Ann Thorac Surg 2007;84:520-521
© 2007 The Society of Thoracic Surgeons
Original Articles: Cardiovascular
Invited commentary
Paul Hendry, MD
Division of Cardiothoracic Surgery, University of Ottawa Heart Institute, 40 Ruskin St, Room H3404B, Ottawa, ON, Canada K1Y 4W7
(Email: phendry{at}ottawaheart.ca).
Infection has been an ongoing major concern in patients supported by implantable ventricular assist devices (VADs). Numerous reports have been published during the last 3 decades documenting infection rates that may include septicemias and nondevice-related infections, as well as more surgically specific infections, including local wound, drive-line, and pocket infections. In most studies describing the general experiences with VADs, it is often difficult to tease out the importance of drive-line infections. The article by Zierer and colleagues [1] from Washington University focuses on late onset drive-line infections that are relatively prevalent in the long-term device patients and very difficult to treat.
Although efforts are made to optimize surgical technique for the creation of the percutaneous drive-line, its postoperative care, and immobilization, the authors provide evidence showing that a majority of drive-line infections are preceded by trauma in the form of traction or torsion of the drive-line. How this can be prevented remains a problem because carrying and manipulating heavy batteries and controllers will eventually result in an inadvertent drop or fumble, which leads to stress at the percutaneous attachment site. The only real solution seems to be the creation of a drive-line that is thinner, more flexible, or elastic, and could decrease the stress at the percutaneous site, or the use of transcutaneous energy transmission and communication.
A change in drive-line for the current generation devices might be difficult due to regulatory and materials issues; however axial flow devices are smaller in size and have thinner, more flexible drive-lines. There is some indication that these differences may be important with recently reported incidences of drive-line infection being less in the Jarvik 2000 (Jarvik Heart Inc, New York, NY) devices compared with HeartMate I (Thoratec Corp, Pleasanton, CA) in patients generally supported for less than 1 year [2]. Similarly, the HeartMate II (Thoratec Corp) and deBakey MicroMed (MicroMed Cardiovascular Inc, Houston, TX) devices have been shown to have lower rates of wound and pocket infections, but with a nonstatistically significant lower rate of drive-line infections [3].
The move to a transcutaneous power and communications system has many obstacles with a significant number of engineering issues to solve regarding methods of power transmission, interference between transcutaneous power and the communications system, the unknown effects of long-term exposure to power transmission across the skin, and issues with temporary detachment from the external power and communications source to mention a few. The LionHeart VAD (Arrow International, Reading, PA) is the first device implanted in humans to lack percutaneous conduits and therefore does not lead to drive-line infections. However, although the device-related infection rate of 35% (including pump pocket, pump, and wound) is still somewhat lower than that reported by the REMATCH trial (ie, 44%, inclusive of drive-line infections), the incidence of sepsis and other common infections were quite similar [4, 5]. Although one site of infection can be eliminated, the problem with infections in these advanced heart failure patients continues to create morbidity.
Device infections continue to be sources of major problems for patients who are support long term with VADs. The article by Zierer and colleagues [1] helps to focus attention on the high incidence of drive-line infections in long-term VAD patients. Hopefully progress in technology and continued heightened vigilance to surgical techniques and wound care will help to reduce the incidence of this serious complication.
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References
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- Zierer A, Melby SJ, Voeller RK, et al. Late-onset driveline infections: the Achille’s heel of prolonged left ventricular assist device support Ann Thorac Surg 2007;84:515-521.[Abstract/Free Full Text]
- Siegenthaler MP, Martin J, Pernice K, et al. The Jarvik 2000 is associated with less infection than the HeartMate left ventricular assist device Eur J Cardio-thorac Surg 2003;23:748-754.[Abstract/Free Full Text]
- Schulman AR, Martens TP, Christos PJ. Comparisons of infection complications between continuous flow and pulsatile flow left ventricular assist devices J Thorac Cardiovasc Surg 2007;133:841-842.[Free Full Text]
- Pae WE, Connell JM, Adelowo A, et al. Clinical Utility Baseline Study (CUBS) Group Does total implantability reduce infection with the use of a left ventricular assist device?The LionHeart experience in Europe. J Heart Lung Transplant 2007;26:219-229.[Medline]
- Holman WL, Park SJ, Long JW, et al. Infection in permanent circulatory support: experience from the REMATCH trial J Heart Lung Transplant 2004;23:1359-1365.[Medline]
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