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Biomedical subjects

S Simonsen

Publications and source records attributed to S Simonsen.

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

Hormonal changes in patients with severe chronic congestive heart failure treated by ultrafiltration.

Plasma atrial natriuretic peptide (ANP), antidiuretic hormone (ADH), plasma renin activity (PRA), and circulatory haemodynamics were studied in five patients with chronic congestive heart failure undergoing ultrafiltration on two consecutive days. The patients were in the New York Heart Association class IV, and were considered candidates for heart transplantation. A mean of 3.3 +/- 0.5 litres of fluid was removed during each ultrafiltration. Plasma ANP concentration remained unchanged during ultrafiltration: 369 +/- 151 pg/ml at start and 316 +/- 116 pg/ml at the end, while plasma ADH concentration and PRA increased from 5.1 +/- 2.1 to 7.5 +/- 3.4 pg/ml (P less than 0.02), and 5.9 +/- 3.0 to 7.7 +/- 3.2 ng/ml (P less than 0.03) respectively (n = 10). After treatment, plasma ADH and PRA declined to baseline values within 1 h. Pulmonary artery, pulmonary capillary wedge, and right atrial pressures decreased significantly, while blood pressure and heart rate remained constant during ultrafiltration. A volume of 3.3 +/- 0.5 litres of fluid was removed, and caused an increase in colloid osmotic pressure from 22.0 +/- 3.0 to 33.7 +/- 3.9 mmHg (P less than 0.02). It was unexpected that plasma ANP concentration did not decline. Due to long-standing severe heart failure the atrial wall may have lost some of its elastic properties, resulting in less ability to adapt to reduced filling pressures. Accordingly, atrial wall stretch remained unchanged, explaining the constant ANP levels. Ultrafiltration treatment caused an increased responsiveness to diuretic therapy, and four patients survived long enough to receive heart transplants.

Adult↗
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↗
PubMed1992

Nitroprusside and regional vascular capacitance in patients with severe congestive heart failure.

BACKGROUND: This study investigates the effects of sodium nitroprusside on regional vascular capacitance in eight patients with severe congestive heart failure (New York Heart Association class IV) and pulmonary hypertension. METHODS AND RESULTS: Regional relative blood volumes in the splanchnic and pulmonary region were determined by equilibrium blood pool scintigraphy. Hepatic venous wedge pressure and the mean of pulmonary artery and pulmonary capillary wedge pressure were used to represent the distending pressures of the splanchnic and pulmonary capacitance vessels, respectively. The dose of sodium nitroprusside was increased stepwise until systolic pulmonary artery pressure decreased below 50 mm Hg. This caused reductions in mean aortic pressure from 89 +/- 5 to 66 +/- 3 mm Hg (p less than 0.005), in pulmonary capillary wedge pressure from 31 +/- 1 to 16 +/- 2 mm Hg (p less than 0.001), and in hepatic venous wedge pressure from 10.0 +/- 1.0 to 5.9 +/- 0.6 mm Hg (p less than 0.005). Intestinal blood volume increased by 26 +/- 7% (p less than 0.005), whereas hepatic blood volume decreased by 9 +/- 3% (p less than 0.02). Pulmonary blood volume was unchanged. Analysis of intestinal and pulmonary vascular pressure-volume relations showed larger or equal blood volumes contained at lower distending pressures, indicating that sodium nitroprusside reduced smooth muscle tone of the capacitance vessels in these regions. The reduction of hepatic blood volume was compatible with passive expulsion of blood subsequent to reduced venous pressure. There was no change in the count rate from the spleen. CONCLUSIONS: Nitroprusside reduced venous pressure in patients with congestive heart failure by active relaxation of intestinal and pulmonary capacitance vessels. Hepatic vascular volume was probably reduced by a passive mechanism.

Gated Blood-Pool Imaging↗
PubMed1992

Single lung transplantation. Surgical experiences with the first seven patients.

Seven single lung transplants are reported. The patients were severely disabled and oxygen dependent below sixty years of age with a poor prognosis. Diagnosis were alfa 1-antitrypsin deficiency (3), sarcoidosis (3) and idiopathic emphysema (1). Multiorgan-harvesting including six hearts, was performed in local or distant hospitals (3). Partial cardiopulmonary bypass simplified transplantation. The surgical procedure was modified with a direct transpericardial approach. Soft tissue wrapping by a vascularized pedicle secured the bronchial anastomosis. The four drug immunosuppressive regimen included cyclosporin A, azathioprine, steroids and antithymocyte globulin. Primary graft function was excellent. Six patients survived the postoperative period and are alive 5-19 months post transplant. Transbronchial biopsies and lung function studies have been helpful in detecting pulmonary rejections. Patient rehabilitation is satisfactory in most patients with improvement in physiologic parameters.

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↗
PubMed1992

Restenosis after percutaneous transluminal coronary angioplasty.

Restenosis after percutaneous transluminal coronary angioplasty was demonstrated in 61 (29%) of 210 successfully treated patients. Mostly it occurred within 4 months after treatment and in arteries less than 3 mm in diameter. Careful clinical follow-up is therefore particularly important early after angioplasty of smaller arteries. Redilation can be performed without increased risk of restenosis.

Angioplasty, Balloon, Coronary↗
PubMed1991

[Gastrointestinal cytomegalovirus infection in patients with heart transplants].

Cytomegalovirus (CMV) infection is a major cause of morbidity in organ transplant recipients. Gastrointestinal CMV disease is a serious and potentially lethal complication requiring treatment with antiviral agents. The symptoms and endoscopic findings are nonspecific. The diagnosis may be decided by histological examination, since CMV inclusions can be verified immunohistochemically in routine sections. In a series of 132 heart transplant recipients, 26 developed CMV-infection. Three of these patients had serious gastrointestinal disease. This report describes the patients with gastrointestinal CMV infection, and briefly discusses symptomatology, diagnostic considerations and suggested treatment.

Adult↗
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

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

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

[Restenosis after coronary angioplasty].

Angiography of 169 patients who had been treated successfully with PTCA showed restenosis in 61. Of these, 38 were successfully treated with a new PTCA, and six developed a new restenosis. Restenosis usually appears during the first four months after PTCA in vessels with a diameter less than three millimeters. The authors emphasize the importance of careful clinical follow-up.

Angioplasty, Balloon, Coronary↗
PubMed1990

Lipoprotein-related coronary risk factors in patients with angiographically defined coronary artery disease: relation to number of stenosed arteries.

To determine whether an index estimating antagonism between low density lipoprotein (LDL) and high density lipoprotein (HDL) would improve separation between groups with and without coronary artherosclerosis, patients undergoing coronary catheterization (35 women and 99 men) were analysed for total cholesterol (TC), HDL cholesterol (HDLc), apolipoprotein A (apo A) and apolipoprotein B (apo B). The subjects were categorized as groups 0, 1, 2 or 3 according to the number of stenosed arteries (greater than 75% areal stenosis). Thirty of the patients showed no significant coronary atherosclerosis (group 0). Serum apo B and TC concentrations were directly related to the number of stenosed vessels, whereas the concentrations of apo A and HDLc were negatively correlated with the number of stenosed arteries. An 'atherogenic Index' (ATH index) calculated as the product of serum concentrations of apo B, and TC minus HDLc divided by the product of apo A and HDLc, proved more satisfactory than individual lipoprotein components for discrimination between subjects with and without stenosis. Accordingly, identification of coronary groups may be improved by using the ATH index.

Angiography↗
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

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

Evaluation for left ventricular aneurysm resection: a prospective study of clinical and haemodynamic characteristics.

A consecutive series of 97 patients with a left ventricular aneurysm (LVA) was evaluated for aneurysmectomy. A wide range in left ventricular (LV) function was found. Angina pectoris was the primary indication (51%) in 55 patients who were operated upon, whereas poor LV function was the main reason (67%) for rejecting surgery in 42 patients. Operative mortality was 9% and exclusively seen in patients with congestive heart failure and/or sustained ventricular arrhythmias. Functional status improved from (NYHA) 3.0 +/- 0.7 to 2.3 +/- 0.5 (P less than 0.0001) after surgery, while haemodynamics at rest remained unchanged. In the medically treated group, 10 patients underwent heart transplantation without mortality during follow-up. Of the remaining 32, 7 had died (22%), all with severely impaired LV function. The best prognosis with no deaths was observed in the 14 medically treated patients with moderate complaints and well preserved LV function. Those with poor LV function and/or ventricular arrhythmias had a poor prognosis whether they were treated medically or by conventional aneurysm surgery. In young selected patients with a short life expectancy, heart transplantation may represent an alternative.

Angina Pectoris↗