The worldwide web hosts a huge variety of sites that focus on how to interpret electrocardiograms (ECGs) in a step by step manner, as well as in the context of clinical scenarios. I found the sites given here extremely useful for dealing with patients with real electrocardiograms on the wards.

I like a more wordy and fairly comprehensive resource that goes through the process of reading an electrocardiogram one step at a time. The ER Club and EKG Interpretation, found at http://students.med.nyu.edu/erclub/ekghome.html, has a very easy to read writing style, and the author (Henry Feldman) chooses to insert the relevant basic physics under the appropriate interpretation heading. You will find a quick discussion of lead placement under the axis discussion.

When you have a basic grasp of the electrocardiogram, sometimes all you need is a quick summary site because, for example, you have forgotten some of the criteria for ventricular hypertrophy. Reading an EKG, at www.uab.edu/emig/yellow_book/yb_reading_ekg.htm, gives a quick list of the steps involved in interpreting an electrocardiogram, with all the relevant criteria. It also has a bonus "Pearls" section in which it lists the classic findings of clinical conditions such as pericarditis, hyperkalaemia, and digitalis toxicity. Unfortunately there are no tracings to accompany the section but you can easily draw in the appropriate waveform.

For those of us who prefer textbooks to websites, the Introduction to ECG Interpretation, hosted by the University of Wisconsin at www.fammed.wisc.edu/pcc/ecg/ecg.html, is a course that is designed to teach electrocardiogram interpretation at the medical student level. This site is more formal than the one by Feldman and is also easier to navigate with buttons that allow you to jump to the electrocardiogram step of your choice. There are also quizzes at the end of each content area, which allow the whizzes to test their craft without going through the preceding learning material. This site also includes links to a series of clinical cases, which begin with a clinical description of a patient and their electrocardiogram tracing. When you have arrived at your own interpretation, or not, you can view the answer, which discusses the electrocardiogram in a stepwise fashion and ends with a clinical impression.

If you enjoy clinical cases, eMedicine features ECG Cases arranged by diagnosis at www.emedicine.com/ekgotwindexbydx.html. Unfortunately, the diagnosis is clearly listed as the title of each case. For a site based on clinical cases that requires you to unearth the diagnosis, ECG Wave-Maven is an excellent resource, provided by Harvard Medical School at http://ecg.bidmc.harvard.edu/maven/mavenmain.asp, and includes 285 electrocardiograms for you to interpret in a clinical context. The answers also give references to journal articles that discuss similar electrocardiogram findings in case you are longing for more information about the giant Osborn waves seen in systemic hypothermia.

With all of this wonderful information, you now need to present the case in a professional manner to wow your consultant. Thankfully, Flesh and Bones, located at www.fleshandbones.com/guides/medicine.cfm#ecg, provides survival guides for general medicine, including how to present an electrocardiogram.

Electrocardiogram interpretation is a skill that becomes more rewarding with the more time you invest. So pick the site that suits your learning style and your present needs, and good luck.

Competing interests: None declared.