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Biomedical subjects

P Rentrop

Publications and source records attributed to P Rentrop.

At least 55 records · Page 3Linked to original sources
PubMed1980

Right ventricular function at rest and during exercise in patients with coronary heart disease.

Biplane cineventriculograms of the right ventricle at rest and during exercise were made of 16 patients with a right coronary artery stenosis of greater than 50% and less than 90% to explain the alteration of the volumes and function of the right ventricle during exercise-induced angina pectoris. The right ventricular enddiastolic volume increases from 113 +/- 6.6 ml/m2 to 133.9 +/- 9.8 ml/m2 (P less than 0.001). The endsystolic volume increases from 48.9 +/- 4.1 ml/m2 to 52.9 +/- 5.3 ml/m2. The stroke volume index increases from 64 +/- 5.5 ml/m2 to 81 +/-8.3 ml/m2 (P less than 0.001). At the same time the ejection fraction increases from 56.5 +/- 2.9% to 60.2 +/- 3.2% (P less than 0.05). The left ventricular enddiastolic pressure increases from 12.8 +/- 1.5 mm Hg to 26.6 +/- 1.6 mm Hg (P less than 0.001). The enddiastolic pressure of the right ventricle increases from 5.8 +/- 0.5 to 12.2 +/- 0.8 mm Hg (P less than 0.001). The mean velocity of diameter shortening, VD, increases from 0.9 +/- 0.06 D/s to 1.12 +/- 0.09 D/s (P less than 0.05). Exercise-induced angina pectoris leads to a considerable increase of the left ventricular enddiastolic pressure and therefore to an increase of the right ventricular afterload. The increase of afterload in patients with a right coronary artery stenosis is compensated by a considerable increase of the enddiastolic volume: the pump-function during exercise-induced angina pectoris is maintained by an increase of preload.

Angina Pectoris↗
PubMed1980

[Results of quantitative myocardial scintigraphy with thallium-201 at rest and after maximum exercise--critical analysis of predictive value and clinical application (author's transl)].

In 20 normal individuals and 60 patients with CAD, myocardial scintigraphy with thallium-201 was performed after maximum exercise and two hours later at rest. The evaluation of digitized scintigrams was performed quantitatively by means of a 14-halfsegment model. Using ROC analysis, sensitivity and specificity were estimated. Furthermore the predictive value of a thallium scintigram was evaluated by means of the bayesian theorem, comparing the data with coronary angiography and partly also with exercise ventriculography. At a specificity of 90%, sensitivity of scintigraphy for CAD was 97% in 34 patients with previous myocardial infarction and 85% in 26 patients without infarction. Sensitivity for the extent of CAD was 93% for 44 vessels, perfusing infarcted myocardium and 67% for 96 vessels, perfusing non-infarcted myocardium. Sensitivity decreased with increasing extent of CAD and was higher for Cx than for LAD. The predictive value of a positive or negative scintigram was analyzed for different prevalences of CAD. At a low prevalence, e.g. 5%, the predictive value of a pathological scintigram is only 32%, consequently thallium scintigraphy is not applicable as a general screening procedure. At a high prevalence, e.g. 90%, the predictive value of a normal scintigram is only 40%. Therefore thallium scintigraphy seems not to be able to differentiate whether a coronary artery stenosis is hemodynamically significant or not. This was in agreement with the data from exercise cineventriculography. A high predictive value of thallium scintigraphy of about 85% is obtained only in the case of a medium prevalence of CAD, e.g. in asymptomatic patients with pathological Ecg or in patients with atypical angina pectoris. An improvement of the predictive value of myocardial scintigraphy would require other radionuclides than thallium-201, to use higher activities and to allow Ecg-gated myocardial scintigraphy.

Adult↗
PubMed1980

[Reduction in cardiotoxicity of ionic contrast media used in coronary angiography by added calcium--Clinical study (author's transl)].

In 16 patients with CAD, hemodynamic and electrophysiologic side effects were examined following selective coronary artery injections with Urografin 76%, a commonly used ionic contrast medium. A Millar transducer tipped catheter was placed in the left ventricle for continuous pressure recording also during injections. The unmodified contrast medium decreases peak left ventricular pressure (-22 +/- 8%) and dp/dt max (-27 +/- 13%) markedly at injection. With added calcium (22.5 mEq/l) this cardiodepressive reaction becomes diminished to -15 +/- 7% and -13 +/- 8% respectively with high significance (p < 0.001). This positive effect is even more marked using higher volumes of contrast material for injection. In contrast to animal experiments, calcium did not completely compensate the negative inotropic reaction even in higher concentration (33.75 mEq/l). The marked sinus slowing (-29 +/- 14%)--observed in patients and not influenced by the calcium addition--has an additional effect in the sense of a "negative frequency-inotropism" and is responsible for the residual cardiodepressive reaction. An influence on electrophysiologic side reactions can also be observed with added calcium but only in injections with higher volumes of contrast medium. QT-elongation, T-wave changes are reduced significantly. We did not see any unfavorable reactions caused by added calcium. The cardiodepressive side effects on the contractile force by commonly used ionic contrast media can be reduced by adding calcium in the above-mentioned concentration. This may be helpful when studying high risk patients and using high injection volumes.

Adult↗
PubMed1980

[Quantitative Tl-201 scintigraphy in diagnosis of severity and location of coronary artery disease. Comparison of a Tl-score to invasive and non-invasive parameters (author's transl)].

Thallium-201 scintigraphy was performed in 20 normals and 60 patients (pts) with angiographically proven coronary artery disease (CAD) at rest after maximal exercise for evaluation of severity and location of CAD. The Tl-scintigrams were quantified by a Tl-score. The results of the Tl-score were compared with invasive and non-invasive parameters. Sensitivity asnd specificity of the Tl-score in evaluation of CAD was 90%. In normals, there were no significant differences from rest to exercise (Tl-score less than or equal to 1.2). Twenty-six of the pts with CAD, who had no evidence of myocardial infarction, showed a significant increase of Tl-score from 5.0 +/- 1.7 to 8.7 +/- 2.6 after exercise (p < 0.001). In 34 pts with CAD and a history of MI, Tl-score increased from 24.9 +/- 3.1 to 33.3 +/- 3.8 (p < 0.001). Exercised-induced ischemia was assessed by exercise electrocardiography in 48%, by Tl-score in 62% and by angina pectoris in 77%. In 37 pts, the Tl-score was compared with the coronary score, ejection fraction (EF) and local wall motion derived from biplane cineventriculograms. There was a significant correlation between the Tl-score and the EF: y = 79.13 - 1.11 x, n = 74, r = 0.688 (p < 0.001). No correlation was found between the coronary score and the Tl-score. Hypokinetic wall motion disturbances were assessed by Tl-score in 34% only, whereas akinesia and dyskinesia were detected in 86% (p < 0.001). The data suggest that Tl-scintigraphy even with a quantitative Tl-score is not sufficient for exact assessment of extent and severity of CAD.

Adult↗
PubMed1980

[Qualitative and semi-quantitative analysis of local wall motion abnormalities by gated-blood-pool in comparison to biplane cineventriculography (author's transl)].

Left ventricular wall motion at rest was assessed by the following three methods in 37 patients of whom 12 patients had coronary artery lesions of > 75% and Ecg-signs of transmural MI: A) qualitative analysis of GBP, B) semi-quantitative analysis of GBP, C) qualitative analysis of a biplane cineventriculogram. Sensitivity and specificity of each method were evaluated based on the cineventriculographic findings. Specificity of method A was 83%, of method B 100%. Sensitivity of method A was 88%, of method B 84%. Concordance of methods B and C was 92.8% (167/180 left ventricular segments). Discordance between the two methods was found only in 1 segment judged to be akinetic and in 12 segments judged to be hypokinetic by one of the two methods.

Adult↗
PubMed1979

[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↗
PubMed1979

[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↗
PubMed1979

[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↗
PubMed1978

[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↗
PubMed1978

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↗
PubMed1977

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↗
PubMed1977

[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↗
PubMed1977

[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↗
PubMed1977

[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↗