Nonplanar Angle Research Articles

Invited Commentary

Invited Commentary

Changes in Mitral Valve Annular Geometry After Repair: Saddle-Shaped Versus Flat Annuloplasty Rings

Saddle-shaped annuloplasty rings are being increasingly used during mitral valve (MV) repair to conform the mitral annulus to a more nonplanar shape and possibly reduce leaflet stress. In this study utilizing three-dimensional transesophageal echocardiography we compared the effects of rigid flat rings with those of the saddle rings on the mitral annular geometry. Specifically we measured the changes in nonplanarity angle (NPA) before and after MV repair. Geometric analysis on 38 patients undergoing MV repair for myxomatous and ischemic mitral regurgitation with full flat rings (n = 18) and saddle rings (n = 18) were performed. The acquired three-dimensional volumetric data were analyzed utilizing the "Image Arena" software (TomTec GmBH, Munich, Germany). Specifically, the degree of change in the NPA was calculated and compared before and after repair for both types of rings. Both types of annuloplasty rings resulted in significant changes in the geometric structure of the MV after repair. However, saddle rings lead to a decrease in the NPA (7% for ischemic and 8% for myxomatous MV repairs) (ie, made the annulus more nonplanar), whereas flat rings increased the NPA (7.9% for ischemic and 11.8% for myxomatous MV repairs) (ie, made the annulus less nonplanar); p value 0.001 or less. Implantation of saddle-shaped rings during MV repair surgery is associated with augmentation of the nonplanar shape of the mitral annulus (ie, decreases NPA). This favorable change in the mitral annular geometry could possibly confer a structural advantage to MV repairs with the saddle rings.

Three-Dimensional Echocardiographic Assessment of Changes in Mitral Valve Geometry After Valve Repair

Application of annuloplasty rings during mitral valve (MV) repair has been shown to significantly change the mitral annular geometry. Until recently, a comprehensive two-dimensional echocardiographic evaluation of annular geometric changes was difficult owing to its nonplanar orientation. In this study, an analysis of the three-dimensional intraoperative transesophageal echocardiographic evaluation of the MV annulus is presented before and immediately after repair. We performed three-dimensional geometric analysis on 75 patients undergoing MV repair during coronary artery bypass graft surgery for mitral regurgitation or myxomatous mitral valve disease. Geometric analysis of the MV was performed before and immediately after valve repair with full rings and annuloplasty bands. The acquired three-dimensional volumetric data were analyzed in the operating room. Specific measurements included annular diameter, leaflet lengths, the nonplanarity angle, and the circularity index. Before and after repair data were compared. Complete echocardiographic assessment of the MV was feasible in 69 of 75 patients (92%) within 2 to 3 minutes of acquisition. Placement of full rings resulted in an increase in the nonplanarity angle or a less saddle shape of the native mitral annulus (137 +/- 14 versus 146 +/- 14; p = 0.002. By contrast, the nonplanarity angle did not change significantly after placement of partial rings. Mitral annular nonplanarity can be assessed in the operating room. Application of full annuloplasty rings resulted in the mitral annulus becoming more planar. Partial annuloplasty bands did not significantly change the nonplanarity angle. Neither of the two types of rings restored the native annular planarity.

3D geometry of a normal tricuspid annulus during systole: A comparison study with the mitral annulus using real-time 3D echocardiography

This study was done to explore the 3D geometry of the normal tricuspid annulus and compare it with the mitral annulus (MA), using real-time 3D echocardiography (RT3DE) and newly developed 3D computer software. Thirteen left ventricular (LV) and 13 right ventricular (RV) volumetric images were obtained using RT3DE from normal subjects. LV and RV volumetric data were segmented into 16 rotational apical planes (angle increment=11.25 degrees ) around the rotational axis from the apex through the center of two annuli, using newly developed 3D software (TomTec, Co., Munich, Germany). Two hinge points of the MA and the TA were traced in each plane during early and late systole. The MA and the TA were then automatically reconstructed with those 32 traced points. 3D surface (3DMAA, 3DTAA) and 2D projected areas (2DMAA, 2DTAA) of the annuli were calculated automatically as well, from those fitted data. For a comparison between the two annuli, the 3D and 2D area measurements of both annuli were corrected (c) according to the height of each patient (c2DMAA, c2DTAA, c3DMAA, and c3DTAA). Non-planarity of the annuli was estimated by their non-planar angles (MA: the angle between the anterior and posterior parts of the annulus; TA: the angle between the septal and free wall parts of the annulus). The TA revealed a less non-planar saddle shape than did the MA, which had a significantly wider non-planar angle (167.7+/-3.2 vs 145.5+/-6.1 degrees , p<0.01) and a round or oval appearance on the projected view. The c2DTAA was significantly larger than the c2DMAA during early systole (p<0.01). However, there was no significant difference between the c3DTAA and c3DMAA during early and late systole (p>0.01). We assessed the 3D geometry of the MA and the TA by 3D reconstruction using RT3DE and newly developed computer software. The TA had a less non-planar shape compared with the MA, with either a round or oval appearance on the projected view.

Acute Geometric Changes of the Mitral Annulus after Coronary Occlusion: A Real-Time 3D Echocardiographic Study

We performed real-time 3D echocardiography in sixteen sheep to compare acute geometric changes in the mitral annulus after left anterior descending coronary artery (LAD, n=8) ligation and those after left circumflex coronary artery (LCX, n=8) ligation. The mitral regurgitation (MR) was quantified by regurgitant volume (RV) using the proximal isovelocity surface area method. The mitral annulus was reconstructed through the hinge points of the annulus traced on 9 rotational apical planes (angle increment=20°). Mitral annular area (MAA) and the ratio of antero-posterior (AP) to commissure-commissure (CC) dimension of the annulus were calculated. Non-planar angle (NPA) representing non-planarity of the annulus was measured. After LCX occlusion, there were significant increases of the MAA during both early and late systole (p<0.01) with significant MR (RV: 30±14 mL), while there was neither a significant increase of MAA, nor a significant MR (RV: 4±5 mL) after LAD occlusion. AP/CC ratio (p<0.01) and NPA (p<0.01) also significantly increased after LCX occlusion during both early and late systole. The mitral annulus was significantly enlarged in the antero-posterior direction with significant decrease of non-planarity compared to LAD occlusion immediately after LCX occlusion.

Geometric changes of mitral annulus assessed by real-time 3-dimensional echocardiography: Becoming enlarged and less nonplanar in the anteroposterior direction during systole in proportion to global left ventricular systolic function

We sought to investigate the geometric changes of the mitral annulus during systole in relation to global left ventricular (LV) systolic function using real-time 3-dimensional (3D) echocardiography. Real-time 3D echocardiography was performed in 23 patients with global LV systolic dysfunction with ejection fraction of 37 +/- 19% and 9 control subjects with ejection fraction of 62 +/- 4%. Volumetric data were divided into 9 rotational apical planes (angle increment = 20 degrees) using 3D software. Nine rotational annular dimensions (ADs) were measured in all planes in early and late systole. Nonplanar angle (NPA) of the annulus between two vectors from two hinge points of the annulus in the anteroposterior plane to the center between two commissures in the commissure-commissure plane was measured during early and late systole. Fractional changes of NPA and AD were defined as changes in percentage during systole. NPA significantly increased during systole (early, 145 +/- 12 degrees; late, 160 +/- 9 degrees; P < .01). Among 9 ADs, 3 anteroposteriorly directed ADs showed the most prominent fractional increases during systole in all patients. Both fractional changes of NPA ( R 2 = 0.87, P < .01) and the anteroposterior dimension, AD 1 ( R 2 = 0.85, P < .01) showed significant positive correlation with global LV systolic function. Real-time 3D echocardiography demonstrated that saddle shape of the mitral annulus was getting enlarged and less nonplanar mainly in the anteroposterior direction during systole. These geometric changes were proportional to the global LV systolic function.

Influence of the orifice inlet angle on the velocity profile across a flow convergence region by color Doppler in vitro.

The converging flow field proximal to a leaking valve is determined among other things by the orifice inlet angle formed by the leaflets. Thus, the inlet angle affects the determination of regurgitant flow rate by the flow convergence method. Based on the hypothesis of spheric isovelocity surfaces, others had postulated that a local velocity within the flow convergence should change inversely proportional to changes in the three-dimensional inlet angle. This concept would allow correction of the determination of regurgitant flow for nonplanar orifice inlet angles. We tested this concept in vitro. In a flow model, the flow convergence region proximal to different orifice plates was imaged by color Doppler: funnel-shaped, planar and tip-shaped (inverted funnels) orifice plates, with circular orifices of 2- and 7-mm diameter. Velocity profiles across the flow convergence along the flow centerline were read from the color maps. As predicted, the local velocities were inversely related to the inlet angle, but only at the 2-mm funnel orifices, this effect was inversely proportional to the three-dimensional inlet angle (i.e., in agreement with the mentioned concept). However, for any 7-mm orifice and/or inlet angle of > 180 degrees, the effect of the inlet angle was considerably less than predicted by the aforementioned concept. With increasing orifice diameter and with decreasing distance to the orifice, the effect of the orifice inlet angle was reduced. The effect of the orifice inlet angle on the flow convergence region is modulated by orifice size and the distance to the orifice. Therefore, correction of flow estimates in proportion to the three-dimensional inlet angle will lead to considerable errors in most situations of clinical relevance, namely to massive overcorrection when analyzing velocities located close to wide orifices.

Theoretical and experimental study on the structure of 1-(5-X-fur-2-yl)-2-nitro-2-Y-ethylenes

The molecular structures of eight 1-(5-X-fur-2-yl)-2-nitro-2-Y-ethylenes are studied by using three semiempirical methods and NMR spectroscopy. Concerning geometries, AM1 and PM3 methods predict planar structures for the furyl-2-nitroethylene skeleton, whereas MNDO predicts nonplanar dihedral angles for the exocyclic double bond respect to furan ring and nitro group. Distortions in the furyl-2-nitroethylene framework predicted by MNDO method are especially large in molecules with bulky substituents in the double bond. There are significant differences in the results obtained by the three methods for the prediction of the most stable conformation. AM1 always coincides with 1H NMR results in predicting the conformational preferences around the single bond separating furan ring from exocyclic double bond. MNDO method sometimes coincides with the experiment in predicting the most stable conformation. However, this coincidence depends on the degree of distortion of planar structures that this method predicts for these compounds. The PM3 method, in spite of its correct prediction of planarity for such chemicals, is always in disagreement with the most stable conformation predicted by the 1H NMR experiment.

Energy-Minimizing Structures For Low-Angle Grain Boundaries in Zinc

Dislocation models for low angle grain boundaries have been widely known since 1950 and the proposed structures have been extensively confirmed by transmission electron microscopy, although most studies have been confined to the cubic metals. A generalization of the earlier geometrical work, known as the 0-lattice, represents the state of the art in predicting grain boundary structures on a purely geometrical basis, but the analysis is always predicated on the assumption that grain boundaries are basically planar defects. In some work on precipitation in the Al-Zn-Mg system Vanderwalker and Vander Sande observed non-planar low angle grain boundaries, although these may have been the results of pinning by embryonic precipitates or other solute interaction effects: we have observed non-planar boundaries in pure zinc where no such pinning effects are available to explain the puckering.

On the stability and structure of β-fluoro-substituted radical anions of acetamides. An EPR study at 3 K

An EPR study at 3 K of X-ray irradiated monofluoroacetamide does not reveal a radical anion species, despite the fact that the radical anion in trifluoroacetamide is stable at 77 K. This difference in stability has been found to be dependent on the conformation of the -CF 3 group (eclipsed) versus the -CFH 2 group (staggered). The eclipsed conformation permits effective σ-π hyperconjugation in stabilizing the radical anion. An INDO calculation of CF 3CONH 2 − suggests that the radical site is pyramidal rather than planar with a non-planar angle of 32° and a dihedral angle for the eclipsed fluorine, relative to the nearly π-like orbital, of 30°.

Improvement in the design of preshaped coronary catheters

AbstractBecause of the slanted relationship between the origins of coronary arteries and the adjacent sinus, a nonplanar angle of 45 degrees is proposed to be incorporated In the distal part of the preshaped coronary catheters that need the aortic valve for direction toward the coronary ostla. This angulation will Improve the catheter function and reduce the risk of coronary angiography.

INDO study of the anion radicals of acetic acid and acetamide. Nonplanarity and barriers to methyl group rotation

The anion radicals of acetic acid and acetatamide were investigated by using the INDO method. Energy calculations suggest that the radical RC(X/sub 1/)(X/sub 2/) (with R = CH/sub 3/; X/sub 1/ = O/sup -/, OH; X/sub 2/ = OH and NH/sub 2/ is pyramidal rather than planar with a nonplanar angle phi = 27/sup 0/ in the case of R-C(O/sup -/)(OH). A comparison of the calculated and experimental ..beta..-proton and /sup 13/C hyperfine splittings (hfs) suggests a slightly different value for phi (=35/sup 0/). This latter value is in reasonable agreement with the value of 40/sup 0/ calculated previously from experiment. INDO calculations for the remaining radicals give similar values for phi. For nonplanar radical structures, it was found that the angular dependence of the INDO-calulated ..beta..-proton hfs did not obey a simple cosine square rule. Instead the calculated splittings have been fit by using the relation ..cap alpha../sub ..beta../sup H/ = B/sub 1rho//sup ..pi../ cos theta + B/sub 2rho//sup ..pi../ theta with B/sub 1rho//sup ..pi../ = 8.8 and B/sub 2rho//sup ..pi../ = 28.0 G for the acetic radical. The threefold barrier height (V/sub 3/) as obtained from the INDO calculations was found to increase monotonically with phi. This suggestsmore » that the relatively high activation energies (>2.5 kcal/mol) reported for acetic acid and acetamide anions in our previous work are therefore a consequence of pyramidal geometry at ..cap alpha.. carbon. In light of these results, our previously reported threefold potential barrier heights for CH/sub 3/ rotation in acetic acid and acetamide radicals, which were analyzed by using a simple cosine square relation, have been reevaluated. The present analysis of our previous experimental data, including nonplanarity, gives a better fit yielding activation energy parameters as 2.4 to 2.6 kcal/mol for these radicals. These values are slightly lower than those values previously reported (2.7 to 3.1 kcal/mol), where the effect of nonplanarity on the ..beta..-proton splittings was not considered.« less

A vibronic analysis of the [formula omitted], [formula omitted] electronic transition in thiophosgene

The visible asborption spectrum of thiophosgene has been recorded under conditions of high resolution and long path length and has been assigned as an π ∗ ← n, a ̃ 3A 2 ← X ̃ 1A 1 electronic transition. Progressions in ν 1′, ν 2′, ν 3′, ν 4′, ν 1″, ν 3″, and ν 4″ have been identified in the spectrum and have been analyzed in terms of vibronic transitions between a planar ground state and a nonplanar excited state. A barrier height of 726 cm −1 and a nonplanar equilibrium angle of 32° were obtained for the upper state from a fit of the energy levels of a Lorentzian function to the observed levels in ν 4. The origin of the system was assigned to a band at 17 492 cm −1. The oscillator strength of the singlet-triplet system relative to the corresponding singlet-singlet system was obtained by comparing the intensities of selected singlet and triplet bands in their region of spectral overlap. The high intensity, f = 2 × 10 −5, observed for the transition results from a spin-orbit coupling between the a ̃ 3 A 2(π ∗, n) state and the 1A 1(π ∗,π) state. This mechanism predicts that the major bands in the triplet system should be polarized in the direction of the thiocarbonyl bond.

Analysis of the 2973-Å Absorption System of Phosgene

The near-ultraviolet absorption of phosgene has been assigned to a π* ← n, 1A2 ← 1A1, electronic transition from vapor-phase spectra recorded under conditions of high resolution and low temperature. Progressions in ν1′, ν2′, ν3′, ν4′, and ν4″ have been identified in the spectrum and have been analyzed in terms of vibronic transitions between a planar ground and a nonplanar excited state. A barrier height of 3170 cm−1 and a nonplanar equilibrium angle of 32.5° were calculated for the upper state from a fit of the energy levels of a Lorentzian–quadratic potential function to the observed levels of ν4. The false origin, 401, of the spectrum has been assigned to the band at 33 631 cm−1. An oscillator strength of f = 1.04 × 10−3 has been obtained for the A21 ← A11 transition.

The 1A 2- 1A 1 transition in thiocarbonyl difluoride at 23477.1 cm −1

Bands of the 1A 2 ← 1A 1 system of F 2CS have been photographed in absorption under conditions of moderately high resolution and at −77°C under low resolution. The spectra have been analyzed in terms of ν 1′, ν 2′, ν 3′, ν 4′, and ν 4″. A barrier height of 3100–3400 cm −1 and a nonplanar equilibrium angle of 30.5–34.1° is calculated for the 1 A 2 state.

General practitioners in hospital.

An acute general hospital of 68 beds at Tamworth, a Midland town of 50,000 people, is staffed by general practitioners for both inpatient and casualty work. During the period 1967-8 there were 889 general practitioner admissions to the hospital for intermediate surgical and medical care, the average length of stay being 6.3 days and the average cost per case pound44.3. Of these patients 96 were transferred to other hospitals. The patients, doctors, and standard of medical care have benefited from this kind of service. A "satellite" hospital of this type therefore has an important role in the community for carefully selected types of cases.