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Biomedical subjects

T Frøysaker

Publications and source records attributed to T Frøysaker.

At least 19 recordsLinked to original sources
PubMed1992

Hemodynamic evaluation of the CarboMedics prosthetic heart valve in the aortic position: comparison of noninvasive and invasive techniques.

Seventy-three patients with a CarboMedics aortic bileaflet valve prosthesis were examined by Doppler ultrasonography, and 27 of them were also assessed by transseptal catheterization. The ultrasonic mean systolic gradient was 17.1 +/- 5.6 mm Hg for valve size 19 mm, falling gradually with increasing valve size to 6.8 +/- 2.5 mm Hg for size 27 mm. The catheter mean systolic gradient was consistently smaller than the ultrasonic gradient (4.3 +/- 4.8 mm Hg), but Tobit regression analysis showed a significant association between the two methods. In all patients both methods revealed negligible to small amounts of retrograde leakage, which is assumed to be a normal finding for this valve. The effective flow areas of the valves calculated from the ultrasonic data were similar to the in vitro calculated flow areas. The hemodynamic potential of this valve is therefore completely utilized in vivo. The effective orifice area corrected for body surface area increased with increasing valve size, which demonstrates a moderate valve-patient mismatch.

Adult↗
PubMed1992

Patency of the internal mammary artery used as sequential graft.

In 28 patients with the left internal mammary artery (IMA) used as a sequential coronary artery graft, clinical and angiographic evaluation was made 19-47 months postoperatively. Patency was 96% in the proximal anastomoses and 93% in all the anastomoses. Angiography, however, showed optimal function in only 75% of the distal graft ends. These observations indicate that routine use of left IMA as a sequential graft should be restricted to experienced surgeons. Clinical and angiographic findings did not always correlate, emphasizing that evaluation of IMA-graft patency should include angiography.

Adult↗
PubMed1992

Morbidity risk factors in human cardiac transplantation. Histoincompatibility and protracted graft ischemia entail high risk of rejection and infection.

Data from the first 103 human heart transplantations performed on 100 recipients (aged 14-62 years) at a single center from November 1983 to January 1990 were analyzed in order to detect morbidity-causing risk factors. Cumulative one- and five-year graft survival was 82% and 68%. Multivariate analysis revealed three independent risk factors for early rejection, viz. HLA-DR and HLA-B mismatches and no prior cardiac surgery. Graft ischemic time exceeding 71 min was an independent risk factor for rejection, especially for moderate or severe events, and for infection. HLA-DR mismatch was an independent risk factor for moderate and severe rejection events and for infections. Finally, patients operated on because of end-stage ischemic heart disease were at significantly higher risk of rejection than those with other cardiac disorders. The study has several implications: Prospective tissue typing for cardiac transplantation and selection of donors may have an impact on graft function: Damage to the graft by prolonged ischemia may be reduced by improved organ preservation.

Adolescent↗
PubMed1991

[Results of 6 1/2 years of heart transplantation at Rikshospitalet].

We discuss our experience from 6 1/2 years of orthotopic heart transplantation at Rikshospitalet (the National Hospital). 112 grafts were performed on 109 patients (19 women and 90 men), mean age 47 years (range 14-63). In the first nine patients the immunosuppressive regimen consisted of cyclosporine A and prednisolone, and in the last 100 azathioprine was added (triple medication). There was no operative mortality. 21 patients died, giving an 81% cumulative survival, with a significantly better prognosis among those who received triple immunosuppressive regimen. The main complications were rejection, infection and arrhythmia. Since our main problem was rejection it is concluded that careful supervision, concentrated on as few cardiologists as possible, and a liberal indication for myocardial biopsy, are decisive for the prognosis.

Adolescent↗
PubMed1991

[Single lung transplantation as treatment of terminal lung diseases].

The article describes the first cases of single lung transplantation in Norway. The indication for surgery was end-stage pulmonary disease (1 sarcoidosis, 2 emphysema) in three severely disabled patients requiring administration of oxygen. The operation necessitated cardiopulmonary bypass in all patients. Primary graft function was excellent. Epidural analgesia, peripheral pulse oxymetry and continuous monitoring of mixed venous oxygen saturation aided early extubation. The initial postoperative course with a four drug immunosuppressive regimen has been encouraging. Rejection is monitored by clinical examination, chest x-ray, serial pulmonary function tests and transbronchial biopsies.

Adult↗
PubMed1991

Risk factors for total and cause-specific mortality in human cardiac transplantation. Prolonged extracorporeal bypass time: a high risk factor for rejection and infection.

Data from the first 103 human heart transplantations in 100 recipients performed at a single centre from November 1983 to January 1990 were analysed to detect risk factors for overall and cause-specific mortality. Twenty-two patients died. Cumulative 1 year graft survival was 82% and 5 year, 68%. Acute and chronic rejection was the cause of death in 9 patients, disseminated infection in 8 and cancer in 3. One patient died from cerebral haemorrhage and 1 from acute cardiac failure. The mean observation time was 803 days (range: 1-2 308 days). Total follow-up was 226.6 graft years. Risk factors were analysed by univariate and multivariate methods. The type of immunosuppression regimen and recipient age above 50 years were independent risk factors for mortality. Histocompatibility mismatching (HLA-DR) and type of immunosuppression were independent risk factors for lethal rejection and a female recipient was an independent risk factor for lethal infection. Prolonged time on extracorporeal bypass was an independent risk factor for both lethal rejection and infection, and also for overall mortality. The impact of extracorporeal bypass time on rejection and infection is discussed, and the importance of prospective HLA matching in heart transplantation is stressed. The association between recipient female sex and infection remains uncertain.

Adolescent↗
PubMed1991

Effects of chronic amiodarone treatment on human myocardial beta adrenoceptor density and adenylate cyclase response.

STUDY OBJECTIVE: The aim of the study was to evaluate the effect of chronic treatment by amiodarone on beta adrenoceptor density and adenylate cyclase response in human myocardium. DESIGN: Density of beta 1 and beta 2 adrenoceptors was measured by radioligand binding assay. beta Adrenoceptor stimulated production of cAMP was measured by adenylate cyclase assay. EXPERIMENTAL MATERIAL: Right auricular tissue from five patients on chronic amiodarone treatment was compared with that from nine patients in similar clinical and haemodynamic state undergoing coronary bypass surgery. MEASUREMENTS AND MAIN RESULTS: beta 1 and beta 2 adrenoceptor subtypes were quantified using the highly beta 1 selective antagonist Sandoz 204 545. The total beta adrenoceptor density was 28% lower in the amiodarone treated group than in the controls (42.0 v 58.3 fmol.mg-1 protein, p less than 0.02), beta 1 adrenoceptors were 25% lower (33.1 v 44.3 fmol.mg-1 protein, p less than 0.02), and beta 2 adrenoceptors were 36% lower (8.9 v 14.0 fmol.mg-1 protein, p less than 0.02). The cAMP production following non-selective beta adrenoceptor stimulation (isoprenaline 5 mumol.litre-1) was reduced by 38% in the amiodarone treated group (14.2 to 8.7 pmol.min-1.mg-1 protein, p = 0.05). Terbutaline stimulated cAMP production was reduced by 49% (8.3 to 4.3 pmol.min-1.mg-1 protein, p = 0.03). Fluoride stimulated cAMP production was not significantly different (9.4 v 8.4 pmol.min-1.mg-1 protein, p = 0.15). CONCLUSIONS: Chronic treatment with amiodarone is associated with a non-selective downregulation of beta adrenoceptors. beta Adrenoceptor stimulated cAMP production was also reduced. The "beta blocking effect" of amiodarone is probably related to downregulation of beta adrenoceptors.

Adenylyl Cyclases↗
PubMed1991

Intrapericardial left atrial aneurysm diagnosed by transoesophageal echocardiography and nuclear magnetic resonance imaging.

A case of intrapericardial left atrial aneurysm is described in a 38-year-old woman, who presented with invalidating paroxysmal atrial fibrillation. The diagnosis was suspected by 2D-echocardiography, and confirmed by transoesophageal echocardiography and magnetic resonance imaging. Chest X-ray, right and left ventricular and coronary angiography were normal. The aneurysm was surgically removed, and the patient has subsequently remained free from symptoms.

Adult↗
PubMed1990

Heart transplantation in patients with severe pulmonary hypertension and increased pulmonary vascular resistance.

Irreversibly increased pulmonary vascular resistance is a contraindication for cardiac transplantation. At our hospital patients referred for recipient evaluation with systolic pulmonary artery pressure greater than 50 mmHg and pulmonary vascular resistance greater than 2 Wood units (Wu) are tested with intravenous sodium nitroprusside for reversibility. In 23 patients whose increased systolic pulmonary artery pressure (67.4 +/- 10.4 mmHg) and resistance (4.8 +/- 2.4 Wu) were reduced by nitroprusside, orthotopic heart transplantation was performed without early mortality. Right heart catheterization after transplantation revealed a significant and persistent fall of the elevated pulmonary artery pressure and pulmonary vascular resistance. We conclude that if severe pulmonary hypertension and elevated pulmonary vascular resistance are reversible with nitroprusside, the patient can safely undergo heart transplantation.

Adult↗
PubMed1989

[Treatment of unstable angina pectoris].

We present the results of an acute revascularisation program for unstable angina. Of the 63 consecutive patients included in the program 61 had significant coronary artery disease. Coronary bypass grafting was performed in 39 and percutaneous transluminal angioplasty in 9. There were two perioperative myocardial infarctions and one death in hospital. 13 patients were found unsuitable for revascularisation. At follow-up (14-26 months) 60 patients were still alive (95%). In the revascularised group 30 patients (65%) were free of angina pectoris. Accordingly, in patients who do not respond to medical therapy, acute revascularisation may be performed with low operative mortality, low incidence of perioperative myocardial infarctions, and good long term results.

Angina Pectoris↗
PubMed1989

Experiences with closed chest, temporary atrio-arterial, ventricular bypass with a centrifugal pump after open heart surgery.

Twelve patients with refractory myocardial failure following open heart surgery were treated with a temporary left (10), right (1) or biventricular (1) assist circuits driven by extracorporeal pumps. Ten of 11 patients were weaned from the pump oxygenator. During left ventricular assist, maximal pump flow was 2.2 +/- 0.6 l/min per m2 at a cardiac index of 2.5 +/- 0.9 l/min per m2. Diuresis was above 1 ml/kg body weight per h in 7 of 9 patients perfused for 13-36 h. Seven patients were weaned from the assist pump after 13-33 h of ventricular bypass with 4 hospital survivors. Two patients died after circulatory assistance of multiple organ failure, 1 from cerebral damage. In the other patients, the main problems were cardiac. Three patients are currently long term survivors 12-17 months after surgery.

Cardiopulmonary Bypass↗
PubMed1989

Encircling endocardial ventriculotomy for malignant ventricular arrhythmias. Effect on cardiac performance.

Cardiac performance and hemodynamics were studied with radionuclide ventriculography in 19 survivors of aneurysmectomy and encircling endocardial ventriculotomy for recurrent, sustained ventricular arrhythmia (group I). To characterize the effect of the ventriculotomy on cardiac function, comparisons were made with a similar group of patients who underwent aneurysm surgery for angina pectoris and/or congestive heart failure (group II). Functional classification revealed no difference between the groups and they achieved the same level of exercise after surgery. No intergroup difference was found postoperatively with respect to right or left ventricular ejection fraction, regional ejection fractions, peak ejection rate, cardiac index or stroke volume. Peak filling rate was also similar, as were cardiac volumes. Exercise did not change any parameter of this intergroup similarity. The authors conclude that most patients with moderately impaired left ventricular function who undergo left ventricular aneurysmectomy with encircling endocardial ventriculotomy do not differ in postoperative hemodynamics and systolic or diastolic function from those treated with simple aneurysmectomy.

Adult↗
PubMed1988

Improvement in cardiac performance and exercise tolerance after left ventricular aneurysm surgery--a prospective study.

Forty two patients were studied prospectively by rest and exercise radionuclide ventriculography before and after (10 +/- 4 months) left ventricular aneurysm resection. Functional classification (NYHA) improved from 3.0 +/- 0.6 to 2.3 +/- 0.5 (p less than 0.0001) with an increase in double product (p less than 0.01) and total exercise workload (p less than 0.04) over preoperative values. End-diastolic volume was significantly reduced (p less than 0.0001) and resting global left ventricular ejection fraction (LVEF) improved significantly (p less than 0.03) after surgery, as did regional ejection fractions of the lateral/inferior wall (p less than 0.01). Cardiac index (CI) at rest, however, remained unchanged. Under exercise, improvement of global (p less than 0.0003) and regional ejection fractions (p less than 0.02) was more pronounced and a significant increase was also observed for CI (p less than 0.003). Improvement in left ventricular performance occurred both in patients with single and multiple vessel disease, but was more distinct in the latter group who additionally received coronary artery bypass grafts. These patients were furthermore postoperatively able to increase global LVEF at exercise (p less than 0.05). We conclude that aneurysm resection with or without coronary bypass relieves cardiac symptoms and improves exercise tolerance and left ventricular function at rest and on exercise in most patients.

Adult↗
PubMed1988

Plasma atrial natriuretic peptide in cardiac transplant recipients. A prospective study.

Cardiac transplantation in 10 patients with congestive heart failure resulted in reduction of high plasma concentrations of atrial natriuretic peptide (ANP), preoperatively five-fold above normal, to a level two-fold above normal, which was maintained throughout a 12-week follow-up period. Cardiac function was normalized in all patients. Transient increases in plasma ANP, in four cardiac recipients 3-10-fold their basal levels, could neither be related to rejection episodes nor to cardiac dysfunction, but rather to signs of fluid and sodium retention. High plasma ANP levels in cardiac transplant recipients suggest that the capacity to secrete ANP is preserved in the transplanted heart.

Adolescent↗
PubMed1988

Unstable angina pectoris. Experience with an acute revascularization program.

One year's experience of an acute revascularization program for unstable angina pectoris is presented. In the total material of 63 patients, significant coronary artery stenosis was found in 61 and normal coronary arteries in two. Coronary artery bypass grafting was performed in 39 patients (62%) and percutaneous transluminal angioplasty in nine (14%). There were two perioperative myocardial infarctions and one hospital death. Thirteen patients were not eligible for revascularization. At follow-up (14-26 months) 60 patients were still alive (95%). In the revascularization group, one patient had died, but of the remaining 46 patients, 30 (65%) were free of angina pectoris, and in addition six had only minor symptoms.

Adult↗