Myocardial infarction affects the heart rate and pulse rate, and how the heart rate and pulse rate change during an infarction depends on the vessels involved and the location of the myocardial infarction. If the myocardial infarction occurs in the right coronary artery, the clinical manifestation is inferior myocardial infarction, which affects the blood supply to the coronary sinus, resulting in a general slowing of the heart rate and lowering of the blood pressure. If the myocardial infarction occurs in the anterior descending or gyral branch, the clinical manifestation is anterior or high lateral wall myocardial infarction, which will show an increase in heart rate in the early stage and may be accompanied by arrhythmia, the most common being ventricular arrhythmia, that is, premature ventricular beats. If not treated promptly, the patient may go into shock, at which point there will also be a drop in blood pressure and a slowing of the heart rate.