhythmias may not lead to structural changes in the heart, but shortness of breath and fatigue may occur, and therefore cardiac ultrasound does not show abnormalities. For those who have shortness of breath and fatigue but no abnormality on ultrasound, other auxiliary tests should be performed under the guidance of a doctor to find out the cause of the disease and treat the primary disease.