Evidence-based medicine and myocardial protection--where is the evidence?

OBJECTIVE: Myocardial protection with cardioplegia is an integral component of most cardiac surgical procedures, providing protection of the heart by limiting metabolic activity and increasing the myocardium's capacity to withstand ischemia for prolonged periods of time. Cardioplegia has greatly affected the landscape of cardiothoracic surgery since its introduction in the 1960s, but, to this day, there continues to be a debate over what the ideal cardioplegic solution should be. The goal of this analysis is to describe current practices in cardioplegia and to point out the lack of quality human research and subsequent publications that prevent best practices from being utilized. METHODS: This study is a systematic review of journal publications pertaining to the composition of commonly used cardioplegic solutions. Four main types of cardioplegia were assessed to give a narrower field of examination; specifically, microplegia, del Nido, Custodiol HTK, and 4:1 blood cardioplegia. Other combinations of cardioplegia, including St. Thomas's Solution and the University of Wisconsin (UW) Solution, were considered when applicable according to the context of the publication being reviewed. Factors being assessed consisted of scientific validity, nature of the test subject (isolated organ vs. animal vs. human studies), experimental setup (retrospective trials vs. randomized clinical trials) and patient outcomes. RESULTS: There are very few randomized clinical trials with human subjects comparing commonly used cardioplegic solutions. Numerous retrospective studies exist, but often show similar intraoperative and postoperative outcomes between the solutions. Some solutions, del Nido cardioplegia in particular, were found to have few or no significant human trials to back the rigor required in such a highly specialized field as cardiovascular surgery. A wide variation in the types of surgeries and primary outcomes were included in the publications, so it is difficult to perform an accurate systematic review of the topic. CONCLUSION: Uniform variables among different studies would be preferable for analysis of this topic; thus, it is the researchers' recommendation that the collection of multicenter data be undertaken in order to more fully answer this research question.Comparative effectiveness studies to associate commonly used solutions are needed. Without this research, surgeon preference remains the primary determining factor for deciding which cardioplegic solution to use. Cardioplegia selection should rely more on higher scientific research, using evidenced-based medicine and ranking of clinical studies.

Congenital malformations of the external, middle, and inner ear produced by isotretinoin exposure in mouse embryos.

Isotretinoin (Accutane), a widely used dermatologic drug, produces severe congenital malformations when used during pregnancy. The isotretinoin teratogen syndrome consists of multiple cardiovascular and craniofacial anomalies, most commonly involving the external ear. This study examined the pathogenesis of isotretinoin teratogenicity in a mouse model, using microdissection and histologic examination of fetal mouse ears after treatment with the drug at various stages of embryonic development. In this study, earlier treatment times frequently produced microtia similar to that seen in affected infants, as well as recognizable patterns of temporal bone and ossicular abnormalities; exposure at a later developmental stage resulted in facial tags with less severely affected ears. Possible teratogenic mechanisms of isotretinoin are discussed. Suitability of the mouse model for studying human congenital craniofacial malformations, such as Goldenhar's and Treacher Collins Syndrome, is also explored.

The effect of intravelar veloplasty on velopharyngeal competence following pharyngeal flap surgery.

Clinical experience from primary palatoplasty and studies of velopharyngeal valving suggest that intravelar veloplasty (IVVP) could increase the achievement of velopharyngeal competence in patients undergoing pharyngeal flap surgery. In order to test this hypothesis, a group of 91 patients undergoing superiorly based, high-attached, lined pharyngeal flaps along with intravelar veloplasty were compared retrospectively with 39 patients who underwent the same procedure without intravelar veloplasty. Comparison of speech evaluation and pressure-flow data demonstrated no difference in attainment of velopharyngeal competence between the two groups. Though theoretically sound, intravelar veloplasty did not appear to improve the results of pharyngeal flap surgery. The high incidence of postoperative hyponasality in both the study and control groups suggests a possible need for increased lateral port size in performing the procedure.

Nontraumatic subluxation of the atlantoaxial joint: Grisel's syndrome.

Grisel's syndrome is defined as subluxation of the atlantoaxial joint not associated with trauma or bone disease. Primarily an affliction of children, the disorder may occur in association with any condition that results in hyperemia and pathologic relaxation of the transverse ligament of the atlantoaxial joint, including several common otolaryngic entities. Grisel's syndrome has been noted infrequently in the otolaryngologic literature; this paper reports a case from West Virginia University Hospital of a 6-year-old boy with radiographic evidence of retropharyngeal cellulitis following meningitis progressing to atlantoaxial subluxation. Discussed are the pathophysiologic aspects of Grisel's syndrome with an anatomic explanation recently described to account for the syndrome.