Lack of a phenotype in transgenic mice aberrantly expressing COL2A1 mRNA because of highly selective post-transcriptional down-regulation.
We reported previously that a 1.9-kb 5'-fragment from the human COL1A1 gene drove transcription of a promoterless human COL2A1 gene in tissues of transgenic mice that normally express the COL1A1 but not the COL2A1 gene. In the present study, we have established that the aberrant transcription of the COL2A1 gene did not produce any gross or microscopic phenotype, because the transcripts were not efficiently translated in cells that do not normally express the COL2A1 gene. In two lines of transgenic mice, the mRNA levels from the transgene were 30% to 45% of the mRNA for the proalpha1(I) chain of type I procollagen, the most abundant mRNA in the same tissues. Analysis of collagens extracted from skin of the transgenic mice indicated that triple-helical type II collagen, with the normal pattern of cyanogen bromide peptides, was synthesized from the transgene. However, the level of type II collagen in skin was less than 2% of the level of type I collagen. Hybridization in situ indicated the presence of mRNA for both COL2A1 and COL1A1 in the same cells. Immunofluorescence staining for type II collagen, however, was negative in the same tissues. The results, therefore, indicated that many mesenchymal cells in the transgenic mice had high steady-state levels of the homologous mRNAs for type I and type II procollagen, but only the mRNAs for type I procollagen were efficiently translated. (+info)
Subxiphoid surgical approach for epicardial catheter-based mapping and ablation in patients with prior cardiac surgery or difficult pericardial access.
BACKGROUND: Percutaneous epicardial mapping and ablation are successful in some patients with ventricular epicardial reentry circuits but may be impossible when pericardial adhesions are present, such as from prior cardiac surgery. The purpose of this study was to evaluate the feasibility of direct surgical exposure of the pericardial space to allow catheter epicardial mapping and ablation in the electrophysiology laboratory when percutaneous access is not feasible. METHODS AND RESULTS: In 6 patients with prior cardiac surgery or failed percutaneous pericardial access, a subxiphoid pericardial window was attempted. In all 6 patients, manual lysis of adhesions exposed the epicardial surface of the heart through a small subxiphoid incision and allowed placement of an 8F sheath into the pericardial space under direct vision. Access to the diaphragmatic surface of the heart with ablation catheters was achieved in all patients, and catheter manipulation to the lateral and anterior walls was possible in 4 patients. Three-dimensional electroanatomic voltage maps revealed low-amplitude regions in the inferior or posterior left ventricular epicardium. A total of 16 ventricular tachycardias were induced, and 14 were abolished by radiofrequency ablation. Ablation was limited by intrapericardial defibrillator patches adherent to the likely target region in 2 patients. All patients had chest pain consistent with pericarditis early after the procedure that resolved within a few days. There were no other complications. CONCLUSIONS: A direct surgical subxiphoid epicardial approach in the electrophysiology laboratory is feasible for patients with difficult pericardial access who require ablation of epicardial arrhythmia foci. (+info)
Epicardial catheter ablation of ventricular tachycardia using surgical subxyphoid approach.
We report the case of a patient presenting with a previous inferior myocardial infarction complicated by incessant monomorphic ventricular tachycardia resistant to antiarrhythmic drugs. Because endocardial catheter ablation failed and because of focal endocardial activation arising from the left ventricular inferior wall, an epicardial location of the reentry circuit was suspected. Catheter mapping of the pericardial space through a surgical subxyphoid approach performed in the electrophysiological laboratory confirmed the epicardial location of the arrhythmogenic substrate and allowed us successfully to ablate and cure the patient. Surgical subxyphoid approach can be performed in the electrophysiological laboratory when epicardial ablation is needed in case of inadvisable, difficult, or failed non-surgical percutaneous access. (+info)
Reliability and accuracy of cirtometry in healthy adults.
OBJECTIVE: To determine the intrarater and interrater reliability of cirtometry (measurements of the circumference of the chest and abdomen taken during respiratory movements) as well as its correlation with pulmonary volumes measured by respiratory inductive plethysmography. METHODS: A total of 40 healthy individuals were evaluated. The mean age was 28 years. The measurements were taken in the supine position at three different time points: at rest, at maximal inspiration, and at maximal expiration. Two trained investigators, each of whom was blinded as to the results obtained by the other, performed the measurements. The Friedman test was used to determine intrarater reliability, and the Wilcoxon test, together with the intraclass correlation coefficient, were used to determine interrater reliability. The correlation between the cirtometry measurements and the plethysmography results was obtained using Spearman's correlation coefficient. The level of significance was set at 0.05 for all tests. RESULTS: Intrarater reliability was satisfactory. Regarding interrater reliability, statistically significant differences (2.8 cm at the most) were found in all sets of measurements. However, through the analysis of the intraclass correlation coefficient, the investigators were found to be responsible only for a small portion of the variability (1.2-5.08%) found among the measurements. When the cirtometry measurements were compared to the volumes measured by respiratory inductive plethysmography, low correlations (range, r = 0.170-0.343) were found. CONCLUSIONS: The findings of this study suggest that, although cirtometry is a reliable measurement, it does not accurately measure pulmonary volumes. (+info)
Laparoscopic treatment of subxiphoid incisional hernias in cardiac transplant patients.
BACKGROUND: Symptomatic subxiphoid incisional hernias present difficult surgical problems, especially in immuno-suppressed cardiac transplant patients. Here, we describe the laparoscopic repair of subxiphoid incisional hernias in patients with a history of cardiac transplantation. METHODS: Four patients with subxiphoid hernias who had previously undergone heart transplantation were identified from a prospective database. Each underwent a laparoscopic repair with mesh implantation. RESULTS: Three patients had a previous open repair. The mean age was 62.5 years, an average of 64.3 months after transplantation. At the time of surgery, all patients were immunosuppressed, and each had a subxiphoid, poststernotomy incisional hernia. Gore dual mesh was used in 2 patients, while Parietex mesh was used in 2. Mean operative time was 122 minutes, and all were completed laparoscopically. The mean length of stay was 6.5 days, and the mean defect size was 286.25 cm(2). There was a significant correlation between hernia size and length of stay (P=0.037). Postoperatively, one patient (25%) developed pulmonary edema, and 1 patient (25%) had a prolonged ileus. CONCLUSION: Symptomatic subxiphoid incisional hernias are a challenging surgical problem in patients with a history of sternotomy. Laparoscopic repair is safe and effective in immunosuppressed patients who have previously undergone cardiac transplantation. (+info)
Minimally invasive epicardial injections using a novel semiautonomous robotic device.
Postoperative elongation of the xiphoid process --report of a case--.
We report a case of a 66-year-old man who presented with an abnormal sensation, tenderness, and pain in the middle of his chest in May 2006, two years after a mitral valve replacement for severe mitral regurgitation and a MAZE operation for chronic atrial fibrillation elective cardiac. He was immediately admitted, and the x-ray examination revealed an abnormal elongation of the xiphoid process. At the time of discharge after the initial operation in 2004, x-rays indicated that the length of the xiphoid process was 3 cm; however, in 2006 it had elongated to 6 cm and was prominent in the anterior view. The patient underwent surgical extirpation of the xiphoid process while he was under local anesthesia. Histological examination of the resected xiphoid process revealed no signs of neoplastic or maligant change. The cause of the elongation of the xiphoid process was believed to be distraction tissue neogenesis. The xiphoid process, which fractured and separated from the sternum at the initial operation, was pulled down inferiorly by the rectus abdominis muscles, following which the xiphoid process became elongated and reconnected with the sternum. In cases of a fractured or amputated xiphoid process after median sternotomy, the xiphoid process should be resected to avoid its neogenesis. (+info)