Heart rate. Generally, your heart rate can be measured by checking your heart rate. An ECG may be helpful if your heartbeat is difficult to detect or too fast or infrequently accurate. An ECG can help your doctor determine the degree of abnormal heartbeat (tachycardia) or bradycardia. An ECG can indicate cardiac arrhythmias. These conditions may occur when any part of the cardiovascular system is malfunctioning. In some cases, medications, such as beta-blockers, cocaine, amphetamines, and over-the-counter cold drugs and allergies, can cause arrhythmias. Heart disease. An ECG can show evidence of a previous or ongoing heart attack. Patterns on the ECG may indicate which part of your heart is damaged, as well as the degree of damage. An ECG performed during symptoms may help your doctor to see that chest pain is caused by reduced blood flow to the heart muscle, such as chronic angina pectoris. The ECG test in thane can provide clues about enlargement of the chambers or walls of the heart, heart failure, and other heart problems. If your doctor finds any problems with your ECG, he or she may order additional tests to determine if treatment is necessary.