Search PubMed⌕ Search

Biomedical subjects

V Hombach

Publications and source records attributed to V Hombach.

At least 181 records · Page 10Linked to original sources
PubMed1990

[Implantation of Strecker stents in the iliac and femoropopliteal region].

The aim of implanting vascular endoprosthesis is to avoid acute complications and restenosis after percutaneous transluminal angioplasty. The Strecker stent is a new development, based on the principle of balloon-expandable endoprosthesis. We treated seven patients (five male, two female) aged 48 to 84 years (average 68 years) with Strecker stents in the iliac and femoropopliteal region. The indications for the implantation of stents were restenosis, reocclusion, recoiling, and kink stenosis. Also, acute complications as dissection or intimal flaps after PTA were stented. The implantation of the Strecker stents was in every case without technical complications. The condition of three patients suffering from a stage III, according to Fontaine's classification, improved to stage IIa after treatment. In three out of four patients with a stage IIb, clinical symptoms were changed to stage IIa after stenting. One patient had an acute thrombosis during the intervention, which could not be solved by local thrombolysis. The Doppler sonographic index increased after treatment to an average of 0.31. The follow-up period up to six months showed persistent clinical improvement. Intimal hyperplasia with stent occlusion or thromboembolic occlusions was not observed. The Strecker stent is a technically non-problematic system, which is qualified for the endoprosthetic therapy of the iliac and femoropopliteal region.

Aged↗
PubMed1990

[The role of radionuclide ventriculograms in determining the indications for valve replacement in chronic aortic valve insufficiency].

Timing of aortic valve replacement (AVR) in chronic aortic regurgitation (AR) remains a difficult problem in clinical practice. Radionuclide ventriculography (RNV) yields information on the extent of valvular regurgitation, the enlargement and the systolic function of the left ventricle. A "well-timed" AVR is defined by 1) postoperative improvement of clinical symptoms, decrease in left ventricular end-diastolic volume (EDV) and normalization of ejection fraction (EF) as well as by 2) greater improvement under surgical therapy as compared to conservative management. In "too early" AVR the latter condition is not fulfilled, while in "too late" AVR the first condition is not accomplished. In this study 54 patients with chronic aortic incompetence were evaluated by RNV to see whether these three groups ("too early", "well timed", "too late" AVR, resp.) can be separated by the relation between EDV and regurgitant volume (RV), the level of the EDV and the clinical status. The examination was based on pre- and postoperative RNV studies as well as on follow-up studies. A good postoperative result can be expected in cases with a preoperative EDV/RV-ratio similar to that observed in 30 patients with AR in whom AVR was not indicated. In contrast, in the majority of those cases with an EDV/RV-ratio exceeding this normal range the postoperative outcome will be unsatisfactory. If the EDV/RV-ratio is normal, AVR should be performed in cases with an EDV exceeding 400 ml, while in cases with an EDV between 300-400 ml AVR is only indicated in the presence of additional symptoms (NYHA greater than or equal to II).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1990

[What is the value of high resolution electrocardiography in the identification of patients at risk?].

Sudden cardiac death occurs in the Federal Republic of Germany with an incidence of 60,000 to 90,000 per year. Ambulatory ECG monitoring has demonstrated that in about 80% of such events, the heart rhythm before and during sudden cardiac death shows ventricular tachycardia leading to ventricular fibrillation and circulatory standstill. From experimental studies it is known that the substrate for precipitation of the ventricular arrhythmia is localized injury in myocardial tissue with conduction delays and conduction blocks resulting in inhomogeneous spread of the impulse between normal and injured myocardium enabling the existence of an electrical re-entry circuit. Anisotrophy, that is differing velocities of conduction parallel and perpendicular to fiber direction as well as dispersion of repolarization appears responsible for propagation of the circuit. Because of the delayed impulse spread, the late depolarization after the end of the QRS complex can be detected in the ECG as ventricular late potentials by means of high resolution systems. Ventricular late potentials may be regarded as indicative of increased electrical vulnerability of the ventricles. Prevalence of ventricular late potentials: In our own studies using the signal-averaged ECG technique, ventricular late potentials were found most frequently in patients with coronary artery disease and only in 6/100 healthy subjects, in 5/30 patients with dilated cardiomyopathy, in none of 30 patients with aortic stenosis or ten with "small vessel disease". With continuously-registered high resolution electrocardiography but not with the signal-averaged ECG, patients with dilated cardiomyopathy or QT-syndrome can be found to have labile, intermittent ventricular late potentials. In patients with coronary artery disease, the number of those in whom ventricular late potentials can only be detected with continuously-registered high resolution ECG in addition to signal-averaged technique lies between 6 and nearly 30%. With respect to frequency analysis of the ST-segment, which is based on the hypothesis that the fractionated signals in arrhythmogenic areas are of higher frequency than the normal low frequency signals of the ST-segment in normal myocardial areas, there is only limited experience and no data from larger collectives.(ABSTRACT TRUNCATED AT 400 WORDS)

Adolescent↗
PubMed1989

Acute hypothyroidism has no effect on pulmonary vascular resistance.

The effect of acute hypothyroidism on the pulmonary circulation was studied in 9 nonobese athyreotic patients by right heart catheterization at rest and during exercise. The patients were studied while they were hypothyroid 2 weeks after ceasing triiodothyronine treatment and while they were euthyroid on replacement therapy. At rest, pulmonary blood flow [4.0 +/- 0.6 l/min vs 5.8 +/- 1.0 l/min, p less than 0.01] and systolic pulmonary artery pressure [18 +/- 3 mmHg vs 23 +/- 2 mmHg, p less than 0.01] were lower when the patients were hypothyroid than when they were euthyroid. The mean and diastolic pressures in the pulmonary artery and the pulmonary capillary pressures were not different among the groups. Likewise, thyroid hormone levels had no significant effect on pulmonary vascular resistance [100 +/- 25 dyn-s-cm-5 vs 90 +/- 23 dyn-s-cm-5]. With supine exercise, pulmonary blood flow [10.1 +/- 1.6 l/min vs. 13.2 +/- 2.0 l/min, p less than 0.01], mean pulmonary artery pressure [25 +/- 6 mmHg vs 30 +/- 6 mmHg, p less than 0.02], and systolic pulmonary artery pressure [36 +/- 6 mmHg vs 44 +/- 8 mmHg, p less than 0.01] were lower when the patients were hypothyroid. The diastolic pulmonary artery pressure and the pulmonary capillary pressure were similar in both thyroid states. Again, thyroid deficiency had no effect on pulmonary vascular resistance [81 +/- 23 dyn-s-cm-5 vs 76 +/- 24 dyn-s-cm-5]. The lower systolic pressures in the pulmonary artery seen in hypothyroidism are probably due to the decreased systolic volume load of the pulmonary circulation.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1989

[Stress testing of long-term type I diabetic patients with radionuclide ventriculography].

Left ventricular function was assessed by means of radionuclide ventriculography in 42 patients with long-standing (13 +/- 5 yrs) insulin-dependent diabetes mellitus and in eleven healthy age matched control subjects. Only diabetics were included in the study without diabetes related cardiac risk factors such as hypertension and CAD in order to evaluate diabetes specific changes of cardiac function. No differences were seen between diabetics and controls concerning heart rate and functional parameters of left ventricle in systole and diastole. The rapid filling period was not prolonged. According to our radionuclide data there is no evidence of diabetes related impairment of ventricular function in young patients with long-standing type-1-diabetes mellitus.

Adult↗
PubMed1989

The contraction fraction (CF) in myocardial studies with technetium-99m-isonitrile (MIBI)--correlations with radionuclide ventriculography and infarct size measured by SPECT.

Criteria for the detection of coronary artery disease in nuclear cardiology include visualization of perfusion defects and functional impairment of contraction. The purpose of this study is to combine both methods in one procedure with the new myocardial perfusion tracer, 99mTc-methoxy-isobutyl-isonitril (MIBI), reducing time and radiation burden to the patient. Following an uncomplicated recovery, ten patients with first myocardial infarction participated in this study. Radionuclide ventriculography (RNV) was performed at rest and during exercise. Within 2-3 days, 370 MBq 99mTc-MIBI were injected and SPECT acquisition commenced 1 h later. Data processing included a scar image in polar coordinates. Areas of significantly reduced tracer uptake were expressed as a percentage of the total myocardial area. Directly following SPECT, resting and maximum exercise gated planar LAO images were recorded and the contraction was quantified. The concept of the contraction fraction (CF) rested on the end systolic change in count distribution: their increase in density and their centripetal concentration. For comparison, geometrical inner edge detection techniques were also applied. All algorithms for describing an EF equivalent were verified by computer simulations, showing a perfect correlation over a wide range of preset EFs. When applied to the patient studies only the non geometric methods revealed a good correlation with the ejection fraction (EF) obtained by RNV, and with the infarct size measured by SPECT.(ABSTRACT TRUNCATED AT 250 WORDS)

Humans↗
PubMed1989

Acute hypothyroidism slows the rate of left ventricular diastolic relaxation.

The effect of acute thyroid hormone deficiency on left ventricular diastolic filling was studied by radionuclide ventriculography with simultaneous right heart catheterization in nine athyreotic patients without cardiovascular disease. The patients were studied when they were hypothyroid and when they were euthyroid on replacement therapy. Peak filling rate and the time to peak filling were used to characterize diastolic function. The time to peak filling was defined as the interval from end-systole on the radionuclide time-volume curve to the time of occurrence of peak filling. The peak filling rate was determined in absolute terms from the normalized radionuclide peak filling rate and from the end-diastolic volume, which was derived from the radionuclide ejection fraction and from the thermodilution stroke volume. In all patients, the values for peak filling rate were lower in the hypothyroid than in the euthyroid state (287 +/- 91 mL/s vs. 400 +/- 118 mL/s, delta = 41 +/- 13%, p less than 0.01). Peak filling always occurred during the first half of the diastolic interval. The time to peak filling was not significantly affected by the thyroid state (170 +/- 10 ms vs. 159 +/- 21 ms, delta = 7 +/- 10%). Left ventricular filling pressure as reflected by the pulmonary capillary wedge pressure and end-systolic volume were similar in both thyroid states (6 +/- 2 mmHg vs. 8 +/- 2 mmHg (1 mmHg = 133.32 Pa) and 32 +/- 11 mL vs. 32 +/- 7 mL, respectively). The data suggest that the rate of active diastolic relaxation is decreased in short-duration hypothyroidism.(ABSTRACT TRUNCATED AT 250 WORDS)

Acute Disease↗
PubMed1989

Effects of carvedilol on left ventricular function and arrhythmias during repeated short-time myocardial ischemia in experimental pigs.

The effects of carvedilol, a new vasodilating beta-blocking drug, were studied in experimental pigs during short-term acute myocardial ischemia. In 21 anesthetized pigs 0.01, 0.03, and 0.1 mg/kg b.w. carvedilol was studied during repeated 2-min distal LAD-occlusions and a 60-min-period of ischemia. Left ventricular volume was continuously measured by the impedance catheter method. Intravenous administration of 0.01 mg/kg carvedilol resulted in a significant decrease of heart rate (-13%), dp/dtmax (-32%), and ejection fraction (-9%), slight changes of systolic pressure (-3%), and an increase of vascular resistance (+24%), indicating a beta-blocker effect without vasodilation-while the first vasodilatory effect was found at a dose of 0.1 mg/kg. During ischemia carvedilol had no influence on the time-course or the extent of systolic bulging of the ischemic myocardium, but the ischemia-induced decrease of left ventricular ejection fraction was diminished. Both during short-term ischemia, as well as during the 60-min-ischemia-period carvedilol significantly reduced ventricular premature beats. During the 60-min-ischemia-period activation delay measured from local DC-electrograms of the ischemic myocardium, as well as the occurrence of activation block were not altered by carvedilol, as was the incidence of ventricular fibrillation (69%). We conclude that at low dosages the beta-blocking effect of carvedilol exceeds the vasodilating properties. This may also hold true in patients with cardiac failure; they are more sensitive to beta-blocking drugs. During ischemia carvedilol slightly reduces the ischemia-dependent decrease of global ventricular function and it has an antiarrhythmic effect. Therefore, it may be protective in patients with acute myocardial infarction.

Adrenergic beta-Antagonists↗
PubMed1989

[Quantification of the myocardial scar with technetium-99m-isonitrile (MIBI) in emission computerized tomography (SPECT)--comparison with serial creatine kinase determinations and radionuclide ventriculography].

Estimation of the size of myocardial infarction is of major interest for clinical patient management and a simple and reliable method is still searched for. In this study the potential of the new myocardial perfusion tracer, Technetium-99m (Tc-99m) methoxy-isobutyl-isonitril (MIBI) combined with emission computertomography (SPECT), is tested vs. the standard procedures of serial plasma creatine kinase (CK) measurements and radionuclide ventriculography (RNV). In 10 patients with first myocardial infarction, integral values for CK were obtained during the acute phase. Following three weeks of uncomplicated recovery the patient was referred for both types of myocardial imaging within four days. 370 MBq Tc-99m-MIBI were injected with the patient supine and at rest. One hour later SPECT acquisition commenced. The reconstructed slices were rearranged to long and short axes slices, which served to calculate a functional "scar image" in polar coordinates. The color-coded areas of significantly reduced tracer uptake were expressed in percent of the total myocardial area. RNV was performed with the patient supine and at rest, the left anterior oblique angle being optimized for septum visualization. Infarct localizations were antero-apical (three), anterolateral (two), postero-lateral (one), and posterior (four).(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗
PubMed1988

[High-frequency angioplasty in coronary disease. Initial clinical experiences].

After extensive animal experiments a new method of high-frequency current coronary angioplasty (HFCA) via a specially developed catheter system was used in ten patients with haemodynamically significant coronary artery stenoses. In eight patients the stenoses affected the anterior interventricular branch (AIVB), in one patient each the circumflex branch and the right coronary artery, respectively. In nine patients the stenosis cross-section was reduced by at least 20% (from a mean of 91.9% +/- 5.8% to 52.6 +/- 17.5%). In three patients HFCA was followed by balloon angioplasty. The total number of applications per patient ranged from 3 to 12 (mean total duration of current flow: 3.9 +/- 1.0 s). There was only one severe complication, in a patient with subtotal AIVB occlusion after initially successful HFCA: balloon angioplasty successfully restored the lumen to the post-HFCA state. The new technique of HFCA is worthy of further development. It promises to be a valuable addition or alternative to balloon coronary angioplasty.

Adult↗
PubMed1988

Pathophysiological aspects of predominant preload lowering on pulmonary circulation, gas exchange, and the biventricular function in patients with chronic obstructive lung disease.

A group of 21 patients with various degrees of chronic obstructive pulmonary disease underwent radionuclide ventriculography with hemodynamic monitoring to assess the extent to which pulmonary artery pressures and pulmonary vascular resistance can be lowered by the vasodilator molsidomine. Molsidomine (N-carboxy-3-morpholino-sydnonimin-ethylester) is similar to nitroglycerin in its mode of action. After hemodynamic and radionuclide data acquisition, at rest and during submaximal exercise in the steady state, 2 mg molsidomine was injected intravenously. Rest and exercise measurements were repeated 45 min after molsidomine injection. In patients with mild to moderate disease (group 1), pulmonary artery resting pressures decreased by 12% (p less than 0.05) at rest by 22% (p less than 0.01) during exercise after the administration of the drug. Total pulmonary resistance during exercise decreased significantly (p less than 0.01) as a result of marked decrease of pulmonary artery pressure (PAP) compared with a minimal decrease in cardiac index (CI). In patients with severe disease (group 2), only the resting values of PAP decreased while the relationship between pressure and flow was unchanged. During the exercise period, the preload parameters of the right and left ventricles decreased by an average of 30%. With regard to gas exchange, only the arterial PO2 at rest decreased slightly but significantly (p less than 0.05) after molsidomine, while the coefficient of oxygen delivery was not affected by the drug. However, in four patients arterial PO2 was markedly reduced by the drug. Right ventricular ejection fraction increased significantly (p less than 0.01) both at rest and during exercise in group 1 and during exercise in group 2 after administration of molsidomine.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗
PubMed1988

The clinical significance of coronary angioscopy in patients with coronary heart disease.

The feasibility and safety of coronary endoscopy was evaluated in three sets of investigations: in 7 cadaver hearts, in 11 patients undergoing coronary bypass surgery, and in 30 patients during routine cardiac catheterization prior to coronary balloon angioplasty (PTCA). In three of the seven cadaver hearts the lumen of the arteries appeared normal. In three diffuse atherosclerotic lesions, and in one, a high-grade, tight stenosis were observed. In nine of eleven patients in the operation room, the lesions of interest could be visualized, and high-grade stenoses were found in all. In addition, in three patients with unstable angina pectoris, fresh thrombi were seen at the site of stenosis. In six of the nine patients, the periphery of the native coronary vessel was found to have no further stenotic regions. During cardiac catheterization in 17/30 patients, the lesion of interest could be examined angioscopically, and in 13 instances the stenosis appeared excentric and irregularly shaped. In three instances, multiple ulcerations were seen in the stenotic area. In two of the five patients, intimal ruptures were found following PTCA, which could not be documented angiographically. Coronary endoscopy provides valuable additional information on the nature and appearance of atherosclerotic lesions. It can be performed clinically without great harm to the patients. Despite some limitations, it will probably become a routine diagnostic tool in patients undergoing routine coronary angiography, balloon angioplasty or high-frequency angioplasty, and coronary bypass grafting.

Angioplasty, Balloon↗
PubMed1988

Cardiac function by magnetic resonance imaging.

Gated magnetic resonance imaging of the heart displays cardiac structures with excellent resolution. This ability should be useful for assessment of cardiac physiology where acquisition of systolic and diastolic images is required. In this study, left ventricular ejection fraction was determined in 50 patients from oblique long axis views of the left ventricle using the area length formula. Angulated views were obtained by electronic gradient angulation. For comparison, all patients had monoplane angiocardiography in the RAO position. Forty-five patients were also studied by radionuclide ventriculography. Ejection fractions determined by MRI and angiocardiography were closely correlated (r = 0.90). Correlation between MRI and radionuclide ventriculography was also acceptable (r = 0.79). In addition to global left ventricular function, MR images provide information about regional wall motion. In order to acquire a three-dimensional set of images at various phases of the cardiac cycle, shorter imaging times are mandatory. A new imaging technique with potential for functional studies uses low flip angles, short repetition times and gradient refocused echoes. Up to 40 images can be obtained within one cardiac cycle. When displayed in a looped fashion, visual assessment of cardiac motion, intracardiac blood flow, and systolic wall thickening is possible. Potential advantages of functional studies by MRI are the concomitant acquisition of anatomical information and the three dimensional frame of reference.

Angiocardiography↗
PubMed1988

Coronary angioscopy during cardiac catheterization and cardiac surgery.

Coronary angioscopy (CA) was performed in 30 patients (pts) during cardiac catheterization (Group 1) and in 11 pts during coronary bypass surgery (Group 2) using ultrathin fiberoptic angioscopes (phi 1.2-1.8 mm). For percutaneous CA (Group 1) the angioscope was introduced through a 9F guiding catheter from the femoral artery. The viewing field was cleared by flushing Ringer's solution and short-time occlusion of the coronary ostium by the guiding catheter. In Group 2 CA was performed retrogradely from the distal arteriotomy and through the bypass vein during flushing with cardioplegic solution. In Group 1 in 17/30 pts the coronary artery could be successfully examined by CA. In 13 pts the obstruction was eccentric and irregular shaped. In 2/5 pts, in whom CA was performed successfully pre and post balloon dilatation, CA after PTCA revealed an intimal rupture without clinical or angiographical signs of the intimal dissection. In Group 2 in 9/11 pts good visualization of stenoses could be achieved. At the obstruction site CA revealed thrombi in 3 pts and ulcer in 1 pts. In contrast to angiography, which estimates the lumen diameter of a segmental lesion, CA gives information about the luminal shape and the underlying substance of the obstruction (e.g. atheroma, thrombus, ulceration). The main problems in percutaneous CA are the insufficient intraluminal guidance, the insufficient depth of view of the angioscopes, and the limited examination time.

Cardiac Catheterization↗