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Biomedical subjects

G Kober

Publications and source records attributed to G Kober.

At least 109 records · Page 6Linked to original sources
PubMed1989

[Can the progression of coronary heart disease be modified by calcium antagonists?].

Experimental atherosclerosis in animals preferentially induced by cholesterol-rich food can be successfully suppressed by calcium channel blocking agents such as verapamil, nifedipin, nicardipin, and diltiazem. The question whether calcium channel blockers can favorably influence atherosclerosis in humans remains a matter of debate. A few observational investigations in the past showed positive results of calcium channel blocker therapy in patients with angiographically proven coronary artery disease (CAD). At present three prospective randomized clinical trials are under way (INTACT-study, FIPS-study, study from the Montreal Heart Institute). Target variable is the severity of coronary atherosclerosis assessed by angiography both at entry into the study and after 2-3 years of treatment. 445 patients after coronary bypass surgery were included in the FIPS study (Frankfurt Isoptin Progression Study) and were randomly allocated to either verapamil 120 mg t.i.d. or placebo treatment. Extent of coronary atherosclerosis, assessed by repeat angiography 1 and 3 years after randomization, is expressed by scores with separate evaluation of non-bypassed vessels, segments distal to the peripheral bypass insertion, bypassed segments and grafts. The 1-year follow-up was completed for 162 patients (Group A = 80 patients; group B = 82 patients). There was a homogeneous distribution in both groups for all clinical variables, graft patency rates (76%/75%), and the incidence of clinical events (myocardial infarct, need for cardiac surgery or PTCA, cardiac death: 5%). The overall progression of atherosclerosis in the first year after bypass surgery was small. Thus, the question of whether calcium channel blockers can retard progression of coronary atherosclerosis cannot be answered before completion of the aforementioned trials.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1988

[Opening of chronic coronary artery occlusions with a recanalization catheter].

Percutaneous transluminal angioplasty for recanalization was attempted for 44 chronic coronary arterial occlusions in 41 patients (two occluded vessels in three patients). In 11 instances the occlusion could be passed with a guide-wire. In the other 33 this was not possible. In 25 of them a 3, 4 or 5 F recanalization catheter, its end tapered to 2 or 3 F, was used. In this way re-opening was possible in 17 cases (68%). The catheter made it possible to splint or stiffen the guidewire to keep it straight, superselectively inject contrast medium, measure the pressure distal to the occlusion, and gradually bougie-like enlarge the resulting subtotal stenosis. A total of 28 of 44 coronary occlusions were re-opened (64%). All these patients were functionally improved. At subsequent angiography (a mean of 3.6 months later) 22 of 25 vessels had remained open, but ten had narrowed and three had become re-occluded.

Adult↗
PubMed1988

[Long-term results of transluminal valvuloplasty in calcified aortic valve stenosis].

Transluminal valvuloplasty (TVP) was attempted in 11 patients, aged 38-82 years, with calcified aortic valve stenosis (AS). The transvalvular systolic pressure gradient was reduced from a mean of 91 +/- 28 to 44 +/-30 mm Hg. Two patients had needed an emergency with decompensated AS in cardiogenic shock, died during the operation, another died of the consequences of an endocarditis. One patient had an inadequate TVP: a renewed TVP was subsequently performed at another hospital, followed by an operation for severe aortic regurgitation produced by the second TVP. In four patients left-heart catheterization 3-12 months post-dilation demonstrated considerable restenosis. One patient was significantly improved clinically (but no angiography had as yet been performed) four months after the TVP. Doppler echocardiography in this patient, too, demonstrated renewed increase in transvalvular pressure gradient. The results demonstrate that, because of the high rate of recurrence, TVP is at present only rarely indicated for calcified AS.

Adult↗
PubMed1988

[Reopening of long-segment occluded aortocoronary venous bypasses. Short- and long-term results].

Recanalization of an occluded aortocoronary vein bypass was achieved in six out of seven patients (aged 57 +/- 4 years) 3-40 months after operation and 2-16 weeks after occlusion. The recanalization was done with a specially modified catheter introduced into the stump of the occluded vessel: urokinase was infused followed by balloon dilatation. Subsequent treatment included administration of nitrates, calcium antagonists, aspirin and heparin for at least three months. Repeat coronary angiography after 3-6 months (mean 4.3 +/- 1.0 months) demonstrated vessel patency in four of the six bypasses. One of them, severely stenosed, was again successfully dilated. It is concluded that bypass recanalization can be attempted if the occlusion occurred only a few weeks previously, angiography demonstrates a bypass stump and the state of the peripheral coronary artery makes good outflow likely.

Angioplasty, Balloon↗
PubMed1988

Coronary hemodynamics during left and right coronary arteriography with an ionic and nonionic contrast medium.

The direct effects of ionic amidotrizoate (iodine content 370 mg/ml, osmolality 2.1 osmol/kg) and nonionic iopamidol (iodine content 370/ml, osmolality 0.8 osmol/kg) on the coronary circulation were intraindividually compared in 10 patients suffering from coronary heart disease. In accordance with a double-blind, crossover protocol, both contrast media were injected into the left and right coronary arteries (8 ml and 5 ml per injection, respectively). Injections of both dyes into the left coronary artery caused a similar decrease in heart rate. The prolongation in the QT interval was significantly greater after amidotrizoate (p less than 0.05). Systolic (p less than 0.01) and diastolic (p less than 0.05) aortic pressures decreased to a greater extent following amidotrizoate injection. Each contrast agent produced a similar increase in coronary sinus flow, but iopamidol resulted in a smaller decrease in coronary vascular resistance (p less than 0.05). After right coronary artery injections, both contrast media caused bradycardia and prolongation of the QT interval, a decrease in systolic and diastolic aortic pressure, a rise in coronary sinus flow, and a lowering of coronary vascular resistance. Though most changes were more pronounced following amidotrizoate injection, the differences in the ionic and the nonionic agent were not statistically significant. Thus, after selective coronary arteriography, both contrast media caused a transient drop in coronary vascular resistance and a rise in coronary sinus flow despite a decrease in aortic pressure. The effects of amidotrizoate were more marked, which might be attributed to the higher osmolality of this ionic contrast medium. Coronary hemodynamics, however, usually returned to baseline values within 1 minute.(ABSTRACT TRUNCATED AT 250 WORDS)

Angiography↗
PubMed1988

Ultrastructural localization of calcium in the myocardium of cardiomyopathic syrian hamsters.

Cardiomyopathy of the Syrian hamster is characterized by myocardial calcium overload and focal myocardial necrosis. The cause of the myocardial calcium overload is not yet fully understood. In this study, the ultrastructural localization of calcium was determined in normal hamster hearts and in non-necrotic and necrotic myocardium of cardiomyopathic hamsters (strain BIO 82.62). In many cells from the non-necrotic myocardium of the cardiomyopathic hamsters the calcium deposits, visible as 20 nm particles, were confined to the inner leaflet of the plasma membrane, the T-tubules and the intercalated disks. This corresponds to the calcium distribution found in normal hamsters and other mammalian species. A number of morphologically normal cells, however, displayed an increased amount of calcium precipitate in the mitochondria as well as at the sarcolemma indicating that, in the cardiomyopathic hamster, focal calcium overload is detectable cytochemically in cells which otherwise do not show gross abnormalities. In cells showing morphological signs of myolytic degeneration a marked redistribution of calcium precipitate took place. Sarcolemma became devoid of calcium deposits whereas an enormous amount of clustered precipitate occurred in largely swollen mitochondria. These data are in support of a relationship between impaired ion homeostasis and degeneration events in cardiomyopathy. Furthermore, there appears to be a clear parallelism in calcium redistribution between hypoxic and cardiomyopathic myocardium.

Animals↗
PubMed1988

Dose-dependent relaxation of human venous vessel strips with regard to chronic nitrate pretreatment.

Helical segments of human saphenous veins harvested at coronary bypass surgery were mounted in an organ-bath (Krebs-Henseleit buffer, pH 7.4; 37 degrees C; 95% O2/5% CO2 insufflation). After equilibration (60 min) and determination of basal tone the segments were depolarized and contracted by 24 mM potassium chloride. Then relaxation under isometric conditions was induced by cumulative concentrations of isosorbide dinitrate (ISDN) in a range of 10(-9) M to 10(-5) M. In vein segments from patients not pretreated with nitrates a concentration-response curve could be shown ranging from 8.4 +/- 4.5% to 71.9 +/- 8.6% (mean +/- SD). The relaxation pattern was not influenced by a 2-week pretreatment of patients with ISDN 20 mg twice daily or 40 mg four times daily even if the latter therapy was continued until 1 hour prior to surgery. Immersion of vessel strips in Krebs-Henseleit buffer containing 10(-6) M ISDN for 60 min prior to relaxation did not affect relaxation either. However, immersion of vessel segments in buffer medium containing 4.4 X 10(-4) M ISDN for 60 min led to a shift of the concentration-response curve by the factor 100 (EC50). Thus, chronic nitrate pretreatment of patients including high doses did not influence relaxation behaviour of isolated vessel segments. Induction of tolerance under in vitro conditions required concentrations exceeding the therapeutic limits. The most probable underlying mechanism is exhaustion of sulfhydril containing groups at the site of the smooth muscle cells. This hypothesis was supported by the finding that addition of cysteine into the organ-bath could widely reverse tolerance.(ABSTRACT TRUNCATED AT 250 WORDS)

Dose-Response Relationship, Drug↗
PubMed1988

Recurrent restenosis after transluminal coronary angioplasty--dilatation or surgery?

In a total of 333 patients who had undergone a first successful transluminal coronary angioplasty (TCA), restenosis occurred in 17% (follow-up angiography was performed in 94% of patients). The restenosis rate was higher in bypass stenoses (45%) and re-opened vessels (54%). Repeat dilatation of restenoses had a high acute success rate (93%) and only few severe complications (2%). In this group the restenosis rate was 33%. Thirteen patients with recurrent restenoses (11 patients with two, and two patients with three recidivations) underwent a total of 41 dilatation attempts. The degree of stenoses (prior to the first TCA, 89%; prior to second TCA, 82%; prior to third TCA, 74%), the number of eccentric stenoses (8, 7, 5, respectively) and the length of the stenotic obstruction (5.2 mm, 4.7 mm, 4.3 mm, respectively) decreased. Accordingly, exercise tolerance improved (99 W, 133 W, 146 W, respectively). To date, follow-up angiography and functional investigations have been performed for 10 out of 13 patients. Good long-term results were observed in seven patients. Further restenoses occurred in three patients. It is concluded that repeat angioplasty is a reasonable therapeutic approach even for patients with recurrent restenoses.

Aged↗
PubMed1988

Effects of 5 mg sublingual nitrendipine in patients with precapillary pulmonary hypertension due to pulmonary fibrosis.

In 10 patients with precapillary pulmonary hypertension due to pulmonary fibrosis, the arterial blood pressure, right heart hemodynamics, cardiac output, and arterial oxygen partial pressure were measured to evaluate the benefits of acute sublingual (5 mg) nitrendipine. Additionally, the effect of oxygen enriched air was compared to control. At rest, nitrendipine significantly diminished arterial blood pressure [102 +/- 3 to 93 +/- 3 mm Hg (mean +/- SEM)], right atrial pressure (5.7 +/- 0.9 to 3.4 +/- 0.8 mm Hg), mean pulmonary artery pressure (33.4 +/- 3.5 to 29.8 +/- 3.3 mm Hg), and pulmonary artery wedge pressure (13.0 +/- 2.0 to 6.8 +/- 0.8 mm Hg). During exercise, nitrendipine reduced mean pulmonary artery pressure (54.5 +/- 4.8 to 49.3 +/- 4.7 mm Hg) and right atrial pressure (9.3 +/- 1.3 to 6.8 +/- 1.4 mm Hg). A diminuation of arterial partial oxygen pressure did not occur at rest (63.2 +/- 3.8 mm Hg) or during exercise (50.9 +/- 5.1 mm Hg). Thus, nitrendipine causes a slight but significant improvement of right heart hemodynamics. The occurrence of arteriovenous intrapulmonary shunting due to vasodilatating effects of nitrendipine can be excluded. Also, nitrendipine can safely be used in combined arterial hypertension and pulmonary fibrosis.

Administration, Sublingual↗
PubMed1988

[Simulation of a coronary vascular complication in transluminal coronary angioplasty by reversible intima folding].

The injection of contrast material into the right coronary artery via a guiding catheter while a Harzler dilatation catheter had already been introduced revealed an inhomogeneous filling of the vessel suspicious of an extensive thrombosis or a dissection. On completion of the angioplasty and removal of the balloon catheter, the artery again filled homogeneously showing a good angioplasty result. It is concluded that a complication had only been faked during angioplasty due to intimal folding and subsequent flow obstruction following the insertion of the balloon catheter.

Aortic Dissection↗
PubMed1988

[A catheter for imaging the persistent ductus arteriosus].

Nonsurgical techniques for patent ductus closure require precise knowledge of ductus diameter, length and shape. Angiographic visualization, especially in adults, may be difficult, due to the high flow and overlap of the aorta or the pulmonary artery. We have developed a new catheter for visualizing a patent ductus without intraarterial injection of contrast dye. A smooth latex balloon is mounted near the tip of this catheter and when it is filled with dye, the balloon fits the contours of the ductus. Ductus diameter may be established by measuring the diameter of the balloon. Furthermore, the hemodynamic consequences of ductus closure may be observed with the balloon occluding the ductus.

Adolescent↗
PubMed1988

[Quantitative coronary angiography: methodologic principles of a densitometric procedure].

In a defined short segment of a coronary artery, the amount of contrast medium depends on the cross-sectional area of the artery. The density of the coronary angiogram in the corresponding region reflects the amount of contrast medium. During projection of a single coronary angiographic frame, light intensity at the respective region can be measured by means of a light sensor. In phantom studies, light intensity was proportional to the amount of contrast medium in the corresponding area. This was the case even after dilution of the contrast medium (correlation coefficient r = 0.96-0.99). In a concentric stenosis model, a good correlation was found between the real cross-sectional area and the cross-sectional area measured by densitometric analysis (r = 0.97). Even in the model of eccentric stenoses, the correlation was linear (r = 0.96). Thus, it seems basically possible to densitometrically measure the cross-section of a coronary stenosis in relation to a normal segment. Unlike video densitometry, this method requires only very little apparatus.

Absorptiometry, Photon↗
PubMed1988

[Results of balloon valvuloplasty in pulmonary valve stenosis].

Percutaneous balloon pulmonary valvuloplasty was performed in 17 consecutive patients, ranging in age from eleven years to 67 years (mean age: 40 +/- 17 years). The peak to peak pressure gradient was reduced by 16 to 167 mm Hg, the mean pressure gradient decreased from 99 +/- 42 to 46 +/- 22 mm Hg. In six patients there was a pressure gradient above 50 mm Hg after the procedure. Within three months it decreased due to regression of infundibular hypertrophy and ranged from 26 to 46 mm Hg after one year. There were no serious complications. One patient experienced a brief episode of syncope. Another patient developed a pulmonary incompetence which was without hemodynamic significance. Percutaneous balloon pulmonary valvuloplasty offers an alternative method for treating pulmonary stenosis not only in children but also in adults.

Adolescent↗
PubMed1987

The Frankfurt experience in restenosis after coronary angioplasty.

Three hundred and thirty-three of 356 patients underwent angiographic follow-up from 1 to 18 months (mean 5.6 months) after percutaneous transluminal coronary angioplasty (PTCA). This is a reangiography rate of 94%. Recurrence rate after the first PTCA was 15% (n = 289). Restenosis rate was defined as an increase from immediate post-PTCA stenosis of more than 30%, or the loss of at least half of the initial gain in luminal diameter. Patients who needed a second angioplasty due to restenosis (n = 30) had a restenosis rate of 33%. Patients with angioplasty in the aortocoronary bypass (n = 14) had a restenosis rate of 45%. All patients were treated before, during and at least 4 to 6 months after the procedure with 60 to 100 mg of isosorbide dinitrate daily plus 160 to 360 mg of verapamil or 100 to 150 mg of gallopamil and 1.5 g of acetylsalicylic acid. In a second retrospective study 111 of 399 patients had the acetylsalicylic acid therapy discontinued or decreased. Forty-two of them developed restenosis (38%), whereas only 49 of 288 patients who continued to receive 1.5 g aspirin developed restenosis (17%). The restenosis rate was 32% in those who received the reduced dose of aspirin. Thus, a large dose of acetylsalicylic acid given before, during and 4 to 6 months after the procedure seems to be necessary to achieve a low rate of restenosis after PTCA.

Angioplasty, Balloon↗
PubMed1987

[Can beta-receptor blockers trigger coronary spasm?].

Beta-blockers are frequently administered in therapy of arterial hypertension and coronary heart disease. They mostly lead to an asymptomatic increase of peripheral and coronary resistance. Three patients in whom there were indications of a deterioration of myocardial blood flow under beta-blockade were observed within a few weeks. After discontinuation of the beta-blockers and instituting a therapy with calcium antagonists, both a reduction of ischemia in the exercise ECG and a reduction of symptoms could be observed. The possibility that beta-blockers trigger coronary spasms and thus give rise to unfavorable effects on myocardial blood flow must be considered in the context of therapy monitoring, especially in patients with coronary heart disease.

Cardiac Catheterization↗
PubMed1987

The haemodynamic side-effects of ionic and non-ionic contrast media in the presence of pulmonary hypertension: experimental and clinical investigation.

The haemodynamic side-effects of ionic (amidotrizoate) and non-ionic (iopamidol) contrast media after injection into the right atrium were compared in experimental and clinical studies. Pulmonary hypertension was induced in 10 dogs by embolization of the pulmonary vascular bed with agar-agar solution (mean pulmonary artery pressure = 44.2 mmHg). Iopamidol (1.5 ml kg-1) caused a moderate decrease in pulmonary and systemic vascular resistance, slight increases in right ventricular end-diastolic pressure and a marked rise in right ventricular contractility (dP/dtmax). Amidotrizoate (1.5 ml kg-1) caused considerable systemic vasodilation and initial increases in pulmonary vascular resistance and pressure followed by a substantial increase in right ventricular end-diastolic pressure and a decrease in contractility. Central and peripheral haemodynamics were measured in 20 patients with pulmonary hypertension (mean pulmonary artery pressure = 38.1 mmHg) due to valvular heart disease before and following injections with 40 ml of both types of contrast medium in randomized order. Heart rate, cardiac output and right atrial pressure rose significantly more after amidotrizoate and this contrast medium caused more extensive systemic vasodilation and a larger decrease in aortic pressure as compared to iopamidol. Pulmonary artery pressure went up moderately with both contrast media. It is concluded that non-ionic low-osmolality contrast media like iopamidol induce less pronounced haemodynamic alterations, in particular less increase in right ventricular filling pressure. This may be beneficial to patients with pulmonary hypertension undergoing angiocardiography or digital subtraction angiography.

Adult↗