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Biomedical subjects

V Hombach

Publications and source records attributed to V Hombach.

At least 199 records · Page 11Linked to original sources
PubMed1988

Pathophysiology of unstable angina pectoris--correlations with coronary angioscopic imaging.

Different patho-anatomical and functional factors are considered to be involved in patients with unstable angina pectoris. Among these are a pre-existing plaque based on coronary atherosclerosis, the development of fissures or dissections of the plaque (often combined with thrombus formation at the site of the plaque) coronary vascular tone, and theoretically primary aggregation of platelets at a site of apparently normal vascular endothelium. Several comprehensive studies on patients who died from acute myocardial infarction or unstable angina, have convincingly shown that complications of an atherosclerotic plaque like fissures, dissections and thrombus formation may be present in 60 to 90% of cases. In addition, two groups of investigators, who have applied coronary angioscopy for direct visualization of offending coronary arteries, have confirmed these results, since in about 60-80% of patients with unstable angina complicated atheromata, i.e. rupture, ulceration, thrombus formation, could be documented, whereas in all patients with stable angina an uncomplicated atheroma was seen angioscopically. On the basis of these results a hypothetical sequence of events in patients with stable angina, unstable angina and acute myocardial infarction has been proposed. Stable angina pectoris may be seen in patients with uncomplicated atheroma in one of the major coronary artery branches. When dissections, ulcerations and thrombus formation occur as a complication of a formerly smooth plaque, patients show the clinical syndrome of unstable angina. If an occlusive thrombus develops, the patient will run into a fresh myocardial infarction.(ABSTRACT TRUNCATED AT 250 WORDS)

Angina Pectoris↗
PubMed1988

ST segment changes in healthy volunteers during Holter monitoring and exercise stress test.

The analysis of ST segment changes during Holter monitoring is one important diagnostic method for detection and diagnosis of silent myocardial ischaemia. To assess the specificity and sensitivity of ST segment alterations as a diagnostic tool, 106 healthy medical students (43 females, 57 males, aged 18-36 years, mean age 26 +/- 4 years) and 26 children (14 females, 12 males, aged 12-17 years, mean 14 +/- 3 years) with no history of heart disease and normal findings during physical examination were studied by exercise stress test and Holter monitoring. Criteria for exclusion were a history of hypertension, diabetes mellitus and ST segment alterations during conventional 12-lead ECG. Due to these criteria, eight volunteers had to be excluded from the study. The exercise stress test (maximum work load protocol) revealed no pathological ST segment depressions. During Holter monitoring seven episodes of ST segment depressions (greater than or equal to 1.0 mm planar or downsloping, duration greater than or equal to 1.0 min) were found. Typical ST segment depressions detected by Holter monitoring may be found in healthy subjects. Therefore this finding has to be considered cautiously as a diagnostic tool for evaluation of patients with suspected coronary heart disease.

Adolescent↗
PubMed1988

[Global and regional left ventricular function following acute coronary artery occlusion and emergency aortocoronary venous bypass operation].

Complications following percutaneous transluminal coronary angioplasty (PTCA), such as coronary artery occlusion, spasm, or dissection, frequently require urgent surgical intervention. Out of 26 patients from our hospital, 12 who underwent emergency coronary bypass grafting because of balloon catheter complications with a total ischemic time of 100-255 min, were restudied in the late postoperative period by clinical examination and by coronary and left ventricular angiography. Left ventricular angiograms were evaluated quantitatively for global and regional function using the AVD system (Siemens Elema, Erlangen). Electronmicroscopic results from myocardial biopsy samples, taken intraoperatively from the presumed center of the ischemic zone, were compared with the clinical results. An improvement of left ventricular function parameters could be seen in patients with reperfusion intervals within 130 min. In the case of intermittent perfusion of the occluded vessel (catheter perfusion with arterial blood, intermittent spasm) operative revascularization proved to salvage jeopardized myocardium. There was a close correlation between the degree of left ventricular dysfunction and histological results, coronary morphology and clinical staging. In conclusion, the efficacy of myocardial protection by emergency bypass surgery depends mainly on coronary morphology and above all on reperfusion intervals.

Adult↗
PubMed1988

[Methods for the detection of ventricular late potentials. High amplification ECG, signal averaging technic, frequency analysis and intracardiac mapping].

Circumscribed areas of injured myocardium which lead to late ventricular depolarization represent the pathologic-anatomic substrate for reentry mechanisms potentially capable of propagating ventricular tachycardia at the ventricular level. If the myocardial area from which delayed ventricular depolarization and, consequently, late potentials eminate, exceeds a critical minimal size, documentation of such signals can not only be achieved with direct endocardial mapping or catheter mapping but also by means of special high-resolution ECG techniques from the body surface. Since high amplification of the conventional ECG results in registration of noise signals in amplitude of up to 50 microV, late potentials with their amplitudes at the body surface ranging from 5 to a maximum of 20 microV, can only be discriminated after substantial enhancement of the signal-to-noise ratio. The noise arises from no less than three sources: physiologic noise, for example, from muscle activity; electronic noise from amplifiers and background noise of 50 or 60 Hz, respectively. To improve the signal-to-noise ratio, currently three methods are employed: sequential or temporal signal averaging, spatial signal averaging and fast Fourier transformation analysis of the frequency spectrum of the highly-amplified ECG. Temporal signal averaging has the purpose of smoothing randomly-occurring background noise and, at a specified point in time of the ECG cycle, to sum the signal incurred. The effectivity of this technique, however, is subject to certain conditions: the signal to be registered and the background noise must be independent from each other, the noise must be stationary and show normal random distribution, the signal of interest must be periodic and/or coupled with a fixed interval to a point in the ECG cycle which can be used as a trigger. The quality of the averaged signal is dependent on trigger stability. There are three approaches to trigger processing: voltage threshold determination, slope detection and the pattern matching technique, the accuracy, reliability and time-consumption of which increases in the order listed. A trigger stability of +/- 0.5 ms is necessary to detect ventricular late potentials with sufficient sensitivity and without meaningful deformation or attenuation of their form and temporal extent. Intercurrently, a number of commercially-acquirable signal averaging computers have been made available which differ with respect to registration and analysis.(ABSTRACT TRUNCATED AT 400 WORDS)

Atrioventricular Node↗
PubMed1988

[Ventricular late potentials in acute myocardial infarct].

Ventricular late potentials are regarded as an expression of delayed impulse conduction in an area of myocardial ischemia and, accordingly, indicative of a preformed reentry circuit. Late potentials can be detected in chronic, stable coronary artery disease and their presence correlates closely with impairment of ventricular function and with the probability of future occurrence of tachyarrhythmic events or sudden cardiac death. While repetitive ventricular arrhythmias in the chronic stage of coronary artery disease result almost invariably from circling intraventricular wavefronts, tachyarrhythmias associated with acute myocardial infarction appear attributable to differing pathomechanisms. According to experimental studies, in acute myocardial infarction, three phases of arrhythmogenesis can be differentiated: phase 1 encompasses the first hours after vessel occlusion which generally corresponds with the prehospital phase. Due to the difference in potential of up to 25 mV between ischemic and nonischemic cardiac muscle areas, an injury current is called into existence which leads to depolarization of normal cardiac muscle tissue. The ectopic impulses so precipitated, the conduction of which is supported by the functional inhomogeneity of the infarcted region, are capable of initiating reentry tachycardia. During phase 2, a few hours to days after the ischemic event, only the subendocardial Purkinje fibers in the infarcted region exhibit focal arrhythmogenicity. In contrast to the working myocardial cells, the latter survive due to their immediate proximity to the cardiac chamber and show, ischemia-induced, a propensity to high-frequency impulse formation in terms of abnormal automaticity. Similar to the experimental findings, the cause of the frequently-observed ventricular arrhythmias in the early hospital phase appears predominantly attributable to a focal arrhythmia mechanism. During phase 3, several days to weeks after the acute myocardial ischemic event, reentry mechanisms again are in the foreground in which the electrophysiologic changes in the Purkinje fibers, in terms of increasing desynchronization, together with conduction barriers arising through the infarct scar, pave the way for reentry phenomenon. After abrupt restoration of patency of a previously occluded vessel the very frequent "reperfusion arrhythmias" are also attributable primarily to reentry mechanisms due to inhomogeneous improvement of the conduction properties in the region of the reperfused myocardium. Ventricular late potentials can be registered both invasively by means of epi- or endocardial leads as well as noninvasively from the body surface.(ABSTRACT TRUNCATED AT 400 WORDS)

Atrioventricular Node↗
PubMed1988

[Diagnostic significance of angioscopy in patients with coronary heart disease].

Coronary angioscopy (CA) using ultrathin fiberscopes was performed in 30 patients with coronary heart disease during cardiac catheterization and in 11 patients during bypass surgery. For percutaneous CA the angioscope was introduced from the femoral artery through a 9F guiding catheter. During short-time occlusion of the coronary ostium by the tip of the guiding catheter the viewing field was flushed with Ringer's solution. Intraoperative CA was performed both by the retrograde and antegrade way during flushing with cardioplegic solution. Percutaneous CA was successful in 57% of patients. 13 patients showed eccentrically and irregularly shaped stenoses and 3 of these patients had an additional plaque rupture. In 2/5 patients CA after PTCA revealed intimal dissections not visualized by angiography. Intraoperative CA was successful in 9/11 patients. In 3 patients nonocclusive thrombi were found at the site of the coronary lesion. Additionally we studied the efficacy of angioscopic guidance during intravascular radiofrequency application. In 11/11 thrombotically occluded peripheral vessels this new method allowed a nearly complete recanalization. There was only one perforation of the vessel. We conclude, that CA is a powerful diagnostic tool providing prognostically relevant information in the diagnosis of coronary heart disease.

Animals↗
PubMed1988

[Diagnosis of myocardial ischemias with long-term electrocardiography: spontaneous variability and modification by nitrate therapy].

To evaluate spontaneous variability of ST-segment changes within the Holter ECG, in 20 patients with documented coronary heart disease (CHD) long-term ambulatory ECG recordings were performed over 3 consecutive days, when the patients were only receiving short-acting nitrates. ST-segment alterations per day were measured as the area beneath the baseline (mV x min), and were compared day-to-day intraindividually. The intra-day variations of ST-segment area alterations were a factor of about 10, when compared with the baseline values. Following administrations of 120 mg ISDN ret. at the beginning of day 4, the number of anginal attacks was reduced, as was the acute medication with short-acting nitrates. There was also a trend to reduction of ischemic ST-segment changes, but these reductions could not be confirmed statistically. In studies on the course and therapeutic interventions of patients with CHD, the phenomenon of spontaneous variability of ST-segment alterations must be taken into account--as applies also to the arrhythmia analysis within the Holter ECG--and the recording period must probably be prolonged beyond the 24-h limit presently used.

Adult↗
PubMed1988

[ST segment changes in long-term ECG in healthy heart probands].

100 healthy medical students were studied with 24-h Holter monitoring for ST-segment evaluation. Six recordings (1.8% of males and 11.6% of females) contained at least one episode of horizontal or downsloping ST-segment depression of at least 0.1 mV or more and 1 min duration in the V-5-like lead. Since ST-segment elevations (in 73% of the recordings in the V-5-like lead, and in 40% in the V-2-like lead) and discordant (negative) T-waves associated with ST-segment depressions (in 31% of the recordings in the V-2-like lead) were commonly seen, these ECG findings have to be considered as nonspecific. During exercise tests using a protocol of maximal work load, not one of these healthy individuals displayed typical ST-segment depressions indicative of myocardial ischemia. Therefore, typical documented ST-segment alterations in Holter-ECG recordings should be used with caution when observed in individuals with suspected coronary heart disease, particularly when they are female.

Adolescent↗
PubMed1988

[Blockade of the left stellate ganglion using a drug reservoir pump. A new treatment method in the QT syndrome].

In patients with long QT syndrome (LQTS) the therapy of first choice is the administration of propranolol (2-4 mg/kg of body weight daily). If not effective alone, a combination of propranolol and phenytoin (200 mg daily) has proved to be effective. Nevertheless, in about 7% of cases medical therapy failed to prevent serious arrhythmic events. A 28-year-old woman suffered tachyarrhythmic episodes despite medical treatment. After additional pharmacological blockade of the left stellate ganglion, using an implantable pump catheter system (Secor) a stable heart rhythm could be achieved. No more syncopes were reported in this patient. In the case of failing medical therapy, the implantation of a pump catheter system could be an alternative method to surgical left ganglion stellectomy.

Adult↗
PubMed1987

[Activity-initiated rate-adapted pacemaker therapy. Clinical results].

In a prospective study of 23 patients the clinical effects of rate-adapted activity-sensed (by mechanical resonance oscillations) pacing (Activitrax system) were tested over a mean period of 8.1 +/- 3.8 months. This form of pacemaker treatment was used when, after exercise and on long-term ECG monitoring, the spontaneous heart rate had not exceeded 85 beats per min and there had been symptoms of decreased exercise tolerance. Lasting improvement in physical exercise tolerance was achieved in 11 of 17 patients after changing from fixed-rate to rate-adapted pacing. Treadmill ergometry, randomised in the fixed-rate or rate-adapted mode, brought about a significant rise in exercise tolerance (P greater than 0.01). Contrary to results after external influences, insufficient rate increases in five patients in the course of static stress was of clinical significance and thus narrow the indications for this type of pacing.

Adult↗
PubMed1987

[An automatic implantable cardioverter-defibrillator. The initial clinical experience].

An automatic, implantable cardioverter-defibrillator (AICD) which generates a high-energy current impulse is now available for the management of treatment-resistant malignant ventricular arrhythmias. Such a device (manufactured by Intec/CPI) was implanted into eight patients with coronary heart disease or dilated cardiomyopathy, and in four after surgery for postinfarction ventricular arrhythmias. All patients had had life-threatening episodes of ventricular fibrillation or tachycardia: the arrhythmias were refractory to multiple drug therapy (mean of 6.8 antiarrhythmia drugs per patient). The threshold energy for converting ventricular fibrillation was 9.6 Joules +/- 5.7. Except for one bacterial infection of the electrodes, there were no serious complications. During a mean observation period of 13.6 months 21 electrophysiologically induced and 105 spontaneous tachyarrhythmias were successfully terminated by the AICD. No malfunctions occurred and there was no death due to an arrhythmia.

Arrhythmias, Cardiac↗
PubMed1987

[Cor triatriatum dextrum].

Cor triatriatum dextrum is a rare malformation of the right atrium usually without typical signs or symptoms. Today the intra vitam diagnosis of C.t.d. is done by echocardiography and angiocardiography. Once the diagnosis is established, surgical correction of this anomaly is possible in symptomatic patients. When the presence of an abnormal membrane in the right atrium is not recognized before operation, the outcome may be unsatisfactory.

Cor Triatriatum↗
PubMed1987

[Diagnosis of cor triatriatum dextrum with imaging procedures].

Cor triatriatum dextrum is a rare malformation of the right atrium usually without typical signs or symptoms. Today the intra vitam diagnosis of C.t.d. is done by echocardiography, MR and angiocardiography. Once the diagnosis is established, surgical correction of this anomaly is possible in symptomatic patients.

Angiocardiography↗
PubMed1986

[Regression of coronary sclerosis in familial hypercholesterolemia IIa by specific LDL apheresis].

The long-term effect of specific LDL plasma immunabsorption on the course of coronary arteriosclerosis was tested in ten patients with familial hypercholesteremia type IIa (seven females, three males; age range 15-57 years). Available were ECG, bicycle ergometry, hemodynamic and angiographic data. These tests were repeated seriatim in the course of the LDL immunabsorption. It was found that exercise tolerance markedly increased, ischemic ST-changes became less marked and the initial hemodynamic parameters remained unchanged. The morphology of the coronary arteries was influenced lastingly: among 22 stenoses only one progressed, there was no further progression in 11 stenoses and regression in ten. When there was generalized arteriosclerosis, progression occurred in two of 79 coronary artery segments, progression was arrested in 56 and regression was noted in 21 of 79 segments. These results demonstrate that specific LDL plasma immunabsorption for the elimination of LDL cholesterol favorably influences the course of coronary arteriosclerosis in patients with familial hypercholeremia type IIa. The findings support the lipid theory of atherosclerosis and coronary arteriosclerosis, at least in this special group of patients.

Adolescent↗
PubMed1986

[First clinical experience with coronary endoscopy].

In four different groups coronary endoscopy and endoscopy of peripheral vessels was carried out, using two ultrathin fibre endoscopes with a working length of 120 cm and a diameter of 1.4 or 1.8 mm. In a first series of seven cadaver hearts, normal vessels were found in three, one had high-grade stenosis and in the remaining three there were flat whitish atheromatous changes, rather scar-like in appearance. In a second series of 16 patients, the vascular wall in the iliac region was easily visualised in ten, while six showed diffuse atherosclerotic changes of the wall. In a third group of eight patients, coronary endoscopy was carried out at the time of balloon-catheter dilatation; endoscopy was successful in five patients. In two of them, the stenosis or occlusion to be dilated by balloon was visualised. In a fourth series, good visualisation of the vessels was obtained intraoperatively in seven out of nine patients, and in addition the course of the vessel distal to the stenosis as well as the site of anastomosis with the venous bypass graft could be seen. No serious side-effects of the procedure have yet been observed. Coronary endoscopy opens up a new dimension in the morphological assessment of coronary vascular changes. The method must, however, still be regarded as experimental.

Angioplasty, Balloon↗