Diabetic Foot: The Heart of the Matter

  Providing wound care to patients who live with diabetes is further complicated by the admixture of other conditions commonly present with this chronic disease. However, the significance of these comorbid complications is only evident once the astounding rates of death and disability are appreciated. Among Medicare beneficiaries between 2006 and 2008, the one-year death and major adverse cardiovascular event (MACE) rate among those experiencing diabetic foot ulcers (DFUs) was 11%.¹ Moderate-to-severe peripheral artery disease (PAD) typically contributes to this wounding, and critical PAD with wounding (without the presence of diabetes) is attended by a one-year, 25% cardiovascular mortality rate.² The subset of patients who live with both critical PAD and diabetes has even worse outcomes. As such, the importance of taking into account the cardiovascular status of all DFU patients is paramount for all wound care clinicians. The highest priority must be given to avoiding potentially fatal events such as myocardial infarctions and cerebrovascular accidents.

Honing in on the Heart

  It’s very tempting (and maybe even expedient in a sense) for wound care clinicians to focus on the wound-impacted limb alone when caring for their patients. However, a narrow-focused approach that does not invoke true wholistic care will only exacerbate the chance for heart attack and/or stroke at a near-incalculable rate. While never unavoidable, gauging the likelihood of a cardiovascular incident can be better anticipated without unnecessary testing when there’s a full appreciation of where the patient stands at the first point of care. This assessment begins by comprehensively reviewing the patient’s cardiovascular history, including previous surgeries. These procedures can directly impact one’s wound care.   Coronary bypass procedures often involve the use of the saphenous vein and could lead to the creation of wounds to the leg, which can further impact revascularization attempts within the limb (lack of autologous vein for bypass procedures). They can also result in a chronically edematous limb and create “zones” of relative hypoperfusion at the scar sites. The presence of an automatic implantable cardioverter defibrillator (AICD) or pacemaker must also be accounted for if electrocautery will be used during wound debridement or if MRI is desired for osteomyelitis evaluation. Additionally, an AICD reveals the presence of a dysrhythmia and the likelihood that prescribed medications will affect future medication choices for moderate sedation procedures. Existing prescriptions can also create drug conflicts (ie, metoprolol and ketorolac or sotolol and ciprofloxacin, etc). The practitioner is better equipped with this information up front as opposed to trying to determine what is occurring during an unexpected cardiovascular event. The presence of an AICD also informs the practitioner of the likelihood of depressed cardiac function, possible prior heart failure, and, in all probability, an ejection fraction of less than 30%. This wealth of event-preventative information should arise from collecting the patient’s medical history; meanwhile, a social history can reveal the probability of unreported COPD due to heavy tobacco abuse (an additional major risk factor for coronary and cerebrovascular events). It may be possible and worthwhile for the wound care clinician to assess whether patients are currently under the care of a cardiovascular specialist who may be capable of producing results from recent electrocardiograms, echocardiograms, stress tests, cardiac catheterizations, and/or carotid Doppler exams. Fellow practitioners who may have cared for the patient prior and have intimate knowledge of cardiovascular status can share opinions related to patient care and serve as resources for questions regarding possible change in health status while reassuring the wound care provider of related risk factors of office-based procedures. The DFU patient may appear to have a poorly controlled cardiovascular status with elevated blood pressure or resting tachycardia; however, this may have been controlled prior to the pain or infection. This should not be simply assumed, however, as some patients have poorly controlled hypertension at baseline and can experience dangerous elevations in blood pressure with minimal bedside debridements.

Further Assessments

  After discussing the presentation of the wounded extremity, the conversation should turn toward the patient’s cardiovascular status. One helpful line of questioning involves tolerance to exertion. For example, assessing one’s habits at a supermarket or large store can provide valuable insight. Can the patient walk to and from his/her car without stopping, or must he/she lean on a cart throughout (or is a motorized cart needed)? Can the patient walk a flight of stairs without stopping? What limits does the patient have — overall fatigue, shortness of breath, leg pain, etc? Each of these clues has different implications. Overall fatigue can be due to deconditioning, heart failure, COPD, etc. Shortness of breath is similar, but with pulmonary causes increasing and cardiac causes also present. If leg pain is the limiting factor, claudication, lower back pain, or low cardiac output may all be participating in the patient’s difficulties, which should specifically be probed at night, as heart failure may cause nocturnal dyspnea or difficulty breathing when lying flat. If the patient needs several pillows or has to sleep sitting up, many caution flags should start to wave regarding the severe degree of cardiac impairment that exists. The decision to repeat or obtain new cardiac assessment tests is dependent on the information provided by the patient and on how much time has passed since tests were obtained. If symptoms have not changed in the last six months, testing during this time is likely sufficient. Determining tests that are sufficient to reassure the wound care practitioner should be based on the intensity of therapy needed. If only dressing changes are required (far less impact than debridements or resections), then less proof of cardiovascular competence is necessary. It is straightforward to appreciate that if the patient reports new chest pain, pressure, or constriction (or an increase in one of these is found) that immediate referral to a cardiovascular specialist is indicated for full workup. If the patient has an increased respiratory rate and is pursing his/her lips with each breath, then referral or return visit to a pulmonologist may be appropriate. Avoiding cardiovascular events requires attention to detail and a brief yet thorough line of questioning. Routinely ordering electrocardiograms or echocardiograms in asymptomatic patients who can tolerate exertion is likely of low yield. On the other extreme, ignoring changing symptoms and new complaints is hazardous and invites complications. In all, the most important goal is being able to recognize that an undisclosed problem exists and that a referral to the proper practitioner is necessary. Additionally, caution is heightened once the severity of a cardiovascular condition is defined. This form of care is cost effective, protective for the patient, and avoids events where a practitioner’s insight could be called into question. One’s clinical acumen will also be hailed by patients when a condition such as a carotid artery bruit that signaled a potential pending stroke is identified, even if the patient expected the primary focus to be on the existing DFU. Cornelius A. Davis, III is a physician at Genesis Heart Institute, Genesis Medical Center, Davenport, IA.

References

1. Margolis DJ, Malay DS, Hoffstad OJ, et al. Incidence of diabetic foot ulcer and lower extremity amputation among Medicare beneficiaries, 2006 to 2008: Data Points #2. 2011 Feb. 17. In: Data Points Publication Series [Internet]. Rockville (MD): Agency for Healthcare Research and Quality (US); 2011-. Accessed online: www.ncbi.nlm.nih.gov/books/NBK65149 2. Hirsch AT, et al. ACC/AHA 2005 practice guidelines for the management of patients with peripheral arterial disease (lower extremity, renal, mesenteric, and abdominal aortic): a collaborative report from the American Association for Vascular Surgery/Society for Vascular Surgery, Society for Cardiovascular Angiography and Interventions, Society for Vascular Medicine and Biology, Society of Interventional Radiology, and the ACC/AHA Task Force on Practice Guidelines (Writing Committee to Develop Guidelines for the Management of Patients with Peripheral Arterial Disease): endorsed by the American Association of Cardiovascular and Pulmonary Rehabilitation; National Heart, Lung, and Blood Institute; Society for Vascular Nursing; TransAtlantic Inter-Society Consensus; and Vascular Disease Foundation. Circulation. 2006; 113(11): e463-654.