Biomedical subjects

Douglas Wirthlin

Publications and source records attributed to Douglas Wirthlin.

3 recordsLinked to original sources

PubMed2005

Physician supply, treatment, and amputation rates for peripheral arterial disease.

OBJECTIVE: To test whether the availability of vascular surgeons and interventional radiologists in a region affects revascularization and amputation rates for patients with peripheral arterial disease (PAD). METHODS: We identified all patients with PAD in the Medicare claims database in 1994 and tracked their claims through 1999. We aggregated risk-adjusted data on the 143,202 patients who survived through 1999 by Hospital Referral Region and merged this data with information on local physician supply and other regional characteristics. Instrumental variables analysis was used to account for unobserved illness severity. Main outcome measures were risk-adjusted rates of lower extremity bypass surgery, angioplasty, and amputation by region. RESULTS: Increasing vascular surgeon supply in a region by approximately one standard deviation (.30/10,000 Medicare beneficiaries) is associated with a 0.9 percentage point increase in bypass surgery rates and a 1.6 percentage point reduction in amputation rates. We find weaker evidence that greater availability of interventional radiologists increases angioplasty rates and reduces amputation rates. Factors reflecting regional attractiveness, such as the rating of a region based on climate, recreation, crime, and other attributes, were strong independent predictors of the number of vascular surgeons and interventional radiologists in an area. CONCLUSIONS: Availability of specialists affects outcomes for PAD patients. Regional variability in specialists who treat PAD is influenced by factors other than regional medical needs. Policies aimed at increasing the supply of vascular surgeons and interventional radiologists and their provision of bypass surgery in underserved areas may help to reduce regional disparities in amputation.

Aged↗

PubMed2002

Overexpression of a constitutively active protein kinase G mutant reduces neointima formation and in-stent restenosis.

BACKGROUND: Neointima formation after arterial injury is associated with reduced vascular cyclic guanosine monophosphate (cGMP) and cGMP-dependent protein kinase (PKG), a major cGMP effector in vascular smooth muscle. We tested the effect of PKG overexpression on the neointimal response to vascular injury. Methods and Results- Infection of cultured rat aortic smooth muscle cells (RASMCs) with an adenoviral vector specifying a cGMP-independent, constitutively active PKG mutant (AdPKGcat) reduced serum-induced migration by 33% and increased serum-deprivation-induced apoptosis 2-fold (P<0.05 for both). Infection with wild-type PKG (AdPKG), in the absence of cGMP, did not affect migration or apoptosis. Two weeks after balloon-injured rat carotid arteries were infected with 1x 10(10) pfu AdPKGcat (n=12), AdPKG (n=8), or a control adenovirus (n=8), intima-to-media ratio was less in AdPKGcat-infected arteries than in AdPKG- or control adenovirus-infected vessels (0.26+/-0.06 versus 0.61+/-0.12 and 0.70+/-0.12, respectively, P<0.05 for both). Two weeks after intramural administration of 1.75x10(10) pfu AdPKGcat (n=8) or a control adenovirus (n=8) into porcine coronary arteries with in-stent restenosis, luminal diameter was greater in AdPKGcat-infected arteries than in control adenovirus-infected vessels (2.32+/-0.16 versus 1.81+/-0.13 mm, P=0.028), associated with reduced neointimal area (3.30+/-0.24 versus 4.15+/-0.13 mm(2), P=0.008), neointima-to-vessel area ratio (0.42+/-0.05 versus 0.58+/-0.04, P<0.05), and percent stenosis (45+/-6% versus 70+/-4%, P<0.05). CONCLUSIONS: Expression of a constitutively active PKG reduces neointima formation after balloon injury in rats and reduces coronary in-stent restenosis in pigs. PKGcat gene transfer may be a promising strategy for vasculoproliferative disorders.

Adenoviridae↗

PubMedDate not supplied

Vascular complications arising from maldeployed stents.

The authors present 6 unusual vascular complications secondary to maldeployed or undeployed vascular stents. They retrospectively reviewed patients referred for complications of vascular stent placement from September 1998 to March 1999. Information on patient history was obtained from a computerized database and clinical document file. Radiographic information was obtained from arteriograms, ultrasound, and computed tomography imaging. Case 1 describes an undeployed stent in the superior mesenteric artery with subsequent thrombosis in addition to celiac occlusion secondary to attempted balloon angioplasty. Case 2 refers to a malpositioned stent placed in the aortic arch and proximal left common carotid artery. Case 3 involves an undeployed coronary stent that migrated to the right distal posterior tibial artery, causing vascular occlusion and chronic pain. In Case 4, an attempted stent placement into the left iliac artery resulted in an undeployed stent lodged across the aortic bifurcation. Case 5 illustrates a partially deployed stent occluding the left renal artery that was unamenable to further angioplasty. Case 6 demonstrates arterial dissection with a pseudoaneurysm following stent placement for right subclavian stenosis. Five patients required operative intervention. Increased use of stents may escalate the number of complications requiring operative intervention. Foreign bodies can migrate distally and potentiate thrombotic occlusion of vessels. Caution must be used not only at the time of deployment but also in the follow-up period. Continued surveillance becomes important after vascular stent placement.

Aged↗