Diazaphospholene-Catalyzed Radical Reactions from Aryl Halides.

Diazaphospholenes are widely used as hydride transfer catalysts, however their use in radical reactions is a recently emerging area. Here, we show prior stoichiometric radical cyclizations of aryl iodides mediated by diazaphospholene hydrides are made catalytic by the combination of phenylsilane and alkali metal salts to regenerate the diazaphospholene hydride. The scope was expanded to include aryl bromides, which benefit from visible light irradiation. Twenty one substrates underwent cyclization, including a dearomative cyclization. Extension to six intermolecular radical hydroarylations with arenes, thiophenes, and a pyridine was also accomplished.

Heavy Metals Make a Chain: A Catenated Bismuth Compound.

Catenation is common for the light main-group elements whereas it is rare for the heavy elements. Herein, we report the first example of a neutral molecule containing a Bi4 chain. It is prepared in a one-step reaction between bismuth trichloride and bis(diisopropylphosphino)amine in methanol suspension. The same reaction carried out in dichloromethane gives quite different products. All products have been characterized spectroscopically and using single-crystal X-ray analysis.

Novel Transcatheter Mitral Valve Prosthesis for Patients With Severe Mitral Annular Calcification.

BACKGROUND: Treatment of mitral regurgitation (MR) in the setting of severe mitral annular calcification (MAC) is challenging due to the high risk for fatal atrioventricular groove disruption and significant paravalvular leak. OBJECTIVES: The objective of this study was to evaluate the potential for transcatheter mitral valve replacement in patients with severe MAC using an anatomically designed mitral prosthesis. METHODS: Nine patients (77 ± 6 years of age; 5 men) were treated with the valve, using transapical delivery performed under general anesthesia and with guidance from transesophageal echocardiography and fluoroscopy. RESULTS: Device implantation was successful with relief of MR in all 9 patients. There were no procedural deaths. In 1 patient, left ventricular outflow tract obstruction occurred due to malrotation of the prosthesis, and successful alcohol septal ablation was performed. During a median follow-up of 12 months (range 1 to 28 months), there was 1 cardiac death, 1 noncardiac death, no other mortality, and no prosthetic dysfunction, and MR remained absent in all treated patients. Rehospitalization for heart failure occurred in 2 patients who did not die subsequently. Clinical improvement with mild or no symptoms occurred in all patients alive at the end of follow-up. CONCLUSIONS: Transcatheter mitral valve replacement in severe mitral annular calcification with a dedicated prosthesis is feasible and can result in MR relief with symptom improvement. Further evaluation of this approach for these high-risk patients is warranted.

Late presentation of esophageal injury after transesophageal echocardiography.

Esophageal injury is a rare complication of intraoperative transesophageal echocardiography (TEE) associated with cardiac surgery. We report two cases of delayed presentation (2 and 6 days after surgery) of esophageal injury that were likely due to TEE. The differential diagnosis of postoperative pleural effusion or anemia must include esophageal injury from TEE, even 6 days after the procedure.

Anterior leaflet augmentation for ischemic mitral regurgitation.

BACKGROUND: Mitral valve repair improves survival and quality of life in patients with ischemic mitral regurgitation (MR). Although many repair methods exist for this condition, the ideal approach remains unknown. The purpose of this study is to describe a simple technique for repair of ischemic MR that addresses the pathophysiology of tethered leaflets and to report its early results. METHODS: The technique consists of pericardial patch enlargement of the anterior mitral leaflet and placement of a flexible annuloplasty band. Candidates for the repair had ischemic cardiomyopathy and echocardiographic evidence of moderate or severe Carpentier type IIIb MR. Patients were followed with serial echocardiography. RESULTS: Between January 2002 and November 2003, 25 adult patients underwent anterior leaflet augmentation for ischemic MR. Mean age was 64.8 +/- 10.6 years, and mean left ventricular ejection fraction was 0.36 +/- 0.14. Preoperative MR by transesophageal echocardiography was severe in 84% of patients and moderate in 16%. Annuloplasty band sizes were 27 mm to 31 mm (mean, 28.4 +/- 1.1 mm). Concomitant coronary artery bypass grafting was performed in all patients. Transesophageal echocardiography immediately after repair revealed MR to be none or trace in 80% of patients and mild in 20%. No intraoperative conversion to valve replacement was performed. In follow-up, 2 patients have experienced moderate MR and are being treated medically, and no patients have mitral stenosis. At 2 years, actuarial freedom from moderate or greater MR is 81%. CONCLUSIONS: For patients with ischemic MR, anterior leaflet augmentation is a simple and reproducible method of valve repair that addresses the pathophysiology of tethered leaflets. Early results in a small number of patients have been encouraging.

Failure of argatroban anticoagulation during off-pump coronary artery bypass surgery.

Heparin-induced antibodies create vexing problems during cardiac surgery. Although alternative medications have been used for intraoperative anticoagulation, the results have been sufficiently variable that no one medication is recommended. In our case, due to the poor reversibility of the antithrombin agents, argatroban was chosen as a heparin substitute due to its short half-life and its anticoagulation assessment using the activated clotting time (ACT). Unfortunately, our experience was that argatroban does not provide adequate anticoagulation during off-pump coronary bypass surgery, even when the ACT is maintained at more than 380 sec.

Eight-year results of aortic root replacement with the freestyle stentless porcine aortic root bioprosthesis.

BACKGROUND: Stentless porcine aortic valves offer several advantages over traditional valves. Among these are superior hemodynamics, laminar flow patterns, lack of need for anticoagulation, and perhaps improved durability. METHODS: One hundred four patients were operated on from September 17, 1992, to October 31, 1997, as part of a multicenter worldwide investigation of the Medtronic Freestyle stentless porcine bioprosthesis. All patients received a total aortic root replacement. The patients were evaluated postoperatively at discharge, at 3 to 6 months, and yearly by clinical examination and color flow Doppler echocardiography. RESULTS: Operative mortality was 3.9%. No patient experienced structural valve deterioration, nonstructural deterioration, perivalvular leak, or unacceptable hemodynamic performance. At 8 years, survival was 59.8%. Freedom from thromboembolic complications was 83.3%. Freedom from postoperative endocarditis was 96.9%. Freedom from reoperation was 100%. Mean systolic gradients did not change over the time period studied. They were 6.4 +/- 3.8 mm Hg at 1 year and 6.7 +/- 2.6 mm Hg at 8 years. Correspondingly, effective orifice area was 1.9 +/- 0.7 cm2 at 1 year and 1.8 +/- 0.8 cm2 at 8 years. The incidence of any aortic insufficiency also did not change over the length of follow-up. At 1 year, 98% of patients had no or trivial aortic insufficiency and 2% had mild aortic insufficiency. At 8 years, 100% of patients evaluated were free of any aortic insufficiency. CONCLUSIONS: The Medtronic Freestyle aortic root bioprosthesis can be used safely to replace the aortic root or aortic valve for aortic valve and aortic root pathology. Total root replacement allows optimal hemodynamic performance with no significant aortic regurgitation. Results up to 8 years show excellent survival and no signs of degeneration. Further follow-up is still needed to determine valve durability.