Left ventricular (LV) pseudoaneurysms form when cardiac rupture is contained by adherent pericardium or scar tissue. Although LV pseudoaneurysms are not common, the diagnosis is difficult and they are prone to rupture. We evaluated the clinical presentation, diagnostic accuracy of imaging modalities, results of therapy and prognosis of 290 patients with LV pseudoaneurysms. Most cases of LV pseudoaneurysm were related to myocardial infarction (particularly inferior wall myocardial infarction) and cardiac surgery. Congestive heart failure, chest pain and dyspnea were the most frequently reported symptoms, but >10% of patients were asymptomatic. Physical examination revealed a murmur in 70% of patients. Almost all patients had electrocardiographic abnormalities, but these were usually nonspecific ST segment changes; only 20% of patients had ST segment elevation. Although radiographic findings were also usually nonspecific, the appearance of a mass was present in more than one half of patients and may be an important clue to the correct diagnosis. Left ventricular angiography was the most definitive test and can be useful in planning surgery since concomitant coronary angiography can be performed. Regardless of treatment, patients with LV pseudoaneurysms had a high mortality rate, especially those who did not undergo surgery. Because the symptoms, signs, electrocardiographic abnormalities and radiographic findings seen in patients with LV pseudoaneurysms can be indistinguishable from those in patients with coronary disease alone, a high clinical index of suspicion is needed to avoid missing the diagnosis.

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Debonding of the prosthetic/polymethylmethacrylate interface has been implicated in the initial failure process of cemented total hip arthroplasties. However, little quantitative understanding of the debonding process, as well as of the optimum interface morphology for enhanced resistance to debonding, exists. Accordingly, a fracture-mechanics approach has been used in which adhesion at the interface is characterized in terms of the interface fracture energy, G (J/m2), and shown to be a strong function of the morphology, debonding length, and loading mode of the interface. Double-cantilever-beam and four-point-flexure fracture-mechanics samples containing four clinically relevant prosthetic surface preparations were prepared to survey a range of interface roughness and loading modes. Adhesion at the interface could not be characterized with a single-valued material property but was found to exhibit resistance-curve behavior in which resistance to debonding increased with both the initial debond extension and the roughness of the interface. Values of debonding initiation, Go, were relatively insensitive to the roughness of the surface and the loading mode, whereas steady-state fracture resistance of the interface, Gss, increased significantly with the roughness and shear loading of the interface. These quantitative results suggest that debonding of the prosthetic/polymethylmethacrylate interface may be primarily attributed to surface interactions such as interlocking and the pullout of rough asperities that occur behind the debond tip. A simple mechanics analysis of such interactions was performed and revealed increases in the fracture resistance of the interface that were consistent with experimentally measured values.

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