Percutaneously adjustable pulmonary artery band. An experimental study.

Several forms of congenital heart lesions with increased pulmonary flow can be effectively palliated by pulmonary artery banding. In addition, banding has aroused renewed interest to induce left ventricular hypertrophy in infants with simple transposition of the great arteries. Occasionally a need arises to readjust the band to obtain an optimal degree of banding after operation. For percutaneous control of the degree of constriction after pulmonary artery banding, we developed a readjustable vessel occluder. The occluder consists of a stainless steel snare coated with polyethylene, an enveloping polyvinyl catheter (5F and 8 to 12 cm in length), and a screw adjuster, which is a stainless steel cylinder, 7 by 20 mm, containing a bolt and a nut. By means of a specially designed needle driver (1.0 mm in diameter), the screw adjuster can easily be driven percutaneously without a skin incision. The maximum stroke of the screw is 14 mm by 34 revolutions. One complete revolution of this screw corresponds to a change in diameter of 0.14 mm and to a change in circumference of 0.44 mm. Six mongrel dogs ranging in weight from 5 to 10 kg underwent banding of the pulmonary artery or the ascending aorta with this device. Follow-up evaluation by cardiac catheterization and angiocardiography was performed up to 2 months after implantation of the device. This band could be effectively and finely adjusted up to 2 months after implantation and no complication was seen. This preliminary study suggests that this new device may be applicable in patients with congenital heart disease and excessive pulmonary blood flow.

Internal banding for palliation of truncus arteriosus in the neonate.

A method for surgically limiting pulmonary blood flow in the critically ill neonate with truncus arteriosus is described. Two recent cases utilizing this technique are presented. Comparisons are made between this and other palliative surgical procedures used in truncus arteriosus.

Retarding liver cancer growth in the rat by transient repeated hepatic dearterialization.

The effect of repeated ischemic episodes to experimental liver tumors is studied in a group of inbred Wistar-Furth rats. A vascular occluder model was developed specially for the purpose of delivering intermittent compressions to the hepatic artery in the rat. With five daily 1-hr occlusions of the hepatic artery, rats benefited from significantly reduced tumor growth rates compared with controls that underwent sham operation (P less than 0.05). In contrast to results from previous pig experiments, it is demonstrated by angiographic studies that repeated transient dearterialization does not entirely overcome the problem of collateral vessel formation in the rat. Tumor neovascularization continues irrespective of whether the tumor is being dearterialized. It is also observed that in both normal and tumor rats, collateral channels from the left gastric artery temporarily open up when the hepatic artery is obstructed but disappear on reestablishment of flow. As such types of collateral flow are beyond our control, it is imperative that future developments in vascular occlusion therapy should aim at shortening ischemia time and combining with chemotherapy.

A new model for inducing transient cerebral ischemia and subsequent reperfusion in rabbits without craniectomy.

An artificial ball removable by an attached fiber was injected into the middle cerebral artery (MCA) of 16 rabbits, allowing the study of transient (5, 10, 15, or 30 minutes) cerebral ischemia without craniectomy. Measurements of available oxygen (aO2) in the ischemic core (the ventral part of the temporal area) followed by histologic examination verified the embolization. Electroencephalographic power spectra and steady (direct current) potentials were recorded bilaterally on the convexity remote from the actual lesion but still supplied by the MCA. Local cerebral blood flow and aO2 in the border zone between the anterior cerebral artery and the occluded MCA were measured. Embolization caused typical ischemic changes ipsilaterally and alterations characteristic of diaschisis contralaterally. Extreme border zone hyperemia developed without significant aO2 changes in the same region. Restoration of circulation via the circle of Willis induced gradual normalization. Our model for controlled embolization and recirculation proved suitable for detailed studies of the complex changes in brain function caused by transient ischemia.

Pancreatic duct occlusion in the rat: report and assessment of a new technique.

Temporary reduction of the exocrine pancreatic secretion may be desirable in various experimental models. In the rat this can be achieved by obstructing the connection between the pancreas and the duodenum. A new, simple technique of pancreatic duct occlusion using metal hemostatic clips is described. The reduction of secretion produced by the procedure was assessed by measuring duodenal protein, amylase, and trypsin during stimulation with cholecystokinin. Stimulated duodenal amylase activity 1 and 4 weeks following duct occlusion was reduced by approximately 80% compared with sham-operated controls, whereas proteolytic activity was reduced by 96 and 60%, respectively. The magnitude and duration of pancreatic insufficiency achieved by this technique is equivalent to that achieved with more complicated methods.

Microsurgical endarterectomy under barbiturate protection: a prospective study.

Carotid endarterectomy has the potential to improve on the natural history of untreated carotid artery disease with respect to subsequent infarction in symptomatic patients with causative angiographic lesions. This benefit of a reduced risk of stroke can be realized only if the perioperative morbidity and mortality rates are kept low. An approach to symptomatic carotid artery bifurcation disease is outlined, with a defined protocol of microsurgical endarterectomy utilizing barbiturate protection during the period of potential focal temporary cerebral ischemia. This protocol includes preoperative antiplatelet therapy, barbiturate anesthesia, the avoidance of an internal shunt, the use of the operating microscope, and strict control of postoperative hypertension. A series of 200 consecutive endarterectomies performed within this protocol in 180 patients and the resultant combined permanent morbidity and mortality rate of 1.5% are reported.

Treatment of transsphincteric anal fistulas by the seton technique.

Twenty-one patients with high transsphincteric fistulas treated by the seton technique were re-examined after two to 14 years. None had recurrent fistulas, but 13 (62 percent) had some degree of continence disturbances. All patients with anal deformities had continence disorders.

The mechanism of spinal cord injury after simple and double aortic cross-clamping.

Ischemic spinal cord injury after cross-clamping of the descending aorta can occur independently of aortic disease. In a previous study we had shown a precipitous uniform fall of spinal surface oxygen tension downstream to the clamping site irrespective of level. In the present paper, the hemodynamic changes in the spinal and aortic collateral circulation were investigated. Pressures were measured in the proximal, distal, and excluded aortic segments (descending thoracic and lumbar aorta) as well as in the intercostal and the lumbar arterial beds. Before high aortic occlusion, pressures in the intercostal and lumbar arterial beds were lower than aortic pressure. Along with the postclamping fall in distal arterial pressure, intercostal and lumbar arterial bed pressure decreased further but remained above aortic pressure. Exclusion of the thoracic aorta by double clamping restored intercostal bed pressure almost to control, whereas exclusion of the abdominal aorta hardly affected lumbar bed pressure. We conclude that spinal collateral circulation is more highly developed in the thoracic than in the lumbar region. After aortic cross-clamping, blood tends to drain away from the spinal cord rather than supplying it longitudinally. Under clinical conditions, therefore, retrograde bleeding into the opened aorta as well as into the aorta downstream to the distal clamp should be minimized and larger vessels originating from the aorta should promptly be anastomosed to the graft.

[Ambulatory thrombectomy of a graft. Transcutaneous clamping]. / Thrombectomie ambulatoire d'un greffon. Clampage transcutané.

Thrombectomy of a graft in ambulatory patients can be performed simply under local anesthesia, avoiding admission to hospital of patients with shunts. The technique is applicable to two types of shunt: arterio-arterial shunts for lower limb arteriopathy and arteriovenous shunts of a dialysis for chronic renal failure. The advantages are twofold: dissection of a subcutaneous graft is avoided and the patient can either immediately reinstitute activity if arteritic or dialysis for renal failure. The method is effective if the thrombus is of accidental origin, failures resulting from proximal or distal stenosis, their evaluation being possible during thrombectomy.

Glucose clamping and cardiovascular function in endotoxic dogs.

Fasted mongrel dogs were anesthetized with pentobarbital sodium and instrumented for the continuous measurement of blood glucose (BG), a lead II electrocardiogram, and pressures in the left ventricle (LV), pulmonary artery, and aorta. Cardiac output was measured every 15 min using thermodilution and LV stroke work, and pulmonary and systemic resistances were calculated. After a 30-min pretreatment period, glucose clamping was initiated. The desired glucose levels were reached within 45 min (hypoglycemic 20 +/- 1 mg/dl, n = 11; normoglycemic 85 +/- 1, n = 7; hyperglycemic 156 +/- 3, n = 7). At this point dogs were treated with either endotoxin (8 mg/kg to 6 hypoglycemic, 4 normoglycemic, and 4 hyperglycemic) or saline (5 hypoglycemic, 3 normoglycemic, and 3 hyperglycemic). All infusions were terminated after 2 h glucose clamping, and all dogs were monitored either until death or for a maximum of 10 h. Hypoglycemic clamping curtailed survival in endotoxic dogs. Hyperglycemic clamping markedly prolonged survival. Normoglycemic clamping left survival time unchanged compared with untreated dogs. The effects of glucose clamping on cardiovascular function during endotoxic shock paralleled the effects on survival. Cardiovascular function was also depressed in hypoglycemic-clamped saline dogs. It is concluded that glucose dyshomeostasis may be a crucial factor in the development of fatal cardiovascular dysfunction and shock after endotoxin administration.

Experimental evaluation of gastric banding for treatment of morbid obesity in pigs.

The effectiveness and complications of gastric banding were evaluated in 15 miniature pigs. A Gore-tex or Dacron graft was employed to encircle the stomach. The animals were divided into five groups, three pigs in each group. Group 1 had a 13 mm pouch stoma with a Gore-tex band, Group 2 had a 16 mm pouch stoma with a Gore-tex band, Group 3 had a 13 mm pouch stoma with a Dacron band, Group 4 had a 16 mm pouch stoma with a Dacron band, and Group 5 had a sham operation. The weight variation in the control group was significantly higher than that in the other groups at the ninth postoperative week (p less than 0.05). There was no significant difference among Groups 1, 2, 3, and 4. The gastric band had migrated distally in seven pigs. It was located in the body of the stomach in four animals and in the pylorus in three. These three pigs died from stenosis of the pylorus. The band had eroded and penetrated all stomach layers in three other animals. There was no difference in the incidence of postoperative complications between the Gore-tex and Dacron band groups. The use of this simple operation in the treatment of the morbidly obese patient should be applied with caution.

Study of renovascular hypertension in rats: I. The role of the contralateral, non-clipped kidney in two-kidney, one-clip hypertension in rats.

We attempted to produce two-kidney one-clip renovascular hypertension in SD rats, using hemoclips 0.2mm in diameter. After 12 weeks, 10 of the 16 rats were hypertensive. At this point, one-kidney, one-clip models were prepared by contralateral nephrectomy in five of the 10 hypertensive rats and in all six normotensive rats. Postoperatively, these 11 rats developed hypertension. Four to 6 weeks later, the clip was removed from the renal artery in five two-kidney and 11 one-kidney hypertensive rats. After unclipping, all the rats became normotensive although the extent of the fall in blood pressure in the one-kidney model was significantly greater than in the two-kidney model. The roles of the contralateral non-clipped kidney in the evolution of two-kidney, one-clip Goldblatt hypertension appear to be dual; sometimes depressing elevated blood pressure and sometimes maintaining it. Thus, it is postulated that in the six initially normotensive rats, its action was predominantly antihypertensive, while in the other 10 hypertensive rats, the presence of a contralateral non-clipped kidney served to develop and maintain hypertension even after unclipping.

A technique of clipping giant intracranial aneurysms with the preservation of the parent artery.

Several methods are currently available for the treatment of giant intracranial aneurysms. In this report, we emphasize the technique of temporary trapping of the aneurysm followed by aspiration and collapse, and subsequent clipping. This method permits the preservation of the parent vessel and avoids the need for creating a microvascular bypass. Two cases are presented to illustrate this technique; in one case the patient had a giant middle cerebral artery aneurysm, and in the other a giant carotid-ophthalmic artery aneurysm. Both aneurysms were successfully clipped with preservation of the major vessels and a good result. On the basis of the configurations of their necks, giant aneurysms can be classified into three groups. The different methods of treating these aneurysms are reviewed with respect to this classification.

Effect of lung inflation on pulmonary vascular resistance by arterial and venous occlusion.

To explain the changes in pulmonary vascular resistance (PVR) with positive- and negative-pressure inflation (PPI and NPI, respectively), we studied their effects in isolated canine left lower lobes perfused at constant flow rate. The venous pressure was kept constant relative to atmospheric pressure during lung inflation. The total arteriovenous pressure drop (delta Pt) was partitioned with the arterial and venous occlusion technique into pressure drops across arterial and venous segments (large indistensible extra-alveolar vessels) and a middle segment (small distensible extra-alveolar and alveolar vessels). PPI caused a curvilinear increase in delta Pt due to a large Starling resistance effect in the alveolar vessels associated with a small volume-dependent increase in the resistance of alveolar and extra-alveolar vessels. NPI caused an initial decrease in delta Pt due to reduction in the resistance of extra-alveolar vessels followed by an increase in delta Pt due to a volume-dependent increase in the resistance of all vessels. In conclusion, we provided for the first time evidence that lung inflation results in a volume-dependent increase in the resistance of both alveolar and extra-alveolar vessels. The data suggest that while the volume-related changes in PVR are identical with PPI and NPI, there are pressure-related changes that can be different between the two modes of inflation.

Barogenic rupture of the esophagus (Boerhaave's syndrome): successful treatment of a late case.

This article presents a case of barogenic (postemetic) rupture of the esophagus that was diagnosed more than 48 hours after the acute event and subsequently treated successfully. The initial approach of direct esophageal repair, pleural drainage, antibiotics, and intravenous hyperalimentation was not successful. The repair site disrupted, and the patient became critically ill and septic. Salvage of the patient with closure of the fistula and normal alimentation was accomplished by partial distal esophageal occlusion, utilizing a serrated (Miles) vena cava clip.

[The value of Adams and de Weese's technic of cava clipping]. / Der Stellenwert des Cava-Clippings nach Adams und de Weese.

Indications and methods of inferior vena cava interruption in the management of recurrent pulmonary embolism are discussed. The results of a collected series are analyzed with special regard to the partial interruption technique using the Adams and de Weese clip. Five of our own cases, followed up 1 year postoperatively, are presented.