Radiological site characterizations: gamma surveys, gamma/226Ra correlations, and related spatial analysis techniques.

Radiological surveys of a uranium mill site in Colorado and several proposed uranium recovery sites in Wyoming were conducted in 2006 and 2007. Advancements in Global Positioning System (GPS)-based gamma scanning systems combined with gamma/Ra correlations and Geographic Information Systems (GIS)-based spatial analysis techniques produced comprehensive and detailed characterizations of the spatial distributions of gamma exposure rates and Ra concentrations in surface soils across extensive study areas. Aside from limitations on gamma-based estimates of soil Ra related to soil heterogeneity or gamma shine effects, soil sampling results to date show good general agreement between estimated and measured values. Spatial characterization aspects of the survey approach are clearly more effective than conventional grid sampling methods, particularly for such large sites. Example project applications, data collection and analysis methods, challenges encountered, and resulting mapped estimates of various aspects of these radiological parameters are presented.

The Quebec Heart Institute: 50 years of excellence in cardiology.

The Quebec Heart Institute was established in 1957 at the Laval Hospital in Sainte-Foy, Quebec. Since then, clinical and research activities have made this Institute one of the largest tertiary care cardiology centres in Canada. With its vast catchment area of more than 3,000,000 people, the Institute has developed a strong collaboration with referral physicians centred on clinical, teaching and research interests. The Institute pioneered several aspects of cardiac surgery, invasive cardiology, echocardiography, basic research and, more recently, a network of researchers and clinicians working in the field of 'metabolic cardiology'. The first 50 years of the Quebec Heart Institute are depicted in this overview, which will also introduce this special supplement to The Canadian Journal of Cardiology.

Impact of implant technique following freestyle stentless aortic valve replacement.

BACKGROUND: Stentless aortic bioprostheses have excellent hemodynamics and clinical outcomes. The purpose of the present study was to determine whether implant technique of the Freestyle aortic root bioprosthesis impacts clinical outcomes or hemodynamic performance. METHODS: The long-term multicenter study of the Freestyle stentless aortic bioprosthesis includes 500 consecutive patients implanted using the subcoronary and 162 using the full root technique. Clinical outcomes and echocardiographic hemodynamics were compared through 5 years. RESULTS: There were no differences between groups in time to death, valve-related death, or reoperation. The incidence of operative death was higher in the full root than in the subcoronary group (odds ratio 3.97, p = 0.001). Patients in the subcoronary group were more likely to have New York Heart Association functional class III or IV symptoms at 1 year (1.7% versus 0%, p = 0.04) and 5 years postoperatively (4.4% versus 0%, p = 0.02). Mean gradient was lower (p = 0.0004) and effective orifice area larger (p = 0.04) in the full root group. Left ventricular mass index decreased in both groups. The preponderance of patients in both groups had no or trivial aortic regurgitation through 5 years. CONCLUSIONS: Full root implantation of the Freestyle stentless aortic bioprosthesis was associated with higher operative mortality, but somewhat better hemodynamics, functional class, and freedom from aortic regurgitation. Higher operative mortality argues against the empiric replacement of the ascending aorta in the absence of aortic root pathology. In appropriately selected patients, both implant techniques are viable alternatives for valve implantation.

Hemodynamic performance at rest and during exercise after aortic valve replacement: comparison of pulmonary autografts versus aortic homografts.

BACKGROUND: The Ross procedure and aortic homografts have both been shown to have superior hemodynamic performance after valve replacement, but there have been few comparisons. METHODS: Sequential Doppler echocardiograms were performed up to 5 years after aortic valve replacement in 132 patients with the Ross procedure and 111 patients with an aortic homograft (AH). Measurements included assessment of valvular regurgitation and calculations of valve effective orifice area (EOA) and mean transvalvular gradients; the same measurements were also performed at the level of the pulmonary homograft in the Ross patients as well as during maximum exercise in 20 Ross patients and 14 AH patients. RESULTS: Aortic valve hemodynamics were stable during follow-up for both procedures and values at 1 year showed larger indexed EOAs (1.77+/-0.45 versus 1.42+/-0.35 cm(2)/m(2), P<0.001) and lower gradients (2+/-3 versus 4+/-3 mm Hg) for the Ross procedure; similar findings were also observed during exercise (1.99+/-0.44 versus 1.36+/-0.39 cm(2)/m(2), P<0.001 and 7+/-3 versus 17+/-11 mm Hg). Prevalence and severity of aortic regurgitation were low in both groups, although 4 patients (1 Ross, 3 AH) underwent a second operation for this reason. Also, various degrees of pulmonary homograft stenosis were found in 20% of Ross patients, 4 of which underwent a second operation. CONCLUSION: Both procedures provide continued excellent hemodynamics of the aortic valve. The Ross procedure has a slight advantage, but this is somewhat counterbalanced by the deterioration of the pulmonary homograft in up to 20% of patients. Further studies aimed at clarifying longer-term outcomes as well as preventing pulmonary homograft stenosis with the Ross operation are clearly needed.

Pacemaker contact sensitivity: case report and review of the literature.

Pacemaker contact sensitivity is a rare condition. Less than 25 reports of pacemaker skin reaction have been described over the past 30 years. This report describes one patient who developed contact dermatitis after implantation of two subsequent pacemakers. The diagnosis was made with skin patch tests that were positive to polyurethane 75D and polysulfone beige, two of the pacemaker and connector components. Review of the literature and general guidelines for the management of this unusual condition is depicted in this report.