Fibromuscular Band Research Articles

Left ventricular fibromuscular band is not a specific substrate for idiopathic left ventricular tachycardia.

A fibromuscular band has been detected in patients with idiopathic left ventricular tachycardia, and this band has been suggested to be the anatomic substrate for the arrhythmia. Whether the fibromuscular band is a specific substrate for the tachycardia was systematically evaluated in a large group of consecutive patients with and without idiopathic left ventricular tachycardia. Conventional transthoracic two-dimensional echocardiography and multiplane transesophageal echocardiography were performed in 18 patients with idiopathic left ventricular tachycardia that was responsive to calcium blockers (group 1, tachycardia patients) and 40 patients with paroxysmal supraventricular tachycardia (group 2, control patients). There were 17 men and 1 woman, with a mean age of 29 +/- 11 years, in group 1 patients, and 21 men and 19 women, with a mean age of 42 +/- 12 years, in group 2 patients. The QRS morphology during tachycardia in group 1 patients displayed a pattern of right bundle-branch block with superior axis in 15 patients, indeterminate axis in 2 patients, and inferior axis in 1 patient. Radiofrequency ablation successfully eliminated the tachycardia in all 18 patients; the successful ablation site was located at the inferior apical septum in 11 patients, at the midseptum in 6 patients, and at the anterior lateral wall in 1 patient. Transthoracic echocardiography detected the fibromuscular band in 11 of the 18 patients, whereas multiplane transesophageal echocardiography detected the band in 17 of 18 patients. The fibromuscular band extended from the interventricular septum to the apex of the left ventricle. In group 2 patients, transthoracic echocardiography detected the fibromuscular band in 22 and multiplane transesophageal echocardiography detected the band in 35 of the 40 patients. The presence of a fibromuscular band in these two groups of patients was not statistically different. The presence of a left ventricular fibromuscular band is not a specific anatomic substrate for idiopathic left ventricular tachycardia.

Prostate capsule: Computerized morphometric analysis of its components

Objectives There is little objective information on what is designated as being the prostate capsule. We have quantified objectively with computerized image analysis the percentage of smooth muscle fibers (SMFs) surrounding the surgical specimens of radical prostatectomies. Methods Ten radical prostatectomy specimens were used. Six different parts from each prostate lobe were analyzed. Thirty different fields were examined from each tissue section. For tissue sections, different stains were used: hematoxylin and eosin, Masson's trichrome, and immunohistochemical staining with antiactin for the SMFs. Results The mean thickness of the prostate capsule was 0.5 to 2 mm. The mean percentages of SMFs in the different regions of the prostate capsule was 30.6%. No difference was noted between the percentage of SMFs in the prostatic capsule compared with that in the prostate parenchyma itself (30.7%). Conclusions This study provides objective evidence to demonstrate that the prostate does not have a true capsule. This capsule represents a fibromuscular band that probably should be considered as the extension of the internal parenchyma.

Extrinsic Compression of the Renal Artery by Diaphragmatic Crus

Extrinsic compression of the renal artery due to a fibromuscular band originating from the diaphragm was encountered in a 26-year-old patient who had systemic hypertension associated with stenosis and kinking of one of her renal arteries. After surgical decompression, the renal artery assumed a normal expansion with disappearance of hypertension. Six other cases of extrinsic compression of the renal artery have been found in the literature. Surgical treatment is mandatory in all cases because the mechanism that causes the lesion makes percutaneous transluminal angioplasty illusory.

The Prostatic Capsule

Pathologic evaluation of tumor extent in a radical prostatectomy specimen for prostatic adenocarcinoma is extremely important in staging and planning further therapy. We studied whole-organ sections of 50 prostate glands, obtained at either radical prostatectomy for adenocarcinoma or cystoprostatectomy for bladder cancer, to evaluate the so-called capsule of the prostate, the prostatic apex, and the surgical margins. The outer surface of the prostatic portion of the specimen was totally inked with different colors for the anterior, posterior, left, and right areas. Cross sections were processed for histologic examination, and the apex (distal 1.5 cm) was amputated and radially sectioned (like a cervical cone). We found that the "capsule" is made up of a band of concentrically placed fibromuscular tissue that is an inseparable component of the prostatic stroma. The outer surface of this tissue gives rise to a few bundles of fibromuscular stroma that penetrate and disappear into the periprostatic connective tissue stroma. The apex is sparse in glandular elements, particularly in the anterior portion, and the outer fibromuscular layer is no longer present. Thus we conclude that the prostate does not have a true capsule, but only an outer fibromuscular band.

Total correction of double-outlet ventricle with concordant atrioventricular relation, dextrocardia, pulmonary stenosis, and situs inversus

A case of successful surgical correction of double-outlet right ventricle with concordant atrioventricular relation, pulmonic stenosis, and situs inversus is described. Transposition of the great vessels was not present. Intracardiac repair with a Teflon tunnel conduit gave an excellent result. Proper resection of the subpulmonic obstructing fibromuscular band required no patch reconstruction of the outflow tract.

Ventricular septal defect in tetralogy of Fallot

A study of 67 surgically unaltered specimens of tetralogy of Fallot at The Johns Hopkins Hospital revealed a group of 28 hearts in which the ventricular septal defect was surrounded entirely by muscular tissue. Since part of this muscle lay in the space between the tricuspid and aortic valve annuli, where it occupied a position taken by the parietal band in the normal heart, it is postulated that this muscle represents an inferior division of the embryonic infundibular septum (parietal band) in these specimens. The superior division of the parietal band forms the anterior margin of the ventricular septal defect and the superior border of the stenotic infundibulum. A similar but more rudimentary inferior portion of the infundibular septum may have been present in another 16 of the 67 specimens, as represented by a fibrous or fibromuscular band separating the aortic and tricuspid valve annuli.

Acquired right ventricular outflow obstruction in a child with neurofibromatosis

A case of severe acquired localized right ventricular obstruction in an 8 1 2 - year-old child with von Recklinghausen's syndrome is presented. The similarity of this case to vascular involvement in previously reported cases is pointed out. It is suggested that vascular lesions in neurofibromatosis may have varied manifestations and that this syndrome should be thought of in the future as a generalized disease which may affect any part of the cardiovascular system. For the lesion here reported, excision of the fibromuscular band has resulted in disappearance of her pressure difference, murmur, and right heart failure.