This week’s CXR brought to us by Dr. Kondamudi
60yo Male with HFrEF and ED presents for device implantation, below is post- procedure CXR (click on image for full screen)
The device placed is a biV PPM and ICD or CRT-D.
It is important to be able to discern a cardiac device by imaging (as in this case) and EKG when a patient presents with a cardiac complaint. More often than not, the history and indications behind the device will not be readily available.
On CXR the way to differentiate between an implantable cardioverter defibrillator (ICD) and pacemaker (PPM) (or rather, to confirm defibrillation capability) is by looking for the thick shock coil that is specific to an ICD. This is because the shock coil helps transmit the high energy shocks required for defibrillation. Different models have 1 or 2 shock coils. Once a thick coil is confirmed, it can be assumed that the device has defibrillation function.
To diagnose a cardiac resynchronization therapy (CRT) device by imaging, we have to recall its physiological purpose. In patients with heart failure with reduced ejection fraction (HFrEF) significant conduction delays can cause dyssynchrony across the ventricles, which can lower cardiac output. To rectify this, a lead is used to pace the LV, typically along with a pacing lead in the RV (occasionally, CRT can be done with only an LV lead) to resynchronize their cardiac cycles. Hence the term cardiac resynchronization therapy. Thus the best way to confirm CRT capability is to look for an LV lead. Recall that when placing the LV lead (transvenous method), it is wired through the coronary sinus, backwards through the cardiac venous system, onto the epicardium of the LV. If this lead is visualized, then the device is providing resynchronization therapy. I find inverting the image can aid with visualizing the lead.
Picture Courtesy of Uptodate
You may see leads in the RA and RV, but this does not help elucidate whether the device has CRT or ICD capabilities. Remember, an ICD has pacemaking capabilities (e.g. anti-tachycardia pacing to break supra-ventricular and ventricular tachyarrythmias).
This has clinical implications, because a patient’s presentation can always be related to malfunction of a cardiac device. For example, if a patient has a CRT-D device by imaging, but does not appear to be BiV pacing on EKG (a topic outside the scope of this post), then the HF exacerbation could be related to ventricular dyssynchrony, in which case the function of the device would need to be investigated.
Supplementary Reading: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4286824/
The indications for CRT are:
The 2013 American College of Cardiology Foundation /American Heart Association/Heart Rhythm Society (ACC/AHA/HRS) guideline for the management of HF and the 2012 ACC/AHA/HRS focused update for device-based therapy included the following indications for CRT in patients in sinus rhythm with LVEF ≤35 percent
- NYHA functional class II, III or ambulatory class IV symptoms on guideline-directed medical therapy (GDMT) and LBBB with a QRS duration ≥150 ms, (strong recommendation with strong evidence for NYHA class III/IV and weaker evidence for NYHA class II).
- NYHA functional class III or ambulatory class IV on GDMT with non-LBBB pattern with a QRS duration of ≥150 ms (weak recommendation with strong evidence).
- NYHA function class II, III, or ambulatory class IV on GDMT, LBBB with a QRS duration 120 to 149 ms (weak recommendation with weak evidence).
- On GDMT and undergoing placement of a new or replacement device with anticipated requirement for significant (>40 percent) ventricular pacing (weak recommendation with weak evidence).
The 2013 European Society of Cardiology (ESC) guidelines on cardiac pacing and CRT included the following indications for CRT in patients in sinus rhythm with LVEF ≤35 percent
- NYHA functional class II, III, or ambulatory IV despite adequate medical treatment and LBBB with QRS duration >150 ms (strong recommendation with strong evidence).
- NYHA functional class II, III, or ambulatory IV despite adequate medical treatment and LBBB with QRS duration 120 to 150 ms (strong recommendation with weaker evidence).
- NYHA functional class II, III, or ambulatory IV despite adequate medical treatment and non-LBBB with QRS duration >150 ms (weak recommendation with weak evidence).
These guidelines were based on trials that demonstrated decreased mortality, hospitalizations, and symptoms with CRT in patients with an EF < 35% and QRS ≥120 to 140 ms. Interestingly a QRS duration < 150 ms and lack of reduction in QRS duration after CRT, predict poor clinical response to CRT. Additionally, most studies involved patients with an LBBB, so take the generalization of CRT benefits to RBBB and nonspecific intraventricular conduction delay with a grain of salt.
There is a left sided pneumothorax. The patient was asymptomatic, but this post procedural CXR was significant enough to warrant chest tube placement.
Complications associated with transvenous cardiovascular implantable electronic device (CIED) lead implantation include bleeding, infections, lead dislodgment, pneumothorax, air embolism, cardiac perforation, thrombosis of the implant vein, and rarely death.