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Biomedical subjects

R Erbel

Publications and source records attributed to R Erbel.

At least 397 records · Page 22Linked to original sources
PubMed1992

Acute hemodynamic effects of nicorandil in coronary artery disease.

Nicorandil is a potent vasodilator with antianginal and anti-ischemic properties that acts on both the coronary and the peripheral vascular bed. Because of its dual vasodilatory mechanisms mediated by an increase in cyclic GMP similar to that of nitrates and by a selective increase in the K+ conductance of the smooth muscle cell membrane, nicorandil unloads the right and left ventricles at rest and during exercise. Thus, compared with the classic nitrates, nicorandil is a more balanced vasodilator, i.e., it affects not only the venous capacitance vessels (as predominantly affected by nitrates) but also the arterial resistance vessels. In clinical pharmacologic trials, nicorandil has been administered intravenously (2 to approximately 14 mg) as well as sublingually and orally in single doses of 10-60 mg. In patients with coronary artery disease and impaired left ventricular function, the decrease in preload resulted in a significant improvement of cardiac output. Depending on the doses applied and the patient populations studied, observed decreases in systemic blood pressure were consistent with decreases in peripheral vascular resistance. The effect on heart rate was small, and no influence on atrioventricular conduction could be detected. Nicorandil enhanced exercise capacity in patients with ischemic heart disease. This benefit can be attributed to the reduction in loading of the right and left ventricle as well as to an improvement of regional wall motion abnormalities secondary to the coronary dilatory properties of the drug. Nicorandil appears to be a valuable additive to the antianginal and anti-ischemic management of coronary artery disease.

Animals↗
PubMed1992

Intravascular ultrasound imaging of arterial wall architecture.

Intravascular ultrasound (IVUS) is a promising new technique for assessing vascular morphology and structure. Controversy exists whether the three-layer appearance of the arterial wall correctly reflects the histologic structures of the intima, media, and adventitia. We performed an experimental study to clarify the three-layer appearance. The vessel wall architecture was analyzed by IVUS on eight different kinds of plastic cylinders, 24 normal blood vessels from pigs, and 59 human arterial segments. A distinct three-layer appearance was observed on all the plastic cylinders when the ultrasound beam was perpendicular to the wall. A three-layer appearance was also seen in the arterial wall, in the muscular (iliac, femoral artery) and elastic types (aorta), when the echo beam was perpendicular to the vessel wall. The three-layer pattern was even observed on the arterial wall when the intima was removed. Furthermore, the removed intima itself provided a three-layer image. Histologic examination showed that there was no correspondence between the IVUS three-layer appearance and the intima, media, and adventitia. Moreover, we also performed IVUS on nine patients who suffered from aortic dissection. Intravascular ultrasonic visualization of the dissected intima showed a distinct three-layer pattern. The pattern disappeared when: (1) the echo beam was not perpendicular to the vessel wall; (2) there was connective tissue around the vessel wall; (3) there was arterial wall calcification; or (4) the vessel wall was too thick or the distance between the ultrasound transducer and the vessel wall was too large.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1992

Dissection following balloon angioplasty of aortic coarctation: review of the literature.

Balloon angioplasty of the coarctation of the aorta can result in intimal or medial or even adventitial dissections as demonstrated by in vitro studies and animal experiments. As a typical sign of stretching of the aortic wall, patients complain of pain during the angioplasty procedure. In the literature, aortic wall rupture and ventricular fibrillation during the procedure are reported. Additional sudden deaths can occur within 40 hours after the procedure. Mortality ranges from 0.1% to 2.5%. By transesophageal echocardiography, monitoring of balloon angioplasty, control of the positioning of the balloon, and control of the results and detection of complications are possible. Intimal as well as medial dissections can be detected with observed healing for intimal but also medial dissections. In order to avoid the patient's discomfort, intraaortic ultrasound will be used in the future, when major methodological improvements are done. Computed tomography demonstrates medial dissections but is not able to visualize intimal dissections. Using computed tomography and magnetic resonance after angioplasty of the coarctation of the aorta, irregularities are described in up to 17% of the patients. For angiography, a low detection rate of medial dissections has to be expected, when not biplane angiographies of the whole thoracic aorta are performed. Medial dissections can be seen, but intimal dissections are missed. In conclusion, a review of the literature demonstrates a high incidence of intimal and medial dissections after angioplasty of the coarctation of the aorta with spontaneous healing in most patients. As is the way with coronary angioplasty, aortic wall ruptures are rare, but stand-by surgery is necessary.

Aortic Dissection↗
PubMed1992

Current status of phosphodiesterase inhibitors in the treatment of congestive heart failure.

The phosphodiesterase inhibitors have been recognised as potent inotropic and vasodilating drugs. In acute congestive heart failure they increase cardiac output, decrease left pulmonary capillary wedge pressure, and reduce total peripheral resistance with an improvement in loading conditions of the failing heart. Their potency in reversal of symptoms of acute congestive heart failure is quite similar to, or even better than, treatment with intravenous catecholamines and sodium nitroprusside. In chronic congestive heart failure, however, these agents increase mortality and have deleterious effects in the outcome of patients with severe left ventricular dysfunction.

Acute Disease↗
PubMed1992

Surgical treatment of myocardial bridging causing coronary artery obstruction.

Nine patients with obstruction of coronary artery blood flow caused by myocardial bridging underwent surgery after failure of medical treatment. The diagnoses were made angiographically at rest or during beta-stimulation. Impaired blood flow was found only in the left anterior descending artery in seven patients and additionally in the diagonal branch in two. The operations, performed with cardiopulmonary bypass consisted of complete dissection of the overlying myocardium. All patients survived the operation. Major intraoperative complications were accidental opening of the right ventricle in two patients. Postoperative scintigraphic and angiographic studies demonstrated restoration of coronary flow and myocardial perfusion without residual myocardial bridges under beta-stimulation. Surgical relief of myocardial ischemia due to systolic compression of intramyocardial coronary arteries can be accomplished with low operative risk and with excellent functional results.

Adult↗
PubMed1992

[Two-dimensional transesophageal echocardiography (clinical value)].

The introduction of two-dimensional echocardiography (echo 2D) complemented by doppler techniques has allowed to assess the dynamic function of the heart. However in 10-15% patients the standard transthoracic method (TEE) does not provide complete echocardiographic image due to obesity, emphysema and deformations of thorax. These difficulties have been later overcome by transesophageal probe, but it made the examination possible only in one plane-monoplane TEE (m-TEE). Transesophageal echocardiography the biplane probe (bi-TEE), introduced in late 80s has permitted the heart and aorta visualization in two perpendicular planes: transverse (T) and longitudinal (L). The purpose of our study was to establish the diagnostic value of biplane transesophageal echocardiography in comparison with hitherto existing monoplane echocardiography (transverse plane). The study group consists of 60 patients (aged 19-78 years) with various diseases of heart and aorta. We performed biplane transesophageal examinations with the use of Aloka SSD-870 echocardiograph connected with the biplane probe (45 patients) or new, prototypical matrix probe (15 patients). For the heart and aorta assessment the typical projections were used. The advantages of biplane TEE compared with monoplane TEE are as follows: 1) more favorable left ventricular examination, 2) better assessment of the heart apex, 3) the ability to investigate the right heart; tricuspid valve, right ventricular outflow tract, pulmonary valve, pulmonary trunk and right pulmonary artery, 4) precise imaging of both atrial' structures: cavities, intraatrial septum, foramen ovale, left atrial appendage, venae cavae and pulmonary veins, 5) possibility of thoracic aorta diagnostics, especially in ascending aorta.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1992

[Noninvasive quantification and classification of the severity of aortic stenosis using Doppler echocardiography].

The exact determination of the severity of valvular heart disease represents the basis for the indication for surgery. Apart from the clinical findings, the estimation of the severity has, up to now, been based on the chest x-ray, the electrocardiogram, and the carotid pulse curve. By means of cardiac catheterization, the aortic valve gradient is determined and the aortic valve area is calculated using the Gorlin equation. Doppler echocardiography allows for a noninvasive gradient assessment. The peak and mean pressure gradients as well as the aortic valve area can be calculated. Echocardiography provides additional information about the severity of the left-ventricular hypertrophy, the heart size, as well as about secondary complications. Doppler echocardiography was performed in 95 patients to determine the peak pressure gradient. This Doppler-derived gradient correlated well with the catheterization-derived invasive gradient. The correlation coefficient was r = 0.81, for the mean gradient r = 0.77, and for the aortic valve area r = 0.87. Based on the classical determination of the severity of aortic stenosis by means of cardiac catheterization, a Doppler-derived mean pressure gradient > 54 mm Hg or a peak pressure gradient > 89 mm Hg and an aortic valve area > 0.7 cm2 are specific for severe aortic stenosis. A mean pressure gradient between 40 and 54 mm Hg or a peak pressure gradient of 67 and 89 mm Hg and an aortic valve area of 0.7 and 1.3 cm2 indicate moderately aortic stenosis.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1992

[Diagnostic goals in aortic dissection. Value of transthoracic and transesophageal echocardiography].

The combination of different ultrasound techniques like transthoracic, suprasternal, subcostal and transesophageal echocardiography have a high sensitivity and specificity in the diagnosis of aortic dissection. The limitation of this combined ultrasound technique is related to the visualization of the ascending part of the aortic arch which, cause of the interposition of the trachea, can not be visualized completely. The beginning or the end of a dissection in this part of the aorta may be misinterpreted. False negative results are rare. False positive results due to artefacts resulting from reverberations in an ectatic ascending aorta have to be taken into account. The most important diagnostic aims in acute or chronic aortic dissection can be described: 1. confirmation of the diagnosis by visualization of the intima membrane, 2. the differentiation of the true and false lumen depending on visualization of spontaneous echocardiographic contrast thrombus formation, slow or reduced reversed flow, systolic diameter reduction and signs of entry jet into the false lumen, 3. detection of intimal tear, demonstrating communication by two-dimensional or color Doppler echocardiography, 4. determination of the extent of the dissection with classification according to DeBakey type I, II and III or Stanford A and B with differentiation to communicating or non-communicating dissection, antegrade or retrograde dissection limited to the descending aorta or expanding to the ascending aorta, 5. detection of wall motion abnormalities as a sign of preexisting coronary artery disease or myocardial ischemia due to ostium occlusion by an intimal flap, coronary artery rupture or collapse of the true lumen during diastole, 6. detection and grading of aortic insufficiency, 7. detection of side branch involvement by suprasternal, subcostal and abdominal sonography, which will gain the information which side can be chosen for cannulation or catheterization at the femoral artery, 8. detection of pericardial pleural effusion and mediastinal hematoma as a sign of emergency as rupture can occur within minutes. Without surgical intervention have be performed. Based on these informations, surgery can be performed in all acute situations in type A dissection without further investigations. This decision is particularly important in patients with signs of emergency like pericardial or pleural effusion or mediastinal hematoma.

Aortic Dissection↗
PubMed1992

[Intravascular ultrasound in patients with suspected aortic dissection: comparison with transesophageal echocardiography].

Thirteen patients with suspected aortic dissection (two women, 11 men, age 61 +/- 10.8 years) underwent transesophageal echocardiography (TEE), intravascular ultrasound (IVUS), angiography, and in part computed tomography (CT). TEE was performed using 3.5 or 3.75 MHz ultrasound transducers. IVUS examination was done using a 6F 20 MHz "rotational-tip" IVUS catheter (Boston Scientific) advanced over a guiding-wire positioned in the ascending aorta by the "side-saddle" technique. In two patients it was not possible to advance the catheter into the abdominal aorta. Of the remaining 11 patients, eight had aortic dissection (six Typ III, one Typ II, and one Typ I, de Bakey classification). Two patients had aortic aneurysms without dissection and one patient had a perforation of the ascending aorta. TEE, CT, and angiography led to the correct diagnosis in all patients, while IVUS failed to provide precise information within the ascending aorta and the aortic arch. Reasons were the limited scanfield of the 20 MHz transducer and the inability to steer and position the IVUS catheter. Contrary to the limited value in the ascending aorta, IVUS could successfully scan the entire descending aorta, including the dissection membrane and the originating vessels, if the max. diameter was less than 4 cm. No adverse effects occurred. Intravascular ultrasound allows to scan the entire aorta in patients with suspected aortic dissection. The current limitations can be solved only by the introduction of steerable and/or low frequency catheters.

Aged↗
PubMed1992

[The correlation between measurements performed by intravascular echography and quantitative digital angiography in large- and small-caliber arteries].

Intravascular ultrasound is a new promising technique that appears as a very useful complement to standard angiography in the study of atherosclerosis. Specifically, intravascular ultrasound provides by itself, information of great value concerning vessel wall characteristics. Nevertheless, before taking any decision with the results provided by this new technique, we must validate this information with that provided by other more conventional techniques like standard angiography. Accordingly, we have analyzed in 25 patients, 50 images of the abdominal aorta and 77 images of the coronary arteries taken from arterial segments free of atherosclerotic involvement. With the use of a calibrated small grid located over the patient's thorax, we have analyzed "in the same points" the images obtained with intravascular ultrasound and those provided by contrast angiography using a quantitative angiographic analysis. In the abdominal aorta the vessel diameter measured by intravascular ultrasound and angiography was 17.8 +/- 0.39 mm vs 18.6 +/- 0.42 mm (NS), whereas in the coronary arteries it was 2.76 +/- 0.39 mm vs 2.98 +/- 0.37 mm (NS), respectively. The correlation between both techniques was good for both types of arteries (r = 0.93 in the abdominal aorta and r = 0.87 in the coronary arteries). We conclude, that in our experience and with the methodology used, there is a good correlation between the measurements of the vessel diameters obtained by both intravascular ultrasound and digital angiography in arteries of different sizes, being the correlation even better in large arteries.

Adult↗
PubMed1991

[Computer-assisted analysis of wall motion of the right ventricle in a normal patient sample and diagnosis of right heart infarction using transesophageal echocardiography].

Using 2D and M-Mode transesophageal short axis cross sections, right ventricular systolic wall motion was quantified in 15 normal patients. A further group of 39 patients with right ventricular infarction was investigated. In the normal group fractional shortening of the septum was -19.6% (-45 to 8%), that of the lateral wall 51.6% (37 to 73%), of the posterior wall 33.9% (5 to 50%) and of the anterior wall 42.7% (18 to 57%). Right ventricular infarction (RVI) was associated in 33 patients with posterior left ventricular infarction (85%) and in three patients with anterior infarction. In two cases only an isolated RVI was found. Right ventricular dilation occurred in 24 patients (61%). Hemodynamic criteria were fulfilled in eleven out of 21 patients (53%). RVI was confirmed in one patient by surgery and in ten patients by autopsy. Recognition of regional wall motion abnormalities by transesophageal echocardiography permits an accurate bedside identification of RVI. 2D and M-Mode registration of the short axis improves RVI assessment. Wall motion analyses offer the possibility to determine the extent of right ventricular infarction.

Adult↗
PubMed1991

[Heart involvement in mixed connective tissue disease (MCTD)].

The incidence of cardial involvement in mixed connective tissue disease (MCTD) was investigated by two-dimensional echocardiography. Pericardial manifestation was found in two patients. Mitral valve prolapse was detected in 61% of the patients, which may indicate a specific cardial involvement in MCTD. Myocardial changes were rare.

Adult↗
PubMed1991

Results of intracoronary stents for management of coronary dissection after balloon angioplasty.

Dissections after coronary balloon angioplasty are risk factors for acute or subacute vessel closures. Intracoronary stenting was developed to avoid these complications by pressing the intimal and medial flaps against the vessel wall, thus reducing the risk of acute thrombosis. A total of 22 stents were implanted into the coronary arteries of 15 patients with dissections after balloon angioplasty causing angina pectoris or ischemic electrocardiographic changes. Stent delivery was successful in all cases. In 1 patient acute stent thrombosis was documented and treated successfully by thrombolytic therapy. Another patient underwent coronary artery bypass surgery 24 hours later because of persisting angina. Angiograms after 24 hours documented vessel patency in the remaining 14 patients. Late control angiograms after 4 to 6 months were obtained in 12 of 14 patients. Vessel patency without significant restenosis was observed in 8 patients, restenosis in 3 and reocclusion in 1 patient. All 3 patients with multiple stent implantation had restenosis (n = 2) or reocclusion (n = 1), compared with 1 patient with single stent implantation. Thus, intracoronary stenting appears to be a secure and effective method of handling bailout situations caused by dissection after balloon angioplasty, with good long-term results when only a single stent is implanted.

Aged↗