May 6, 2024

Good morning, 

This month we will be focusing on cardiac devices since many patients are discharged with implanted devices that treat a specific abnormality with their hearts. One of these devices is a left ventricular assist device (LVAD), which is used to treat severe left-sided heart failure that is refractory to other treatments.  

What is an LVAD?

An LVAD is a mechanical pump that is implanted inside a patient and used in the treatment of severe heart failure. The pump sucks blood out of the left ventricle and pumps it into the aorta to improve the native heart’s ability to generate blood flow to the rest of the body. The manufacturer and generation of the pump varies. In addition, current generation LVADs produce non-pulsatile flow, meaning that for the majority of LVAD patients, you will not be able to feel a pulse despite having a normal cardiac output. A picture of the Abbot HeartMate 3 from their website is included below as a reference:  

1. This is the LVAD pump and is implanted inside the body.

2. This is the controller. It tells you how much battery power is left in the battery packs, gives information on how the device is currently functioning, and provides warnings if the device is sensing an issue.

3. These are the battery packs. When assessing a patient with an LVAD, it is important to ensure the batteries are charged and plugged in since the device will not function without them. 

4. This is the driveline. It is the connection between the controller, which is outside the body and the pump, and is internal. Given that this leaves the body, it can be a source of infection for the patient.  

How are LVADs used?

There are three scenarios in which LVADs are commonly used. 

1. Bridge to recovery: Some patients develop severe CHF (Congestive Heart Failure) but will eventually recover. An example of such a situation would be when someone develops heart failure from myocarditis, which is an infection of the heart. The LVAD is placed to support the patient while the heart recovers. Once the heart recovers enough, the LVAD is removed.  

2. Bridge to transplant: The case when a patient is on the transplant list and has an LVAD placed to keep him/her alive until a transplant becomes available. 

3. Destination therapy: The case when a patient is not a candidate for a transplant, and the heart is not expected to recover, but they are too symptomatic from heart failure even on maximal medical therapy. An LVAD is placed to increase life expectancy and minimize symptoms of heart failure.  

Potential LVAD patient risks of complications: 

1. Hematologic complications: LVADs are pro-thrombotic, meaning patients need to be on blood-thinning medications to prevent these clots from forming. Clots can turn off the device and cause ischemic strokes as well as limb and bowel ischemia. In addition, clots can form inside the pump and cause the device to stop working (pump thrombosis). Patients using blood-thinning medications are also at risk of bleeding. 

2. Cardiac complications: LVADs are placed in patients who have severe heart failure, meaning that these patients are still at risk of other issues associated with severe heart failure, such as arrhythmias. The LVAD can cause enough forward flow for good perfusion even when the heart is in VT (Ventricular Tachycardia) or VF (Ventricular Fibrillation) meaning that LVAD patients can often tolerate ventricular arrhythmias better than non-LVAD patients. This is still a problem since the LVAD only supports the left heart, and these arrhythmias also affect the right heart. If the right heart fails, no blood will be delivered to the left heart, causing the whole system to fail. 

3. Infection: Just like any other device that is inserted into the body, the device can become infected. Due to the driveline leaving the body, it can serve as a source of infection, in addition to a nidus for the infection. 

4. Device dysfunction: LVADs were placed because a patient had severe heart failure. If the device fails (for any reason), the patient goes back to having severe heart failure and will likely be very symptomatic, be in cardiogenic shock, and/or rapidly go into cardiac arrest. For this reason, troubleshooting device problems is very important since it might be the only thing that keeps the patient alive. Thankfully, each device has its own troubleshooting guide to reference and patients (and their families) are trained by the teams that place LVADs to troubleshoot issues. 

Understanding how LVADs work and why they are placed helps EMS responders evaluate and treat these patients when they are having a medical emergency.  

Be safe and keep up the awesome work! 

Jordan Singer, MD

May 13, 2024

Good morning, 

As we continue focusing on cardiac devices, we recognize that many patients are discharged home with implanted devices that treat a specific abnormality with their hearts. One of these devices is a left ventricular assist device (LVAD), which is used to treat severe left-sided heart failure that is refractory to other treatments. Last week, we had a quick overview of the device to understand how it works. This week, we will discuss how to treat the critically ill LVAD patient. Management is broken up into three phases: preparation, patient assessment, and treatment.

Preparation

While LVADs are becoming more common, they are still rare. It is important for EMS agencies to be aware of who in their communities have LVADs. It is common practice for patients and hospitals to reach out to local EMS when a patient is discharged home with an LVAD to allow EMS providers to prepare for complicated medical emergencies that may occur in these patients. EMS agencies should request a copy of the specific troubleshooting guide for the specific device that the patient has. Crews can periodically review the guide to keep the information fresh. It is similar to how we should review protocols that we do not use as often. When we get dispatched to the patient, we can even bring the troubleshooting guide to review while en route and reference if the patient does not have the guide available on scene.

Assessment

The first step in assessing the patient is to determine stability or if they are critically ill. If the patient is stable, then we should assess the device, assess for perfusion, and then follow the appropriate protocol based on the issue at hand. 

Assessing the device: Auscultate the heart and listen for the hum of the LVAD. If the hum is not present, this should raise concerns about the device having had a critical error. We also should look at the controller and ensure no errors are triggering, and that the device has enough battery life.  

Assessing perfusion: LVAD patients often do NOT have a pulse since the LVAD provides non-pulsatile flow and the patient’s native heart is too weak to make a pulse. It prevents us from obtaining manual blood pressures (BPs) and from using automatic cuffs. It also prevents us from obtaining a heart rate. We need to use alternative means of assessing perfusion such as mental status, capillary refill, color and temp of extremities, and ETCO2.  

Routine assessment per protocol: Last week, we discussed specific complications that LVAD patients are at risk of, but we should also remember that these patients can have more routine problems such as urinary tract infections, pneumonia, and trauma. 

Treatment

The next step would be to treat any issues that arise during your assessment. 

• If a patient is awake, but has signs of hypoperfusion, we should address this immediately. LVAD patients are very preload dependent and often respond very well to a fluid bolus. Placing an IV and trialing a 500 ml bolus is a good place to start. If you are concerned about right-sided heart failure, you can consider going straight for push dose epinephrine; this will get the right heart to beat harder and faster and may temporize the right-sided heart failure. If the patient is septic, he/she might require a combination of fluids and push-dose epinephrine. 

• If the patient is experiencing a ventricular arrhythmia, we should treat them just as if they were having the same arrhythmia and did not have an LVAD. It is completely safe to shock patients with LVADs and the electricity will not damage the device. The only caveat is we should not put the pads directly over the device and should likely use the antero-posterior pad position.  

• If you do not hear a hum and/or the controller gives critical errors, you should assume the device is not functioning properly and should prioritize troubleshooting the device over everything else. Remember that this device is likely the only thing keeping this patient alive, so the best thing we can do for them is to get the device working again. We should check that the batteries are charged and plugged into the device, that the driveline cable is not kinked, and try to address any warnings that are on the controller. 

• If the patient is pulseless, apneic/agonal, and unconscious + no machine hum, try to quickly troubleshoot the device, and if simple measures do not work, we should start chest compressions and advanced cardiovascular life support (ACLS) care. Fixing the device would be optimal since that will likely immediately lead to return of spontaneous circulation (ROSC), but if this cannot be done, the only option left is CPR. Chest compressions can dislodge the LVAD, which would kill the patient, but if we do not do CPR in this situation, the patient is dead anyway. We should provide cardiac arrest care to these patients as if they do not have an LVAD. 

Be safe and keep up the awesome work! 

Jordan Singer, MD

May 20, 2024

Good morning, 

This month we will focus on cardiac devices. Many patients are discharged home with implanted devices that treat a specific abnormality with their hearts. Over the last two weeks we reviewed left ventricular assist devices (LVADs). This week we will review pacemakers which are used to treat chronic bradyarrhythmias.  

What is the purpose of pacemakers?

This device automatically treats patients who develop bradyarrhythmias. These are commonly placed in patients who go in and out of high-grade AV block or complete heart block. The shocks delivered to the heart are so minor that they cannot be felt (pacers do not go off). When a patient’s intrinsic heart rate drops below a certain programmed cut-off (which is often 60 bpm), the pacemaker turns on and maintains a ventricular rate at that cut-off. When the patient’s intrinsic heart rate is greater than the cut-off, the pacemaker does nothing.  

What types of problems can patients have related to their pacemaker?

If the patient is markedly bradycardic, assume that the pacer has failed since the job of the pacemaker is to prevent marked bradycardia. In this situation, EMS should treat the bradycardia as if the patient did not have a pacemaker. If the patient is stable, then use supportive care. If the patient is unstable, we would use medications and transcutaneous pacing. If we decide to pace the patient, we should be careful not to place the pads directly over the device. Of note, hyperkalemia can often cause bradyarrhythmias that do not respond to pacing. EMS should consider this potential cause of a pacer failing, and if the suspicion is high enough, treat it with calcium in addition to other treatments the protocol mentions for hyperkalemia.  

Pacemakers are implanted devices used to treat chronic or recurrent bradyarrhythmias. Malfunctions are not common, but when they occur, EMS providers need to be ready to treat them. The good news is that treating bradyarrhythmias in the setting of pacemaker malfunction is identical to their treatment in patients who do not have pacers. 

Be safe and keep up the awesome work! 

Jordan Singer, MD

May 27, 2024

Good morning, 

This month we continue focusing on cardiac devices. Many patients are discharged home with implanted devices that treat a specific abnormality within their hearts. Last week, we discussed pacemakers, and prior to that, we reviewed left ventricular assist devices (LVADs). This week, we will review automatic implantable cardioverter-defibrillators (AICD), which are used to treat recurrent ventricular tachyarrhythmias such as ventricular tachycardia (VT) and ventricular fibrillation (VF).  

What is the purpose of AICDs? 

This device automatically treats patients who develop VT/VF. They are implanted in patients who are at high risk for developing these rhythms, such as patients with severe congestive heart failure and patients who experience sudden cardiac arrest for VT/VF for unclear reasons. The device will analyze the patient’s rhythm in real time and deliver the appropriate electrical therapy based on how the AICD was programmed and the patient’s rhythm. 

What types of problems can patients have related to their AICD?

There are three possible scenarios: 

1. The device fails to treat ventricular arrhythmia. In this situation, you have a patient who has an AICD and is in VF or VT, but the device is not providing a defibrillation. It can be for a variety of reasons, but we would use standard Advanced Cardiac Life Support (ACLS) care as per our protocol to treat the patient; note that we should not place our pads directly over their device. 

2. The device delivers an appropriate shock. In this situation, the patient had a potentially fatal episode of VT/VF, and the AICD did its job and saved the patient’s life. If the patient is in a stable rhythm, we should strongly encourage transport since we want to medically optimize the patient and decrease the odds of further VT/VF episodes. If the patient is going in and out of VF/VT recurrently (AKA electrical storm), the device is the only thing keeping that patient alive. We do what we can to decrease the VT/VF episodes and rapidly transport them to the hospital for additional care. 

3. The device is shocking the patient for rhythms other than VT/VF, which would be delivering inappropriate shocks. Unfortunately, there is not much we can do in the field to prevent these shocks, but we should consider sedation and/or analgesia to help lessen the distress from these shocks, which can be very painful. Once in the hospital, a magnet can be placed on the AICD to prevent further shocks while we figure out why the device keeps going off. 

AICDs are common devices that can treat potentially fatal cardiac arrhythmias. They often do not cause issues for patients, but EMS providers need to understand them so that we can effectively treat these issues when they arise. 

Be safe and keep up the awesome work! 

Jordan Singer, MD