53 yo M w/ PMHx of HTN, CAD, and CHF s/p LVAD placement presents to the ED w/ c/o CP. Patient reports he had mild CP overnight but this morning woke up with increasing SOB and severe CP radiating to his R arm. He immediately called 911 and his RN coordinator. Patient now in the ED reports his CP has almost resolved and he is no longer SOB. He reports no recent changes in medications, no travel, leg swelling, asymmetry, or calf pain, no HAs, visual changes, or extremity weakness, no bleeding of gums or BRBPR or melena. He has been compliant w/ his medical regimen and was last seen by cardiologist 3 days ago.
HR: No pulse palpable! BP: Unable to attain! R 16 T 98.6 O2 Sat: Poor waveform
GEN: Patient is alert and talking to you, does not appear to be in acute distress
CV: no S1 or S2 appreciated, constant humming sound audible similar to washing machine
Lungs: +crackles in bilateral bases, no wheezing, moving air well, no asymmetry
Abdm: Soft, non-tender, catheter noted on R side of epigastrium connected to waist belt “device.”
Ext: 1+ bilateral pitting edema, no erythema, no asymmetry, no calf tenderness
Rest of exam unremarkable.
Sinus rhythm w/ rate of 72, T-wave inversions in inferior leads II, III, and aVF, no ST changes
The physician is able to identify the machine by looking at the patient’s tag on the waist and it’s color and contacts the LVAD team…
A ventricular assist device (VAD) is a mechanical pump used to support heart function and blood flow in people w/ decompensating advanced heart failure who fail to improve or stabilize w/ optimal medical therapy.
The basic parts of a VAD include a small tube that carries blood out of your heart into a pump, another tube that carries blood from the pump to your blood vessels which deliver blood to your body, and a power source.
A VAD can be used as a bridge to cardiac transplantation (to sustain life until a donor heart becomes available), as destination (or permanent) therapy, or as a bridge to recovery of heart function. Most patients receiving mechanical cardiac support will have a left ventricular assist device (LVAD) although there are right ventricular and bi-ventricular devices available.
VADs are typically inserted into patients who have worsening New York Heart Association (NYHA) Class IV heart failure despite inotropic plus or minus intra-aortic balloon pump support. Such patients often also have end organ dysfunction or other potentially reversible medical conditions that may be temporary contraindications to cardiac transplantation. VADs may be life-saving in these deteriorating patients who might otherwise die before a donor heart becomes available or they are even placed on the list. New evidence also demonstrates they can improve secondary organ function and may optimize patients prior to transplantation, reduce pulmonary hypertension, and improve nutritional status, all of which are associated with improved overall morbidity and mortality and post-transplant survival.
There is growing consensus that the current classification of patients with NYHA Class IV symptoms does not offer adequate description to allow for optimal selection of patients for the current options of medical vs. pacing therapies vs. mechanical circulatory support vs. cardiac transplantation.
Patients considered for mechanical circulatory support can now be classified using the 7 profiles plus 3 modifiers developed through INTERMACS. Further understanding these profiles and their impact on outcome will hopefully shed light on the appropriate selection of patients and therapies in the advanced stages of heart disease.
1. Critical cardiogenic shock
2. Progressive decline on inotropic support
3. Stable but dependent on inotropic support
4. Symptoms at rest on home oral therapy
5. Exertion intolerant
6. Exertion limited
7. Advanced NYHA class III symptoms
Patients w/ Intermac (not NYHA) classifcation 2 generally need definitive intervention in days, patients w/ class 1 need intervention in hours. Patients in 3-5 are usually considered for elective intervention.
As survival rates w/ VAD support have improved, the use of these devices as permanent has increased.
VADs have evolved over the years. They can broadly be divided into first, second, and third generation devices according to their mechanism of action. The first generation of ventricular assist devices were the pulsatile positive displacement pumps. These devices are now less commonly used as they require more extensive surgery and have increased thrombotic complicatons and are less durable. There has been a dramatic shift from use of the first generation pulsatile pumps to use of the second generation devices which are continuous (non-pulsatile) axial or centrifugal flow pump devices. By the first half of 2007, more than 99% of FDA approved LVAD implants were continuous flow devices. These devices are smaller, more durable, and require a less extensive surgery and have lower incidence of infection and thrombosis. Third generation, continuous-flow VADs are being designed for long durability, compact size, minimization of thrombus, and simplified surgical implantation and are already available in Europe and Japan.
Continuous flow devices greatly alter the physical exam in supported patients. This presents a major challenge to physicians and first responders in assessing these patients. Continuous flow left ventricular assist devices (LVAD) supported patients frequently have no palpable pulse and blood pressure may not be measurable by auscultation. An echocardiogram is indicated in continuous flow VAD-supported patients if there are unexplained symptoms of fatigue, device alarms, defibrillator discharges, dizziness, or signs of increased right heart failure. It is important to note that the EKG is NOT affected by these devices and can be reliably used to assess for ischemia and/or arrhythmia.
In order to obtain an estimate of the BP in these patients, the physician must use either US and/or doppler w/ a manual cuff. The cuff is inflated until there is loss of blood flow to the radial artery and then deflated, the pressure at which there is return of flow is the patient’s approximate MAP (as these patients have continuous flow).
It is safe to use defribillation pads in these patients in the case of an arrhythmia, pads should be placed in their normal anatomic position. In the case of cardiac arrest confirmed by the abscense of flow w/ US/doppler, the physician should perform CPR, it is important to be absolutely sure as it is possible to displace or damage the VAD during compressions, it is important to note however that new evidence may reveal that the risk of device displacement is much lower than previously feared and with the new smaller devices the risk is thought to decrease even further.
Take Home Points:
- VAD improve morbidity and mortality
- Immediately contact VAD team/coordinator when these patient’s present to the ED
- The type of device can be determined by the color on the patient’s controller belt.
- Become familiar w/ Intermac heart failure classification system
- New devices work via continuous flow, estimate MAP by using US/doppler and manual cuff, the pressure at which there is return of flow is the estimated MAP (not SBP)
- Defibrillation pads are safe and should be placed in their normal anatomic location
- CPR should be used when appropriate however it is absolutely vital to be sure given the risk of device displacement/dysfunction
- These patients require chronic anticoagulation and those w/ continuous flow devices develop an acquired von Willebrand syndrome, they are therefore at increased risk for GI bleeding and hemorrhagic strokes
Special thanks to Dr. Felipe Teran for inspiring this pearl.
For further information please see Dr. Weingart’s podcast and materials on this topic available.