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Biomedical subjects

H Kuhn

Publications and source records attributed to H Kuhn.

At least 181 records · Page 10Linked to original sources
PubMed1980

The effect of tetraethylammonium chloride on calcium fluxes in smooth muscle from rabbit main pulmonary artery.

1. In the first part of this investigation we studied the experimental conditions under which the 'lanthanum method' gives valid estimations of the changes in intracellular calcium induced by either tetraethylammonium chloride (TEA) or high K in the rabbit main pulmonary artery. Subsequently, the effect of TEA on Ca movements in this blood vessel was measured. 2. The uptake of 140La by the vascular tissue is time- and concentration-dependent; it is separated into an early and a late phase. La binds to at least two classes of extracellular sites with affinities of 0.06 and 4.76 M. 3. A 1 hr exposure of the vascular strips to a 1 mM-La solution appears to be a convenient treatment for removal of Ca from the extracellular space. Under these conditions (a) 45Ca efflux from an intracellular compartment loaded with Ca during exposure to TEA or K is virtually blocked, (b) there is no major penetration of La into the smooth muscle cells as revealed by electron microscopy, and (c) there is no change in the size of the extracellular space. 4. TEA increases in a concentration-dependent manner the La-resistant 45Ca content (maximum increase 0.18 m-mole 45Ca/kg wet weight in response to 70 mM-TEA). There is a linear relationship between log concentration TEA and 45Ca influx. 5. The calcium antagonist verapamil (10(-6) and 10(-5) M) inhibits the TEA-induced 45Ca influx. 6. The increase in 45Ca influx produced by K (20 or 30 mM) is markedly enhanced by TEA. 7. The noradrenaline-induced increase in 45Ca accumulation is not influenced by TEA. 8. 45Ca efflux from the La-resistant Ca space is increased by TEA both in the presence and in the absence of non-radioactive Ca in the medium. 9. It is concluded that TEA contracts the vascular smooth muscle cells of the rabbit main pulmonary artery by an increase in the Ca permeability of the cell membrane.

Animals↗
PubMed1980

Amiodarone.

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Amiodarone↗
PubMed1980

[Hypertrophic non-obstructive cardiomyopathy (HNCM)--clinical, hemodynamic, electro-, echo- and angiocardiographic studies (author's transl)].

In order to characterize the clinical picture of hypertrophic non obstructive cardiomyopathy (HNCM) symptoms, ECG, echocardiogram, left ventricular angiogram, hemodynamics, the clinical course and the familial incidence were analyzed in 49 patients. The most striking findings in the ECG were slight or deeply negative T-waves with a maximum in leads V4 or V5. The diagnostic specifity for HNCM in 22 consecutive cases with this abnormal finding of unknown etiology was 91%. The 2-dimensional echocardiogram and the ventriculogram revealed a funnel-shaped obliteration of the apex of the left ventricle in 94% (wall thickness of the basis was 14.8 +/- 2.9 and at the apex 19.3 +/- 5.3 mm compared to 8.5 +/- 1 and 8.6 +/- 1.2 mm in normal subjects). The M-mode echocardiogram showed asymmetric septal hypertrophy in 72% and symmetric hypertrophy or a thicker posterior wall in 28%. By endomyocardial catheter biopsy (n = 9) and in two patients who died, no storage disease was detected. An abnormal increase of mean pulmonary artery pressure at exercise was measured in 59%. The clinical course (n = 37, follow-up 5.1 years in the mean) was stable in 68%, 5% died. There was a significant negative correlation between functional class and IVS/PW ratio, left ventricular enddiastolic diameter and enddiastolic volume and a significant positive correlation between functional class and left ventricular enddiastolic pressure. The familial incidence was 15%. The data demonstrate that HNCM is a well definable clinical entity which seems to be more frequent than it has been assumed before.

Adolescent↗
PubMed1980

[Hemodynamic effects of medical and surgical therapy of hypertrophic obstructive cardiomyopathy (author's transl)].

In order to assess the hemodynamic effects of medical (propranolol) and surgical (transaortal subvalvular myectomy) therapy, we determined in 20 patients with hypertrophic obstructive cardiomyopathy the following circulatory parameters at rest and during maximal exercise before and after therapy: heart rate, stroke volume, cardiac output, and pulmonary artery pressure. 9 patients were re-investigated after medical therapy of 3.5 weeks to 7 months (averaging 3 months) with a daily dose of 120 to 360 mg (mean 198 +/- 80 mg) propranolol, 11 patients 1 week to 28 months (averaging 7.5 months) after operation. Propranolol induced a significant reduction of heart rate and cardiac output averaging 20.9% and 20.3%, respectively (p in both cases < 0.0001) at equal exercise levels, no change in stroke volume, and a slight increase in the pathologically elevated exercise mean pulmonary artery pressure, with the pulmonary vascular resistance remaining unchanged. Although 3 of the 9 patients reported a slight subjective improvement, exercise capacity did not change significantly from a mean of 66.7 to 69.4 watts. Myectomy, on the other hand, induced no change in heart rate, but a significant increase in exercise stroke volume by 14.9% (p < 0.025) and a distinct increase in cardiac output by an average of 11.2% (not significant), whereas the pathologically elevated exercise mean pulmonary artery pressure fell significantly by 23.8% from a mean of 45.0 to 34.3 mm Hg (p < 0.025). 10 of the 11 surgically treated patients reported a usually marked subjective improvement, and the exercise capacity increased from an average of 61.4 to 81.8 watts (p < 0.01). Thus, the clinical and functional result of surgical therapy was significantly better than that of medical therapy and included, in contrast to medical therapy, a significant hemodynamic improvement and increase in exercise capacity.

Adult↗
PubMed1980

[Thallium-201 myocardial scintigraphy in patients with normal coronary arteries and normal left ventriculogram - comparison with hemodynamics, metabolic and morphologic findings (author's transl)].

36 consecutive patients with chest pain and/or severe ventricular dysrhythmias, but normal coronary arteries and normal left ventriculogram, underwent thallium-201 myocardial imaging at rest and during exercise. The myocardial scintigram was abnormal in 27 patients (group A) and normal in only 9 patients patients (group B). To answer the question, whether the scintigram was false positive or a correct expression of a myocardial disorder not detectable with angiocardiographic methods, we compared the scintigraphic results with the findings of resting and exercise ECG (n = 36), mean pulmonary artery pressure during exercise (n = 27), myocardial lactate extraction during highrate atrial pacing (n = 14) and light- and electronmicropic examination of right ventricular endomyocardial biopsies (n = 14). The resting ECG was abnormal in 7 of 27 patients of group A and 1 of 9 patients of group B, the exercise ECG in 20 of 27 patients of group A and 1 of 9 patient B. An abnormally elevated exercise pulmonary artery pressure was measured in 10 of 21 patients of group A and 1 of 6 patients of group B. High rate atrial pacing induced an abnormal myocardial lactate extraction in 3 of 13 patients of group A, but not in the single investigated patient of group B. All 12 examined patients of group A and 1 of 2 patients of group B had abnormal biopsy findings. The high incidence of abnormal findings in group A compared to the rare incidence in group B suggests, that the abnormal myocardial scintigrams in patients with chest pain and normal coronary arteries is likely not false positive but reflects a myocardial disorder not being recognized on angiography.

Adult↗
PubMed1979

[The applicability of systolic time intervals in patients before and after aortic valve replacement (author's transl)].

In order to evaluate the systolic time intervals (STI) for characterizing the left ventricular pump function and the clinical course in patients with aortic valve disease, 35 patients with aortic stenosis (AS) and 25 patients with aortic insufficiency (AI class III or IV (NYHA) were studied before and 1 year after valve replacement either with Björk-Shiley, Lillehie-Kaster or Starr-Edwards aortic prostheses. Left ventricular ejection time index (LVETI), preejection period index (PEPI) and PEP/LVET were determined and compared with cardiac index (CI), stroke volume index (SVI) and ejection fraction (EF). Prosthetic valve replacement leads to a high significant decrease of LVETI from preop. 468 +/- 31 ms to postop. 394 +/- 26 ms (mean normal values 415 ms) and an increase of PEPI from 100 +/- 26 ms to 136 +/- 25 ms (normal 132 ms) as of PEP/LVET from 0.21 +/- 0.09 to 0.41 +/- 0.12 (normal 0.31). Pre- as well as postop. there is no difference in STI between AS and AI. Also the groups with the three prosthetic valve types do not differ significantly. LVETI and PEPI correlate only postop. with CI and SVI, but PEP/LVET correlates well with EF (r = -0.73) before and after operation. The comparison of STI with the hemodynamic data suggest that preop. values of STI near normal and postop. LVETI below, PEPI and PEP/LVET above the mean values of the whole group with aortic valve replacement indicate left ventricular pump dysfunction. The STI are helpful in the pre-/postop. follow-op of patients with severe aortic valve disease to characterize the clinical and hemodynamic course.

Aortic Valve↗