Quantitative analysis of intracoronary optical coherence tomography measurements of stent strut apposition and tissue coverage.

BACKGROUND: The introduction of optical coherence tomography (OCT) as an intracoronary imaging modality has allowed accurate assessment of strut apposition and neointimal tissue coverage. This study set out to assess the inter and intraobserver variability of measurements of acute stent apposition and strut tissue coverage using OCT. METHODS: Thirty patients were studied (14 immediately after stent implantation and 16 during follow-up angiography [mean of 4.7+/-2.8 months]) using OCT (LightLab, Westford, Massachusetts, US). Data analysis was performed by 2 experienced observers. Struts were classified as "embedded", "protruding" or "malapposed" to the vessel well and recorded as percentage of total struts. Intimal coverage at follow-up was measured as the thickness of tissue covering each strut expressed in mum. Intra and interobserver variability was assessed by Bland-Altman plots and by calculation of the intraclass correlation coefficient (ICC). RESULTS: An average of 3967 struts was examined by each observer and, overall, 53.7% of struts was embedded, 36.4% protruding and 9.9% malapposed. Low intraobserver variability for all measures of strut apposition was found, with repeatability coefficients that ranged between 5.1% and 9.3% and ICC exceeding 95% in all cases. Interobserver variability was also low (repeatability coefficients 6.6-10.8 and ICC>91.3%). Mean intimal thickness in the follow-up group was 172.5 microm. Bland-Altman plots demonstrated a low intraobserver and interobserver variability for intimal thickness, with repeatability coefficients 26.7 mum and 24.1 mum, respectively and ICC exceeding 98.6% for both. CONCLUSIONS: Low intra and interobserver variability can be expected when analyzing OCT data for stent apposition and tissue coverage. This supports the validity of OCT as a clinical and research tool in the setting of intracoronary stent imaging.

Optimal reperfusion strategy for acute myocardial infarction.

Primary percutaneous coronary intervention has proved to be a superior intervention strategy for acute myocardial infarction than pre-hospital thrombolysis. Both strategies are being used in the UK in parallel, and time to intervention is crucial with both strategies. The Myocardial Infarction National Audit Project registry is showing a gradual move towards percutaneous coronary intervention as the strategy of choice when available.

Difficulties and limitations in minimally invasive repair of pectus excavatum--6 years experiences with Nuss technique.

OBJECTIVE: In 1998, Dr Donald Nuss proposed minimally invasive repair of pectus excavatum (MIRPE) which did not require the osteochondrous parts of the anterior chest wall to be resected. The paper aims at presenting the authors' own 6 years of experience in funnel chest repair with MIRPE technique. Also, many technical problems of this method are discussed. MATERIALS AND METHODS: Between 1999 and 2005, 461 patients (99 female and 362 male, aged 3-31 years, mean age 15.2 years) with pectus excavatum were operated with the Nuss technique. All patients were operated-on according to the original operative protocol proposed by Donald Nuss. With growing experience, own modifications were introduced. Insertion of two bars was done in 17.4%, transverse sternotomy in adolescents with rigid anterior chest wall in 7.8%, limited excision of the rib cartilages in 5.9%, and parasternal fixation of the bar to prevent it from rotating in 59.7% of patients. RESULTS: There were no deaths. Intraoperative complications were noted in 19 (4.1%) patients and postoperative ones were observed in 43 (9.3%) patients. The operative time ranged from 25 to 130 min (52 min on average). In 192 (41.6%) patients, an epidural block was used. The hospital stay ranged from 4 to 12 days with the mean of 5.3 days. A redo procedure for the bar rotation was necessary in 13 (2.8%) patients. The support bar has been removed in 260 (56.4%) patients so far. In all the patients, an adequate contour of the anterior chest wall has been maintained. CONCLUSIONS: MIRPE proposed by Nuss has all the features of a minimally invasive procedure and is straightforward. Better clinical results are achievable in patients under 12 years of age with a symmetric deformity. In older patients (over 15 years of age) with a rigid chest or with an asymmetric deformity, additional procedures are required to achieve a comprehensive correction of the deformity. Recent results and forward clinical observations may give proof to establish MIRPE as a method of choice in funnel chest correction.

KCNQ1 gene mutations and the respective genotype-phenotype correlations in the long QT syndrome.

KCNQ1 (formerly called KVLQT1) is a Shaker-like voltage-gated potassium channel gene responsible for the LQT1 sub-type of LQTS. In general, heterozygous mutations in KCNQ1 cause Romano-Ward syndrome (LQT1 only), while homozygous mutations cause JLNS (LQT1 and deafness). To date, more than 100 families with mutations in this gene have been reported, most with their own novel 'private' mutations. The majority of these mutations are missense. However, other types of mutations, such as deletions, frame-shifts and splice-donor errors have also been reported. There is one frequently reported mutated region (the 'hot-spot'). KCNQ1 is now believed to be the most commonly mutated gene in LQTS. The combination of normal and mutant KCNQ1 alpha-subunits has been found to form abnormal IKS channels, hence mutations associated with the KCNQ1 gene are also believed to act mainly through a dominant-negative mechanism (the mutant form interferes with the function of the normal wild-type form through a 'poison pill' type mechanism) or loss of function mechanism. Even in the case of carriers of the same mutation, it is currently unknown why there are significant clinical phenotype variations in LQT1 patients. This question could be answered by increasing the number of patient genotypes studied. LQT1 patients experience a majority of their cardiac events (62%) during exercise, and only 3% occur during rest or sleep. Of the patients who experienced cardiac events while swimming, 99% were LQT1. Auditory stimuli are rare and occur in only 2% of patients. However, both lethal and non-lethal events follow the same pattern.