Direct Dissection Research Articles

Direct surgical treatment of atrioventricular node reentrant tachycardia

Atrioventricular node reentry tachycardia is a common type of supraventricular tachycardia. Rarely is it incapacitating and refractory to drug therapy, but when it is, the only option in therapy until recently has been atrioventricular node ablation or antitachycardia pacemaker insertion. The purpose of this paper is to review the case histories of four patients in whom we have surgically abolished atrioventricular node reentrant tachycardia while intentionally preserving atrioventricular node conduction. All four patients had atrioventricular node reentrant tachycardia confirmed by electrophysiologic study as diagnosed by established criteria. One patient had a left posterior atrioventricular accessory pathway, in addition to atrioventricular node reentrant tachycardia. All patients underwent intraoperative epicardial and endocardial mapping. Direct surgical dissection of the atrioventricular node node was performed in all four patients during normothermic cardiopulmonary bypass. Early and late postoperative electrophysiologic studies were used to evaluate the success of the surgical dissection. None of the patients had any evidence of dual atrioventricular node pathways or spontaneous or inducible atrioventricular node reentrant tachycardia postoperatively. At last follow-up (15 weeks to 21 months postoperatively), all patients were free from arrhythmias and cardiac medications, all were in normal sinus rhythm, and all had a subjectively improved life-style. This technique of direct surgical dissection of the atrioventricular node during normothermic cardiopulmonary bypass has allowed for complete cure of atrioventricular node reentrant tachycardia, while maintaining normal atrioventricular node function in these four patients.

The effects of food restriction and exercise on site-specific differences in adipocyte volume and adipose tissue cellularity in the guinea-pig. 1. Superficial and intra-abdominal sites.

The volume and number of adipocytes were measured in fourteen anatomical sites of adult guinea-pigs kept in small cages and fed ad lib., kept in small cages and on restricted diet or fed ad lib. and exercised. In the sedentary ad lib.-fed animals, there was no significant correlation between percentage body-weight as adipose tissue, as determined by direct dissection, and mean adipocyte volume based on samples from many different sites. The correlation was significant, though not high, for sedentary, restricted-diet animals and for exercised specimens. The correlations between the volume of adipocytes from left-right pairs of sites, and from sites around the same limb, were highly significant under all conditions studied. The correlation between the volume of adipocytes from sites other than left-right pairs of sites was weaker and in some cases statistically insignificant in sedentary ad lib.-fed guinea-pigs. The volume of adipocytes from sites in the groin region, the mesenteries and medial to the trapezius muscle failed to correlate in many cases with the volume of adipocytes from other sites sampled. The number of adipocytes at each site was similar in the exercised and sedentary ad lib.-fed animals. The restricted-diet, sedentary group had fewer adipocytes at all sites studied except the omental and mesenteric fat mass and the groin sites. It is suggested that moderate regular exercise or fasting gives rise to closer coordination between adipocytes at different sites because central factors regulating adipocyte volume become more prominent than local factors.

New theory on the mechanism of erection involving hitherto undescribed vessels.

47 cadaver penises were investigated by means of plastic, corrosion casts, direct dissection under a stereomicroscope, tissue clearing, and light microscopy. "Shunt" arteries connecting the deep arteries in the corpora cavernosa with vessels in the corpus spongiosum were found. When the penis is flaccid these arteries probably allow blood to pass through the corpora cavernosa directly into the veins of the corpus spongiosum. Constriction of the shunt arteries may divert blood through the helicine arteries into the spaces of the corpora cavernosa, thus producing tumescence and erection. 20 of the cadaver penises had no direct vascular connection between the corpora cavernosa and the corpus spongiosum or glans. This supports the hypothesis that such fistulae, which have been reported in impotent patients are pathological structures.

Cell surface proteins of differentiating rat cerebellar cells maintained in dispersed cell culture.

The complement of cell surface proteins of differentiating rat cerebellar neurons maintained in dispersed cell cultures was evaluated by the combined methods of lactoperoxidase-catalyzed radioiodination and miniature sodium dodecyl sulfate polyacrylamide gel electrophoresis. Pure neuronal cell samples were obtained by direct dissection of such cells from the surfaces of the culture vessels. The electrophoretic profiles of cell surface proteins (CSP) from neurons maintained for 1, 7, 14, 21 and 28 days in vitro (DIV) were compared. It could be seen that while the pattern was relatively constant between 7 and 28 DIV, several differences existed between profiles from 1 and 7 DIV. The earliest stage was characterized by a prominent polypeptide triplet having molecular weight of approximately 48,000, 56,000 and 71,000 daltons. Later stages of development (7-28 DIV) were characterized by a greater number of high molecular weight surface polypeptides relative to the earliest stage. Comparison of electrophoretic profiles of CSPs of neurons and nonneuronal cells indicated that a number of polypeptides were not shared by these classes of cells.

Anatomical basis of radiodiagnosis of the adrenal gland.

Studies on 220 human adrenal glands were carried out microscopically, microangiographically and by direct dissection following preliminary filling of the vessels with injection masses. The position, size and shape of the adrenals, as well as their intrinsic and extrinsic arterial and venous vasculature were assessed. In the present work attention was directed mainly to the venous architecture. The understanding of venous pattern is of considerable importance to those who perform and evaluate adrenophlebography. The latter examination represents the most useful method of radiological assessment of adrenal glands.

DISTRIBUTION OF ANDROGEN METABOLIZING ENZYMES IN ISOLATED TISSUES OF HUMAN FOREHEAD AND AXILLARY SKIN

The distribution of androgen metabolism in human skin was studied using tissues isolated either by direct dissection of axillary skin or by dissection of collagenase-digested forehead and axillary skin. All tissues (epidermis, sweat glands, sebaceous glands, hair follicles and dermis) were found to contain 17beta-, 3beta- and 3alpha-hydroxysteroid dehydrogenase (HSD) activities, 3beta-hydroxysteroid dehydrogenase-delta4--5 isomerase (delta5-3beta-HSD) activity and 5alpha-reductase activity. All tissues converted testosterone into 5alpha-dihydrotestosterone. In confirmation of previous histochemical studies, over 90% of the delta5-3beta-HSD of forehead skin was found in the sebaceous glands. In forehead skin, 40--66% of the 5alpha-reductase activity was in the sebaceous glands, while in axillary skin 50--70% was in the sweat glands, especially the apocrine glands. There was a more even distribution of 17beta-HSD activity in skin tissues than histochemical studies have indicated previously. Knowledge of the distribution of these enzymes has helped in the understanding of the function of androgen metabolism in skin.

Improved method for cannulation of the right lymph duct in dogs.

We have developed a relatively simple technique for cannulating the right lymph duct in the dog. We have successfully cannulated 19 of 20 dogs and have obtained stable lymph flows for up to 6 h. We make a skin incision over the origin of the pectoralis superficialis muscle and extend it laterally and cephalically until it is parallel and lateral to the external jugular vein. Using the cephalic vein as a landmark, we identify the cervical lymphatic which lies deep to the external jugular vein. We trace the cervical lymphatic posteriorly to the lymphatic ampulla, which is located at the external jugular and axillary venous junction. The ampulla receives the cervical, axillary, and right lymph ducts. We place a ligature around the ampulla and tie it off, forming a lymphatic pouch and obstruction lymph flow into the vein. We then cannulate the cervical lymphatic and advance the catheter into the ampulla and tie it in place. All lymphatic branches draining into the ampulla, except the right lymph duct, are ligated, enabling us to collect lymph form only the right duct. The high success rate is due, we believe, to the fact that we approach the right duct high in the neck and cannulate via the cervical lymphatic. We avoid direct dissection over the right lymph duct, and usually we do not have to cannulate the right duct directly.

Ureteroneocystostomy without dissection of the submucosal tunnel

A technique of ureteroneocystostomy with fixation of the ureter to the bladder musculature denuded from the mucosa was studied in dogs. The intravesical portion of the ureter shrank to half its original length after the operation. This portion preserved its muscular structure and was overgrown by the bladder mucosa to more than half its circumference. The submucous canal thus formed for the ureter prevented reflux in every animal. The technique avoids the formation of strictures. It is recommended if direct dissection of a submucous canal is impracticable.

Distribution of pulmonary stretch receptors in the intrapulmonary airways of the dog

Fifty-eight pulmonary stretch receptors from 41 dogs have been localized in the intrapulmonary airways of the left lung through a direct dissection into the lung parenchyma. The intrapulmonary stretch receptors account for 44.4% of the total and their distribution in the intrapulmonary airways was 7.6% in the lobar bronchi, 18.4% in bronchi having a diameter greater than 1 mm and 18.4% in the remaining airways. Of all the receptors 82.8% were at an average distance of 3.1±0.2 cm (S.E.) from the lung root, thus within a volume approximately equal to 1 25 of the end-expiratory volume of the lung. The concentration of stretch receptors along the intrapulmonary airways was calculated from the surface area of the bronchial tree at different levels on the assumption of 2000 receptors from one lung. These data, together with those referring to extrapulmonary airways, show that the concentration nearly doubles going from the upper intrathoracic trachea to the lobar bronchi (from 34.8 receptors/cm 2 to 60.5/cm 2) and then sharply decreases to 7.0/cm 2 in bronchi having a diameter greater than 1 mm and 0.2/cm 2 in the smaller intrapulmonary airways.

Duodenal Decompression in Gastrectomy

THE problems related to dissection and closure of the duodenum in gastrectomy for duodenal ulcer constantly stimulate surgeons to develop improved technics in their management. In general, the methods employed constitute an indirect or a direct approach to treatment of the duodenal ulcer. Representative of the former are the Bancroft operation,1 McKittrick's two-stage gastrectomy,2 vagotomy and gastroenterostomy,3 vagotomy and pyloroplasty4 and vagotomy with antral exclusion.5 All these methods avoid direct dissection of the ulcer and duodenal closure. They seek to accomplish permanent healing of the retained ulcer or, in McKittrick's procedure, amelioration of local inflammation to permit safer dissection after . . .

Results and technique of stripping operation for varicose veins.

• The principles here outlined for the surgical treatment of varicose veins in the lower extremity are based on 2,660 stripping operations done over a five-year period and on 510 secondary operations for persistent or recurrent varicosities. Stripping means the removal of the incompetent part of the venous system. A length of vein that is not too tortuous can be removed by passing a stripper through it either from a proximal to a distal incision or vice versa; it is also possible to pass the stripper in both directions, for instance, from the knee. Veins too tortuous to permit passage of the stripper must be removed by dissection or evulsion. If the great saphenous vein is involved it must be ligated flush with the femoral vein at their junction, and the dissection at the groin is exacting. All other veins coming into the femoral vein laterally and medially should be ligated and removed by direct dissection, and the medial and lateral superficial branches of the great saphenous system should be prepared for removal if they are large. The flash bleeding that follows stripping usually stops soon, and the broken smaller tributaries retract. If bleeding persists, packing of the channel and ligation or removal of the responsible tributaries may be necessary. Follow-up studies over a period of years have shown that excellent results, with a minimum of secondary operations, can be achieved by proper preparation of the patient, appropriate choice of anesthetics, and good after-care.

Location and innervation of the corpus cardiacum in the larvae of some Calliphorinae (Diptera).

THE retrocerebral endocrine organs of the third instar larvae of Calliphora erythrocephala Mg., Calliphora vomitoria Linn., Lucilia sericata Mg., Lucilia caesar Linn., and Protophormia terrae-novae R–D. have been examined, by direct dissection with methylene blue supravital staining and in serial sections, in order to elucidate a number of hitherto obscure points. Descriptions of these organs in C. erythrocephala are given by Thomson1 and by Possompes2 but disagree in some details. The latter's term ‘peritracheal glands’ for the large cell component of the ring of Weismann3 has been adopted here.

The Relative Amounts of Grey and White Matter in some Normal and Pathological Brains.

The marked complexity of the convolutions of the brain of man, as compared with the lower animals, has suggested to numerous writers that the higher intellectual and other mental faculties characteristic of the human subject are in more or less direct relationship to the amount of grey matter in the brain. Attempts have therefore been made to measure the amount of grey matter in the brains of persons of very different degrees of intelligence and mental development. Owing to the highly complicated nature of the convolutions of the human brain, the method of estimation by direct dissection of the grey matter from the underlying white matter has not been adopted except in the case of a very few brains, most workers having approached the subject by indirect methods. Some observers have directed their attention to the measurement of the surface area of the grey matter, others to the determination of the absolute amount of cortex. Danilewsky, as a result of observations upon the specific gravity of the brain and of the grey and white matter, has calculated that the cortex forms 30 per cent. of the total brain weight. Donaldson, on the other hand, has estimated the grey matter of the hemisphere as forming 50 per cent. of the whole.