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Biomedical subjects

S Iversen

Publications and source records attributed to S Iversen.

At least 37 records · Page 2Linked to original sources
PubMed1994

An investigation into the discriminative stimulus and reinforcing properties of the CCKB-receptor antagonist, L-365,260 in rats.

The discriminative stimulus properties of the selective CCKB-receptor antagonist, L-365,260 were evaluated in rats trained to discriminate diazepam (2 mg/kg) or morphine (5 mg/kg) from vehicle, using a two-lever food reinforced technique. In the diazepam drug discrimination, the benzodiazepine-receptor agonist FG8205 (0.063-2 mg/kg) produced dose-related drug associated responding, whereas L-365,260 (0.125-4 mg/kg) treated animals showed vehicle appropriate behaviour. In rats trained to discriminate morphine from saline, L-365,260 (0.063-4 mg/kg) produced saline lever responding. When a dose of 1 mg/kg L-365,260 was administered in combination with morphine, the dose response curve for drug lever responding was not significantly affected. This was in contrast to the effect produced by the opiate antagonist naloxone (0.3 mg/kg) which shifted the dose-response curve to the right. Another group of rats underwent training to discriminate a dose of 6 mg/kg L-365,260 from vehicle. None of the animals learned the discrimination within 50 daily training sessions. In addition, unlike morphine (3 mg/kg), or changing the training dose of cocaine, intravenous administration of L-365,260 (0.3-10 mg/kg) did not modify lever pressing or the number of injections received by rats trained to self administer cocaine (0.25 mg/injection). L-365,260 (0.1-3 mg/kg) produced a dose-related inhibition of pentagastrin-stimulated gastric acid secretion in vivo. When administered dissolved in a mixture of ethanol/propylene glycol/saline, the ID50 was 0.83 mg/kg, and when suspended in an ethanol/carboxymethylcellulose vehicle, it was 0.7 mg/kg. It was concluded: 1) that L-365,260 does not produce discriminative stimuli similar to either diazepam or morphine; 2) that the potentiation of morphine-induced behaviour by L-365,260 does not extend to the discriminative stimulus properties of morphine; 3) that L-365,260 itself does not produce readily discriminable interoceptive stimuli in rats; and 4) that L-365,260 does not substitute for the reinforcing drug cocaine.

Animals↗
PubMed1994

Laser welding--suitable for vascular anastomosis?

Carotid arteries of 21 piglets were transsected and reanastomosed either by laser welding (Neodym:YAG laser) or by conventional suture anastomosis. Histological specimens of the anastomoses obtained 2 to 32 days after the operation showed less foreign body reaction and intimal hyperplasia after laser welding than after suturing. There was, however, no significant difference when comparing occurrence of thrombosis, patency rate, or growth of the anastomosis in growing animals. Neither our study nor a review of the literature of laser-assisted vascular anastomosis in microvessels and large arteries up to 5 mm diameter could establish a definite clinical application for laser welding in vascular anastomosis.

Anastomosis, Surgical↗
PubMed1994

Pulmonary arteries and lung parenchyma in chronic pulmonary embolism: preoperative and postoperative CT findings.

PURPOSE: To evaluate the role of computed tomography (CT) in diagnosis of chronic thromboembolic pulmonary hypertension, assessment of surgical operability, and follow-up after surgery. MATERIALS AND METHODS: Seventy-five patients with chronic thromboembolism were examined with CT; 63 underwent thromboendarterectomy, and postoperative CT scans were acquired in 23. CT scans were analyzed for vascular and parenchymal changes, and findings were compared with those on lung scintigrams and with surgical results. RESULTS: CT findings allowed confirmation of the diagnosis of chronic thromboembolism and ensured technical operability (sensitivity, 77%; specificity, 100%; overall accuracy, 80%) by means of direct visualization of thrombi in central pulmonary arteries in 53 patients. CONCLUSION: CT enables demonstration of pulmonary thromboembolism with criteria pertaining to pulmonary arteries and to lung parenchyma and enables assessment of technical operatibility and confirmation of surgical success.

Adult↗
PubMed1994

[Surgical treatment of thromboembolism-induced pulmonary hypertension].

Non-resolved chronic pulmonary thromboembolism is a frequent cause of pulmonary hypertension. In long-standing disease hypertension is progressive due to intimal and medial changes in the perfused vessels. Non-resolution of thromboemboli is often associated with underlying coagulopathies; the presence of a lupus anticoagulant may pose a significant problem in the peri-operative management of these patients. Pulmonary thrombendarterectomy presents an efficient option of treatment which is feasible in the majority of patients. By means of pulmonary angiography and computed tomography operability is verified by the often difficult recognition of thromboembolic changes in the central pulmonary arteries. Patients with solely peripheral thromboembolic changes or primary pulmonary hypertension must be excluded. In presence of significant exertional dyspnea and/or pulmonary pressure elevation surgery is indicated. Mortality is high and mainly related to unrelieved pulmonary hypertension or pulmonary complications; pulmonary reperfusion edema, respiratory failure or pneumonia and sepsis. In all survivors the reduction of pulmonary hypertension is highly significant and persistent. Thromboembolic pulmonary hypertension may be treated curatively in most patients by thrombendarterectomy. Correct selection of surgical candidates is mandatory, and the patients should preferably be diagnosed and undergo surgery in an early stage of their disease.

Adolescent↗
PubMed1993

Endoventricular patch plasty improves results of LV aneurysmectomy.

From May 1985 to December 1991 52 patients were operated upon for postischemic left ventricular aneurysm (LV-A). Between May 1985 and July 1989 25 patients (group I) with a mean age of 59 (46-72) years underwent conventional aneurysmectomy with direct closure of the left ventricle (LV) and a mean of 1.9 (0-3) additional bypass grafts (54% triple-vessel disease). The hospital mortality was 8% (2/25) and the late mortality during a median follow-up time of 34 months was 28% (7/25) with a 4-year survival of 66%. Improvement in the quality of life (NYHA from 2.6 to 2.1, P = 0.078) and global left ventricular ejection fraction (EF) (from 35 to 38%) proved to be unsatisfactory in conjunction with the high late mortality rate. Between August 1989 and December 1991 a prospective series of 27 consecutive patients (group II) with a mean age of 61 (45-71) years underwent endoventricular patch plasty guided by two-dimensional transthoracic echocardiography (TTE) before and after surgery. The patch size and position were calculated preoperatively by measuring the distances from the mitral annulus to the infarct area which were reproduced during surgery with a simple ruler. A mean of 2.1 (0-4) bypass grafts were added with 62% of the patients having triple-vessel disease and 19% left main stenosis (P = 0.05, group I versus II). All patients have survived to date. One patient had to be excluded, giving a median follow-up time of 14 months for 26 patients. At the 6 months' control, the mean NYHA class was improved from 2.7 to 1.6, (P = 0.0001).(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗
PubMed1993

Troponin T--a reliable marker of perioperative myocardial infarction?

Following cardiac surgery, electrocardiography and creatine kinase isoenzyme MB (CK-MB) activities are of limited value in diagnosing a non-transmural infarction. With the recent availability of an assay to detect serial levels of the specific cardiocyte contractile protein troponin T the possibility has been increased of closing a diagnostic gap among cardiosurgical patients. Ninety patients with severe diffuse three-vessel disease undergoing myocardial revascularization were grouped by their postoperative electrocardiographic (ECG) findings (group I--unchanged ECG; group II--new Q-waves representing perioperative myocardial infarction (PMI)). Serial levels of troponin T and the activity of CK-MB were measured 6, 12, 24 and 48 h after aortic unclamping. The course of CK-MB activity was compared to a profile and values derived from patients with unchanged (n = 1312) or new Q-wave ECGS (n = 89). In 72 patients (80.0%) with unchanged postoperative ECG (group I) serial troponin T levels remained constantly low and reached a median peak value of 0.37 microgram/l (quartile 0.13-0.50 microgram/l) after 24 h. Serial CK-MB activities demonstrated the typical non-ischemic course with a monoexponential decline from an initial median peak value of 15.5 U/l (quartile 12.0-21.0 U/l) to 7.0 U/l (quartile 6.0-9.0 U/l). In seven patients (7.8%) with new Q-waves and a pathologic CK-MB profile (group II) troponin T reached median levels of 10.47 micrograms/l (quartile 6.34-12.50 micrograms/l) (P < 0.001 I vs II). Four of five patients with a new right bundle branch block demonstrated low troponin T levels below 1 microgram/l and a normal CK-MB profile. Among six patients with unchanged QRS-configuration and elevated troponin T levels between 0.84 and 4.99 micrograms/l CK-MB activity showed a characteristic PMI pattern in two patients. Troponin T is characterized by a very narrow margin of normal values represented by a maximum third quartile of 0.50 microgram/l. A singular value of troponin after 6 h or 24 h may be sufficient evidence to confirm the diagnosis of a PMI.

Aged↗
PubMed1993

[Detection of chronic recurrent pulmonary emboli using spiral-CT].

Chronic recurrent pulmonary emboli may lead, in rare cases, to progressive pulmonary arterial hypertension which cannot be treated medically. These patients may be helped by bilateral pulmonary thrombendarterectomy. The value of spiral CT in the diagnosis of this condition was demonstrated in 31 patients. In 12 patients, thrombi could be shown to be the cause of the pulmonary arterial hypertension. Indirect criteria were vascular occlusions, changes in calibre and mural irregularities which were shown in varying degrees in all patients. In 22 of 31 patients there was non-homogeneity of perfusion with greater opacification of the perfused lung parenchyma. In 11 patients scars related to pleural surfaces were seen. Typical changes of right heart insufficiency (cardiomegaly, widened central pulmonary arteries) were shown in all patients by CT.

Adult↗
PubMed1992

[Long-term follow-up of thrombolytic treatment of acute infarct in combination with acute and elective revascularization].

From March 1983 to June 1986 in 206 patients with acute transmural myocardial infarction, combined intravenous and intracoronary therapy with streptokinase was initiated. After intravenous thrombolysis and randomization in two groups we performed a coronary angiography with selective intracoronary lysis. Infarct related vessels still occluded after intracoronary streptokinase application were opened mechanically in group I. In group II we performed additionally a percutaneous transluminal coronary angioplasty (PTCA) after mechanical recanalisation (occluded vessels) or after thrombolysis (open vessels). In 85 of 87 cases in group II, PTCA could be performed in the acute phase. Elective PTCA was performed in 22 patients of group I (21%) and in nine patients of group II (9%). Up to five years after myocardial infarction, coronary artery bypass grafting (CABG) was necessary in 22 patients (21%) of group I and in 23 patients (22%) of group II. Within four weeks after infarction CABG was performed in 32% and 17% of group I and II respectively. The six-year survival rate was 78% in group I and 82% in group II. Taken all patients together, the six-year survival rate was significantly higher (p = 0.002) for those with early reperfusion (less than or equal to 3.5 h). The survival rates of CABG-patients, PTCA-patients and patients without reperfusion were 91%, 74% and 65% respectively. Streptokinase thrombolysis results, combined with acute or elective PTCA and/or coronary bypass surgery, in a high six-year survival rate after acute transmural myocardial infarction. This rate is about 20% higher than ten years ago.

Angioplasty, Balloon, Coronary↗
PubMed1992

[Pulmonary thrombendarterectomy in thromboembolic pulmonary hypertension. The indications and early results].

Pulmonary thrombendarterectomy was performed in 32 patients (14 men and 18 women; mean age 38 +/- 15 years) with thromboembolic pulmonary hypertension (New York Heart Association stage III: n = 22; stage IV: n = 10). The preoperative arterial pO2 averaged 59 +/- 11 mm Hg; pulmonary vascular resistance (PVR) and mean pressure (MPAP) were increased to 1,045 +/- 430 dyn.s.cm-5 and 53 +/- 12 mm Hg, respectively. The perioperative death rate was 22% (7 of 32). In the 25 survivors the pulmonary hypertension was reduced to a PVR of 194 +/- 75 dys.s.cm-5, MPAP of 28 +/- 6 mm Hg. Subsequent re-examination in 15 patients (NYHA stage I: n = 14, stage II: n = 1) after a mean of 17 +/- 5 months demonstrated an arterial pO2 averaging 92 +/- 6 mm Hg and, in 14 patients, echocardiographically normal right-ventricular volumes and function. The primary success was confirmed in eight patients by haemodynamic measurements. These data indicate that thrombendarterectomy can effectively treat the increased PVR in most patients at all stages of the disease.

Angiography, Digital Subtraction↗
PubMed1992

Sarcoma of the pulmonary artery: report of two cases and a review of the literature.

Primary tumours of the pulmonary arteries are rare neoplasms seldom diagnosed during the patient's life time. We report on two cases of pulmonary artery sarcomas diagnosed during life time of the respective patients in intra-operative frozen sections by histopathological examination. Case 1 was of a 55-year-old man with a fibrosarcoma originating from the main pulmonary trunk. Case 2 was of a 43-year-old woman with a malignant fibrous histiocytoma originating from the right pulmonary artery. In both patients a radical tumour resection under cardiopulmonary bypass was attempted. Both patients, however, had a local tumour recurrence and died 18 months (patient 1) and 6 months (patient 2) after surgery. A review of pulmonary artery sarcomas is given.

Adult↗
PubMed1992

Surgical treatment of myocardial bridging causing coronary artery obstruction.

Nine patients with obstruction of coronary artery blood flow caused by myocardial bridging underwent surgery after failure of medical treatment. The diagnoses were made angiographically at rest or during beta-stimulation. Impaired blood flow was found only in the left anterior descending artery in seven patients and additionally in the diagonal branch in two. The operations, performed with cardiopulmonary bypass consisted of complete dissection of the overlying myocardium. All patients survived the operation. Major intraoperative complications were accidental opening of the right ventricle in two patients. Postoperative scintigraphic and angiographic studies demonstrated restoration of coronary flow and myocardial perfusion without residual myocardial bridges under beta-stimulation. Surgical relief of myocardial ischemia due to systolic compression of intramyocardial coronary arteries can be accomplished with low operative risk and with excellent functional results.

Adult↗
PubMed1992

Efficacy of phosphodiesterase inhibitor enoximone in management of postcardiotomy cardiogenic shock.

The efficacy of the phosphodiesterase inhibitor enoximone for reversal of severe postcardiotomy low cardiac output syndrome was investigated in 13 cases of cardiogenic shock refractory to conventional treatment consisting of beta-adrenergic agonists (n = 13) combined with vasodilators (n = 7), and intra-aortic balloon counterpulsation (n = 5). Following a bolus of 1 mg/kg enoximone, cardiac and stroke volume indices increased from 1.56 +/- 0.27 l/min/m2 and 16.3 +/- 3.3 ml/m2, respectively, to 2.72 +/- 0.67 and 27.8 +/- 7.1 (both p < 0.001). Mean arterial pressure fell, from 77 +/- 11 to 68 +/- 9 mmHg (p < 0.05), as did atrial filling pressures (LAP and RAP), LAP from 21.3 +/- 5.5 to 15.9 +/- 2.9 and RAP from 16.6 +/- 2.3 to 13.7 +/- 2.1 mmHg (both p < 0.01). The heart rate rose by only 5%. Enoximone therapy was maintained by a continuous infusion (5-7.5 micrograms/kg/min) for 40.6 +/- 8.6 hours (range 14-92). All hemodynamic parameters remained stable throughout treatment. Six patients died of sepsis and/or multiorgan failure but seven were discharged from hospital. Enoximone thus improved hemodynamic performance significantly in cardiogenic shock after open-heart surgery. It also has proved valuable in cardiac failure when conventional therapy was unsuccessful.

Aged↗
PubMed1992

Reoperation and the centrifugal pump?

Postperfusion syndrome is still a problem in long cardiac operations using extracorporeal circulation (ECC). To evaluate whether or not centrifugal blood pumping during open heart surgery is beneficial, a randomized, prospective study was undertaken of 50 consecutive patients undergoing elective coronary artery bypass grafting. The patients were divided into two groups of 25 each. In group 1 a centrifugal pump (Biomedicus) was used as arterial blood pump, while in group 2 a roller pump (Stöckert) was used. The two groups did not differ significantly and the number of variables during surgery was kept low (identical perfusion set, two surgeons, minimal cardiotomy suction). The parameters studied included the cellular elements of the blood and components indicating their functional integrity, such as PMN-elastase, plasma hemoglobin, beta-thromboglobulin, and thrombin-antithrombin III complex and D-dimer as representatives for activated coagulation and secondary fibrinolysis. Blood and urine samples were taken every 15 min during ECC, on arrival in the intensive care unit, and 1, 3, 6, 12, and 24 h thereafter. No difference between the groups was found in regard to bypass time, ECC flow and volume, fluid balance, and clinical outcome. Significant differences in favor of group 1 were found in plasma hemoglobin (P less than 0.05), beta-thromboglobulin (P less than 0.01), D-dimer (P less than 0.05), and platelet counts (P less than 0.5). These differences were clearly ECC-time-dependent and became statistically significant after 90 min bypass. We conclude that roller pumps still can be safely used for standard cardiac procedures.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗
PubMed1992

[Diagnostic goals in aortic dissection. Value of transthoracic and transesophageal echocardiography].

The combination of different ultrasound techniques like transthoracic, suprasternal, subcostal and transesophageal echocardiography have a high sensitivity and specificity in the diagnosis of aortic dissection. The limitation of this combined ultrasound technique is related to the visualization of the ascending part of the aortic arch which, cause of the interposition of the trachea, can not be visualized completely. The beginning or the end of a dissection in this part of the aorta may be misinterpreted. False negative results are rare. False positive results due to artefacts resulting from reverberations in an ectatic ascending aorta have to be taken into account. The most important diagnostic aims in acute or chronic aortic dissection can be described: 1. confirmation of the diagnosis by visualization of the intima membrane, 2. the differentiation of the true and false lumen depending on visualization of spontaneous echocardiographic contrast thrombus formation, slow or reduced reversed flow, systolic diameter reduction and signs of entry jet into the false lumen, 3. detection of intimal tear, demonstrating communication by two-dimensional or color Doppler echocardiography, 4. determination of the extent of the dissection with classification according to DeBakey type I, II and III or Stanford A and B with differentiation to communicating or non-communicating dissection, antegrade or retrograde dissection limited to the descending aorta or expanding to the ascending aorta, 5. detection of wall motion abnormalities as a sign of preexisting coronary artery disease or myocardial ischemia due to ostium occlusion by an intimal flap, coronary artery rupture or collapse of the true lumen during diastole, 6. detection and grading of aortic insufficiency, 7. detection of side branch involvement by suprasternal, subcostal and abdominal sonography, which will gain the information which side can be chosen for cannulation or catheterization at the femoral artery, 8. detection of pericardial pleural effusion and mediastinal hematoma as a sign of emergency as rupture can occur within minutes. Without surgical intervention have be performed. Based on these informations, surgery can be performed in all acute situations in type A dissection without further investigations. This decision is particularly important in patients with signs of emergency like pericardial or pleural effusion or mediastinal hematoma.

Aortic Dissection↗
PubMed1992

Effects of tolazoline and prostacyclin on pulmonary hypertension in infants after cardiac surgery.

OBJECTIVE: To evaluate the hemodynamic effects of tolazoline and prostacyclin in infants with pulmonary vasospasm after cardiac surgery. DESIGN: Prospective cohort study. SETTING: Pediatric ICU. PATIENTS: The cohort consisted of 42 infants and children with congenital heart disease and pulmonary hypertension who underwent corrective surgery and were monitored postoperatively using pulmonary artery catheters. Fourteen infants (2 to 12 months old) in this group required postoperative treatment with tolazoline or prostacyclin. INTERVENTIONS: Tolazoline was administered as a bolus of 0.5 mg/kg for treatment of persistent pulmonary hypertension or acute pulmonary hypertensive crisis. If its effectiveness was proved after 30 mins by hemodynamic measurements, a continuous iv infusion of 0.5 mg/kg/hr was established. Higher doses of tolazoline were avoided. If tolazoline treatment did not fulfill the criteria for pulmonary vasodilation, prostacyclin was given by continuous iv infusion at a starting rate of 5 ng/kg/min, followed by 10 ng/kg/min. In three patients, the infusion rate was increased to 15 ng/kg/min. RESULTS: Bolus administration of tolazoline resulted in a distinct pulmonary vasodilation in seven infants: mean pulmonary artery pressure and pulmonary vascular resistance decreased by an average of 35% and 45%, respectively. In these patients, tolazoline was infused over the following 12 to 72 hrs. One infant who received tolazoline for 72 hrs developed a clinically important gastrointestinal hemorrhage. In seven nonresponders to tolazoline, prostacyclin (PGI2) at an infusion rate of 5 ng/kg/min led to pulmonary vasodilation in five patients, at an iv infusion rate of 10 ng/kg/min in all seven infants studied. The latter dose of PGI2 reduced the mean pulmonary artery pressure by an average of 37%, and pulmonary vascular resistance by 43%. Transient withdrawal of prostacyclin in five infants demonstrated its short half-life and clinical effectiveness. Apart from a facial flush, no side-effects were encountered using PGI2 as an infusion over durations ranging from 12 to 504 hrs. CONCLUSIONS: These data suggest that, if tolazoline in a relatively low dose proves to be inefficient, prostacyclin can still be used as a safe and effective drug for treatment of pulmonary vasospasm. Prostacyclin offers more than a pharmacologic alternative to increased tolazoline dosages.

Drug Evaluation↗
PubMed1991

[Chronic thromboembolic cor pulmonale in pacemaker-associated right atrial thrombi. Pulmonary thromboendarterectomy with removal of the electrodes as a life-saving measure].

Life-threatening chronic cor pulmonale occurred in a 22-year-old woman with congenital 3 degrees atrioventricular block, 6 years after implantation of a pacemaker and 3 1/2 years after removal of the pacemaker (the electrodes were too firmly attached to be removed). The emboli originated from the right-atrial thrombi which had formed around the electrodes left in situ. The embolic source shrank during systemic administration of urokinase, initially 600,000 IU in 60 min, then 100,000 IU per hour, and pulmonary perfusion improved transiently. Nonetheless the patient became breathless on the slightest physical exertion. Recurrent syncopal attacks with marked increase of pulmonary artery pressure necessitated pulmonary thrombendarterectomy and removal of the electrode and wires. Thereupon the patient's condition clearly improved so that 6 months postoperatively her exercise tolerance was again unimpaired.

Adult↗