Dr Hannah Wilkin-Crowe, Dr Vikram Baicher, Dr Mark Fenner
In this case-based article we will go through the emergency management and logistical considerations of treating Ventricular Tachycardia in a young person with Duchenne Muscular Dystrophy.
At the end of the article we have a discussion with a Paediatrician with Cardiology expertise, and will explore some wider questions around the case.
Let’s get to it…
All clinical details have been altered to anonymise this case.
You are working in a tertiary Paediatric Emergency Department. Whilst writing up some notes from your last patient the triage nurse Heather asks you to look at an ECG.
Unlike the normal ECGs you’re used to looking at, this one looks a bit different….
You ask where the patient is and Heather points to a very well-looking 17 year old called Akbar.
You notice that Akbar is in a motorised wheelchair which has a chest harness, head support and that he is wearing splints on both of his legs. He seems comfortable in himself.
‘Hello Akbar, how are you?”
Akbar replies, ‘I’m ok thank you, just feel a bit funny’
You and Heather move Akbar to resus with his mother Fatima.
When you arrive you take a history. Akbar has been feeling a bit unwell for 3 or 4 days. He’s had some vague chest discomfort at times and felt a little sick although he hasn’t actually vomited. He’s had no fever, diarrhoea, cough or cold. Fatima comments that Akbar has seemed more tired than normal and at times a little short of breath.
Akbar and Fatima explain that he has Duchenne’s Muscular Dystrophy (DMD) and takes Perindopril 4mg once daily.
He has never had any heart rhythm problems and thinks his last ECHO was pretty good.
You examine Akbar in the chair where he is comfortable and find:
- A-Self
- B-Chest clear, RR 18
- C-HR 230-250, Sats 97% in air, BP 110/74, CRT <2s
- D-Soft abdomen
- E-Tone normal for him
- PEARL
- Temp 36.5
You explain to Akbar that you think his heart is in an abnormal rhythm and that he needs to have some blood tests and cannula sited in order to help figure out what’s going on. He may also need some medication to address the problem. Heather kindly inserts a venflon whilst you look at some recent clinic letters.
Heather takes off some blood and sends for FBC, UE, PO4, Ca2+, Mg, LFTs, TFTs and a blood gas.
Akbar’s blood gas comes back looking like this…
- pH 7.37
- PCO2 5.4
- HCO3 22.4
- Hb 171
- Glucose 6.6
- Lactate 2.3
- Potassium 4.7
- Sodium 140
- Calcium 1.13
Recent clinic letter:
| Diagnosis: Duchenne muscular dystrophy Preserved cardiac function (borderline low/normal) Plan: Transition to Adult Cardiology services |
You notice the Echo report attached to the clinic letter….
| Summary: Technically difficult study with poor image quality. Limited scan done while in wheelchair. No significant valvular abnormalities LV systolic function impression of borderline low RV systole function presumed to be preserved No significant diastolic function abnormality |
At this point you pause and collect your thoughts…. What do you think of Akbar’s ECG?
The rhythm strip is broad and fast – this looks like VT. However Lead 1 looks narrow complex – could this be something else?
Is it really showing what you think it’s showing?
It is! Heather has just done a repeat and hooked Akbar up to some monitoring.
Could Akbar’s diagnosis of Duchenne’s alter your approach?
Akbar’s recent ECHO seems reassuring, but the diagnosis of DMD makes you feel somewhat anxious. Because Akbar is stable and in a safe place you decide there is time to phone a friend.
Akbar is stable but it looks like he is in VT. You are unsure how his diagnosis of DMD might affect your management. Given Akbar’s age and the lack of in-house Paediatric Cardiology expertise, you follow the Adult referral pathway to Cardiology and speak to the Adult Cardiology Nurse Specialist who kindly offers to come to CED and review Akbar with the Adult Consultant Cardiologist.
You explain this to Akbar and his mother. Akbar is happy to be cared for under adult services and understands that there is more on-site Cardiology expertise than there is within Paediatrics.
The cardiology Consultant and Cardiac ACP come to review Akbar. You discuss the potential management options which vary slightly between Paediatric and Adult guidelines. These are summarised below and here
Together you make a plan:
- Give magnesium. Magnesium is an important factor in the Na/K-ATPase enzyme system, aiding the transport of sodium and potassium across cell membranes and improving cardiac stability.
- Safely sedate Akbar to facilitate cardioversion. Trial adenosine to assess for any possible underlying rhythm before moving to DCCV if necessary. Up to a maximum of three synchronised shocks are planned. If unsuccessful then move to amiodarone.
After calling the anaesthetic team, you run through the potential pitfalls in your plan and mitigate them:
What if adenosine or DCCV fails?
a. Move to amiodarone infusion
What if we precipitate VF?
a. Prepare for VF arrest therefore Heather asks 2 other nurses to come and support.
b. Fluid bolus, amiodarone, adrenaline are prepared and you allocate roles e.g. CPR, drugs, defibrillator management and interventions e.g. further IV/IO access.
Safety with DCCV – How to do this safely:
- Attach ECG electrodes to the patient in the standard positions, this will allow continuous monitoring throughout the procedure and will facilitate synchronisation of the shock delivery
- Apply the defibrillator pads in the appropriate position to maximise transmyocardial current
- Select the appropriate energy
- Ensure that the defibrillator is set to Synchronised shock. This delivers the shock to coincide with the R wave. An unsynchronised shock could coincide with a T wave and cause ventricular fibrillation. The defibrillator display will change when synchronisation mode is selected to alert the user. A mark is displayed over each R wave and the word sync is visible
- Synchronised cardioversion should also be delivered with the same attention to safety as a defibrillatory shock; always ensure the chest is dry, that no one is in direct or indirect contact with the patient and remove free flowing oxygen from the immediate vicinity (see chapter 9 of ALS handbook for further info)
- Charge the defibrillator and once it is safe to do so press the shock button. Keep the shock button pressed down until after the shock has delivered, there may be a slight delay while it syncs to shock
- Some defibrillators will remain in synchronised mode following delivery while others will not. It is important to confirm the defibrillator is in the correct mode before delivering any further shocks
- If the shock is successful, it is important to reassess the patient using the ABCDE approach, record a 12 lead ECG and correct all reversible factors that may predispose to further arrhythmia
Once sedated by a paediatric anaesthetist, Akbar is given Adenosine 12mg into a venflon in his ACF and immediately flushed with 20mL sodium chloride 0.9%, there was no effect.
You move onto DCCV and follow the steps outlined above. After delivering DCCV you see a change on the 3-lead ECG. A repeat 12-lead ECG is performed…
You see that Akbar’s heart rhythm now looks like sinus and there have not been any complications.
Post Care
After recovery from his sedation, Akbar is transferred to a monitored bed in the cardiology unit and started on bisoprolol. After further inpatient investigation Akbar has an ICD fitted and is discharged with follow up arrangements in place.
Akbar’s case is not an everyday occurrence for clinicians working in Children’s A+E, so you have a chat with a colleague Mark, a Paediatrician with Expertise in Paediatric Cardiology….
How can muscular dystrophy affect the heart?
Muscular dystrophy is an inherited condition typically X linked (boys). Duchenne Muscular dystrophy is the most common type. The dystrophin gene is abnormal and so muscle cells degrade and are replaced by fatty scar tissue. The skeletal muscles are the most notable, with many boys struggling with stairs and then becoming wheelchair bound in teenage years. The abnormal dystrophin gene also affects heart muscle. The scar tissue does not contract and can transmit electrical signals with no refractory period. Patients therefore get two primary problems – impairment in function and arrhythmia.
If there was no recent ECHO available for Akbar would management have altered? i.e. drugs or try to obtain ECHO prior to any intervention?
Patients with Duchenne Muscular Dystrophy really should have an annual echo. In part because changes can occur reasonably quickly, but also because they don’t have symptoms simply because they are not active enough (cannot walk) to elicit breathlessness. Whilst your management may be the same, you should recognise that in later stages of poor function the heart dilates significantly giving a dilated cardiomyopathy picture. This makes cardioversion much more risky, it also impacts time for drugs including sedatives to work.
If a patient who had DMD presented with new SVT – would you follow standard management algorithms or would a Cardiology consultation be warranted first?
Paediatric arrhythmias require sensible consideration of the clinical context. It should be noted that children can sustain cardiac output and are much less likely to develop secondary ischaemia than the typical adult patient. Therefore if the child is tolerating the rhythm you have time to prepare and ask for advice if uncertain.
Regarding VT and SVT with aberrancy, the Resus council flow chart for Paediatric arrhythmias cited above, suggests to treat as VT if unsure whether VT or SVT. Is there any risk in trying adenosine first?
VT in children is very rare. SVT with aberrancy is uncommon. Both typically occur in those with a known cardiac history or previous surgery. It is not unreasonable to attempt treatment of SVT (in the first instance) in a child who is compensating and with resus equipment prepared. Adenosine itself can terminate some forms of VT, but can also induce and potentiate VT so caution is advised. Amiodarone can be equally pro-arrhythmogenic in children and it is not unusual to advise against the slow bolus but to directly start the continuous infusion.
- Here’s a resource that might be helpful in understanding a bit more about VT and SVT with aberrancy – Life in the Fast Lane – VT vs SVT
Key learning points
- If the patient is stable, seek expert opinion before intervention
- Mitigate for anticipated risks e.g VF, familiarity with synchronised defibrillation, drug dosing and team preparation
- Familiarise yourself with local referral pathways. Paediatric cardiology is usually a regional service. You may have some in-house expertise but not always.
- Just because the patient presents to Paediatric ED does not mean you can’t access adult services where clinically appropriate – especially in cases where the young person is transitioning to adult care.
Resources
Authors
Dr Hannah Wilkin-Crowe – Registrar in Emergency Medicine, Nottingham University Hospitals; Dr Vikram Baicher, PEM Consultant, Nottingham University Hospitals; Dr Mark Fenner, Paediatrician with Cardiology Expertise
Brilliant article with many learning points