<prompt> Which of the following is not a component of classical triad of ECG changes in pericardial effusion with cardiac tamponade?Sinus tachycardiaProlonged ST segmentLow voltage QRS complexElectrical alternans  <response>: Ans. B. Prolonged ST segmentProlonged ST segment is not a part of classic triad of ECG findings for pericardial effusion with cardiac tamponade. Classical triad of ECG changes in pericardial effusion with cardiac tamponade includes:- Sinus tachycardia- Low QRS voltages- Electrical alternans best seen in leads V3 and V4 in this case; arrows This triad is highly specific for pericardial effusion, usually with tamponade physiology, but of limited sensitivity 