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A new type of pump, the differential displacement pump, has recently been developed. The new pump and a conventional pneumatic displacement pump were evaluated with respect to pump flow, filling pressures, stroke frequency, and inflow pattern under equivalent test conditions. The pumps were connected via inlet and outlet cannulas to a Donovan hydraulic circulation analogue. The differential displacement pump showed a high sensitivity to filling pressure in the range of 2.3-9.6 L/min/mmHg, and a high efficiency as long as the stroke volume was submaximal. The inflow was continuous and pulsatile with a maximal forward flow velocity during systole as long as the maximal stroke volume was not employed. In contrast, the conventional displacement pump showed low sensitivity to filling pressures, a discontinuous inflow, with a maximal inlet cannula forward flow during diastole and a substantial flow reversal during systole. These results indicate that the differential displacement pump is a better concept with respect to sensitivity to venous return, and that it provides an inflow pattern and regulation of pump flow similar to that of the biologic heart.

A case of the "Barrett syndrome" in a patient with severe ulcerating reflux oesophagitis is reported. Evidence indicating that it is an acquired condition caused by reflux of bile-contaminated gastric juice is presented. The "Barrett ulcer" and the oesophagitis healed following a partial gastrectomy with a Roux-en Y gastrojejunostomy. The substitution of the squamous epithelium of the lower 15 cm of the oesophagus by columnar epithelium of cardia type is apparently irreversible.

In 6 patients with cystic medial necrosis of the ascending aorta and the aortic root complete elective replacement of these structures with coronary reimplantation was performed. Two patients died from postoperative left ventricular failure, 4 patients survived and were hemodynamically unaffected at follow-up. Also the heart size in these patients decreased postoperatively. Survival seemed mainly related to the degree of preoperative cardiac failure and cardiomegaly.

Over a 3-year period continuous intravenous infusion of moderate doses of vasopressin in 13 patients bleeding profusely from hemorrhagic gastritis, was associated with rapid control of the bleeding in 11 patients, while in 2 patients prolonged infusion was required to stop the hemorrhage. In 2 patients there was a relapse of the hemorrhage 3 and 7 days after the initial treatment, which was successfully controlled by renewed vasopressin infusion. There was no mortality and no complications of the vasopressin treatment were encountered. The results compared favourably with the experience from the preceding 3-year period where a comparable group of patients undergoing conventional medical and surgical treatment suffered a mortality of 38%. This study therefore suggests that vasopressin infusion performed continuously with moderate doses over extended periods, improves survival of patients with severe hemorrhagic gastritis through control of bleeding.

Four cases of suture line ulcers after gastric surgery caused by nonabsorbable suture material are presented. The literature is reviewed, and a plea ia made for the use of absorbable suture materials in gastrointestinal surgery.

A variable pattern of organ flow distribution was observed during experimental hypo- and hypercarbia. Mainly two patterns of organ flow changes emerged in that hepatic, renal and skeletal muscle flow showed a decreasing tendency during hypercarbia while gastrointestinal, myocardial and cerebral flow increased during hypercarbia and decreased during hypocarbia. These changes were accompanied by typical central hemodynamic changes including a decrease in systemic and pulmonary vascular resistance during both hypocarbia and hypercarbia which was also accompanied by decreased myocardial contractility.

Thirteen patients between 5 and 13 years were presented as a normal material for statical and dynamical echocardiographic measurements including left ventricular internal diameter in diastole and systole, shortening fraction, cardiac output, mean VCF, maximal normalized and not normalized rates of increase and decrease of diameter. The data were compact and normally distributed, and the rates of diameter change were independent of patients' age and BSA, and may therefore be used as general reference.

Acute gastric volvulus in a young patient with a known chronic torsion of the stomach is reported. Unfamiliarity with the condition resulted in delayed admittance for surgery where a necrotic stomach and left lower pulmonary lobe were removed. The pathogenesis and treatment of this uncommon disorder is discussed.

The experience after implantation of 3,334 Björk-Shiley valves over a 15 year period is described. With a 99.2% follow-up (covering 17,511 patient-years, mean follow-up time 6.3 years) and an autopsy rate of 75% among all fatalities, altogether 19 cases of mechanical failure were documented. There were no mechanical failures among the standard Delrin Björk-Shiley valve (n = 271), the aortic standard Pyrolyte Björk-Shiley (n = 739), or the Monostrut Björk-Shiley valve (n = 377). One of the mitral standard Pyrolyte valves (n = 430) fractured. Among the 1,461 convexo-concave valves, 18 fractured (6/884 with an opening angle of 60 degrees and 12/577 with an opening angle of 70 degrees). The actuarial incidence of mechanical failure at 5 years was 0.6% (with an upper 95% confidence limit of 1.2%) for the 60 degree convexo-concave valve and 2.8% (upper 95% confidence limit of 4.4%) for the 70 degree convexo-concave valve (p less than 0.01). Two groups of valves were especially affected by this complication; the 23 mm aortic 60 degree convexo-concave valve (5 year actuarial incidence 2.2%, upper 95% confidence limit 4.7%) and the 29 to 31 mm mitral 70 degree convexo-concave valve (8.3%, upper 95% confidence limit 14.2%). The hazard function presently indicates a constant (60 degree convexo-concave) or decreasing (70 degree convexo-concave) tendency for mechanical failure. The time interval between the first symptom of mechanical failure and circulatory collapse was significantly (p less than 0.01) shorter after aortic failure than after mitral failure, and no patient with a fractured aortic prosthesis survived long enough to undergo reoperation. The incidence of mechanical failure among patients dying suddenly (but with an autopsy) was 9.6% (95% confidence limits 4.9%-16.6%), and most cases of sudden death were unrelated to the prosthesis. The management of patients with suspected mechanical failure is described. Prophylactic re-replacements are discussed but cannot be generally recommended at present.

The Jarvik-7 total artificial heart has been implanted in 18 patients at the time of this writing. Eleven patients received the 100 ml heart, and the remaining seven were treated with the 70 ml device. To date, five patients have been implanted for permanent use with an average survival in excess of 9 months, and the longest survival is more than 1 1/2 years following implantation of the heart. Complications related to positioning were a contributing factor in the death of one patient. Thirteen patients have received the Jarvik-7 heart as a bridge to transplant. Three died before transplant, and the remaining ten have been transplanted. To date, all are alive, several are home and in excellent condition, and several are still hospitalized but are expected to be released shortly. Three patients have experienced serious complications after transplantation. One patient rejected her heart transplant, was reimplanted with the artificial heart, and now has been sustained for more than 3 months. At this time she is in good condition awaiting a second donor. Selection of the appropriate size Jarvik-7 artificial heart for the individual patient can best be made based on measurements of thoracic dimensions obtained from a computed tomography scan and calculation of body surface area. The appropriate medial or lateral positioning can be determined and decisions concerning the lengths of the grafts and cuffs, excision or nonexcision of the left pericardium, and air drive line position can be made. The Jarvik-7 heart can be successfully used in patients from 50 kg. However, at the lower size limit in patients from approximately 50 to 65 kg, the risk of fit complications is the greatest and availability of an even smaller model heart would be desirable.

A review of the world experience with the implantation of total artificial hearts has been carried out. Thirteen centers throughout the world have implanted 27 total artificial hearts in 26 patients. Eight different types of total artificial hearts have been employed. As of June 1, 1986, five of these individuals have had implants for permanent support. Of the other twenty-one patients, three patients died while on a total artificial heart, seven patients died following transplantation, two patients are waiting for transplant, and nine patients have successfully been transplanted and are presently alive. Various clinical preoperative and postoperative parameters are analyzed in this investigation.

Misinterpretation of confusing cardiac, constitutional, and embolic symptoms delayed the diagnosis of cardiac myxoma and caused two of 18 patients to undergo acute operations during cardiogenic shock with pulmonary edema. In recent cases echocardiographic screening of unclear cardiac symptoms gave the correct diagnosis early. Despite the simple surgical procedure (excision of tumor and underlying endocardium), the postoperative course was complicated by cardiac failure, arrhythmias, and systemic reactions. Prosthetic valve thrombosis and malignancy caused two early deaths. Two patients died later of cerebrovascular insults. Both belonged to a group of five patients having preoperative emboli from fragile myxomas. Four of these five had coronary or cerebral myxomatous pseudoaneurysms. A 6 year follow-up, including recatheterization, showed no tumor recurrence and generally normalization of the clinical condition, heart size, and catheterization findings. Even pronounced mitral insufficiency accompanying left atrial myxomas had subsided spontaneously. Tricuspid insufficiency in two patients with right atrial myxomas persisted, necessitating reoperation in one. When diagnosed, a cardiac myxoma should be removed promptly to reduce cardiac and embolic complications, including myxomatous pseudoaneurysm formation, which might be more frequent than previously recognized.

Intravenous infusion of vasopressin decreased mesenteric arterial- and portal venous flow in dogs. In 4 of 5 high-risk patients, in whom acu te portosystemic shunting was performed, the peroperative intravenous infusion of vasopressin facilitated the surgical procedure by reducing portal pressure and peroperative bleeding from venous collaterals. In 1 patient with reversed portal flow, the portal pressure and flow were not affected by the vasopressin infusion. No undesirable effects of vasopressin were encountered and all patients survived surgery and the early postoperative period.

In a series of 113 patients receiving Hall-Kaster aortic valve prostheses intraoperative- and postoperative hemodynamic studies revealed favourable utilization of the valve orifice for transvalvar forward flow. Angiography demonstrated optimal disc opening and minor valvar regurgitation. A significant clinical improvement and improvement of left ventricular function were observed postoperatively.

A patient with acute ischaemia of the abdominal organs after coeliac- and superior mesenteric artery occlusion is reported. Following vascular reconstruction and resection of gangrenous colon and ileum the main early postoperative problem was hepatic failure. A grave malabsorption syndrome developed necessitating periodic i.v. hyperalimentation. The patient showed no improvement of intestinal function and died 5 months postoperatively from peritonitis.

Intraoperative as well as postoperative assessment of effective orifice area, determined by relating flow through a prosthetic heart valve to the pressure gradient measured across the valve, provides a data base for comparison of different types of cardiac prostheses. As a measure of valve performance, we have used the derivation of both the effective area according to the Aaslid formula measured intraoperatively and to the Gorlin formula measured at a re-catheterization study. We also established the parameter 'effective index area', Ia or Ii. Ia is defined as the ratio between the effective orifice area and the annulus orifice area, and Ii as the ratio between the effective orifice area and the internal orifice area of the valve housing. The patients included in the study had either Lillehei-Kaster, Björk-Shiley or Hall-Kaster aortic valve prostheses inserted. In most of the Lillehei-Kaster prostheses, Ia varied around 0.27 and Ii around 0.56, while the corresponding values in the Björk-Shiley prostheses were 0.35 and 0.56, increasing to around 0.50 and 0.75 respectively in the Hall-Kaster prostheses.