Compare the Old and New ECG

An abnormal ECG does not prove acute cardiac disease. And a normal ECG does not exclude cardiac disease. It is necessary therefore to compare new ECG with ECG's made in the past.

Hallmarks are:

• Is there a change in rhythm?
• Is there a change in frequency?
• Is there a change in conduction time?
• Is there a change in heart axis?
• Are there new pathological Q's?
• Is there a change in R wave size?
• Is there a change in ST?
• Is there a change in T wave?

So, one have to check for changes in all 7 steps.

Change in rhythm

Example: new atrial fibrillation. Atrial fibrillation occurs in ten percent of elderly people (>70 year) without clinical symptoms. Therefore atrial fibrillation in acute dyspnoic patients does not prove atrial fibrillation induced cardiac decompensation. Also other causes (e.g. cardiac ischemia, pneumonia) should be considered. Previous ECG registrations could provide additional information.

Frequency

Example: bradycardia. New sinusbradycardia of 50 beats per minute (bpm) may cause dizziness, however, long existing bradycardias are often without symptoms. Therefore it is important to know about someones normal frequency.

Conduction time

An increase in PQ time may be seen in elderly patients, but may also be caused by the use of medication or by ischemia. Broadening of the QRS complex may be caused by medication or ischemia. An increase in QTc time may be caused by medication, but may also be heridetary. Comparison of previous made ECG registration with new registration may provide the clue.

Heart axis

Ischemia may cause a change in the heart axis, however also heridetary differences in heart axis may occur. Again, a previous ECG differentiates between old and new changes.

Pathological Q's

Hallmark of the comparison between old and new ECG are pathological Q's. New pathologische Q's provide evidence for the occurence of a myocardial infarction in the mean time.

Increase R wave

Decrease of the R wave may a a sign of occured infarction. Tamponade, cardiomyopathy and increased bodysize also decrease the R wave.

Increase of the R wave indicates hypertrofia of the left ventricle (leads V5-V6), or a posterior infarction (V2-V3) or a loss of body weight.

ST segmenten

Nieuwe ST-elevatie past in eerste instantie bij een acuut myocardinfarct. ST-elevatie kan ook chronisch aanwezig zijn bij een aneurysma cordis en enkele weken aanwezig zijn bij een pericarditis.

T toppen

T top inversie heeft veel mogelijke oorzaken. Ischemie, electrolytenstoornissen maar ook stress is een optie. Het is meestal niet specifiek genoeg om hier een onderscheid tussen te maken. T top inversie is dus meer een teken dat er 'iets' aan de hand is. Nader onderzoek (vervolg-ECG's, laboratoriumonderzoek) kan uitwijzen wat dat dan is.