Determination of the mitral papillary muscle positions by the septal‐to‐free wall arc ratio method

Background: Determination of mitral papillary muscle positions is of increasing interest in wide spectrum of clinical cardiology fields. Particularly, relative positioning of the papillary muscles between the inter‐ventricular septum and the left ventricular free wall is of interest. A reproducible method for determination of papillary muscle positions has not been established. In this study a new ‘septal‐to‐free wall arc ratio’ (SFAR) method for measuring papillary muscle positions is presented. The reproducibility of the SFAR method between echocardiographic (ECHO) and magnetic resonance (MRI) modalities and between observers is tested. Methods: Twenty subjects with structurally normal hearts in whom both MRI and ECHO were performed in 2007 were included in the study. Papillary muscle positions were determined using the SFAR method. Inter‐modality (ECHO and MRI) and inter‐observer reproducibility of the methods was assessed by calculating correlation coefficients and the mean difference from agreement. Results: The inter‐modality correlation of the SFAR method was 0·80 (P < 0·0001) for both papillary muscles. The mean difference of measurements from agreement was 4% for the superior and 2% for the inferior papillary muscle. The inter‐observer correlation was 0·93 (P < 0·0001) for superior and 0·90 (P = 0·0002) for inferior papillary muscle. The mean inter‐observer difference from agreement was 2% for superior and 3% for inferior papillary muscle. Conclusions: The SFAR method may be applied in wide range of both scientific and clinical medical fields as a reproducible method for determination of papillary muscle positions with the benefit of estimation of relative papillary muscle positions both from the septum and the free wall.     

Microvolt T wave alternans inducibility in normal newborn puppies: effects of development

INTRODUCTION: The cause of sudden infant death syndrome is unknown, but increased cardiac vulnerability due to repolarization instability may be a contributing factor. The QT interval normally is long at birth and increases further during the first few postnatal months. Although excessive QT intervals indicate increased cardiac vulnerability in the long QT syndrome, the impact of less pronounced QT prolongation during this developmental period is unclear. In adults and older children, the ease of inducing microvolt-level T wave alternans (TWA) is used as a measure of repolarization instability and arrhythmia vulnerability. The aim of this study was to determine if TWA is inducible in normal newborn puppies. METHODS AND RESULTS: Atrial pacing was performed in 15 anesthetized beagle puppies 7 to 35 days old. The pacing drive cycle length was systematically decreased in 20-msec steps from baseline until AV conduction blocked. Pacing was performed for 8 minutes at each cycle length. Three-lead ECGs were recorded continuously during the last 5 minutes of pacing at each cycle length. The recordings were analyzed off-line for the presence of microvolt-level TWA using a sensitive spectral analysis technique. Microvolt-level TWA was present in all puppies. TWA was not present at baseline but developed and increased in amplitude as heart rate increased. The threshold heart rate for TWA did not correlate with age. However, due to age-dependent changes in baseline heart rate, the 7- to 14-day-old animals needed a 50% to 78% increase in heart rate to reach threshold heart rate, whereas the oldest animals needed only a 5% to 25% increase. CONCLUSION: These data suggest that developmentally dependent dynamic repolarization instability exists in puppies as manifest by the inducibility of TWA.     

Autoantibody detection in type 2 autoimmune hepatitis using a chimera recombinant protein

Autoantibodies against cytochrome P450 2D6 (CYP2D6), known as anti-liver/kidney microsome type 1 (LKM1) and/or anti-human formiminotransferase cyclodeaminase, formally known as anti-liver cytosol type 1 (LC1) define type 2 autoimmune hepatitis (AIH). The aims of this work are to develop a sensitive and specific test to detect anti-LKM1 and/or anti-LC1 autoantibodies and to establish the prevalence of anti-LC1. Sera from children with type 2 AIH (n=48) and those from a control group (n=100) were evaluated for anti-LKM1 and anti-LC1 by Enzyme-Linked Immunosorbent Assay (ELISA) and Western blotting. Each serum sample was assayed for reactivity against formiminotransferase cyclodeaminase and CYP2D6 alone or as part of a recombinant chimera protein. By ELISA with recombinant chimera protein, 50 serum samples were positive, 48 from patients with type 2 AIH and 2 from patients with chronic hepatitis C. Twenty-five of 48 (52%) patients studied were positive for both CYP2D6 and LC1 autoantibodies. Anti-LC1, either as the only marker or associated with anti-LKM1, was positive in 34/48 (71%). By Western blotting, anti-LC1 was found in 27/48 (56%) patients. This ELISA technique has proven to be antigen-specific and more sensitive than Western blot for the detection of anti-LC1 and anti-LKM1 autoantibodies. The prevalence of anti-LC1 (71%) confirms it as an important immunomarker in type 2 AIH.     

Surgical management of patients with interrupted aortic arch and severe subaortic stenosis

Ten patients underwent palliative surgery for interrupted aortic arch and severe subaortic obstruction due to posterior displacement of the conal septum. Their ages ranged between 4 and 28 days (mean, 11.0 +/- 7.7 days) and their weights, between 2.1 and 4.2 kg (mean, 2.85 +/- 0.6 kg). Preoperative echocardiography and cardiac catheterization were performed on all patients. The ratios of the left ventricular outflow tract diameters and the ascending aortic diameters to the descending aortic diameters were 0.56 +/- 0.03 and 0.56 +/- 0.06, respectively, compared with 0.81 +/- 0.12 and 0.95 +/- 0.17, respectively, in 20 patients with interrupted aortic arch but without obstruction (p less than 0.001). Four of the 10 patients underwent pulmonary artery banding and insertion of a bypass graft between the ascending and the descending aorta. All 4 died of low cardiac output soon after operation (100% operative mortality). The remaining 6 patients underwent banding and insertion of a graft between the main pulmonary artery proximal to the band, and the descending aorta. All of these patients survived, and all except 1 are doing well 3 months to 4 years postoperatively. The use of a pulmonary artery-descending aorta conduit and of distal pulmonary artery banding provides good palliation for patients with interrupted aortic arch and major subaortic stenosis.     

Feasibility study: real-time 3-D ultrasound imaging of the brain

We tested the feasibility of real-time, 3-D ultrasound (US) imaging in the brain. The 3-D scanner uses a matrix phased-array transducer of 512 transmit channels and 256 receive channels operating at 2.5 MHz with a 15-mm diameter footprint. The real-time system scans a 65 degrees pyramid, producing up to 30 volumetric scans per second, and features up to five image planes as well as 3-D rendering, 3-D pulsed-wave and color Doppler. In a human subject, the real-time 3-D scans produced simultaneous transcranial horizontal (axial), coronal and sagittal image planes and real-time volume-rendered images of the gross anatomy of the brain. In a transcranial sheep model, we obtained real-time 3-D color flow Doppler scans and perfusion images using bolus injection of contrast agents into the internal carotid artery.     

Pacemaker Implantation in Infants and Children: A Simplified Approach

A technique for epicardial pacemaker implantation is described. A single incision is utilized through which the electrode and power pack are implanted. Twelve infants and children were operated on in the last four years using this procedure. The marked improvement in cosmetic appearance and the relative ease in module replacement are major advantages of this method.