Patients with high blood pressure can go into heart failure and present with flash pulmonary edoema. Thus, their lungs can suddenly flood with fluid, and this causes severe breathlessness. The acute problem can quickly respond to treatment. However, there is usually some underlying heart disease, and a clue to this can be found by doing an exercise tolerance test in a laboratory with ECG monitoring. An echocardiogram might also define cardiac performance, and help determine if cardiac (as well as hypertension) medications are needed.