Higher oesophageal temperature at rest and during exercise in humans with patent foramen ovale.

Respiratory system cooling occurs via convective and evaporative heat loss, so right-to-left shunted blood flow through a patent foramen ovale (PFO) would not be cooled. Accordingly, we hypothesized that PFO+ subjects would have a higher core temperature than PFO- subjects due, in part, to absence of respiratory system cooling of the shunted blood and that this effect would be dependent upon the estimated PFO size and inspired air temperature. Subjects were screened for the presence and size of a PFO using saline contrast echocardiography. Thirty well-matched males (15 PFO-, 8 large PFO+, 7 small PFO+) completed cycle ergometer exercise trials on three separate days. During Trial 1, subjects completed a V̇(O2max) test. For Trials 2 and 3, randomized, subjects completed four 2.5 min stages at 25, 50, 75 and 90% of the maximum workload achieved during Trial 1, breathing either ambient air (20.6 ± 1.0°C) or cold air (1.9 ± 3.5°C). PFO+ subjects had a higher oesophageal temperature (T(oesoph)) (P < 0.05) than PFO- subjects on Trial 1. During exercise breathing cold and dry air, PFO+ subjects achieved a higher T(oesoph) than PFO- subjects (P < 0.05). Subjects with a large PFO, but not those with a small PFO, had a higher T(oesoph) than PFO- subjects (P < 0.05) during Trial 1 and increased T(oesoph) breathing cold and dry air. These data suggest that the presence and size of a PFO are associated with T(oesoph) in healthy humans but this is explained only partially by absence of respiratory system cooling of shunted blood.

Histamine-receptor blockade reduces blood flow but not muscle glucose uptake during postexercise recovery in humans.

Skeletal muscle vasodilatation persists following a single bout of exercise and can potentially influence glucose uptake by recovering muscle. To investigate whether blood flow is a rate-limiting component in postexercise muscle glucose uptake, we tested the hypothesis that oral ingestion of H(1)- and H(2)-receptor antagonists, known to attenuate the sustained postexercise vasodilatation, would reduce leg glucose uptake after a bout of cycling. Healthy, recreationally active subjects (n = 8) exercised for 1 h at 60% of peak oxygen consumption on each of two days, with (blockade) and without (control) histamine-receptor antagonism. For 2 h of recovery following exercise, arteriovenous glucose differences were assessed from the radial artery and femoral vein, and leg blood flow was measured using Doppler ultrasonography on the common femoral artery. Femoral blood flow following exercise was 65.4 ± 16.4 ml min(-1) lower on the blockade day compared with the control day (P < 0.05). Likewise, glucose delivery was 0.177 ± 0.045 mmol min(-1) lower with blockade (P < 0.05). However, histamine-receptor antagonism produced no consistent effect on leg glucose uptake following exercise, due to high interindividual variability. In conclusion, while oral ingestion of H(1)- and H(2)-receptor antagonists alters postexercise recovery by attenuating vasodilatation, leg glucose uptake is not universally affected in recreationally active individuals.

Drug-eluting stents for coronary bifurcations: insights into the crush technique.

Sirolimus-eluting stents appear to reduce substantially restenosis following percutaneous coronary bifurcation intervention. The crush technique was devised to reduce restenosis further by improving stent and drug application to the side-branch ostium. We aimed to investigate the performance of drug-eluting stent (DES) platforms with the crush technique, to identify deployment pitfalls, and to clarify the best deployment strategies. Each stage of the crush technique was photographed in a bifurcation phantom. Simultaneous side- and main-branch dilatation (kissing balloons) fully expanded the stent in the side-branch ostium, widened the gaps between stent struts covering the side branch, and eliminated main-branch distortion. With side branches angled at > 70 degrees , sequential (side- then main-branch) inflations may be needed to achieve best results. Postdilatation of the main branch with a balloon of narrower diameter than the deploying balloon caused main-branch stent distortion. These principles applied to all the bifurcation strategies and stent designs tested.

Percutaneous placement of a low-profile stent-graft device for aortic dissections.

PURPOSE: The use of stent-grafts has proved to be safe and effective treatment for complicated aortic dissections but usually requires surgical cutdown to accommodate large-profile devices. Preliminary results of the use of a low-profile design that allows percutaneous access are presented. MATERIALS AND METHODS: Fifteen patients with aortic dissection were treated with use of a low-profile stent-graft. Dissection types included Stanford type A (n = 6) and type B (n = 9). The procedures were performed with use of Perclose devices to achieve hemostasis. The stent-graft device was composed of Gianturco stents connected with longitudinal wire struts covered with radially expanded polytetrafluoroethylene. The delivery sheath sizes were 14-20 F. RESULTS: In 87% of patients (13 of 15), the entry tear was excluded completely. Successful femoral closures were achieved in 93% of patients (14 of 15) with use of the suture-mediated devices. In 7% of patients (one of 15), surgical closure of the femoral arteries was required. The rate of pseudoaneurysm occurrence was 7% (one of 15). Hospitalization ranged from 1 to 30 days with a mean duration of 6.5 days. The 30-day mortality rate was 27% (four of 15). In the remaining 11 patients, entry tear sites were excluded and, on follow-up CT examinations, there was thrombosis and retraction of the false lumen and enlargement of the true lumen. CONCLUSION: Preliminary results of the use of a low-profile stent-graft device to treat aortic dissections show that, in most patients, it can be used with a suture-mediated device without surgical exposure of the common femoral artery.