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Biomedical subjects

M Kaltenbach

Publications and source records attributed to M Kaltenbach.

At least 163 records · Page 9Linked to original sources
PubMed1988

Late results of prosthetic valve replacement for aortic regurgitation and the prognostic significance of the end-diastolic and regurgitated blood volumes.

Between January 1975 and December 1985 214 patients underwent prosthetic aortic valve replacement for isolated aortic regurgitation. Patient follow-up averaged 5.4 years after the operation (range 0.7-10.7 years). Preoperative staging showed 9 patients to be in NYHA stage II, 111 patients in stage III, and 94 patients in stage IV. At follow-up 3 patients complained of increased fatigue, 9 patients remained stable and 167 patients had improved. 103 of these patients were free of symptoms under stress, i.e. NYHA stage I. The hospital mortality was 3.7% (8/214 patients). An additional 26 patients died within an average of 2.8 years. The cumulative 5-year survival rate was 85%; the 10-year survival rate was 81.5%. 10 patients underwent a second operation within an average of 3.4 years. The correlation between the end-diastolic volume and the regurgitated blood volume has prognostic significance. 25 patients with appropriate enlargement of the left ventricle showed a significant decrease of the end-diastolic volume and the roentgenographic heart volume combined with an increase of ejection fraction. None of these 25 patients died from cardiac complications. A control group of 9 patients with myocardial damage showed no significant change in the above parameters. 4 patients in the control group died. We conclude that the relationship of regurgitated blood volume and the left ventricular end-diastolic volume is of prognostic significance for patients with chronic aortic regurgitation presenting with minimal symptoms.

Adult↗
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

Comparison of the antianginal efficacy of isosorbide dinitrate (ISDN) 40 mg and verapamil 120 mg three times daily in the acute trial and following two-week treatment.

Fourteen male patients with exertion-related angina pectoris and reproducible ST-segment depression on stress testing were each treated with isosorbide dinitrate (ISDN) 40 mg three times daily, verapamil 120 mg three times daily and placebo three times daily for two weeks according to a double-blind cross-over protocol. The mean improvement of exercise-induced ST-segment depression amounted to 73% on the first day of ISDN treatment (P less than 0.001) and to 54% following acute administration of verapamil (P less than 0.001). On the last day of continuous treatment, the antianginal efficacy of ISDN was somewhat mitigated (reduction of ST-segment depression: 54%; P less than 0.001), while the effect of verapamil remained unchanged (55%, P less than 0.001). The double product (heart rate x systolic blood pressure) at the end of stress testing decreased most pronouncedly on day 1 of ISDN treatment (-21%; P less than 0.01). On chronic testing, both drugs similarly influenced this parameter: 10-11% (P less than 0.05). The mean global ejection fraction (EF) assessed by gated blood pool scintigraphy on day 13 showed a stress-induced fall from 49 to 44% (P less than 0.05) after the administration of placebo. The respective values with ISDN were 53% at rest and 52% on exercise (n.s.), and after giving verapamil 50% and 47% (n.s.). Thus, ISDN 40 mg and verapamil 120 mg displayed beneficial anti-ischaemic effects in patients with stable exertion-related angina pectoris after acute and chronic administration. The efficacy of ISDN declined somewhat in the course of the two-week treatment, whereas that of verapamil remained unchanged. Beneficial effects of both drugs were also demonstrated with regard to the rate-pressure product. Isosorbide dinitrate 40 mg and verapamil 120 mg administered three times daily can be recommended for the acute and chronic therapy of patients with stable angina.

Acute Disease↗
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

[Comparison of effort-ECG and radionuclide ventriculography in relation to the detection of myocardial ischemia in isolated stenoses of the anterior interventricular branch].

21 patients with LAD-stenoses of at least 70% and 21 patients with LAD-stenoses and additional intramural anterior wall infarctions were studied. 20 patients without heart disease or after successful transluminal coronary angioplasty and 18 patients with intramural anterior wall infarction after successful transluminal dilatation of the LAD (remaining stenosis maximal 30%) served as controls. The normal range of global and regional left ventricular ejection fraction response to exercise was defined based on the data of 25 further patients without relevant coronary heart disease. Thus, a decrease in global ejection fraction and regional wall motion abnormalities were judged pathological. All patients were comparable with respect to age, ejection fraction at rest and work load. Myocardial ischemia could be detected by the exercise ECG in 81% of all patients without infarction and in 71% of patients with infarction. The corresponding values for global left ventricular ejection fraction were 76% and 81%, respectively, and for regional ejection fraction 95% in both groups. No false-positive exercise ECGs were observed in the healthy controls and 2 (11%) in the corresponding group with intramural infarction. The global ejection fraction was pathological in 1 (5%) healthy subject without infarction and in 3 (17%) corresponding patients with infarction. Sectorial analysis revealed 5 and 22%, respectively. Our findings suggest that the exercise ECG has a limited sensitivity to detect myocardial ischemia in patients with isolated LAD-stenoses and intramural myocardial infarction. Radionuclide ventriculography yields pathological values more often; however, false-positive results also occur more frequently.

Adult↗
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

[Coarctation of the abdominal aorta. Experiences with transluminal angioplasty].

Balloon dilatation was performed transfemorally in three patients suffering from coarctation of the abdominal aorta. In two cases the pressure gradient could be reduced markedly from 85 to 55 and from 72 to 32 mm Hg, respectively. At follow-up angiography 3 months later the gradient was reduced further to 12 and 5 mm Hg, respectively. One women patient who had previously been handicapped by claudication intermittens, was free from complaints after balloon dilatation, whereas the other women patient with suprarenal stenosis of the aorta and renal hypertension was normotensive subsequent to balloon dilatation. In the third (male) patient who had already been operated on earlier because of stenosis of the aortic isthmus, dilatation was unsuccessful even if a very high balloon pressure was applied. These experiences support the view--in agreement with other authors--that balloon dilatation in coarctation of the abdominal aorta is a method of low invasiveness that should be attempted before surgery is performed.

Adult↗
PubMed1987

[Transluminal angioplasty of aortic isthmus stenosis in juveniles and adults].

Percutaneous transluminal balloon angioplasty of coarctation of the aorta was performed on eleven patients, aged 5-35 years (mean 25 years). Three patients had had surgical resection of the coarctation previously. There were no complications. The balloons used had a diameter up to 20 mm and were inflated with pressures of 3-5 bar for 10-60 sec. In two of the preoperated patients dilatation did not succeed. It was successful in the remaining nine. In these patients the gradient was reduced from a mean of 58 +/- 17 to 18 +/- 11 mm Hg, the stenosis diameter being increased from 4.5 +/- 2.4 to 11.9 +/- 5.1 mm. In five of six patients, angiography three or twelve months postoperatively demonstrated persisting dilatation. It is concluded that this procedure can be successfully used in both juveniles and adults, not only in children.

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

[Therapy of latent cardiomyopathy with verapamil].

In an open, randomized cross-over trial lasting two months, 21 patients with latent cardiomyopathy were either untreated or received verapamil 120 mg three times daily. Angina and dyspnea improved in 14 of the 21 patients. These symptoms worsened in one, remained unchanged in six (P less than 0.05). During exercise the pulmonary artery diastolic pressure fell from a mean of 25.3 +/- 7.6 to 20.1 +/- 6.6 mm Hg (P less than 0.05); (at rest, from mean of 10.7 +/- 5.2 to 9.0 +/- 4.5 mm Hg - not significant). In nine patients with a raised resting PA diastolic pressure verapamil produced a significant reduction (from 15.4 +/- 2.7 to 11.1 +/- 4.1 mm Hg) (P less than 0.05). All other hemodynamic parameters remained unchanged. These clinically and hemodynamically favorable effects are possibly due to improved diastolic ventricular function by verapamil. In latent cardiomyopathy any impairment of diastolic relaxation may be more important pathogenetically than reduction in systolic ventricular function.

Adult↗
PubMed1987

[Transfemoral valvuloplasty using the balloon catheter in mitral stenosis].

In two female patients (59 and 30 years old) with mitral stenosis, a successful valvuloplasty was carried out with a balloon catheter. After transseptal puncture with determination of the pressure gradient between the left auricle and the left ventricle, the atrial septum was initially dilated with a small balloon and a MediTech balloon catheter with a diameter of 25 mm was pushed forward into the region of the mitral valve via a guide wire. On filling of the balloon, the marked indentation at 3-4 atü hyperbaric pressure initially present could be eliminated. The pressure gradient fell from 8 mm Hg to 2 mm Hg in the first patient and from 12 mm Hg to 3 mm Hg in the second patient. The interventions were without complications. There was a marked clinical improvement with increase of physical exercise tolerance and decrease of dyspnoea in both patients. A mitral valve insufficiency did not occur. The new technique may possibly constitute an alternative to surgical commissurotomy.

Adult↗