Complications include heart failure, an irregular heartbeat, and sudden cardiac death. Other complications include heart failure or an abnormal heartbeat. Sweating, shortness of breath, lightheadedness, and irregular heartbeat may also be experienced. An 'arrhythmia' refers to an abnormal rhythm or speed of rhythm of the heartbeat. Other complications include heart failure or an irregular heartbeat. More severe symptoms may include&colon; shortness of breath, a fast or irregular heartbeat and fever. It has a heartbeat and a pulse. Other tests are suitable when tinnitus occurs with the same rhythm as the heartbeat. Arteries constantly expand and contract with each heartbeat, i.e., the pulse. Excessive doses may cause seizures, irregular heartbeat, and death. Cardiac electrophysiology can be used to observe and treat disorders such as arrhythmia (irregular heartbeat). Serious side effects may include worsening bronchospasm, irregular heartbeat, and low blood potassium levels. Blood is propelled through arteries and arterioles through pressure generated by the heartbeat. An implantable cardiac defibrillator may be recommended in those with certain types of irregular heartbeat. A thumping drum beat was set to mimic her racing heartbeat.