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Biomedical subjects

K Forfang

Publications and source records attributed to K Forfang.

At least 19 recordsLinked to original sources
PubMed1992

Differential effect of selective beta 1 and nonselective beta-adrenoceptor blockade on epinephrine and atropine response in normal humans.

Sympathetic stimulation with epinephrine (EPI) combined with parasympathetic blockade with atropine was studied in 10 healthy volunteers premedicated with placebo or three different beta-adrenoceptor blockers: atenolol (62.5 micrograms/kg, beta 1-selective), propranolol (62.5 micrograms/kg, nonselective), and pindolol (7.5 micrograms/kg, nonselective with intrinsic sympathomimetic activity, ISA). EPI infusion (0.06 microgram/kg/min) after placebo increased heart rate (HR) and systolic blood pressure (SBP) and decreased diastolic BP (DBP). Pretreatment with atenolol reduced the HR increase, and caused similar changes in BP. In contrast, pretreatment with propranolol and pindolol decreased HR and increased BP. Combined EPI and atropine (15 micrograms/kg) after placebo increased HR by 40% without causing BP changes. Similar HR changes were observed after administration of all beta-adrenoceptor blockers, but whereas a marked pressor response was observed after propranolol and pindolol a blunted response was observed after atenolol. Propranolol and pindolol reduced myocardial oxygen demand estimated by the HR x BP product after EPI, but this response was abolished by atropine. Serum potassium decreased from 3.9 +/- 0.2 to 3.2 +/- 0.3 mM after EPi and atropine. This effect was less after atenolol, and potassium increased after premedication with propranolol and pindolol. Our results show that nonselective beta-adrenoceptor blockade has a favorable effect on potassium homeostasis and oxygen demand parameters during EPI infusion but causes a marked pressor response, contrary to a beta 1-selective agent, during combined sympathetic stimulation and parasympathetic blockade. They also highlight the importance of the vasodilator cholinergic system as a defense mechanism in such situations.

Adrenergic beta-Antagonists↗
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↗
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

Effects of atenolol and pindolol on the hypokalaemic and cardiovascular responses to adrenaline infusion.

To investigate if the intrinsic sympathomimetic activity of pindolol could modify its beta-blocking effects on the responses to an adrenaline infusion, 10 healthy volunteers were studied. At an interval of 1-4 weeks each subject received pindolol and atenolol in randomized order before the infusion of adrenaline 0.06 microgram.kg-1.min-1. Pindolol prevented hypokalaemia and significantly decreased the heart rate during the adrenaline infusion. These effects were not observed after atenolol. The diastolic blood pressure was slightly increased during the infusion of adrenaline after pindolol, whereas it remained unchanged after atenolol.

Adult↗
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

Effects of disopyramide on repolarisation and intraventricular conduction in man.

Right ventricular repolarisation and refractoriness after therapeutic doses of disopyramide have been studied in 10 patients with coronary artery disease by recording monophasic action potentials (MAP) during programmed stimulation. Using 2 catheters, with the tip of one in the apex and the other in the outflow tract of right ventricle, conduction intervals for propagation of stimuli in the ventricle were also measured. Disopyramide increased the duration of MAP signals at 90% repolarisation (MAP90), the QT-interval and the right ventricular effective refractory period (V-ERP). The ratio refractoriness/action potential duration was slightly increased. Early premature action potentials were more markedly prolonged in relation to steady-state action potentials. The differences between the shortest and longest premature action potentials, however, were not changed significantly. The conduction intervals of the normal and premature paced beats were significantly prolonged. The observed effects of disopyramide on conduction and action potential duration may be of major importance for its effect on termination and slowing ventricular tachycardias. Its influence on the duration of premature action potentials in man is consistent with the results of in vitro studies.

Action Potentials↗
PubMed1988

Impairment in right ventricular performance after left ventricular aneurysm surgery.

To study the effect of operation for left ventricular (LV) aneurysm on right ventricular (RV) performance, we studied 50 patients before operation with right heart catheterization, RV angiography, and radionuclide ventriculography. Forty patients were followed up and underwent the same investigations 10 +/- 4 months after operation. At baseline, regional RV dysfunction was observed in 89% of the patients whereas global RV dysfunction was present in approximately a third. After operation, no changes in RV regional dysfunction or RV pressures were observed. However, a significant increase in RV end-diastolic (p less than 0.03) and end-systolic volume indices (p less than 0.02) along with a significant decrease in resting and exercise RV ejection fractions (p less than 0.05) was found. We were unable to demonstrate any significant relationship between preoperative RV dysfunction and surgical outcome. We conclude that RV dysfunction is common in patients with LV aneurysm. Current techniques of operative intervention for this type of aneurysm seem to be followed by RV dilatation and impairment in RV function.

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

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↗
PubMed1987

Monophasic action potentials in patients with coronary artery disease: reproducibility and electrical restitution and conduction at different stimulation rates.

Monophasic action potentials were recorded in the outflow tract of the right ventricle in patients with coronary artery disease during ventricular pacing at different basic cycle lengths and programmed stimulation. During continuous pacing (basic cycle length 600 ms) the time for 90% repolarisation (MAP90) and the QTa interval decreased exponentially during the first 1.5-2 min of pacing to 90% of control values. The reproducibility of the monophasic action potential signals and the ventricular effective refractory period were assessed as good when studied after repetitive trains of 8 beats for more than 1.5 min. The reproducibility of conduction, however, was less good. Electrical restitution of MAP90 duration of the premature beats determined at three different basic cycle lengths was different from that in single muscle preparations. The curves showed two phases with unchanged MAP90 durations despite longer coupling intervals. The first phase was close to the ventricular effective refractory period, probably because subnormal conduction left the diastolic interval constant for the earliest premature beats. This indicates that subnormal conduction may influence the premature dispersion of repolarisation.

Action Potentials↗