Posted by Nick Taylor on May 5, 2014 at 1:13 am
1. Describe the ECG
2. What is your diagnosis
3. What would your initial management be?
This ECG demonstrates pacing spikes from a dual chamber pacemaker and failure to capture with a ventricular escape rhythm. There are no captured beats. A captured beat will have the QRS complex occur right after the preceding spike. If you look at the gap between the spikes and the QRS complexes, there is far too long to wait for the QRS.
Failure to capture is analagous to 3rd degree AV block. There is dissociation between the pacemaker (p wave) and the QRS . It just so happens here that the escape rate is half of the PPM rate. Common causes include electrode displacement, low PM output, Increased resistance (scarring, infarct at electrode tip); lead fracture or disconnect; perforated myocardium; battery or box failure
In terms of Management the main initial Question is is the rhythm perfusing or not. ARC guidelines have adrenaline 1st line as a chemical pacing agent and isoprenaline as second line. All these drugs will do is turn up the escape rate and possibly help with some inotropy, but if the escape is non perfusing, making it faster won’t be a very successful strategy.
I would prefer management outline based around:
1. Get the pt safe into a resus bed (get pads on a be ready to externally pace)
2. If the patient is shocked, start pacing and get an adrenaline infusion ready. If ext pacing and inotropic support not helping needs temporary wire ASAP. Consider also airway protection etc depending on how shocked
3. If the patient is not shocked but BP is not normal, commence adren or iso whilst getting urgent PM tech support, Ix for a cause , and informing cardiology
4. If pt has normal BP: get urgent PM tech review whilst preparing back up plan
5. Seek and treat for casues: CXR (lead #) VBG etc
Some hospital’s cardiology unit seems to prefer isoprenaline, I am unable to find evidence to support this , but it may be purely practical, as CCU are not able to run Adrenaline infusions, but can do iso.
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