Usually, instructors of basic ECG classes look for examples of the most common conditions that are likely to be encountered by the learners.  But, sometimes, it is advantageous to show students more unusual presentations to remind them of the infinite possibilities when we care for living beings.  This series is a very good example of what can and does happen to some people with cardiovascular disease.  It will give your students an opportunity to think about possible interpretations, and also about anticipating clinical implications and emergencies that may arise.

The Patient:  This patient is a man in his 80s who has been active his whole life.  He considers himself to be healthy, giving no medical history and denying medication use. He states that he has had a yearly health exam.  Today, he felt “tired and dizzy” while raking leaves.  As he walked to his house to rest, he had a syncopal episode and fell, hitting his head. He was unconscious for a few minutes. A family member called for Emergency Medical Services (EMS). Paramedics found him awake and complaining of bilateral “shoulder and wrist” pain. He had no obvious trauma to his extremities, but had some bruising on his head and face.  He denied recent illness and substance abuse.  He was oriented x3. He was pale and diaphoretic, and complained of nausea. He denied chest or back pain.  He denied shortness of breath.  BP 100/60.  Heart rate bradycardic.  SPO2 above 95%.  He was given aspirin and ondasetron, and transported to a hospital.

This pair of ECGs feature one of our recurring themes:  wide-complex tachycardia (WCT). It is a fascinating topic, as tachycardia has many causes and many mechanisms, and wide QRS also has many causes, with the mechanism being slow conduction through the ventricles. 

Sometimes, it is not possible to diagnose the true origin of a WCT from one ECG, or even serial ECGs.  Is the tachycardia due to increased sympathetic activity (fear, dehydration, exercise, hypoxia, hypovolemia, etc.)?  Or is the fast rate due to reentry, where one impulse gets “caught” in a loop, repeating itself rapidly, and depolarizing the myocardium with each pass?  What is the location of the pacemaker that is responsible for the rhythm?  Is it a supraventricular rhythm that has suffered an intraventricular conduction delay, widening the QRS?  Or is the rhythm originating in a ventricular pacemaker, without the ability to travel on the fast highway that is the intraventricular conduction system? 

If you or your students work in an acute care setting, such as pre-hospital or emergency department, you may not be with the patient long enough or be able to conduct enough tests to determine without a doubt the answers to the above questions.  Some WCTs cause such severe symptoms that they must be dealt with quickly, to avoid rapid deterioration to ventricular fibrillation.  For that reason, there is a widely-accepted rule for WTC treatment:

TREAT ALL WIDE-COMPLEX TACHYCARDIA AS IF IT IS V TACH UNTIL PROVEN OTHERWISE.    

The Patient:    These tracings are taken from a 75-year-old man who became weak while playing golf on a very hot day.  He was pale and diaphoretic.  He was hypotensive, but we do not know his BP reading. He denies chest pain or discomfort. The patient reported a history of lung cancer and hypertension. We have no other history, and unfortunately, no follow-up information.

ECG Number 1:           The first ECG shows the standard 12 leads.  The rhythm is sinus with frequent appearances of PAC couplets.  The sinus rate varies slightly from about 76 bpm to 68 bpm, tending to slow a bit after the premature atrial contractions.  There is a right bundle branch block, and the QRS duration is about .12 seconds (120 ms). The PR interval is slightly log at 223 ms.  We do not know what medications the patient is on, and we do not have an older ECG for comparison.

There are some interesting, if subtle, changes worth mentioning.  The QRS complexes in most leads are fragmented.  That is, they have notching in the terminal S or R waves that is not due to the bundle branch block. This can be a sign of scarring, and can also be considered an equivalent to a pathological Q wave.  Speaking of pathological Q waves, they are seen in the inferior leads, II, III, and aVF.  There are also prominent, though not large Q waves in V4 through V6, leads which normally do not have them. All this points to scarring and possibly long-term coronary artery disease, with possible old M.I.  In addition, the ST segments are not entirely normal.  There is ST depression in the inferior and low lateral leads, a little ST elevation in aVL.  Also, the SHAPES of the ST segments tend to be straight throughout the ECG, instead of the usual curved (concave up) appearance.

The Patient:  This ECG is from a 59-year-old woman who was found by the EMS crew to be unresponsive, with agonal respirations at about 6 breaths per minute. Her pulse was thready at the carotid, and absent peripherally. Her skin was pale, cool, and mottled.  Her BP via the monitor is 81/40, peripheral pulses not being palpable.  An initial rhythm strip showed sinus rhythm at 75 bpm with right bundle branch block and ST elevation.

The patient’s husband gave a history of “difficulty breathing” since sometime this morning, alcohol dependence, hypertension, tobacco use, and insomnia. He said she had been drinking heavily for several weeks.

She was immediately ventilated and intubated, and an intraosseous infusion line established.  A12-lead ECG was done, and it showed a dramatic change in the rhythm and ST segments over the initial strip. She was transported to a nearby hospital with CPR support. She achieved return of spontaneous circulation (ROSC) at the Emergency Department, after having three doses of epinephrine.  Follow up with the ED physician revealed that the patient had suffered a massive gastrointestinal bleed.  This patient, due to loss of a critical amount of blood, had low blood pressure and very poor perfusion, which resulted in damage to her heart (and possibly other organs as well). I do not have further follow up, but will update this if I receive more information.