When is the optimal time to discontinue clopidogrel before in-hospital coronary bypass surgery? A closer look at the current literature.

BACKGROUND: Clopidogrel and other P2Y12 inhibitors have become the standard of care among patients presenting with acute coronary syndromes. A substantial proportion of these patients require surgical revascularization during index hospitalization. HYPOTHESIS: Guidelines recommend a 5-day waiting period off clopidogrel before coronary artery bypass grafting (CABG) to reduce hemorrhagic complications. These recommendations are not routinely followed in clinical practice, while recent studies also propose shorter waiting periods off clopidogrel for patients awaiting in-hospital CABG. METHODS: A preliminary PubMed search was conducted using the following MeSH terms under the publication type "Hemorrhage:" "Clopidogrel," AND "Coronary Artery Bypass." Relevant studies and guidelines were then reviewed and selected based on a predetermined criteria. Studies that formulated the current recommendations for stopping clopidogrel preoperative to CABG are discussed in detail this review. RESULTS: A comprehensive review of recent evidence illustrates mixed bleeding and transfusion outcomes among CABG patients with preoperative exposure to clopidogrel in less than 5 days. CONCLUSIONS: The optimal discontinuation time of clopidogrel before CABG is still poorly defined. The recommendation of a 5-day washout period for clopidogrel should be reconsidered to be on par with current clinical practice.

Fluorination of perovskite-related phases of composition SrFe(1-x)Sn(x)O(3-δ).

Perovskite-related compounds of composition SrFe(1-x)Sn(x)O(3-δ) (x = 0.31, 0.54) have been prepared. X-ray powder diffraction shows that the materials adopt orthorhombic unit cells. The lattice parameters increase with the incorporation of increasing amounts of tin, which is shown by x-ray absorption near edge structure investigation to be present as Sn(4+). (57)Fe Mössbauer spectroscopy indicates that iron in these phases is present as Fe(5+) and Fe(3+) and that the materials adopt the compositions SrFe(0.69)Sn(0.31)O(2.94) and SrFe(0.46)Sn(0.54)O(2.88). We propose that the disproportionation of Fe(4+) in SrFeO(3-δ) to Fe(5+) and Fe(3+) in SrFe(1-x)Sn(x)O(3-δ) is driven by the reduction of local lattice strain. The materials have been fluorinated by reaction with poly(vinylidene fluoride) to give products of composition SrFe(0.69)Sn(0.31)O(2.31)F(0.69) and SrFe(0.46)Sn(0.54)O(2.54)F(0.46). The increased iron to oxygen or fluorine distances as revealed by the extended x-ray absorption fine structure are associated with the reduction of Fe(5+) to Fe(3+) as evidenced by (57)Fe Mössbauer spectroscopy. The (57)Fe Mössbauer spectra recorded from the fluorinated materials at low temperature show the coexistence of magnetic sextet and non-magnetic doublet components corresponding to networks of Fe(3+) coupled through oxide ions. The Sn(4+) ions disrupt the coupling and the size of the networks. The magnetic susceptibility measurements and Mössbauer spectra recorded between 4.2 and 300 K are used to model the magnetic properties of these materials, with the larger networks appearing to possess random spin orientations consistent with spin glass-type materials.

A case series of systemic right ventricular dysfunction post atrial switch for simple D-transposition of the great arteries: the impact of beta-blockade.

BACKGROUND: Patients with atrial switch (Mustard or Senning) repair of D-transposition of the great arteries (D-TGA) are at increased risk for atrial arrhythmias, systemic right ventricular (RV) dysfunction and late mortality. OBJECTIVES: To evaluate case series from a single-centre experience with beta-blocker use in adult, post atrial switch, simple D-TGA patients. METHODS: The Adult Congenital Heart Disease Clinic (Halifax, Nova Scotia) database was used to identify patients with post atrial switch, simple D-TGA. Treatment effect of beta-blockade was evaluated. RESULTS: Eight patients were treated with beta-blockers for systemic RV dysfunction (n=2), arrhythmia (n=2) or both (n=4). Median follow-up was three years, at which time seven of eight patients were still on beta-blockade. Of those patients with complete data, two of five had improved systemic ventricular dysfunction, two of four had improved tricuspid regurgitation and four of six had improved functional capacity, as determined by history or exercise testing. Beta-blockade was well tolerated in seven of eight patients without any significant clinical deterioration. CONCLUSIONS: Beta-blockade was used infrequently in patients with a prior Mustard procedure. When beta-blockade was prescribed to patients with a prior atrial switch procedure, the drugs were well tolerated and were associated with trends toward improved symptoms, less tricuspid regurgitation and improved functional status in patients with reduced systemic RV function. These data support the need for a randomized trial of beta-blockade in patients with a previous Mustard or Senning operation and RV dysfunction.