Hy 2452 HY Cardiac physio

[tommyk]

Hy 2452 HY Cardiac physio
A 45-year-old woman had an overdose of the tricyclic imipramine. Her past medical history is significant for hypertension, atrial fibrillation, diabetes, and asthma. Her medications include furosemide, procainamide, glyburide, prednisone, and albuterol. She has no known drug allergies. She is afebrile, has a blood pressure of 100/60 mm Hg, pulse of 60/min, and respirations of 25/min. She is confused and somnolent, and has shallow respirations. Her physical examination is otherwise unremarkable. On an ECG, which of the following abnormalities would most likely reflect possible cardiac toxicity? (They may show a cardiac ECG graph!, hint hint)
1-ST segment elevation
2-ST segment depression
3-Left QRS axis deviation
4-Right QRS axis deviation
5-Prolongation of the QRS complex
6-Shortening of QT interval
7-Lengthening of QT interval



























































ans) #5 A prolongation of the QRS interval is highly predictive of both cardiac and CNS toxicities from tricyclic antidepressant ingestion. Left deviation of the QRS axis, which can be seen with conditions such as left ventricular hypertrophy and left bundle branch block, is not typically associated with tricyclic cardiac toxicity. Conversely, right deviation of the QRS axis (greater than 120 degrees) is very predictive of cardiac toxicity from tricyclics. Shortening of the QT interval is not seen with tricyclic toxicity, but can be seen with metabolic derangements such as hypercalcemia. ST segment depression nor T wave inversion is directly associated with cardiac toxicity from tricyclic overdose. These changes may be seen, however, in conjunction with the more classic ECG manifestations of tricyclic toxicity (prolonged QRS interval, right axis deviation) if the resulting cardiac toxicity leads to diminished coronary perfusion and ischemia.