Biomedical subjects
J Nitsch
Publications and source records attributed to J Nitsch.
[Myocardial necrosis due to defibrillation or cardioversion].
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Transfemoral catheterization of the coronary sinus by Doppler catheters for determination of coronary flow reserve.
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[Measuring blood flow velocity in the coronary sinus with Doppler catheters].
Measurements of the coronary sinus blood flow velocity with Doppler catheters (Medtronic Floscan; Millar DC201) were performed to assess coronary flow reserve and significance of coronary artery stenosis. In seven patients with normal coronary angiogram coronary sinus blood flow velocity (Doppler catheters) and coronary sinus blood flow volume (thermodilution) were simultaneously recorded. Coronary flow reserve was calculated as the quotient of the peak flow velocity (peak flow volume) and resting flow velocity (resting flow volume) after infusion of 0.5 mg/kg dipyridamole intravenously. The correlation coefficient was r = 0.88. Coronary sinus blood flow velocity was measured in 31 patients at resting conditions and after injection of contrast media during coronary angiography. At resting conditions blood flow velocity was 3.6 +/- 1.5 cm/s (n = 31), 3.5 +/- 1.8 cm/s (n = 9; controls), and 3.6 +/- 1.1 cm/s (n = 9; significant stenosis of the left anterior descending; not significant). After injection of contrast media flow velocity amounted to 2.2-fold resting flow in controls and to 1.5-fold resting flow in patients with stenoses of the left anterior descending artery (p less than 0.01). Measurement of coronary sinus blood flow velocity with Doppler catheters is a valuable adjunct for determination of coronary flow reserve and for assessment of stenosis severity of the left anterior descending artery. Continuous on-line monitoring of phasic flow velocity provides important information of the myocardial perfusion, e.g., during angioplasty.
[The mitochondrial genome and its deletions].
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[Acute myocardial uptake of lidocaine, mexiletine and amiodarone].
To assess acute myocardial uptake of antiarrhythmic drugs, we measured drug concentrations simultaneously in the aorta and in the coronary sinus during diagnostic cardiac catheterization. Measurements were taken 1, 2, 3, 4, 5, 7, and 10 minutes after intravenous bolus application of lidocaine (n = 10, 25 mg), mexiletine (n = 5, 25 mg and n = 10, 100 mg), or amiodarone (n = 10, 25 mg). Drug levels were measured by high-pressure liquid chromatography. Maximal concentrations were observed after 2-5 min. After 3-5 min coronary sinus levels exceeded aorta levels, indicating the end of net myocardial drug uptake. In contrast to lidocaine and amiodarone, no mexiletine was found in the coronary sinus 15 s after the end of drug application, obviously indicating a high myocardial drug content. Furthermore, the data provide an explanation for the acute efficacy of amiodarone. The myocardial uptake may result in various pharmacodynamic effects of antiarrhythmic drugs.
Myocardial oxygen supply in coronary artery disease.
In patients with coronary artery disease investigated during cardiac catheterisation, myocardial blood flow and myocardial oxygen consumption were significantly decreased as compared to control patients without signs of coronary artery disease. At the same time left ventricular function was impaired. In addition to regional contraction abnormalities observed in 77% of the patients, mean heart index and mean left ventricular work were diminished and mean enddiastolic pressure elevated. Among the coronary artery disease group, patients with normal blood pressure had a significantly higher left ventricular enddiastolic pressure than patients with hypertension.
[Indications for pacemaker therapy in ophthalmoplegia plus and Kearns-Sayre syndrome].
Mitochondrial myopathies can affect the skeletal muscle, the central or peripheral nervous system, and they may be associated with chronic progressive external ophthalmoplegia (CPEO). In 7/29 patients with mitochondrial myopathies and CPEO a cardiac involvement (Kearns-Sayre syndrome) was found: incomplete right bundle branch block (n = 1), right bundle branch block (n = 1), left anterior fascicular block and right bundle branch block (n = 2), complete atrioventricular block (n = 3); congestive cardiac failure (ejection fraction 40%) (n = 2); 3/10 patients had prolonged infranodal conduction on His-bundle electrography (HV-interval 60 ms). The cardiac involvement in ophthalmoplegia plus is characterized by progressive impairment of fascicular conduction. The need for prophylactic pacemaker implantation appears to exist in patients with bifascicular block and prolonged His-ventricle conduction.
[Computer-assisted contour detection in a complete heart cycle by levocardiography with adaptive raster tracking--validation of the method].
A method for computer-assisted edge detection in a full heart cycle of the left ventricular cineangiogram is presented. Left ventricular cineangiograms were acquired in the 30 degrees RAO position on cinefilms with 50 frames/s. A selected heart cycle was digitized with a spatial resolution of 512 x 512 pixels and a grey-value range from 0 to 255. In the first frame of the heart cycle a raster was calculated from contour points marked by an operator. The raster was automatically adapted to the left ventricular contour in the following frames. The contour points were determined on the adaptive raster by a gradient method. The automatic calculation of all contours of the systolic contraction was possible in 28 of 30 cineangiograms, operator interaction was necessary in two cineangiograms. The calculation of the diastolic contours requested operator interaction in 4 of 30 cineangiograms. The mean deviation of the calculated from the true contours ranged from -1.2 +/- 1.9 mm to 0.9 +/- 2.9 mm. The correlation coefficients between volumes calculated from the computer-determined and manually drawn contours ranged from r = 0.98 to r = 1.0 at beginning of systole, midsystole, endsystole, middiastole, and enddiastole with a standard error of the estimate between 2.8 ml and 5.2 ml. A repeated automatic determination of the contours after an independent remarking of the starting points resulted in a linear correlation of the calculated volumes with a correlation coefficient of r = 1.0 and a standard error of the estimate between 1.3 ml and 4.7 ml. The correlation coefficient for the ejection fraction was r = 0.99 with a standard error of the estimate of 1.9%.(ABSTRACT TRUNCATED AT 250 WORDS)
[Increased atrial natriuretic peptide in essential hypertension--relation to right atrial pressure behavior].
The role of atrial natriuretic peptide (ANP) in the pathogenesis of essential hypertension has not yet entirely been clarified. We investigated whether the increase of ANP in essential hypertension may be explained by elevated right atrial pressures and/or a different relationship between right atrial pressures and ANP secretion. Patients with stable essential hypertension undergoing right and left heart catheterization because of suspected coronary heart disease had significantly higher ANP levels than normotensives: 58.7 +/- 6.7 pg/ml in hypertensives versus 42.0 +/- 4.1 pg/ml in normotensives (p less than 0.01). Matching hypertensives with normotensives at identical levels of left ventricular enddiastolic pressure revealed significantly higher mean pulmonary artery pressures in hypertensives. Right atrial diastolic pressure (v-wave) after matching for LVEDP was 4.8 +/- 0.5 mm Hg in hypertensives and 3.1 +/- 0.2 mm Hg in normotensives (p less than 0.05). In addition, at any given mean right atrial pressure hypertensives showed higher ANP levels than normotensives. These results demonstrate that hypertensives exhibit raised pressures in the pulmonary artery independent of left ventricular pressure load. The elevation in right atrial pressures and the steeper relationship between these pressures and ANP are a suitable explanation for raised ANP levels in hypertension. ANP in essential hypertension may represent a counterregulation against elevated pulmonary resistance.
Acute induction of sustained ventricular tachycardia: a new porcine model.
In this study we evaluated the possibility of initiating long-lasting ventricular tachycardias acutely, using isolated porcine hearts and thus avoiding an open-chest operation model. This set-up was designed especially to investigate defibrillating or antitachycardiac pacing devices, which terminate these malignant arrhythmias if medical treatment fails. The experiments were performed on 42 pigs, weighing 20-25 kg. After thoracotomy their hearts were removed and adapted to a Langendorff perfusion system. Supplied with their own blood, beating hearts were manipulated in three different ways: direct current impulses (4.5 V, 750 ms) or programmed ventricular stimulation, creation of a small myocardial infarction, and application of antiarrhythmic drugs (ajmalin, lidocaine, sotalol). Out of all possibilities the combination of ajmalin (mean concentration 0.041 micrograms/ml) and a small anteroapical myocardial infarction (3-6 cm2) along with direct current impulses (4.5 V), led to sustained ventricular tachycardias in the highest proportion (93%) of trials (P less than 0.001). The heart rate was 251 beats per minute on average. Lidocaine trials were less successful (53%), while programmed ventricular stimulation and sotalol failed to induce ventricular tachycardias. This study supports the evidence that the combination of ajmalin and a small myocardial infarction with direct current impulses is a reliable model for sustained ventricular tachycardias in isolated pig hearts. Although it is a rather artificial organ model, tachycardias can be induced acutely without any long-term pretreatment. Animal models based on chronic myocardial infarctions will therefore be unnecessary for the investigation of defibrillating systems and antitachycardiac pacing devices.
Repeated intravascular treatment with amiodarone in a fetus with refractory supraventricular tachycardia and hydrops fetalis.
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[The heart ventricle wall in digital subtraction angiocardiography].
Digital subtraction angiography, using a time interval difference mode in relation to a suitable mask, provides a means of showing the myocardium in every phase of the cardiac cycle. The endo- and peri-cardial contours and the thickness of the myocardium in both ventricles can be demonstrated accurately. Artifacts are usually due to displacements of the heart or to tachycardia.
[Reduced myocardial fatty acid utilization in coronary heart disease following symptom limited ergometric stress. Detection of pathologic metabolic patterns using iodine-123-phenylpentadecanoic acid and sequential SPECT].
Regional cardiac free fatty acid metabolism of 41 patients with coronary artery disease (CAD) and of 10 controls with normal coronary arteries was studied by means of I-123 phenylpentadecanoic acid (IPPA), a radioiodinated palmitic acid analog, and sequential single photon emission tomography (SPECT). All patients and controls underwent symptom--limited bicycle exercise, with the tracer being injected at peak stress. More than 99% of left ventricular segment of controls showed homogeneous tracer uptake and release, indicating homogeneous free fatty acid turnover in normal myocardium. Homogeneous postexercise uptake was followed by decreasing segmental activity in 75.1% of normally perfused segments in patients with CAD. Sixty-five percent and 88.6% of segments, assigned to the perfusion bed of 50%-75% and greater than 75% obstructed vessels had decreased IPPA release and/or reduced IPPA uptake. Patients with exercise induced ischemia had focal metabolic abnormalities in jeopardized myocardium for significantly longer time than clinical or electrocardiographic signs of ischemia (p less than 0.01). All patients with CAD and a negative stress test had metabolic abnormalities, but exhibited, compared to ECG--positive patients, less pronounced segmental metabolic aberrations. These findings indicate reduced cardiac utilization and delayed oxidation of IPPA, associated with exercise-induced ischemia in CAD. The metabolic changes suggest a marked sensitivity to ischemia as well as prolonged postischemic abnormalities of cardiac fatty acid metabolism in jeopardized myocardium.
[Functionally significant changes in the shape of the right ventricle in digital subtraction angiocardiography].
Experiences in i.v. digital subtraction angiocardiography (DSAC) including so-called parametric imaging for morphological delineation of the right ventricle are illustrated. 32 patients with different anatomical and haemodynamic disturbances of the right ventricle were subjected to these examinations. Special emphasis is placed on pulmonary stenosis, particularly on its infundibular manifestations. For visualisation of muscular or fibrous bulging or other changes of the outflow tract of the right ventricle, analysis of the amplitudes is very suitable to produce cumulative pictures of ventricular wall motion during a cardiac cycle. Obstructive wall alterations within the infundibular part become visible even if they occur only during certain phases of the myocardial action, usually in late systole than otherwise.
[Distribution of electric potentials in intra- and extracardiac defibrillation].
The implantable defibrillator is a device to treat refractory ventricular tachyarrhythmias. This study was done to evaluate the determinants of defibrillator performance which are not known completely. Different defibrillation electrodes were attached to beating and non-beating isolated pig-hearts (n = 15) and the electric field resulting from defibrillation measured over a distance of 3 mm. From 5 to 20 J a non-linear relation was found between delivered shock energies and the amplitudes of the recorded voltage waveforms. Using two patch electrodes maximal amplitudes were monitored apical in the right (4.6 +/- 0.5 V) and left ventricle (2.1 +/- 0.3 V). The atria only showed 10-25% of the maximal amplitudes. The combination of a patch and a catheter electrode showed similar efficiency. Two catheter electrodes reduced the apical (1.2 +/- 0.1 V) and increased the atrial amplitude (0.75 +/- 0.06 V). The recorded amplitudes in myocardium were half as much compared with blood-/sodium chloride indicating the twofold higher resistance of myocardial tissue. These experiments quantify the dependence of the efficiency of automatic implantable defibrillator systems on the sort and localization of the defibrillation electrodes.
[Comparative studies on 2 radioimmunoassay technics for the rapid determination of human chorionic somatomammotropin (HCS) in normal early pregnancies].
To measure HCS concentrations in serum in early pregnancies, 2 commercially available kits (Pharmacia, Frankfurt, and Amersham-Buchler, Braunschweig) were used. When comparing them, we found that they were nearly of the same quality and equally suited for the measurement of HCS in early pregnancy. We ourselves should prefer to use the Amersham-Buchler kit, because it uses 2 standard curves, covering 2 ranges and thus avoiding to tilute the patients' sera, which decreases the possible pipetting errors and increases the accuracy of the determinations.