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Biomedical subjects

J Dale

Publications and source records attributed to J Dale.

At least 163 records · Page 9Linked to original sources
PubMed1983

Mitral disc valve implantation in the dog: early and late valve thrombosis and its prevention.

Valve thrombosis and its prevention was studied in 33 Labrador retriever dogs who received Hall-Haster mitral disc valves during extracorporeal circulation with extreme hemodilution. Three antithrombotic regimes were used. (1) 12 dogs received 1 g heparin preoperatively, and Warfarin tablets from the first postoperative day. Anticoagulation was controlled with thrombotest (TT), aiming at 20-25% of normal coagulation activity. (2) 9 dogs received 10 mg of heparin intravenously hourly for 10 h, and intravenous injections of Warfarin daily, aiming at TT values of 15-20%. (3) The last 12 dogs had continuous heparin infusion for 24 h, and Warfarin injections before as well as after the operation in doses sufficient to reduce the TT to 10-15% of normal. Stable anticoagulation was very difficult to maintain. Only 15 dogs survived the first postoperative day, 7 were alive after 4 weeks. 7 early and 5 late deaths were due to valve thrombosis. All three antithrombotic regimes were equally ineffective in preventing thrombosis, and more intensive antithrombotic prophylaxis is needed to make the canine model suitable for experimental open-heart surgery.

Animals↗
PubMed1983

False suspicion of coronary heart disease: a 7 year follow-up study of 36 apparently healthy middle-aged men.

Latent coronary heart disease was suspected in 115 of 2014 apparently healthy middle-aged men after a baseline cardiovascular survey. One hundred five of these men underwent angiography and 36 were found to have normal coronary arteries (group 1). A 7 year follow-up survey revealed that: (1) three had died of sudden cardiac death, (2) four had received a diagnosis of cardiomyopathy, (3) one had developed aortic dilatation/aortic regurgitation since the baseline survey, (4) they all had a significantly more rapid decline in their physical performance and maximal heart rate levels from the time of the baseline survey to follow-up than did randomly selected normal controls (group 2), and (5) thallium study results were normal in both groups (27 and 26 patients), but technetium ventriculography revealed a subnormal increase in ejection fraction during exercise (less than 5% units) in 14 of 27 group 1 subjects and in 4 of 26 group 2 subjects. Thus, incipient heart disease may be present in subjects in whom coronary angiographic examination has removed a previous suspicion of coronary heart disease.

Adult↗
PubMed1982

Anterior left ventricular wall circulation in patients with coronary artery disease.

The human anterior left ventricular circulation was investigated at rest and during submaximal atrial pacing by measuring the great cardiac venous blood flow by the constant infusion thermodilution method. Forty-seven patients with angina pectoris participated in the study and were grouped stepwise according to degree of arteriosclerosis in the left anterior descending coronary artery (LAD), from normal to occluded vessel. Special attention was paid to patients with earlier infarcts and to collateral circulation. Blood flow to the myocardium was slightly but significantly reduced only among patients with a subtotal stenosis of the LAD without demonstrable collateral circulation, and only during atrial pacing. This conforms with an increased coronary arteriolar resistance in these patients. Myocardial oxygen extraction was, however, increased in all groups of patients with LAD stenosis from 50% to occlusion, except in patients with an earlier anterior wall myocardial infarction. This suggests a disproportion between oxygen demand and blood flow leading to increased extraction in patients without infarcts and a shunting of blood through scarred myocardium with a low oxygen demand in those with a previous necrosis, and is confirmed by a decreased ratio between myocardial flow and cardiac work. Patients with an increased oxygen extraction may benefit from coronary bypass surgery to the LAD area while those without may not.

Angina Pectoris↗
PubMed1982

Pacing induced angina and platelet reactivity.

Platelet function was studied during pacing-induced angina pectoris in nine patients with coronary heart disease. Blood was sampled via catheters from the coronary sinus and the aorta at rest and during angina. The influence of the sampling procedures on the platelet function was evaluated in blood collected via catheters and via short venflons. The catheter induced pseudopod formation in the platelets. The aggregation response was similar, while platelet retention as measured with Hellem's method for native blood, was slightly lower in blood collected via catheters than via venflons. At rest the maximal rate of primary, ADP-induced aggregation was lower in blood from the coronary sinus than from the aorta, as was the percentage of platelets retained in glass bead columns. The ability of platelets to produce prostaglandin metabolites, estimated from malondialdehyde formation after thrombin stimulation was also moderately, but significantly lower in coronary sinus blood. During pacing-induced angina primary, ADP-induced aggregation and platelet retention values remained significantly lower in blood that had passed the coronary circulation than the aortic blood. There were no differences between aortic or coronary sinus samples collected at rest than during pacing. Unchanged platelet counts indicates that trapping of platelets did not occur. Thus, platelet reactivity was lower in coronary sinus than aortic blood at rest in patients with coronary heart disease, and a moderate pacing-induced angina did not influence this pattern.

Adenosine Diphosphate↗
PubMed1981

Can acetylsalicylic acid alone prevent arterial thromboembolism? A pilot study in patients with aortic ball valve prostheses.

Encouraged by the effective prevention of arterial thromboembolism with a combination of ASA and anticoagulants (9), the present study was done in 77 patients with a single Starr-Edwards aortic ball valve. They received one gm. of ASA daily, then the dose of anticoagulants was reduced gradually and the drug discontinued on average five weeks later. Six arterial embolic episodes occurred in five patients, the incidence being 14.5 complications per 100 patients per year. Five emboli were cerebral, none of them serious, and one was removed from a femoral artery. Four of the embolic episodes occurred in three of the 11 patients with continuous arrhythmia, probably from venus thrombi that developed in the left atrium. The occurrence of only two embolic complications in the 66 patients with sinus rhythm suggests some prevention of arterial thrombus formation on the prosthetic valves. The results indicate that ASA is inferior to anticoagulants in patients with arrhythmia, while it may represent an alternative to anticoagulation in individuals with sinus rhythm. We prefer, however, the combined therapy in patients with aortic valve prostheses because of the strong anti-thrombotic effect achieved by this treatment.

Adult↗
PubMed1981

Prevention of closure of aorto-coronary venous bypass grafts.

Aorto-coronary saphenous vein bypass graft implantation has led to a considerable relief of angina in a great majority of patients. Their functional capacity has been increased, and life possibly prolonged. During the postoperative period approximately ten per cent of the grafts occlude because of thrombosis, and later 2-3 per cent occlude per year. The angina returns in some patients, which is related either to graft closure or to progression of arteriosclerotic disease in the coronary arteries. A randomized clinical study has therefore been started in 142 patients in order to prevent graft closure. Two to three days after operation, one group of 72 receive acetylsalicylic acid, one gm. daily, and anticoagulants, while the 70 patients in the control group receive no antithrombotic drugs, and are asked to avoid anti-inflammatory agents. After 18 to 24 months, they are admitted for follow-up, including re-catheterization with selective angiography of coronary arteries or grafts. The effect of therapy will be assessed from graft potency alone.

Angina Pectoris↗
PubMed1980

Intravascular hemolysis and ultrastructural changes of erythrocytes in lethal canine endotoxin shock.

Intravascular hemolysis and ultrastructure of erythrocytes from liver sinusoids were studied during and after infusion of Escherichia coli endotoxin in Labrador retriever dogs. Endotoxin infusion caused hemoconcentration, and induced disseminated intravascular coagulation (DIC), characterized by a rapid drop of platelet numbers, a gradual consumption of coagulation factors and activation of fibrinolysis. Advanced DIC and circulatory shock gradually developed, and the animals died after 7-15 h. Plasma hemoglobin concentrations did not rise for several hours, but late in the experimental period a significant intravascular hemolysis was constantly found. Circulating adenosine diphosphate (ADP) did not appear. During shock, liver biopsies revealed accumulation of erythrocytes often disintegrated within distended sinusoidal lumina. In advanced shock the fragmented erythrocyte seemed to form occlusive masses within the vessels. A fibrin-like material frequently appeared adjacent to the red cells. However, it did not have the periodicity characteristic for fibrin, and the ultrastructure of the material was very similar to that inside the erythrocytes. None of these changes were induced by saline infusion in control animals. The lack of fibrin formation and the late development of intravascular hemolysis indicate that red cell breakdown was of little importance for the initiation and progress of DIC.

Animals↗
PubMed1980

Development of a canine model for long-term studies after mitral valve replacement with the hall-kaster prosthesis.

The present study was designed for long-term evaluation of the recently developed Hall-Kaster heart valve prosthesis. Mitral valve replacement was performed in 33 dogs. A detailed description of the operative procedure used is given. Extracorporeal circulation was instituted using a nonhemic priming volume resulting in an extreme hemodilution with hematocrit of about 15%. 19 of the animals died within 24 h, while 7 survived the observation period of 4--6 weeks. Thrombus on the valve was the major cause of early and late deaths. Anticoagulants were therefore given, and the therapy was made more extensive as the study progressed. The anticoagulation regime finally comprised warfarin administration preoperatively and throughout the experiment, and heparin infusion during the first 24 h postoperatively. Neomycin was used for preoperative sterilization of the gut. Later, cephalotin and penicillin were given. The use of these anticoagulants and antibiotics was found to be of major significance in providing us with a satisfactory canine model for long-term in vivo evaluation of the prosthesis.

Animals↗
PubMed1980

Blood cells and coagulation during experimental lung insufficiency in dogs.

Thromboembolism of minor vessels in the lungs is almost constantly seen in posttraumtic lung insufficiency. Many investigators consider it as the primary factor in the pathogenesis of this condition. The present paper deals with screening of the coagulation system as part of a more extended project also investigating changes in the fibrinolytic system and the kallikrein-kinin system. The data are also to be compared with morphological findings during the development of experimental posttraumatic lung insufficiency. The experimental syndrome was evoked in Labrador retriever dogs by haemorrhagic hypotension combined with clamping of the portal triad. The surgical procedure was extended to additional thoracotomy in one group of dogs. Group I, without thoracotomy, were followed for 12 hours. Group II, with thoracotomy, were followed until they succumbed (3-14 hours). Thrombotest (TT) showed a steady prolongation of clotting time in both groups, whereas Cephotest did not reveal any alterations, except for a significant prolongation in group II just before collapse. Fibrinogen was markedly reduced in both groups. Platelets and leucocytes were significantly reduced, but only in group II. It is concluded that the present data are indicative of disseminated intravascular coagulation. The involvement of the intrinsic coagulation system is questioned.

Animals↗
PubMed1979

Myospherulosis: further ultrastructural observations.

The changes of myospherulosis were observed in masses from the buttocks of three patients. Ultrastructural examination of parent bodies and spherules from two patients revealed some spherules to contain dense bodies and filaments. Spherules had a double electron dense wall: the outer layer had a thickness corresponding to that of a cell membrane. Incubation of packed red blood cells with tetracycline ointment produced a similar electron dense deposit on the inner aspect of the cell membrane of the erythrocytes. No filaments or parent bodies were seen. Our findings support the hypothesis that myospherulosis represents altered red blood cells. The filaments seen in our patients may represent polymers of haemoglobin. It is suggested that parent bodies may be derived from histiocytes.

Adult↗
PubMed1978

Intravascular hemolysis in the late course of aortic valve.

The degree of intravascular hemolysis was evaluated in 315 patients in the late course of aortic valve replacement. Starr-Edwards aortic ball valves of series 2300 caused significantly more hemolysis than did those of series 1200, as estimated from the serum lactate dehydrogenase levels. Smaller valves of series 2300 caused a higher degree of hemolysis than did the larger ones. Aortic disc valves induced a more moderate red cell destruction than did the ball valves, the Lillehei-Kaster significantly more than the Bjørk-Shiley prostheses. Crushing of red cells is thought to be a more important cause of hemolysis than shearing forces in turbulent blood. Hemolytic anemia represented a problem only in some patients with Starr-Edwards valve type 2300, although iron substitution was necessary also in some with other prostheses, since the hemoglobin-binding capacity of haptoglobin was exceeded in several patients. Valvular or paravalvular leakage was associated with stronger hemolysis in some patients, and should be suspected whenever the rate of red cell destruction increases. Longstanding intravascular hemolysis did not seriously affect renal function.

Anemia, Hemolytic↗