Diagnose and treat disorders and diseases of the cardiovascular system. Perform patient exams and order or conduct diagnostic testing. Develop ongoing treatment and disease-management plans. Prescribe medicine and coordinate referrals as necessary. A cardiologist is a healthcare provider who can treat chest pain, high blood pressure and heart failure, as well as problems with your heart valves, blood vessels and other heart and vascular issues. They can order tests like electrocardiograms, echocardiograms and CTs (computed tomography) to find out what's wrong.