Two-year (mid-term) results for unprotected left main coronary artery percutaneous interventions with drug-eluting stents.

OBJECTIVE: Bypass surgery remains the revascularization strategy of choice for left main trunk coronary artery disease in an unselected group of patients. Drug eluting stents have been proposed as a viable alternative to bypass surgery for left main trunk lesions but their intermediate and long term outcomes are still under scrutiny. METHODS: A series of 50 patients with significant unprotected left main trunk stenosis (>50%) underwent revascularization with drug eluting stents (sirolimus and paclitaxel stents) and were enrolled in a registry. Follow up angiography was clinically driven. Recurrent chest pain and ischemia on myocardial perfusion imaging were clinical parameters that mandated repeat angiography. Prespecified primary endpoints of this registry were defined as major adverse cardiac event at 2 year follow up. RESULTS: No differences in outcomes were noted with either type of drug eluting stent used in this study (Sirolimus versus Paclitaxel). The low major adverse cardiac event rate of 14% at 2 years warrants a randomized control trial in a low surgical risk group of patients comparing bypass grafting with left main trunk percutaneous intervention. CONCLUSION: This registry confirms findings by other investigators about the safety of unprotected LMT stenting in an unselected group of patients. The acceptable MACE rate at 2 years from registries such as this suggests the need for a randomized control trial comparing the two strategies.

Quantitative assessment of regional left ventricular function with cardiac MRI: three-dimensional centersurface method.

OBJECTIVES: The purpose of this study was to provide the first in vivo validation of a three-dimensional (3D) method to quantify regional left ventricular (LV) function with cardiac magnetic resonance (CMR) imaging after myocardial infarction (MI). BACKGROUND: Current cardiac methods to analyze LV function are limited by geometric assumptions and observer biases. METHODS: MI was induced percutaneously by 90-min proximal left circumflex artery balloon occlusion in 25 Yucatan minipigs. Cine and contrast-enhanced (CE) CMR imaging was performed at 5 days (n = 21) and 8 weeks (n = 22) post-MI. Twelve control animals without MI were also imaged. Regional wall thickening was measured orthogonal to the myocardial wall using the centersurface method. The left ventricle was divided into 16 segments (six basal 60 degrees , six middle 60 degrees , four apical 90 degrees ). Normal ranges for segmental wall thickness and wall thickening were defined as mean +/- 2D in control hearts. Hypokinesis was defined as a segmental thickening value below the normal range. RESULTS: Hypokinesis following MI was identified in the inferior, inferolateral and anterolateral segments when compared with controls and corresponded to areas of infarction by CE CMR. The aggregate wall thickening was also expressed as a percentage at 5 days (Infarct zone: 15% +/- 16% vs. NonInfarct zone 33% +/- 20%, P < 0.001) and 8 weeks (Infarct zone 20% +/- 20% vs. NonInfarct zone 32% +/- 22%, P < 0.001). CONCLUSIONS: The centersurface method can quantify regional wall thickening and spatially identify regions of abnormal function in 3D after MI without relying on geometric assumptions. This method may be a valuable tool to quantify regional LV function in the assessment of myocardial viability, ischemia, infarction, and the response to therapeutic interventions.

Granulocyte-colony stimulating factor administration after myocardial infarction in a porcine ischemia-reperfusion model: functional and pathological effects of dose timing.

BACKGROUND: Acute MI results in cardiomyocyte death, left ventricular (LV) dysfunction and adverse remodeling. The use of growth factors may prevent this. The aim of this study was to assess early and delayed administration of granulocyte colony-stimulating factor (G-CSF) in a porcine model of myocardial infarction (MI) and reperfusion. METHODS: MI was induced by balloon occlusion followed by reperfusion. There were 3 groups: Control (n = 11), Early (n = 17), and Delayed treatment (n = 8). The Early group received G-CSF 10 microg/kg/d every other day for 20 days beginning immediately. The Delayed group received G-CSF 10 microg/kg/d daily for 10 days beginning on day 5. Magnetic resonance imaging was performed on days 5 and 56. LV end-diastolic volumes (EDV), end-systolic volumes, ejection fraction, expansion index, sphericity index, thinning ratio, and infarct mass were calculated. Histology was analyzed at 56 days. RESULTS: At 56 days the change in EDV was 53% less in the Early (p = 0.005) and 24% greater in the Delayed (p = NS) group versus Control. The Delayed group also showed a 60% increase in normalized infarct mass (p = 0.055) and an 88% increase in expansion index (p = 0.003). Both groups had significantly less capillary density in the infarct border zone. The Delayed also had decreased arteriolar density in the mid scar. CONCLUSIONS: Early treatment with G-CSF after MI decreases ventricular dilatation, while delayed treatment has a deleterious effect on LV remodeling. This may be related to changes in myocardial vascularity. The effects of G-CSF therapy and its dose timing help to elucidate the results of recent human trials.

Outcomes after standardized screw fixation technique of ankle arthrodesis.

Several methods of obtaining ankle fusion have been described, with numerous studies reporting on patient populations with varied diagnoses and various methods of fixation. This has led to outcome analyses that are difficult to interpret. Our hypothesis is that using a standard method of fusion, without the aid of allograft, a solid ankle fusion can be achieved in patients with end-stage ankle arthritis, and that this outcome can be reflected in standardized outcome tools. Forty-one consecutive ankle fusions in 40 patients were included in our study, with a minimum followup of 3 years. All patients had an ankle arthrodesis using two parallel retrograde 7.3-mm screws and local fibular graft. All but two patients obtained a solid talocrural union (95%), with a mean postoperative improvement in the American Orthopaedic Foot and Ankle Society score of 23 points. Results of our study showed that a simple technique based on sound mechanical and biologic principles can yield excellent outcomes for patients.

Fixation of posterior malleolar fractures provides greater syndesmotic stability.

Syndesmotic injuries are common in ankle fractures. Traditional syndesmosis fixation may be associated with a secondary procedure. When the posterior malleolus is fractured, the posterior syndesmotic ligaments may remain intact and attached to the fragment. Our goals were to establish the incidence of syndesmotic ligament ruptures in pronation-external rotation type ankle injuries associated with posterior malleolar fractures, and to assess syndesmotic stability after fixation of the posterior malleolus compared with using a syndesmotic screw. Fifteen patients who sustained pronation-external rotation Stage 4 ankle fractures that involved the posterior malleolus were evaluated using radiographs and magnetic resonance imaging. No complete tears of the posterior-inferior tibiofibular ligament occurred. A pronation-external rotation fracture pattern with a posterior malleolar fragment was created in 10 lower extremity cadaver specimens with random fixation of the posterior malleolus or the syndesmosis. Compared with the intact specimens, stiffness was restored to 70% after fixation of the posterior malleolus, and to 40% after syndesmosis stabilization. Syndesmotic stability may be obtained more effectively by fixation of the posterior malleolus rather than by using a syndesmotic screw. Although additional clinical investigation is warranted, these concepts may be useful in eliminating syndesmotic screw fixation in select patients.

An analysis of talar surface area occupied by screw fixation in ankle fusions.

BACKGROUND: Ankle arthrodesis remains the benchmark of treatment for end-stage arthrosis of the ankle joint. Despite that, the incidence of nonunion can be as high as 15%. Various strategies have been used to reduce the incidence of nonunion, including multiple compression screws and larger diameter screws to improve mechanical stability and compression. The space occupied by an increasing amount of hardware across a finite surface area available for fusion has prompted concern that this strategy may be counterproductive and may reduce the biological potential of the construct. The purpose of this study was to look at 40 anatomic sawbone specimens of the ankle to determine the amount of talar surface contact area used by the screw fixation during arthrodesis. METHODS: Four groups were created to examine different techniques for arthrodesis. Simulated ankle arthrodeses were done using two- or three-screw fixation with 6.5-mm and 7.3-mm screws. Hardware was subsequently removed and the surface area used by the passing screws was measured. Total surface areas were calculated for each of the 40 specimens. RESULTS: The maximal surface area of the talus occupied by screws occurred when using three 7.3-mm screws. This configuration used 16% of the possible talar surface area available for arthrodesis. CONCLUSION: The use of additional screw fixation when performing an ankle arthrodesis does not sacrifice a major amount of the tibiotalar contact area and will most likely not affect the biologic environment needed to obtain fusion.

An analysis of outcome measures following the Broström-Gould procedure for chronic lateral ankle instability.

BACKGROUND: The Broström-Gould procedure is a commonly recommended operative treatment for chronic ankle instability. Using standardized physician-based outcome scores, the results of this procedure have been uniformly excellent. Current scoring systems, however, do not adequately evaluate mechanical or functional instability. Therefore, outcome data may suggest greater success than is justified. METHODS: A retrospective review was done of 73 patients who had isolated Broström-Gould repairs of the lateral ankle ligaments. The mean time to followup was 64 months. Both the AOFAS ankle-hindfoot score and the Short Form 36 (SF-36) were used to evaluate outcome. RESULTS: The overall American Orthopaedic Foot and Ankle Society (AOFAS) ankle-hindfoot score was 95 of 100 points. Despite that, 17% of patients in the study had functional instability of the ankle that was not reflected in the AOFAS score. The mean physical component score of the SF-36 was 84% and reflected the presence of functional instability. Low correlations were found between the AOFAS ankle-hindfoot score and the SF-36 score. CONCLUSIONS: The current study identified a deficiency in the AOFAS score in evaluating functional ankle stability after the Broström-Gould procedure. A more meaningful analysis of outcomes can be expected using the SF-36 score. The data suggest that greater attention must be paid to functional rehabilitation after ankle stabilization surgery to obtain optimal outcome.