<s>[INST] I have taken 5mg of Lisinopril for the last 18 yrs when I started with asthma and I underwent a discectomy after 4 years of bad pain.Blood Pressure is usually reasonable but lately I've been suffering from a thudding and faster than usual heartbeat more especially in the evening or when I  go to bed.Its uncomfortable and worrying. [/INST] Hi,It can be either arrhythmia or just elevated heart rate from stress or anxiety.I would advise you to have an ECG done. If it comes back normal, but you continue experience same problems, the next step is holter monitoring. It is an examination,when your 24 hour ECG is registered, so your doctor can find out what's going on with your heart when you have complaints.Hope I could help youWishing you good healthIn case of further questions don't hesitate to askRegards, </s>