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Biomedical subjects

P Rentrop

Publications and source records attributed to P Rentrop.

At least 19 recordsLinked to original sources

[Reopening of infarct-occluded vessel by transluminal recanalisation and intracoronary streptokinase application (author's transl)].

Coronary angiography was performed 2 hours after onset of complaints in a 57-year-old patient with acute anteroseptal infarction. Using a wire spiral in the coronary catheter the acutely occluded anterior interventricular branch was reopened. With intracoronary streptokinase (120 000 units in 50 minutes) the recanalisation canal was enlarged. The clinical picture and electrocardiographic findings improved under the influence of treatment. An aorto-coronary bypass operation was performed on the following day. The post-operative angiogram showed marked improvement of left ventricular function. The results indicate that this intervention prevented widespread necrosis.

Angiography

[Recanalization by catheter of the occluded artery after acute myocardial infarction (transluminal recanalization (author's transl)].

Using guide-wires and special catheters the occluded infarct-related coronary artery was recanalized in 10 patients with acute myocardial infarction 6.6 +/- 7.1 hours after the onset of symptoms. There were no complications. Immediately after recanalization there were 80-95% lesions at the site of the previous occlusion. Angiography, performed in 9 patients in the chronic stage of myocardial infarction, revealed patency of the recanalized vessel in all instances. There was a marked decrease in the narrowing at the time of the second angiogram in 6 patients. Changes in left ventricular function from the acute to the chronic stage were assessed in 8 patients: the ejection fraction increased in 6. The results of this pilot study indicate that transluminal recanalization of acutely occluded coronary arteries is possible without harmful side-effects. Early restoration of flow may salvage the jeopardized myocardium. Further application of this method of treatment in selected patients and efforts to improve the technique seem to be justified.

Adult

[The determination of the left ventrical volume curve without background correction and its validation by direct intercomparison with the ejection fractions as determined by biplane laevocardiography (author's transl)].

Background corrections applied on the left ventricular volume curve determined by the "gated blood pool"--method are based on an estimated rather than on a directly measured background. This imposes an uncertainty on the values determined from the volume curve, especially on the ejection fraction. A method which does not require background correction may be applied if all available measurement and evaluation facilities are utilized fully. High temporal and spatial resolution is of fundamental importance, permitting the exact determination of the time-dependent scintigraphic contour variations of the left ventricle during the mechanical action of the heart. A good criterion of the validity of the volume curves with respect to interfering background radiation is the ejection fraction calculated from these curves. The direct intercomparison of 10 ejection fractions obtained by an expanded "gated blood pool"-method, employing cardiac catheterization, immediately before a biplane laevocardiography demonstrated very good agreement. A small systematic underestimation of the ejection fraction by the nuclear method was observed. This understimulation shows that the influence of the true background is small if other interfering count rate contributions or methodical uncertainties are excluded systematically.

Angiography

[Coronary angiographic findings in 308 patients with the clinical diagnosis of intramural myocardial infarction (author's transl)].

308 patients with the clinical diagnosis of intramural myocardial infarction made elsewhere were re-investigated more than eight weeks after the acute event. ECGs and pulmonary "wedge" pressures were recorded at rest and during exercise and coronary angiography performed (Sones' or Judkin's technique). In the first group (1973/74) of 77 patients, 35 (45.5%) had a normal coronary angiogram, compared with 0.7% in a control group with transmural myocardial infarction. A normal coronary angiogram was found in 85% of the 40 patients who had no angina during exercise. In a second group (1974/77) of 231 patients, there was a steady decrease in the number of patients without angina pectoris during exercise, in parallel with a decrease in the number of those with normal coronary angiograms. This change in pattern was apparently due to improved diagnosis in the referring hospitals. Of the 37 patients (first group) with angina during exercise, all but one were subsequently found to have significant coronary arteriosclerosis. It is suggested that most patients with a normal coronary angiogram had sustained a myocarditis and (or) pericarditis which produced the symptoms and the altered ECGs, leading to the misinterpretation of "intramural myocardial infarction".

Adult

Acute coronary occlusion with impending infarction as an angiographic complication relieved by a guide-wire recanalization.

In a 45 year old male patient with a history of previous inferior myocardial infarction and unstable angina pectoris, coronary angiography revealed two-vessel disease: a 60-70% lesion in the middle third of the LAD, and a 90% lesion in the middle third of the very large RCA. There was only a small akinetic segment in the posterobasal region of the left ventricle. During angiography total occlusion of the RCA occurred followed the clinical and electrocardiographic signs of impending inferior reinfarction. Recanalization of the occluded vessel was accomplished by using a guide-wire, which was passed through a Sones catheter, placed in the RCA. The patient's symptoms subsided and the electrocardiographic signs of acute ischemia reverted within eight minutes. Aortocoronary bypass surgery with revascularization of the LAD and RCA was performed within 3 hours after recanalization. Postoperatively there was no evidence of major tissue loss by enzyme or electrocardiographic criteria. Control angiography, performed on the ninth day postoperatively, revealed the graft to the RCA to be widely patent. Left ventricular function was unchanged. It is concluded, that the combined approach of early transluminal recanalization of the acutely occluded RCA followed by successful construction of a graft to this vessel, has averted necrosis of a major portion of the left ventricle. However, general use of this technique does not seem advisable at the present time.

Acute Disease

Hemodynamics at rest and during exercise in 222 patients with coronary heart disease before and after aorto-coronary bypass surgery.

In 222 patients with coronary heart disease hemodynamics at rest and during exercise were measured before and after aortocoronary bypass surgery. A total of 552 grafts were constructed, i.e. an average of 2.47 grafts per patient. Only 10.8% of the patients had a 1-vessel-disease, 59.2% had a 3-vessel-disease. 10.8% of the patients were provided with one graft, 49.7% got 3 or 4 grafts. In 92.8% of the patients the r. desc. ant. was significantly stenosed, and in 94.2% this vessel has been provided with a graft. Preoperatively only 7 patients had no angina pectoris during exercise (bicycle ergometer in supine position, each load lasting 6 min), postoperatively 154 patients have been completely free of angina pectoris. The preoperative angina pectoris-free exercise tolerance was 27.4 +/- 27.4 W (means +/- SD), postoperatively it was 76.5 +/- 33.8 W. The largest increase of exercise tolerance was observed in patients with a 3-vessel-disease (208%). Preoperatively only 10.1% had normal values of pulmonary wedge pressure and cardiac output at rest and during exercise, postooperatively 51.5%. The postoperative normalization of hemodynamics depends on the number of vessels involved (1-vessel-disease 86%, 3-vessel-disease 39.8% normalization) and on the status of the left ventricle (without a previous transmural myocardial infarction 68.4%; with a previous myocardial infarction 41.0%). The effects of revascularization on myocardial ischemia can be evaluated by measurements of pulmonary wedge pressure and cardiac output at rest and during exercise.

Angina Pectoris

[Distribution of scattered X-ray around a U stand in cardiology (author's transl)].

To estimate the stray radiation exposure which will be delivered to the doctor during a coronary angiography we made phantom measurements. The dependence of the stray radiation from the projection angle as well as from the tube tension for fluoroscopy and cinematography was measured in the three space coordinates. Out of these results the exposure per examination can be estimated for each place and hight of the doctor. As an example a determination of exposure under practical condition as well as the means of radiation protection are discussed.

Angiography

[Relationship between coronary angiographic findings and exercise Ecg in patients without transmural myocardial infarction (author's transl)].

In 311 patients (269 men and 42 woman, 20 to 65 years old) without transmural myocardial infarction the results of exercise tests in supine position were compared with the results of coronary angiography. 1. Patients having ischemic ST-segment depression (greater than or equal to 0.1 mV) and angina pectoris during exercise (n = 108) showed a greater than or equal to 50% stenosis of at least one vessel in 86.1%. In men the number of a greater than or equal to 50% stenosis was significantly higher than in women (91.3 vs. 56.2%). In patients without digitalis agreement with coronary angiographic findings is higher than in patients with digitalis (92.7 vs. 79.2%). After excluding women, patients under digitalis and those with an intramural myocardial infarction, agreement was 96.8%. 2. In patients having ischemic ST-segment depression agreement was 30% and in those with angina pectoris 36.8%. 3. In patients having neither ischemic ST-segment depression nor angina pectoris during exercise up to a heart rate of 80% of the age-dependent heart rate limit a coronary angiogram without a greater than or equal to 50% stenosis was found in 87.6%. After excluding patients with an intramural myocardial infarction, women and patients under digitalis, agreement increased to 97.9%. 4. In patients having both ischemic ST-segment depression and angina pectoris during exercise a 2- or 3-vessel disease was more often found than in patients having either ischemic ST-segment depression or angina pectoris, or in those having neither ischemic ST-segment depression nor angina pectoris respectively (57.5% vs. 16.6, 8.9 and 1.9%). 5. The number of positive coronary angiograms, especially of 2- and 3-vessel disease, increases with the degree of an ischemic ST-segment depression and the reduction of exercise tolerance.

Adult

[Can predictability of coronary angiographic findings be improved by additional measurement of pulmonary wedge pressure during exercise? (author's transl)].

The correlation between the three ischemia indicators angina pectoris (AP), ST-segment depression (ST) and excessive pulmonary wedge pressure rise (PCP) during exercise, and the coronary angiographic findings, were analysed in 293 patients without previous transmural myocardial infarction. This patient material consisted of 253 men and 40 women between the age of 20 and 65 years, the mean age being 48. The exercise tests were performed on a bicycle ergometer in supine position and in relatively steady state conditions. Pulmonary wedge pressure was measured by means of a Swan-Ganz floating catheter. The essential findings were: 1. If all three ischemia indicators were positive, the incidence of a positive angiographic finding i.e. a greater than or equal to 50% stenoses in at least one main coronary artery was 96.3%. 2. If only the two classic ischemia indicators were evaluated and positive, the incidence of a positive angiographic finding was only 86.1% (24). This difference is mainly due to false positive results of AP and ST in women. 3. If all three ischemia indicators were negative, the incidence of a negative angiographic finding was 89.2%. 4. If only the two classic ischemia indicators were evaluated and negative the incidence of a negative angiographic finding was as high (87,6% [24]). This lack of difference is due to the fact that patients with a previous intramural infarcion can be free not only of AP and ST but also of PCP during exercise. 5. The combination of AP and PCP, or ST and PCP, is equally reliable in predicting coronary morphology as the classic combination of AP and ST. It follows that PCP measurement is recommended, if one of the classic ischemia indicators cannot be properly evaluated.

Adult

[Function improvement in levography following aortocoronary bypass].

Actively contracting segments, preoperatively akinetic, were found in 8 of 63 patients, evaluated 6-12 months after aortocoronary surgery by coronary angiography. Ejection fraction was increased from 48.1% (S.D. 15.7) to 68.3% (S.D. 11.4). These patients are characterized by two simple clinical parameters: 1. All patients had angina pectoris at rest or at minimum exercise except for one; 2. preoperatively, there was a discrepancy between severe ventriculographic and discreet Ecg findings. These findings prove that myocardial function in coronary artery disease can be impaired at rest by ischemia, without clinical signs of coronary insufficiency, such as angina pectoris. Even severe impairment of left ventricular function is no contraindication for coronary artery surgery, if caused by reversible myocardial ischemia.

Adult

[Effects of dextran, gelatine and homologous plasma on circulation in shock caused by severe anemia in the dog].

Irreversible shock is produced in 28 anaesthetized mongrel dogs by withdrawal of erythrocytes and substitution by dextran, gelatine or plasma to an average Hb of 4.5g%. In contrast to other shock models cardiac output and perfusion pressure are not decreased by this preparation. In order to maintain arterial blood pressue above 90 mm Hg significantly more gelatine than dextran or serum has to be infused. There is no difference in hemodynamic responses after treatment with dextran or gelatine respectively. Both groups treated with colloidal solutions have the same survival rate of 38%. In the serum substituted dogs, however,survival rate is significantly greater (83%). Very likely this is due to a greater buffer capacity preventing severe acidosis, which is observed in the animals treated with colloidal solutions.

Anemia

[Ergometric findings depending on the severity and localization of coronary artery disease (author's transl)].

Ergometric and coronary angiographic findings were compared in 145 patients with proximal lesions of at least 50% of major coronary arteries. 75% of the patients had had a previous myocardial infarction. The following ergometric parameters occur most frequently in 3-vessel disease. (1) coronary insufficiency persisting after myocardial infarction, (2) ST-segment depression of at least 0.2 mV, (3) maximum exercise tolerance limited to less than 75 Watts. However, these parameters cannot predict 3-vessel disease with absolute certainty, nor can they exclude a single vessel disease. 3-vessel disease is not likely, if there is a maximum heart rate of 150 beats per minute or more. There were only slight differences between patients with 1-vessel disease and patients with 2-vessel disease. Patients who were limited at the 50 Watts level were found to have significant LAD disease, either alone or in combination with other vessels, with the exception of one patient.

Adult