Repeat coronary angioplasty.

The potential of repeat percutaneous transluminal coronary angioplasty as a mode of therapy for recurrence of stenosis after initially successful angioplasty was examined on the basis of data on all 514 patients with successful angioplasty at Emory University before April 1982. Recurrence was found in 171 (33%) of the 514 patients. Repeat angioplasty was attempted in 95 patients with a significantly higher primary success rate (97 versus 85%, p less than 0.001) and a lower complication rate (8 versus 15%, p less than 0.10) than those of initial angioplasty. Follow-up documentation was available in all 92 patients with successful repeat angioplasty. A second recurrence of stenosis was found in 26% (24 of 92). A third angioplasty was performed in seven patients; six procedures were successful and there have been no recurrences of stenosis. Repeat coronary angioplasty provides a means to treat recurrence of stenosis. It proved to be very successful and safe and yielded good long-term results. It also increased the percent of patients with documented lasting success after angioplasty from 63 to 78%.

Quantitative Analysis of the Structure and Function of the Marsupial Gills of the Freshwater Mussel Anodonta cataracta.

Gravid females of Anodonta cataracta incubate shelled larvae (glochidia) in the water tubes of their outer demibranchs which, in turn, undergo extensive morphological changes in becoming marsupia. In this study, the brooding gills of A. cataracta were compared to the non-marsupial demibranchs of females and the gills of males. Scanning electron microscopy and video enhanced light microscopy were used, and computer-generated 3D-reconstructions of gill tissue were also prepared from light micrographs of serial histological sections. Marsupial gills possess a tripartite system of water tubes that are not present in non-marsupial gills and include two secondary water channels and one primary water tube (brood chamber) containing glochidia. The lateral dimension (width) of water tubes of the marsupial gills increases nearly 30-fold during brooding, but the anterior-posterior length of the tubes is unaffected. No apparent changes in the morphology of the non-marsupial inner demibranchs were observed. Glochidia are effectively isolated from the surrounding water by secondary septa, positioned between the primary and secondary water tubes. Secondary septa are present during brooding and immediately after larval release, but are not in evidence among females during non-reproductive periods. Quantification by 3D reconstruction revealed that, although secondary water tubes are smaller than the primary water tubes of non-marsupial gills and non-gravid marsupial gills, collectively they provide about the same cross-sectional area as the primary water tubes that are lost to water transport by occlusion with glochidia. However, considering the fluid dynamics of the ciliary gill pump, net water transport through the lumina of marsupial gills is reduced to only about 16% of that in non-gravid marsupial demibranchs.

Migratory Behavior of Ovigerous Blue Crabs Callinectes sapidus: Evidence for Selective Tidal-Stream Transport.

In the late summer and early fall, newly inseminated female blue crabs (Callinectes sapidus) leave low-salinity areas of estuaries and migrate seaward to spawn near the entrance. We tested the hypothesis that migration of female C. sapidus to spawning grounds is facilitated by selective tidal-stream transport (STST). We monitored the swimming direction of adult crabs from a stationary platform located about 1 km inside the entrance to the Newport River Estuary (Beaufort, North Carolina). Swimming activity near the surface occurred primarily at night and most crabs avoided swimming against tidal currents. Eighty-one percent of the crabs observed moving down-estuary toward the inlet during ebb tide were ovigerous females. Of the 36 gravid females captured traveling in ebb currents, 97% possessed dark egg masses containing late-stage embryos. Conversely, nearly all (98%) adult crabs observed traveling in flood currents lacked egg masses, and all the females captured while migrating up-estuary exhibited signs of recent spawning. These observations indicate that ovigerous blue crabs use ebb-tide transport to migrate seaward to spawn and flood-tide transport to reenter the estuary shortly after larval release.

Should coronary arteries with less than 60% diameter stenosis be treated by angioplasty?

We evaluated all patients receiving percutaneous transluminal coronary angioplasty (PTCA) in the past year for mild stenosis (60% or less diameter narrowing, n = 64, group 1) and compared them with a random sample of 330 patients with greater than 60% stenosis (n = 66, group 2) treated during the same year. The degree of coronary stenosis before PTCA was 52 +/- 7% (mean +/- SD) in group 1 and 79 +/- 11% in group 2. The primary success rate was 90% (58 of 64 patients) in group 1 vs 86% (57 of 66 patients) in group 2. The incidence of complications requiring coronary surgery after PTCA failed was similar in both groups (3 of 64 in group 1, 4 of 66 in group 2), but there were four occurrences of myocardial infarction in group 1 and none in group 2 (p less than .05). Recurrence of stenosis was judged on the basis of objective data, 76% of which were angiographic data, in 97% of the patients with primary success. At a mean interval of 5 months with a mean follow-up period of 7 months, 17 of 58 patients (29%) with primary success in group 1 and 24 of 57 patients (42%) in group 2 developed restenosis. In group 1, restenosis was markedly more severe (73 +/- 15%) than initial stenosis (p less than .005), which was not the case in group 2. In conclusion, PTCA in mild stenosis has favorable primary and long-term results, yet carries the risk of myocardial infarction and emergency operation and may, in some cases, even accelerate the disease process.