Insights From the International Registry of Acute Aortic Dissection: A 20-Year Experience of Collaborative Clinical Research.

Acute aortic dissection (AAD) is a life-threatening condition associated with high morbidity and mortality rates, and it remains a challenge to diagnose and treat. The International Registry of Acute Aortic Dissection was established in 1996 with the mission to raise awareness of this condition and provide insights to guide diagnosis and treatment. Since then, >7300 cases have been included from >51 sites in 12 countries. Although presenting symptoms and physical findings have not changed significantly over this period, the use of computed tomography in the diagnosis has increased, and more patients are managed with interventional procedures: surgery in type A AAD and endovascular therapy in type B AAD; with these changes in care, there has been a significant decrease in overall in-hospital mortality in type A AAD but not in type B AAD. Herein, we summarized the key lessons learned from this international registry of patients with AAD over the past 20 years.

Four-component fluorescence of trans-1,2-di(1-methyl-2-naphthyl)ethene at 77 K in glassy media. Conformational subtleties revealed.

The vibronic structure of the fluorescence spectrum of trans-1,2-di(1-methyl-2-naphthyl)ethene (t-1,1) in methylcyclohexane (MCH) solution at room temperature was expected to become better defined upon cooling of the solution to 77 K. Instead, a broad, λexc-dependent fluorescence spectrum was observed in the glassy medium. Vibronically structured t-1,1 fluorescence spectra were obtained in the MCH glass only upon irradiation at the long-λ onset of the absorption spectrum. The application of singular value decomposition with self-modeling on the fluorescence spectral matrices of t-1,1 allowed their resolution into major and minor pairs of vibronically structured spectra that are assigned to two structural modifications of each of two relative orientations of the 1-methyl-2-naphthyl moieties. The difference between the two structures in each pair lies in the direction of rotation of each naphthyl group away from the plane of the olefinic bond. A complex but different conformer distribution is also responsible for the fluorescence spectra of t-1,1 in 5:5:2 (v/v/v) diethyl ether/isopentane/ethyl alcohol (EPA) glass at 77 K. The conformer distributions are also sensitive to the rate of cooling used in glass formation. Conformer distributions based on predicted small energy differences from gas-phase theoretical calculations are of little value when applied to volume-constraining media. The photophysical and photochemical properties of the analogues of the other two conformers of trans-1,2-di(2-naphthyl)ethene, trans-1-(1-methyl-2-naphthyl)-2-(3-methyl-2-naphthyl)ethene (t-1,3) and trans-1,2-di(3-methyl-2-naphthyl)ethene (t-3,3), were determined in solution. However, it is the calculated geometries and energy differences of the t-1,1 conformers [DFT using B3LYP/6-311+G(d,p)] that are essential guides to the interpretation of the experimental results.

Photoisomerization of cis-1-(3-methyl-2-naphthyl)-2-phenylethene in glassy methylcyclohexane at 77 K.

The cis-trans photoisomerizations of cis-1-(3-methyl-2-naphthyl)-2-phenylethene (c-3-MPE) was studied in methylcyclohexane (MCH) glass at 77 K. The fluorescence spectra of c- and t-3-MPE are excitation wavelength (λ(exc)) independent because the steric requirement of the methyl group restricts the conformational space of each isomer to a single conformer. Photocyclization, the dominant reaction pathway of c-3-MPE in solution, is entirely suppressed in MCH glass at 77 K. The only reaction on 313 nm irradiation of c-3-MPE in MCH glass is cis-trans isomerization. As the reaction progresses, the structureless fluorescence of c-3-MPE is replaced by the vibronically resolved fluorescence of the stable conformer of the trans isomer. The results are consistent with photoisomerization by the conventional one bond twist (OBT) pathway. Previously reported results on the photoisomerization of cis-1-(2-naphthyl)-2-(o-tolyl)ethene (c-NTE) are reinterpreted. Calculated geometries and energy differences for c- and t-3-MPE and c- and t-NTE [DFT using B3LYP/6-311+G(d,p)] are consistent with the interpretation of the experimental results.

Importance of refractory pain and hypertension in acute type B aortic dissection: insights from the International Registry of Acute Aortic Dissection (IRAD).

BACKGROUND: In patients with acute type B aortic dissection, presence of recurrent or refractory pain and/or refractory hypertension on medical therapy is sometimes used as an indication for invasive treatment. The International Registry of Acute Aortic Dissection (IRAD) was used to investigate the impact of refractory pain and/or refractory hypertension on the outcomes of acute type B aortic dissection. METHODS AND RESULTS: Three hundred sixty-five patients affected by uncomplicated acute type B aortic dissection, enrolled in IRAD from 1996 to 2004, were categorized according to risk profile into 2 groups. Patients with recurrent and/or refractory pain or refractory hypertension (group I; n=69) and patients without clinical complications at presentation (group II; n=296) were compared. "High-risk" patients with classic complications were excluded from this analysis. The overall in-hospital mortality was 6.5% and was increased in group I compared with group II (17.4% versus 4.0%; P=0.0003). The in-hospital mortality after medical management was significantly increased in group I compared with group II (35.6% versus 1.5%; P=0.0003). Mortality rates after surgical (20% versus 28%; P=0.74) or endovascular management (3.7% versus 9.1%; P=0.50) did not differ significantly between group I and group II, respectively. A multivariable logistic regression model confirmed that recurrent and/or refractory pain or refractory hypertension was a predictor of in-hospital mortality (odds ratio, 3.31; 95% confidence interval, 1.04 to 10.45; P=0.041). CONCLUSIONS: Recurrent pain and refractory hypertension appeared as clinical signs associated with increased in-hospital mortality, particularly when managed medically. These observations suggest that aortic intervention, such as via an endovascular approach, may be indicated in this intermediate-risk group.

Photoisomerization of cis-1,2-di(1-Methyl-2-naphthyl)ethene at 77 K in Glassy Media.

cis-1,2-Di(1-methyl-2-naphthyl)ethene, c-1,1, undergoes photoisomerization in methylcyclohexane, isopentane and diethyl ether/isopentane/ethanol glasses at 77 K. On 313 nm excitation the fluorescence of c-1,1 is replaced by fluorescence from t-1,1. Singular value decomposition reveals that the spectral matrices behave as two component systems suggesting conversion of a stable c-1,1 conformer to a stable t-1,1 conformer. However, the fluorescence spectra are λexc dependent. Analysis of global spectral matrices shows that c-1,1 is a mixture of two conformers, each of which gives one of four known t-1,1 conformers. The λexc dependence of the c-1,1 fluorescence spectrum is barely discernible. Structure assignments to the resolved fluorescence spectra are based on the principle of least motion and on calculated geometries, energy differences and spectra of the conformers. The relative shift of the c-1,1 conformer spectra is consistent with the shift of the calculated absorption spectra. The calculated structure of the most stable conformer of c-1,1 agrees well with the X-ray crystal structure. Due to large deviations of the naphthyl groups from the ethenic plane in the conformers of both c- and t-1,1 isomers, minimal motion of these bulky substituents accomplishes cis → trans interconversion by rotation about the central bond.