Without evidence of benefit, an intervention should not be presumed to be beneficial or safe.

- Rogue Medic

Asymptomatic Sustained Ventricular Fibrillation in a Patient With Left Ventricular Assist Device


ResearchBlogging.org

Also posted over at Paramedicine 101 and at Research Blogging.

Go check out the rest of the excellent material at both sites.

There’s a big difference between mostly dead and all dead. There are even other not quite dead yet categories that we tend to ignore. Asymptomatic Sustained Ventricular Fibrillation is not a group of words that appear to be appropriate together in a sentence. The old Sesame Street segment on which of these doesn’t belong would have a lot of people yelling Asymptomatic.

Sustained Ventricular Fibrillation is something we are familiar with, but in symptomatic patients – symptomatic to the point of being dead. We provide chest compressions to make up for the lack of cardiac output.

The first-generation assist devices are volume-displacement pumps. Consisting of a chamber filled passively or by suction and compressed by externally applied pressure, they provide a pulsatile flow, thereby mimicking the cyclic systole and diastole of the heart. The second generation has been developed with axial-flow, rotary-pump technology, providing a continuous blood flow.[1]

What does continuous flow mean, when assessing a patient?

No pulses, at least no pulses from the device.

On the day of admission, the patient noticed 3 consecutive discharges of the implantable cardioverter defibrillator, prompting him to call emergency medical services. On-site findings showed an alert and asymptomatic patient despite electrocardiographic analysis, exhibiting sustained ventricular fibrillation. Blood pressure measurement using a sphygmomanometer was not successful.[1]

Not an unusual 911 call. My AICD has been shocking me. My doctor told me to call 911 when that happens.

Typically, the AICD has shocked the heart back to the patient’s normal rhythm. A bit of hand holding and a discussion about possible prescriptions for a sedative and an antiarrhythmic, or an adjustment to the doses of these.

This patient is pulseless. Pulseless patients are not rare. A 911 call for a pulseless patient is usually because the pulseless patient is dead.

Contrariwise, a patient talking to me has a pulse. I have had several patients who were awake and talking, but without any palpable pulses. The absence of palpable pulses is different from the absence of pulses. All of these patients, with no palpable pulses, were significantly symptomatic.

conceivably the cardiac output had decreased substantially because of ventricular fibrillation, whereas intra-arterial monitoring revealed a continuous mean arterial pressure of 80 mm Hg (Figure 1B).[1]

respiratory rate (12 breaths/min), body temperature (36.8°C, 98.2°F), and peripheral O2 saturation (92%) were normal. Physical examination revealed a constant precardiac noise derived from the left ventricular assist device pump, whereas heart sounds were not audible. Lungs were clear and peripheral edema was not present.[1]

In other words, asymptomatic and pulseless, but with a more than adequate blood pressure and a good SpO2.

Under these circumstances, pulseless VF (Ventricular Fibrillation), the use of the term VAD (Ventricular Assist Device) is not really accurate. The VAD is working as the pump. The cardiac output is zero with VF. There is nothing to assist.

All of the blood flow is due to the VAD.

Implantable cardioverter defibrillator memory function yielded several adequate but unsuccessful electric shocks delivered in response to ventricular fibrillation, which had developed from multifocal ventricular tachycardia.[1]

Would we be more aggressive with the same presentation, if the patient were still in multiform VT (Ventricular Tachycardia)?

I think that a lot of people would, because they would want to prevent the rhythm from deteriorating to VF. Once the patient is in a rhythm that cannot get any worse, we may relax and be less aggressive.

Can this become worse?

This VF can become symptomatic. Almost all of the labs were within normal ranges. The exceptions were the electrolytes, which were low normal, or low, troponin I at 0.2 ng/mL (normal <0.03 ng/mL) and creatine kinase at 187 U/L (normal <145 U/L).

After supplementation of potassium and magnesium, amiodarone treatment was started, but first followed by 2 unsuccessful attempts of internal cardioversion. Eventually, after 3.5 hours, ventricular fibrillation could be terminated with external electrical biphasic cardioversion at 200 J, resulting in a stable rhythm with atrioventricular sequential pacing (Figure 1C). The intra-arterially determined mean blood pressure of 80 mm Hg remained unchanged.[1]

3 1/2 hours of documented asymptomatic VF.

They have this to state about the increasing use of VADs and the possible interaction/interference of VADs with AICDs (Automated Implantable Cardioverter Defibrillators).

Ventricular fibrillation is a fatal arrhythmia in the absence of circulatory support and inevitably results in death if not treated immediately. Whereas implantable cardioverter defibrillators have been proven to significantly reduce sudden cardiac death caused by ventricular tachycardia and ventricular fibrillation in severe congestive heart failure, their role in patients with left ventricular assist devices remains to be determined. 7,9 In fact, left ventricular assist devices might have a direct effect on implantable cardioverter defibrillator devices with alteration of lead parameters, ventricular tachycardias, and electromagnetic interference, thereby reducing the effectiveness of the implantable cardioverter defibrillator. 11 However, left ventricular assist devices may be able not only to support circulation but also to effectively substitute cardiac pump function in the presence of a malignant arrhythmia, even over a longer period, as previously reported with pulsatile-flow devices. 12-15[1]

Occurrence of sustained ventricular fibrillation in a patient with left ventricular assist device reflects a challenging situation that might be observed more frequently in the future: In 2008, about 4,000 left ventricular assist devices were implanted in the United States, but the numbers are expected to increase significantly. This is particularly true for the use of left ventricular assist devices in destination therapy of congestive heart failure, with the first device (HeartMate II; Thoratec Corporation) recently approved by the Food and Drug Administration for this indication.[1]

The HeartMate II LVAS includes a pump implanted inside the patient’s body and components that remain outside the patient’s body. The pump controller and batteries are worn outside the patient’s body. The system also includes a battery charger/power supply and monitor that remain outside the body..[2]

The extra equipment should be apparent, when assessing a patient with one of these devices. Smaller, less noticeable VADs may soon be available, but they will all probably have external equipment that we should notice.

Seven of the patients (all biventricular; diagnoses: four cardiomyopathy, two acute myocardial infarction, one end-stage coronary artery disease plus acute myocardial infarction) had prolonged arrhythmias that normally would have been lethal (six cases of ventricular fibrillation from 2 to 22 days, one asystole for 3 hours), but complete support of the systemic and pulmonary circulations was maintained in all seven patients with biventricular devices. Mean systemic blood flow during this period (4.6 +/- 0.6 l/min) was unchanged compared with that during sinus rhythm. Six of these patients survived to receive heart transplants.[3]

Up to 22 days of (continuous?) VF.

Blood flow during arrhythmias was not significantly different from blood flow during sinus rhythm.

It remains unclear, however, if sustained ventricular fibrillation during a longer period would have affected hemodynamics and outcome in our patient. Because left ventricular assist device patients are at high risk of developing malignant arrhythmias, which in turn can affect the cannulas’ position, effective treatment of ventricular tachycardias and ventricular fibrillation is recommended in this situation. In fact, slightly increased creatinine and troponin levels, although transient, were suggestive of some end-organ damage in our patient.[1]

Even though the patient was asymptomatic, there may have been damage occurring in the patient’s organs.

It is important to know that cardiopulmonary resuscitation (CPR) with chest compression may be performed in patients with a left ventricular assist device, if deemed clinically indicated. However, this intervention needs to be viewed cautiously because CPR may result in dislocation or damage of the cannulas or ventricle rupture, requiring emergency thoracotomy and heart surgery. CPR may be considered only in some patients who have substantial right ventricular failure, along with severe left ventricular dysfunction. Those patients may not be able to tolerate ventricular fibrillation because the right ventricle cannot deliver blood to the left side of the heart. In these cases, CPR may be necessary to prevent death while waiting for internal or external defibrillation, which can be performed without risk. Further studies are needed to determine the role of serious ventricular arrhythmias and implantable cardioverter defibrillators in patients with left ventricular assist devices.[1]

For the patient who has enough cardiac output to produce signs of life, CPR is probably a bad idea. Rapid transport to a hospital capable of treating patients with a VAD, or capable of transferring a patient with a VAD to a specialty center (just about any hospital), is probably a much better idea.

In theory, patients with sustained VF would not benefit from univentricular support because of the ineffective blood flow across the right heart associated with this dysrhythmia. In patients with refractory VT, particularly VT with a rate of less than 150 beats/min, univentricular mechanical support should be capable of sustaining adequate hemodynamics, because the right heart contributes some forward flow. Two of the most important factors affecting the physiologic flow across the pulmonary vascular bed are the status of the right ventricle and the pulmonary vascular resistance (PVR). If the PVR is elevated, whether because of VT or VF, the flow across the pulmonary vascular bed will be compromised, resulting in diminished LVAD flow. Conversely, if the PVR is low or normal, the LVAD should provide satisfactory flow. Therefore, selective agents to reduce the workload of the right ventricle and decrease the PVR, such as nitric oxide, could be useful in this setting.[4]

With a single chamber VAD, during VF, there might not be adequate blood flow. Compromised blood flow through the right ventricle might explain the elevated troponin and creatinine levels.

Footnotes:

[1] Asymptomatic sustained ventricular fibrillation in a patient with left ventricular assist device.
Busch MC, Haap M, Kristen A, Haas CS.
Ann Emerg Med. 2011 Jan;57(1):25-8. Epub 2010 Jul 31.
PMID: 20674087 [PubMed – in process]

[2] Thoratec HeartMate II LVAS – P060040/S005
FDA (Food and Drug Administration)
Device Approvals and Clearances
Device Approval Notice with links to FDA Approval Letter

[3] Successful biventricular circulatory support as a bridge to cardiac transplantation during prolonged ventricular fibrillation and asystole.
Farrar DJ, Hill JD, Gray LA Jr, Galbraith TA, Chow E, Hershon JJ.
Circulation. 1989 Nov;80(5 Pt 2):III147-51.
PMID: 2680160 [PubMed – indexed for MEDLINE]

I could not find this paper on Circulation’s site, not a link to the abstract. Maybe the Pt 2 means a part of a supplement, that is not included in the archives.

[4] Ventricular assist device support for management of sustained ventricular arrhythmias.
Fasseas P, Kutalek SP, Samuels FL, Holmes EC, Samuels LE.
Tex Heart Inst J. 2002;29(1):33-6.
PMID: 11995847 [PubMed – indexed for MEDLINE]

Free Full Text Article from PubMed Central with links to Free Full Text PDF download

Busch MC, Haap M, Kristen A, & Haas CS (2011). Asymptomatic sustained ventricular fibrillation in a patient with left ventricular assist device. Annals of emergency medicine, 57 (1), 25-8 PMID: 20674087

Farrar DJ, Hill JD, Gray LA Jr, Galbraith TA, Chow E, & Hershon JJ (1989). Successful biventricular circulatory support as a bridge to cardiac transplantation during prolonged ventricular fibrillation and asystole. Circulation, 80 (5 Pt 2) PMID: 2680160

Fasseas P, Kutalek SP, Samuels FL, Holmes EC, & Samuels LE (2002). Ventricular assist device support for management of sustained ventricular arrhythmias. Texas Heart Institute journal / from the Texas Heart Institute of St. Luke’s Episcopal Hospital, Texas Children’s Hospital, 29 (1), 33-6 PMID: 11995847

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Comments

  1. I know you’ve discussed elsewhere the value of taking patients to the closest appropriate facility vs. the closest facility. I’d encourage that sort of thinking here. Not all hospitals are equipped to deal with VADs. Many will be as bumfuzzled by the VAD as the average street medic, perhaps even more so. If the patient is reasonably stable, transportation to the hospital managing his VAD is going to be best for him, and for you.

    • PJ,

      I wrote –

      For the patient who has enough cardiac output to produce signs of life, CPR is probably a bad idea. Rapid transport to a hospital capable of treating patients with a VAD, or capable of transferring a patient with a VAD to a specialty center (just about any hospital), is probably a much better idea.

      By signs of life, I mean something that is significantly worse than asymptomatic. Signs of life implies that you have to seek out the signs of life, rather than the patient being awake and alert and asymptomatic. Whether the local hospitals can handle this is something medical command or the patient would know. Where I am, I have to go out of my way to find a hospital without advanced cardiac capabilities, but I am spoiled.

      A patient, who can only be described as having signs of life, probably should go to the closest hospital, unless the time to a specialty cardiac hospital is not dramatically longer. An emergency physician should be able to do much more for an unstable VAD patient, than a medic in the back of a truck.

      What is reasonable stable is going to depend on the assessment, the time to the various facilities, and a bunch of other things.

      • Precisely. A patient with only “signs of life” is clearly unstable, and should be transported accordingly.

        My intent was to discourage the knee-jerk panic that so often comes from patients with uncommon medical presentations like this. Two examples from my own career come to mind: the MVC patient who was decreed to be an abdominal trauma because she’d had a liver transplant…six years earlier (I overruled that decision), and the gentleman receiving the “stare of life” from an engine company who was too scared to touch him because his AICD was firing periodically and they were concerned for their safety (also overruled, and transported without injury to anyone involved, and without lineman’s gloves).

  2. This case report would be a great scenario for paramedic students post ACLS or really any ACLS class. They’ve been taught algorithm after algorithm. Treating rhythm after rhythm. Never have I read something that screamed “treat your patient, not your monitor” more than this case report!

    As an aside, I have treated a patient with an LVAD and it was pretty neat. He explained a great deal to us, and was well educated about the device. We took his BP at the hospital with doppler. He has a shoreline at his house so he doesn’t need batteries indoors. Our electric company provided pretty high SLA for his power to his home (including preferred handling after storms). His big thing was we began trouble shooting with checking his batteries! I believe he also had scheduled meetings with all of the area fire departments and EMS agencies to explain the device during ConEd. I was very glad to meet him and learn about this device.

  3. Awesome, awsome case! All I have to add…

  4. You could certainly see your expertise within the work you write. The sector hopes for even more passionate writers like you who are not afraid to say how they believe. Always go after your heart.

  5. I see your 22 days and raise you 15 months:

    http://jtcs.ctsnetjournals.org/cgi/content/full/126/4/1190

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