Is small cusp size a limitation for aortic valve repair?†

OBJECTIVES We sought to investigate cusp size limitations for valve repair in patients with aortic regurgitation (AR). METHODS Preoperative computed tomography was performed in 105 patients. Cusp geometric height (GH) and annulus size were measured. Mean patient age was 60.7 ± 13.7 years. Mean GH of 3 cusps was used in the analysis. Annulus cusp mismatch was graded using predicted coaptation length. Patients were categorized by mean GH into group S (GH <16 mm; n = 35) or L (GH ≥16 mm; n = 70). RESULTS Preoperative mean GH was 17.1 ± 2.3 mm. GH and body height were significantly correlated (r = 0.61). Intraoperative mean GH (18.8 ± 2.2 mm) was larger than preoperative mean GH (P < 0.0001). However, postoperative (17.1 ± 2.0 mm) and preoperative mean GH did not differ. Moderate AR was not present on predischarge echocardiography. Mild AR was observed in 51% and 17% of patients in groups S and L, respectively (P = 0.006). During follow-up, moderate or severe AR was observed in 14% and 10% of patients in groups S and L, respectively (P = 0.74). Two patients in group S required reoperation for a regurgitant valve. Twenty (83%) and 15 (21%) patients in groups S and L, respectively, had severe annulus cusp mismatch before surgery. Annulus cusp mismatch resolved in most patients in group L postoperatively, whereas more than half the patients in group S still had severe mismatch. CONCLUSIONS Small cusp size (GH <16 mm) is not necessarily a contraindication in aortic valve repair. However, most patients in this group had annulus cusp mismatch. Root replacement or secure annulus plication is mandatory to correct annulus cusp mismatch.

Conodonts, radiolarians and ostracodes in the Permian E-Lert Formation, Loei Fold Belt, Indochina Terrane, Thailand

Conodonts are rare in the Permian carbonates of Indochina but abundant conodonts and ostracodes have been obtained from turbiditic limestones of the Permian E-Lert Formation along with radiolarians from overlying cherts, all deposited on the margins of the interplatform Nam Duk Basin. Conodonts are typically Tethyan and are very similar to faunas from Sicily and south China. They includeHindeodus gulloides,Pseudohindeodus oertlii,Mesogondolella siciliensisandSweetognathus subsymmetricuswhich indicate a probable late Kungurian – Roadian age range although a Wordian age cannot be excluded.M. siciliensis, which has a high blade and small cusp supposedly typical of warm-water conodonts, is found in deep (<500 m) carbonate turbidites in Thailand and in very deep deposits in Oman and Sicily, but generally not in shallow-water tropical limestones in Thailand, Oman and Sicily. The chert sequence yields a radiolarian fauna consisting of 11 confidently assigned species of whichAlbaillella asymmetrica,A. sinuata,Tormentum delicatumandLatentifistula patagilateratasuggest a latest Kungurian – earliest Roadian age, deposited at a palaeodepth ofc.500 m. Ostracodes consist of 16 genera and 23 species which belong toShivaella,Paraberounella,Carinaknightina,Paraparchites,Shemonaella,Bairdia,Cryptobairdia,Bairdiacypris?,Spinocypris,Pseudobythocypris,Baschkirina,Microcheilinella,Basslerella,PolycopeandCyathus, of whichShivaella elertensis sp. nov.Chitnarin is newly described. The ostracodes are a palaeoecologically mixed assemblage comprising external platform and deeper-water forms, suggesting that the limestone turbidites were deposited on the proximal part of the slope.Cyathus caperataandC. ellipticashow a palaeobiogeographic link to south China.

THE RELATIONS OF TEMPERATURE TO THE POTASSIUM EFFECT AND THE BIOELECTRIC POTENTIAL OF VALONIA

The effect of temperature upon the bioelectric potential across the protoplasm of impaled Valonia cells is described. Over the ordinary tolerated range, the P.D. is lowest around 25°C., rising both toward 15° and 35°. The time curves are characteristic also. The magnitude of the temperature effect can be controlled by changing the KCl content of the sea water (normally 0.012 M): the magnitude is greatly reduced at 0.006 M KCl, enhanced at 0.024 M, and greatly exaggerated at 0.1 M KCl. Conversely, temperature controls the magnitude of the potassium effect, which is smallest at 25°, with a cusped time course. It is increased, with a smoothly rising course, at 15°, and considerably enhanced, with only a small cusp, at 35°. A temporary "alteration" of the protoplasmic surface by the potassium is suggested to account for the time courses. This alteration does not occur at 15°; the protoplasm recovers only slowly and incompletely at 25°, but rapidly at 35°, in such fashion as to make the P.D. more negative than at 15°. This would account for the temperature effects observed in ordinary sea water.