Cardioplegics, generic name Propafenone, should be seen for medically prescribed treatment when left chest pain with atrioventricular block occurs after administration. The medication should be used in accordance with medical advice. Propafenone belongs to the anti-arrhythmic drugs, can improve the threshold potential of cardiomyocytes, significantly reduce the spontaneous excitability of the myocardium, but also reduce the stress of the myocardium, and the effect is relatively long-lasting. It is mainly used in the treatment of paroxysmal ventricular tachycardia, atrial flutter, atrial fibrillation and other diseases. Usually the drug may cause symptoms of atrioventricular block after taking it, and may also cause changes such as atrioventricular block, prolongation of the qt interval, as well as headache, dizziness, dry mouth and other discomforts. It is contraindicated for those who are allergic to the components of the drug, those with severe hypotension, and those with cardiogenic shock. Secondly, in the process of taking the drug, it is necessary to pay attention to such changes as serious damage to the myocardium, severe bradycardia, hepatic and renal insufficiency, significant hypotension, while pregnant women and lactating women need to use the drug under the guidance of a doctor. If the symptoms of atrioventricular block left chest pain appear after taking Propafenone, it is recommended to consult a doctor for treatment. The medication should be used in accordance with medical advice.