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Biomedical subjects

W Klein

Publications and source records attributed to W Klein.

At least 199 records · Page 11Linked to original sources
PubMed1995

Cyclic phenomena in early myocardial infarction.

It has been shown by a number of authors that early myocardial infarction constitutes a dynamic process of cyclic oscillation between coronary occlusion and spontaneous coronary reopening. Infarct-markers, such as ST-segment elevation, serum-creatine kinase isoenzyme MB, the atrionatriuretic peptide (ANP) and serum-myoglobin (Mb) exhibit cyclic behaviour pattern during early AMI and thus reflect episodes of intermittent, spontaneous reperfusion. The latter have recently been verified by angiography. The mechanism underlying the phenomena seen in early myocardial infarction is likely to be based on a constant vasoconstrictive stimulus, deriving from aggregating platelets. The vasoconstriction subsequent to platelet aggregation produces an initial episode of myocardial ischemia. This episode is followed by a hypoxia of the artery wall. Reactive coronary dilation secondary to ischemia is than promoted by the release of vasoactive by-products of anaerobic glycolysis as well as changes in the open propability of certain transmembrane ion channels. Thereafter, the initial coronary occlusion is interrupted by transient vasodilation. A wave of reperfusion follows and leads to reoxygenation and wash-out of ischemia-induced vasodilative components as well as biochemical markers. The vasoconstrictive forces then take over again. This results in repeated waves of reperfusion. A number of arguments in favour of this concepts are discussed in this paper.

Atrial Natriuretic Factor↗
PubMed1994

Contractile failure in early myocardial ischemia: models and mechanisms.

In early myocardial ischemia we find a number of salient electrical and ionic alterations. This article reviews action potential shortening, K accumulation, and contractile failure. Enhanced K efflux during early myocardial ischemia has been attributed to a number of mechanisms, including: the inhibition of active K uptake, osmotic changes, efflux of K ions linked to anion extrusion, cation exchange, altered cellular energy levels, in particular, the opening of ATP-dependent K channels, the involvement of other ion channels, a H/K-ion exchanger, and a catecholamine-dependent pathway. The different mechanisms are discussed. Action potential shortening was described as a salient characteristic of myocardial ischemia in 1954 by Trautwein and Dudel, and was attributed to enhanced outward current. Recently it has been shown by several authors that ATP-dependent potassium channels play a key role in this context. Contractile failure in early myocardial ischemia has been explained by shortening of the action potential duration, reduced cytoplasmic free calcium levels, intracellular acidification, and a rise in inorganic phosphate and Mg. In summary, it is concluded that ATP-dependent K channels may be involved in each of these three phenomena.

Animals↗
PubMed1994

Arthroscopic management of postoperative arthrofibrosis of the knee joint: indication, technique, and results.

From October 1987 through March 1991, 58 patients with postoperative joint stiffness underwent arthroscopic fibroarthrolysis. Forty-six knees in 46 patients were followed. The indication for arthroscopic management was decreased range of motion after surgery. Eighty-seven percent had been treated by arthrotomy. Thirteen percent had been managed by arthroscopic surgery. The indication for primary surgery was a torn anterior cruciate ligament in 74%. The mean interval between arthroscopic fibroarthrolysis and follow-up was 22.1 months. The average age was 32.7 years. A modified Blauth and Jäger score was used for classification of fibroarthrosis: grade I (mild 17.4%), grade II (moderate 63%), grade III (severe 15.2%), and grade IV (bad 4.3%). The gain in range of motion was evaluated by the Cauchoix index: the results were excellent in 54.5%, good in 21.7%, and fair and poor in 23.8%. Pain was evaluated according to a modification of the Lysholm score: 80.4% of the patients experienced a reduction in pain. The sports activity level in the Tegner activity scale increased from 2.3 to 4.8. Patient satisfaction was excellent or good in 56.5% (n = 26), fair in 39.1% (n = 18), and poor in 4.3% (n = 2). On the basis of our retrospective study, we feel that arthroscopic fibroarthrolysis is of benefit to the patients with postoperative joint stiffness even after a prolonged period.

Adult↗
PubMed1994

Autoantibodies to oxidized low density lipoproteins in restenosis following coronary angioplasty.

Oxidized low density lipoproteins (oLDL) play an important role in the pathogenesis of atherosclerosis. Recently, elevated oLDL autoantibodies in serum were shown in patients with severe peripheral atherosclerosis. To evaluate their role in restenosis after percutaneous transluminal coronary angioplasty (PTCA), oLDL autoantibodies were determined in a randomly selected series of 48 males following successful PTCA. Follow-up angiography as well as blood sampling were done 12 months after PTCA; restenosis was defined as > or = 50% reduction in diameter of the coronary artery. Twenty-six patients (mean age: 56 years) showed restenosis (Restenosis Group), whereas 22 (mean age: 53 years) had open vessels (Patent Vessel Group). Both groups did not differ in age, past medical history, fibrinogen and lipid profile as well as in initial angiographic findings. Oxidized LDL autoantibodies were 13 +/- 21 U in the Restenosis Group and 6 +/- 4 U in the Patent Vessel Group, showing no significant difference. Six of 26 patients in the Restenosis Group and 3 of 22 in the Patent Vessel Group (NS) had elevated oLDL autoantibody levels (> or = 10 U). Thus, although there is a trend to elevated oLDL autoantibodies in males with restenosis of coronary arteries, oLDL cannot serve as a strong marker for stenosis following PTCA.

Adult↗
PubMed1994

Long-term outcome and prognostic factors in dilated cardiomyopathy. Preliminary results.

UNLABELLED: To investigate long-term follow-up and identify prognostic factors in patients with dilated cardiomyopathy (DCM) the authors investigated 167 consecutive patients on an outpatient basis. All patients underwent left- and right-heart catheterization; follow-up comprised clinical and echocardiographic investigations. RESULTS: After a mean follow-up period of ninety-three +/- thirty-six months 82 patients (49%; 71 men, 11 women, mean age fifty-five +/- eleven years) were alive. 29 of them (27 men, 2 women, mean age fifty-two +/- nine) showed normal left ventricular ejection fraction (LVEF) after a mean follow-up period of one hundred four +/- forty months. The remaining 53 patients (44 men, 9 women, mean age fifty-six +/- eleven) revealed LVEF similar to that of the first examination. Eighty-five patients died (51%; 73 men, 12 women). Causes of death were the following: progressive heart failure, 24; sudden death, 23; stroke, 3; pulmonary embolism, 2; noncardiac death, 4; unknown causes, 29. The median period from the onset of first symptoms until definite diagnosis was two months in patients with stable conditions, three months in those with normalization of LVEF and twenty-four months in those who died, respectively (P < 0.01). At the time of diagnosis, patients with stable outcome had a mean LVEF (LVEF 1) of 37%, those who returned to normal had 40% (ns). Patients who died had a mean LVEF 1 of 32% and therefore differed significantly from both groups of survivors (P < 0.001). Left ventricular end-diastolic pressure (LVEDP) at the time of diagnosis was highest in patients who died (22 mmHg) and therefore differed significantly from both groups of survivors (normalization: 16 mmHg, stable patients: 18 mmHg, P < 0.001). CONCLUSIONS: According to their results, time until diagnosis, LVEF, and LVEDP are prognostic indicators. No difference was noted between the groups concerning etiology, medical treatment, or functional classification according to the New York Heart Association.

Adult↗
PubMed1994

[ECG of the athlete's heart].

The athlete's heart is characterized by eccentric hypertrophy of all cardiac cavities and there is a close connection to increased tone of the vagal system. As a consequence, not only arrhythmias are observed in the ECG of healthy athletes, but also changes in the QRS complex and in the ST-T-segment. Left ventricular hypertrophy is diagnosed in ECG by a positive Sokolow-Lyon index. The frequent finding of a right ventricular conduction delay is possibly due to hypertrophy of the myocardium in the apex of the right ventricle. The causes of various T wave changes are generally unclear and await further diagnostic clarification. In cases when normalization of the T-wave deviation is observed under stress, such changes are of functional nature. Echocardiography is indicated in any case to establish the heart's size and function; hypertrophic cardiomyopathy has to be excluded. Frequent cardiac dysrhythmias found in athletes are sinus bradycardia and sinus arrhythmia, less often escape rhythms are seen. A arrhythmia more often found in athletes is the respiration-dependent simple atrioventricular dissociation. Also, escape rhythms are observed in some cases with ventricular origin. Finally, a pronounced vagotonia can lead to a prolonged conduction time; AV-blocks of all degrees of severity are observed in athletes. The functional character of these arrhythmias can be easily demonstrated by their disappearance under stress.

Arrhythmias, Cardiac↗