In our latest Clinical Problem-Solving article, a 59-year-old woman with a history of bilateral total hip replacements and a total knee replacement sees her physician for cough, exertional dyspnea, and foot swelling that had developed 2 weeks earlier while she was on vacation in Europe.
New-onset heart failure, particularly in younger patients who do not have coexisting conditions, can be easily misdiagnosed.
• What is the indication for mechanical circulatory support in patients with heart failure?
Early recognition of cardiogenic shock and timely implementation of appropriate stepwise interventions to restore adequate tissue perfusion are necessary to prevent multiorgan failure. If pharmacologic therapies do not restore adequate blood flow, mechanical circulatory support is indicated. When the cause of decompensation is potentially reversible, temporary support tiered to the hemodynamic need can be used; types of support include an intraaortic balloon pump, percutaneous LVAD, and extracorporeal membranous oxygenation. For patients in whom no reversible cause of heart failure is identified, and right ventricular function is adequate, surgical implantation of a durable LVAD may be indicated.
• When is there a role for histopathological evaluation of myocardial tissue in the setting of heart failure, and how specific are the findings?
Histopathological evaluation of myocardial tissue is not a standard part of the evaluation for most cardiomyopathies, but judicious use in certain clinical scenarios is indicated. Amyloidosis and hemochromatosis can generally be ruled out on the basis of the histopathological findings. Findings of hypertrophy and fibrosis are not specific to dilated cardiomyopathy and may be seen in hypertrophic or restrictive cardiomyopathies or in chronic ischemic, hypertensive, or valvular heart disease.
Morning Report Questions
Q: What is the history of metal-on-metal hip implants and what are the adverse events that may be associated with their use?
A: Metal-on-metal hip implants replace traditional ceramic or polyethylene materials with cobalt-chromium alloy for the lining of the head and cup of the prosthesis. Approximately 1 million patients around the world have received such hip prostheses, most of which were implanted between 2003 and 2010. Whereas these implants were intended to last longer than traditional implants, recent data suggest that they have increased failure rates. In addition, cobalt-chromium implants release metal ions into the surrounding tissue and bloodstream. Although the regulatory approval and safety surveillance processes for metal-on-metal hip prostheses have garnered recent attention in major medical journals, relatively little attention has been paid to the potential systemic effects of cobalt-chromium ion release — including the possibility of a potentially reversible cardiomyopathy — particularly in patients without symptomatic or objective findings of failure of implants used in arthroplasty. Noncardiac organ involvement, including thyroid, liver, neurologic, and bone marrow dysfunction, has also been described in association with systemic cobalt toxicity.
Q: What is the typical presentation of cobalt cardiomyopathy?
A: The clinical presentation is often that of a rapidly progressive cardiomyopathy after the onset of symptoms in otherwise fairly young and healthy persons. In more recent years, several cases of presumed cardiomyopathy related to cobalt implants used in arthroplasty have been described in the literature. These reports have typically involved more overt prosthetic failure or resurfacing of the metal-on-metal prosthesis, and in all but one case, the cardiomyopathy was reversible with removal of the prosthesis. Despite data from case reports documenting elevated levels of cobalt in serum and myocardium at the onset of heart failure, the threshold for serum and tissue cobalt levels that cause cardiomyopathy has not been defined.