Theme: ECG findings
Select the ECG finding most likely to result from each of the following
| A. | Flattened P waves |
| B. | Tachycardia |
| C. | Heart block |
| D. | ST elevation |
| E. | Bradycardia |
| F. | U waves |
| G. | QTc prolongation |
| H. | Peaked T waves |
Select the ECG finding most likely to result from each of the following
| NaN. | A young woman with bulimia nervosa who frequently vomits and restricts intake |
| U waves 34% Vomiting can result in hypokalemia. U waves can be seen in hypokalemia along with flattened P waves and a broadened QRS complex. |
| NaN. | A middle aged man with a personality disorder develops a central crushing chest pain whilst on the ward. The paramedics arrive and following an ECG provide treatment for a myocardial infarction |
| ST elevation 93% The most characteristic sign of a myocardial infarction is ST elevation |
| NaN. | The most common ECG finding suspected in a patient started on an SSRI |
| Bradycardia 28% Sinus bradycardia is not uncommon in patients started on SSRIs |
ECG
You need a basic understanding of ECG's for the exams. Don't spend too much time on this as it's a very complex area and you do not need a detailed knowledge.
Rate
Normal rate is 60-100. Less than 60 is called bradycardia and more than 100 is called tachycardia.
PR interval
A normal PR interval is between 0.12 and 0.2 seconds. A PR interval consistently longer than 0.2s is referred to as first degree heart block.
ST segment
An upsloping ST segment (referred to as ST elevation) is indicative of a myocardial infarction. A depressed ST segment suggests myocardial ischaemia.
QTc interval
The normal range for the QTc interval is 0.35-0.45 seconds.
T waves
Are peaked in hyperkalemia, flat and prolonged in hypokalemia, and inverted in normal in some leads and also in ischemia and infarction.
U waves
Can be normal but also can be found in hypokalemia.
The following table illustrates some of the ECG changes associated with psychotropic drugs:
| ECG finding | Associated medication |
|---|---|
| Tachycardia | Clozapine TCAs MAOIs Antiparkinsonian Antipsychotics (generally the older ones) |
| Bradycardia | SSRIs Lithium Cholinesterase inhibitors |
| Heart blocks | TCAs |
| Repolarisation changes (ST segment & T wave changes) | Thioridazine Chlorpromazine |
| QTc prolongation | Wide range of antipsychtiics and antidepressants |
| Torsades/VF | Haloperidol Thioridazine Mesoridazine Chlorpromazine |
