Surgical considerations in the treatment of cardiac myxoma.

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.

Mechanical failure of the Björk-Shiley valve. Incidence, clinical presentation, and management.

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.

Three-year clinical results with the Monostrut Björk-Shiley prosthesis.

Between November 1981 and June 1983, 351 patients underwent valve replacement with the Monostrut Björk-Shiley prosthesis. There were 214 aortic valve replacements, 101 mitral valve replacements, and 31 double (aortic and mitral) valve replacements. Four patients had valve implanted in the tricuspid position, and one patient underwent exchange of a valved, extracardiac conduit. Mean age was 61 years (range 2 to 78) and 186 (53%) were male. Concomitant procedures were performed in 52 patients (15%) and 17 (5%) were emergency operations. Early mortality (4.3%) was related to New York Heart Association Functional Class IV, emergency operation, or the presence of a concomitant procedure. Follow-up was 100% and covered 870 patients-years (mean 2.6 years per operative survivor). Postmortem examination was performed in 38 (79%) of the 48 fatalities. Only one patient suffered a sudden, unexplained death. The 3 year survival rate (early mortality excluded) was 88.6% (aortic valve replacement 89.2%, mitral valve replacement 89.3%, and double valve replacement 82.5%). The 3 year freedom from thromboembolism in patients receiving anticoagulants was as follows: aortic valve replacement 97.5%, mitral valve replacement 92.8%, and double valve replacement 100%. There were no instances of valve thrombosis or fatal embolism. In contrast, there were two instances of aortic valve thrombosis among 34 patients having aortic valve replacement without anticoagulation. The 3 year freedom from valve failure (modified Stanford definition) was as follows: aortic valve replacement 96.0%, mitral valve replacement 93.9%, and double valve replacement 89.7%. There were no mechanical failures. In conclusion, the Monostrut Björk-Shiley valve showed a low incidence of complications. There were no mechanical failures, no fatal emboli, and, when anticoagulants were administered, no valve thromboses.

Magnetic resonance imaging of the brain before and after open heart operations.

Magnetic resonance imaging of the brain was performed in 29 adult male patients before and 1 week after elective coronary artery bypass grafting to study the cerebral effect of cardiopulmonary bypass. The mean age of the patients was 60 years (range, 45 to 69 years). During cardiopulmonary bypass, either a bubble oxygenator without an arterial line filter (n = 9), a bubble oxygenator with a depth adsorption filter (n = 10), or a flat-sheet membrane oxygenator without a filter (n = 10) was used. The mean bypass time was 88 minutes (standard deviation, 31 minutes) and did not differ significantly between the three groups. Preoperative magnetic resonance imaging revealed high signal intensity foci on T2-weighted images (white matter abnormalities) in 17 (59%; 95% confidence limits, 39% to 76%) of the 29 patients, all of which were nonspecific and of the common type considered to be related to aging, and all were unchanged at the postoperative examination. Preoperative and postoperative frontal horn indices, bicaudate diameters, and third ventricle widths did not differ significantly regardless of oxygenator type or whether or not an arterial line filter was used during cardiopulmonary bypass. Two patients (7%; 95% confidence limits, 1% to 23%), both receiving bubble oxygenation (1 without a filter and 1 with an arterial line filter) sustained a cerebral infarction during cardiopulmonary bypass.

Should the lungs be ventilated during cardiopulmonary bypass? Clinical, hemodynamic, and metabolic changes in patients undergoing elective coronary artery surgery.

No beneficial effects were achieved by ventilating the lungs of a group of 10 patients during total extracorporeal circulation for coronary artery bypass operation. Ventilation of nonperfused lungs, which was suggested to prevent postoperative atelectasis, may even have negative effects. Intrapulmonary shunting increased significantly (p less than 0.05), while the shunt fraction in the nonventilated lungs of another group of 10 patients remained unchanged. There were only minor differences between the two groups with respect to systemic and pulmonary hemodynamic changes.

In vitro flow characteristics of the Jarvik-7 prosthesis with respect to filling pressure, stroke frequency, and systolic duration.

The Jarvik-7 total artificial heart (TAH), as an implantable substitute for the natural heart, has become the most widely used prosthesis. Although the performance of the Jarvik-7 prosthesis has been described experimentally as well as clinically, the interrelationship between cardiac output, filling pressure, stroke frequency and systolic duration in a wider perspective has not been reported. Our in vitro evaluation of the pump demonstrates the relation between cardiac output and right filling pressure in the range of 2-17 mm Hg with a stroke frequency varying between 60-130 beats per minute with 40% and 50% systolic duration. With respect to complete ventricular filling, a safer and wider range of right filling pressures and stroke frequencies could be employed to produce various cardiac output values at 50% systolic duration as compared to 40% systolic duration. When complete diastolic filling was present, particularly with a high stroke frequency and a low systolic duration, an increase of the left filling pressure to an extent which in a clinical situation would probably cause pulmonary oedema, was observed. By using a right Jarvik-7/70 ml ventricle and a left Jarvik-7/100 ml ventricle, this buildup of the left filling pressure was completely avoided.

Complete replacement of the ascending aorta and the aortic valve with coronary reimplantation.

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.

The Hall-Kaster disc valve prosthesis: clinical and hemodynamic observations in patients undergoing aortic valve replacement.

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.

Peroperative vasopressin infusion during portocaval shunt surgery.

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.

Regional gastric flow determined by a hydrogen clearance technique in anesthetized and conscious animals.

Gastric microcirculatory studies were performed by a hydrogen clearance technique in anesthetized and conscious cats. The highest flow values were observed in the mucosa, while submucosal flow was higher than muscularis flow. During anesthesia antral blood perfusion exceeded corpus perfusion, but this relationship was reversed in favor of the corpus region in conscious animals.

Regional gastric flow changes after meal stimulation measured by the hydrogen clearance technique in conscious cats.

Regional gastric mucosal flow changes were studied, after meal stimulation, with hydrogen clearance techniques in conscious cats. Generally, a substantial initial increase of corpus mucosal flow was accompanied by a moderate decrease of antral mucosal flow. These changes were reversed at the end of the secretory phase. Autoregulation of gastric flow, with the potential of regional flow increase in areas of augmented metabolic activity, is suggested as a possible explanation of the pattern of antral/corpus mucosal flow shifts accompanying physiological gastric secretory stimulation.

The effect of catecholamines on gastric mucosal flow.

The effect of intravenous administration of adrenaline, noradrenaline, and isoprenaline on gastric mucosal flow, measured by hydrogen clearance techniques, showed that small doses of adrenaline induced slight mucosal vasodilatation in anaesthetized cats. In both anaesthetized and conscious animals both noradrenaline and large doses of adrenaline produced mucosal vasoconstriction, whereas isoprenaline increased gastric mucosal flow. Similar effects were observed in acute experiments after vagotomy. In the awake animal noradrenaline, adrenaline, and isoprenaline depressed pentagastrin-stimulated acid secretion.

Gastric flow measured with hydrogen clearance technique.

Regional gastric flow could be measured by hydrogen clearance technique. This method permitted the simultaneous measurement of flow in the mucosa, submucosa, and muscularis of both the antrum and corpus in anesthetized dogs. The main advantage of this method compared with other techniques used for gastric microcirculatory studies is that it offers the opportunity of repeated flow determinations in an anatomically identical area under various experimental conditions.

Gastric cooling and regional gastric mucosal flow in anesthetized animals.

Regional gastric mucosal flow was measured by hydrogen clearance techniques during gastric cooling. At subnormal temperatures a considerable augmentation of mucosal flow was observed both in the antrum and corpus region. At mucosal temperatures below 15 degrees C, which only could be reached by continuous balloon perfusion of the stomach with chilled water, a moderate decrease of mucosal flow occurred in normothermic animals. On the basis of the presented results it appears debatable whether gastric cooling has any place in the treatment of bleeding from gastric mucosal lesions as a means of reducing gastric mucosal flow.

Changes of regional gastric flow measured by hydrogen clearance techniques after histamine stimulation in conscious animals.

Gastric microcirculatory changes were studied by means of hydrogen clearance techniques in conscious cats during histamine stimulation. A considerable increase of corpus mucosa flow occurred, whereas a less substantial increase of antrum mucosa flow was observed during stimulation with histamine at 2 micrograms/kg/min, intravenously. Stepwise increase of infused histamine was accompanied by a gradual increase of corpus flow in the mucosa, which during supramaximal stimulation decreased slightly but still remained considerably elevated above control values. A similar decrease of antral mucosa flow occurred earlier during maximal stimulation, suggesting shunting of blood from the antrum to the corpus region. Total gastric flow measurements performed in anesthetized animals similarly showed decreased flow at a rate of histamine infusion which produced supramaximal stimulation in the conscious animals. However, total gastric flow remained elevated also during this stage compared with prestimulation values. A hypothesis of a dual effect of histamine on the gastric circulation is suggested, including regulation of flow through generalized vasodilatation and increased metabolic activity in the parietal cell mass.

Effect of pentagastrin on regional gastric blood flow in conscious cats.

Total gastric flow studies indicated that a transient, considerable flow increase was followed by a more moderate increase of total gastric flow during pentagastrin stimulation in anesthetized cats. In conscious cats regional gastric flow studies, using hydrogen clearance techniques, suggested that raised flow to the corpus region during the stimulation period was accompanied by a moderate decrease of antral flow.

A modified nonpulsatile flow system for the in vitro study of cardiac valve prostheses.

An in vitro system was constructed for measurements of resistance to forward flow by cardiac valve prostheses at a wide spectrum of flow rates. There was a close correlation between the known area of constriction (valvular orifice) and that calculated from the flow/pressure relationship using derivations of the Bernoulli equation. This simple setup appears particularly suited to determine hydrodynamic efficiency of various cardiac valve concepts on a comparative basis.

In vitro hydrodynamic performance of various cardiac prosthetic valves tested in a modified nonpulsatile flow system.

Hydrodynamic studies were performed in a modified nonpulsatile flow system to compare the efficiency of various prosthetic cardiac valves in vitro. Apart from direct flow/pressure relations across the valves the effective orifice area available for forward flow was determined by derivations of the Bernoulli hydrodynamic equation. By defining the relationship between calculated effective orifice area and known orifice area of the valves a more precise appraisal of the hydrodynamic characteristics of the various valve designs was possible.

Evaluation of left ventricular function in children. Description of the method and normal values.

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.