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Biomedical subjects

U Dietz

Publications and source records attributed to U Dietz.

At least 37 records · Page 2Linked to original sources
PubMed1993

High frequency rotational ablation: an alternative in treating coronary artery stenoses and occlusions.

OBJECTIVE: To prove the safety and effectiveness of high frequency rotational ablation of coronary artery stenoses and occlusion in humans. SUBJECTS: 106 patients with symptoms (91 men, 15 women) who had 67 significant stenoses, mainly types B and C, and 46-chronic occlusions. MAIN OUTCOME MEASURES: Mean change in diameter stenosis after rotational angioplasty alone and in combination with percutaneous transluminal coronary angioplasty immediately after treatment and 24 hours and six months later; restenosis rates at six months; complication of treatment. RESULTS: Rotational ablation could not be used in five stenoses and 16 chronic occlusions because of inability to reach or cross the lesion with the Rotablator guide wire. In four cases rotational ablation failed. Initial angiographic and clinical success by rotational ablation was achieved in 40 of the 67 stenoses (60%) and in 18 of the 46 chronic occlusions (39%). Additional balloon angioplasty was performed in 45 patients, increasing the success rates to 79% and 54%, respectively. In the 62 stenoses treated by rotational ablation the angiographic diameter stenoses were reduced from 76% (SD 14%) to 32% (14%) after Rotablator treatment alone and from 75% (11%) to 33% (17%) with additional balloon angioplasty. In the 30 chronic occlusions treated by rotational ablation the angiographic diameter stenoses were reduced to 38% (18%). At six months angiographic restenosis was evident in nine of the 25 (36%) stenoses treated with rotational ablation alone, in seven of the 22 (32%) stenoses treated with rotational and balloon angioplasty, and in 14 of the 24 (58%) chronic occlusions. There were no procedural deaths and two patients (2%) underwent emergency coronary artery bypass grafting. Although no transmural infarction occurred, there were five (6%) non-Q wave infarctions (two embolic side branch occlusions, two subacute occlusions, and one acute occlusion). Clinically insignificant slight increases in creatine kinase activity were seen in five patients (6%). Severe coronary artery spasm unresponsive to medical treatment was provoked in seven cases (8%). CONCLUSIONS: High frequency rotational ablation is a safe and effective method for treating type B and C coronary artery lesions with results comparable to percutaneous transluminal coronary balloon angioplasty. The combined use of rotational ablation and balloon angioplasty is feasible and is necessary in about half of all procedures, in most cases because the lumen created by the biggest burr is too small.

Adult↗
PubMed1993

Influence of perinatal risk factors on the involution of the irido-pupillary membrane.

The aim of this study was to assess the influence of common perinatal risk factors on the disappearance of the anterior vascular capsule of the lens (AVCL). Direct ophthalmologic examinations were performed on 75 neonates (27 to 35 weeks gestational age) in the first 24 hours after birth, using the degree of involution of the AVCL to estimate gestational age in high risk pregnancy. Our results show that the gradual disappearance of the AVCL is not influenced by perinatal risk factors, such as maternal preeclampsia, prenatal administration of steroids, neonatal infection and low birth weight, confirming the clinical value of this test in the assessment of gestational age in high risk babies.

Female↗
PubMed1993

[Revascularization measures after acute myocardial infarct].

Thrombolytic therapy in acute myocardial infarction reduces mortality significantly. This acute effect seems to be counterbalanced by the increased mortality during follow-up whether or not the patient has been treated with thrombolytic therapy. Thrombolysis seems to be a first step in the treatment of acute myocardial infarction. Revascularization procedures are able to improve patient prognosis. Long-term follow-up demonstrated this fact whether or not PTCA was performed in the acute setting or on an elective basis. The 6-year survival was 80%. This survival rate was higher for patients who underwent PTCA than for those who were not undergoing PTCA and those who had no reperfusion of the coronary artery. The best prognosis was found for patients with coronary bypass surgery, indicating that revascularization should be the aim of treatment. The 6-year survival rate was found to be 92% and is thus in the range of patients with coronary artery disease. Acute infarct PTCA is limited to patients with cardiogenic shock and is particularly useful for patients with occlusion of the main stem of the left coronary artery. Acute infarct PTCA is also recommended in patients with contraindications for thrombolytic therapy, when interventions can be performed rapidly, when a large infarct size is present and infarct time is less than 4 hours. Whether or not RESCUE-PTCA should be recommended is under investigation. Patients with an open coronary artery have a better prognosis than patients with occluded coronary arteries, but during the acute stage, spontaneous recanalization is present in many patients. The RESCUE study will address this question. Elective PTCA is recommended as well as coronary bypass surgery, when successful reperfusion is achieved and one-or two-vessel disease is present or there is a two- or three-vessel disease or main stem involvement, respectively. In patients with coronary lesions less than 70% conservative treatment is useful. The guidelines of the American College of Cardiology and the American Heart Association are strongly recommended.

Angioplasty, Balloon, Coronary↗
PubMed1992

[Coronary vascular stent implantation--experiences with the first 100 implants].

Coronary stent implantation was performed for blocking elastin recoil, reducing acute complications and restenosis. In 89 (95%) of 91 patients successful stent implantation was possible. No stent embolization occurred. Coronary luminal diameter measured 1.05 +/- 0.57 before PTCA and 1.9 +/- 0.2 mm post PTCA. After stent implantation mean diameter of the coronary artery measured 3.05 +/- 0.2 mm, with a balloon diameter of 3.0. Thus, elastic recoil is nearly completely blocked. In 28 (31%) of 91 patients stent implantation was performed for acute symptomatic dissection in 27 patients and occlusion in one patient. Stent delivery was successful in all. There was no acute occlusion, one acute thrombosis which could be treated with urokinase, no Q-wave-infarct, 4 (14%) non-Q-wave-infarcts and 14 (20%) CK-elevations without ECG changes. Coronary bypass surgery was necessary in 2 patients on an elective base during follow-up. In 72 (90%) of 80 patients follow-up coronary angiograms after 4 to 6 months were performed. Restenosis rate measured 21% overall, 14% for single stent, 60% for multiple stent implantation, and 14% in bail-out situations. Subacute thrombosis occurred in 10 (12%) of 89 patients, 7 (70%) of 10 events after bail-out stenting. Recanalization by thrombolytic and/or PTCA was possible in 9/10 patients. By improving monitoring of anticoagulation, the subacute thrombosis rate could be reduced to 3% even in bail-out situations. Bleeding complication occurred in 10% of the patients.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1992

Percutaneous transluminal coronary rotary ablation with Rotablator (European experience).

This study reports the results from 3 European centers using rotary ablation with Rotablator, a device that is inserted into the coronary artery and removes atheroma by grinding it into millions of tiny fragments. Rotary ablation was performed in 129 patients. Primary success (reduction in percent luminal narrowing greater than 20%, residual stenosis less than 50%, without complications) was achieved by rotary angioplasty alone in 73 patients (57%). An additional 38 patients (29%) had successful adjunctive balloon angioplasty. Thus primary success was achieved in 111 patients (86%) at the end of the procedure. Acute occlusion occurred in 10 patients (7.7%). Recanalization was achieved by balloon angioplasty in 7: urgent bypass grafting was undertaken in 2. Q-wave and non-Q-wave myocardial infarction occurred in 3 and 7 patients, respectively. No deaths occurred. Follow-up angiography was performed in 74 patients (60%). Restenosis, defined as the recurrence of significant luminal narrowing (greater than 50%) occurred in 17 of 37 patients (46%) who underwent rotary ablation alone, and 11 of 37 patients (30%) who had adjunctive balloon angioplasty. The overall angiographic restenosis rate was 37.8%. In conclusion, rotary ablation is technically feasible, and relatively safe in the coronary circulation. The low primary success rate reflects the limited size of the device, which can be introduced through available guiding catheters, and limits the use of rotary ablation as a stand-alone procedure to lesions in small arteries or in distal locations. No reduction in restenosis was seen, but the role of this device combined with balloon angioplasty in larger arteries needs to be further defined.

Adult↗
PubMed1992

[Percutaneous sonographic angioplasty. Initial experimental results].

Aim of the present study was to examine in vitro the effects of a new ultrasound catheter system on atherosclerotic and normal vessels before employing the system in humans. 141 attempts were made on 32 vascular preparations obtained at autopsy. The vessels were opened longitudinally within 24 hours of death, dilated with gelatine and were then "treated" in a waterbath using varying degrees of pressure, angle of incidence, sound intensity and duration of sound. Macroscopic and histological examinations of the preparation showed no morphological change in normal vessels except evidence of pressure by the catheter. In particular, there were no perforations of the vessel wall. In atherosclerotic segments there was significant reduction in the size of plaques following treatment.

Angioplasty, Balloon↗
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↗
PubMed1991

Short and long term results after intracoronary stenting in human coronary arteries: monocentre experience with the balloon-expandable Palmaz-Schatz stent.

OBJECTIVE: Intracoronary stenting was designed to overcome acute complications after percutaneous transluminal coronary angioplasty and to achieve a reduced rate of restenosis, both of which are major limitations of this well accepted method for treating coronary heart disease. This report describes the experience at one centre with the implantation of balloon-expandable Palmaz-Schatz stents and focuses on device related complications and the short and long term angiographic outcome. DESIGN: A retrospective data analysis. PATIENTS: Stenting was attempted in 50 patients. Restenosis after an initially successful angioplasty procedure, inadequate postangioplasty results, saphenous coronary bypass stenoses, and bail-out situations were regarded as indications. MAIN OUTCOME MEASURES AND RESULTS: In 49 of 50 attempted patients 61 stents (1-4 per patient) were implanted. Delivery problems occurred in three patients and were successfully overcome in two patients. Bail-out situations were successfully managed in 16 patients. Complications included acute thrombus formation within the stent immediately after implantation in one patient, which was successfully treated by thrombolysis. One patient was sent for bypass surgery the day after implantation; another died 10 days after implantation for unknown reasons. Subacute stent thrombosis occurred in seven patients 5-9 days after implantation and was successfully treated by thrombolysis or balloon angioplasty in five patients. Bleeding complications occurred in nine patients, five of whom required blood transfusions. Angiography showed long term vessel patency after 4-6 months in 31 (76%) of the 41 patients who were followed up, restenosis in six (14%), and reocclusion in four (10%). Late restenosis or reocclusion was found in five (15%) of 33 patients with a single stent in contrast to five (63%) of eight patients with multiple stents. CONCLUSIONS: Balloon-expandable intracoronary stenting is a feasible method for treating the acute complications of balloon angioplasty. It reduced the rate of restenosis for single stent implantation. Subacute thrombotic events must be regarded as previously unknown and serious complications.

Adult↗
PubMed1991

Low frequency arterial wall movements for indirect blood pressure measurement in man. Validation of a method for non-invasive assessment of blood pressure under the influence of isoprenaline and angiotensin.

In order to measure blood pressure noninvasively, the second derivative of the low frequency wall movements of the brachial artery were registered with a piezo-electric pressure probe during deflation of a Riva-Rocci cuff along with the actual cuff pressure. Two characteristic phenomena of this signal have been suggested to reflect systolic and diastolic blood pressure. Appearance of a positive spike phenomenon (S) was suggested to indicate systolic blood pressure and disappearance of a negative preanacrotic notch (D) to indicate diastolic blood pressure. To prove the validity of these suggestions, these phenomena were assessed in 10 young healthy males during isoprenaline and angiotensin induced changes of blood pressure. Intraarterial (A. radialis) and auscultatory (A. brachialis) blood pressures were recorded simultaneously. Determination of systolic blood pressure with the S phenomenon agreed well with invasive and auscultatory results. Invasive diastolic values agreed well with the cuff pressure at the last signal before disappearance of the preanacrotic notch (D1). Data from auscultation agreed less well with the D1 phenomenon. With increasing doses of isoprenaline, the diastolic measurements (D1) tended to be lower than the invasive ones. However, this discrepancy was far discreeter than that seen with ordinary auscultatory blood pressure measurement. We therefore conclude that registrations of low frequency arterial wall movements yield distinct characteristic spike phenomena useful for measurement of blood pressure in good agreement with the invasive method. In addition, the method provides clearly documented records and should be useful in situations which rely on a valid indirect method.

Adult↗
PubMed1991

[Angiographic and histologic findings in high frequency rotational ablation in coronary arteries in vitro].

High-frequency rotational angioplasty is a recently developed method for coronary angioplasty in the catheter laboratory. An elliptical burr tip (phi 1.25-2.0 mm) with embedded diamant chips (phi 40-50 microns) is rotated by a helical drive shaft at 150,000-180,000 rpm. The burr is advanced over a 0.009-inch coaxial guide wire. To show the effects of this approach in diseased and healthy vessels, which may be present before and behind a stenosis, 17 atherosclerotic coronary arteries of nine human hearts, and 18 normal coronary arteries of nine pig hearts were treated by this method in vitro. Standardized coronary angiography was performed before and after Rotablator treatment, followed by histological examination. From these data the burr-to-vessel-diameter ratio was calculated for each vessel segment and compared with the angiographical and histological outcome. Partial or complete removal of the circumference of the innermost vessel wall layers was observed regularly. The average removal of tissue in human coronary arteries was limited to the intimal layer and in the pig coronary arteries to the internal elastic membrane. In the pig coronary arteries no intimal tears or dissections occurred, in human coronary arteries tears could be seen frequently (13 of 17 vessels (76%)). Media tears were observed in 3 of 17 vessels; one (2%) media dissection could be demonstrated; no perforation occurred. Thus, the in vitro studies suggest that coronary rotational angioplasty has only a slight effect on the vessel segment next to a stenosis, regardless of the burr-to-vessel-diameter ratio.(ABSTRACT TRUNCATED AT 250 WORDS)

Angioplasty, Balloon, Coronary↗
PubMed1990

Coronary stent implantation in acute vessel closure 48 hours after an unsatisfactory coronary angioplasty.

We report the implantation of a balloon-expandable stent in a patient with acute vessel closure in the state of evolving myocardial infarction following 48 hr after unsatisfactory coronary angioplasty. The stent was implanted after successful recanalization of an occluded left anterior descending artery, with repeated unsatisfactory results of balloon angioplasty. Adjunct thrombolytic therapy was contraindicated. No residual stenosis was documented in immediate control angiograms, or after 24 hr, 3 weeks, and 4 months.

Angina, Unstable↗
PubMed1990

[Coronary vessel stent implantation in patients with symptomatic dissections following balloon dilatation].

Dissections after coronary balloon angioplasty are risk factors for acute or subacute vessel closure. Intracoronary stenting was developed to avoid this complication by wrapping the intimal and medial flaps against the vessel wall, which reduces the risk of acute thrombosis. A total of 17 stents were implanted into the coronary arteries of 10 patients with angiographically documented dissections after balloon angioplasty, who presented angina and ischemic ECG changes. Mean minimal stenosis diameter was 1.11 +/- 0.35 mm (65.1%) before, and 1.48 +/- 0.56 mm (53.9%, n.s.) and 2.45 +/- 0.62 mm (23.5%, p less than 0.005), respectively, after balloon angioplasty with and without taking the dissection membrane into account. All patients reported an immediate recovery of their anginal complaints after stent delivery, and ischemic ECG changes disappeared. The mean residual stenosis after coronary stenting was measured as 3.33 +/- 0.23 mm (0%, p less than 0.001). The immediate control angiograms and these after 24 h depicted smooth vessel walls without any irregulations at the site of implantation, and the mean residual stenosis diameter remained unchanged after 24 h (3.3 +/- 0.23 mm; 1.2%, p less than 0.001). No patient suffered acute myocardial infarction, one patient underwent coronary bypass surgery because of persisting episodes of angina pectoris. Thus, intracoronary stenting seems to be a secure and effective method to handle dissections after balloon angioplasty, and perhaps reduces the rate of acute complications and the need for emergency bypass surgery after coronary balloon angioplasty.

Aged↗
PubMed1990

New mechanical devices for treatment of coronary artery disease.

Percutaneous high-speed coronary rotablation allows to remove arterio-sclerotic material from the vessel wall. A diamond-coated (15-30 microns) brass burr drill fastened to a flexible drive shaft rotating and tracking along a drill coaxial guide wire is used. The turbine rotates the drive shaft at 150,000-190,000 rpm. High-frequency rotational angioplasty was successful in 27 of 28 patients, but in about 34% additional PTCA was necessary. Only one patient went to bypass surgery, and myocardial infarction (CK less than 150 u/l) occurred in only one of 28 patients. No vessel perforation was observed. All vessels were open at 24 h control. The restenosis rate was not increased. The main indication for high-speed rotational angioplasty seems to be rigid sclerotic lesions that cannot be passed by a conventional balloon catheter. Whether restenosis rate can be reduced by this method will be judged in future studies. In order to avoid acute complications of PTCA and to reduce restenosis rate, coronary stents were developed. Self-expandable and balloon-expandable stents are available. It could be demonstrated that these stents can be used as a bail-out system and can block elastic recoil of coronary arteries. The major remaining problem is that of subacute closure of coronary vessels. In order to prevent this, treatment with coumarine, acetylsalicylic acid, and dipyridamol is necessary. Coronary stents can be successfully delivered in more than 90% of the patients, as demonstrated by a cooperative study. In a highly selective patient group using single stents, restenosis rate measured 15%, but was higher in patients with multiple stents.

Angioplasty, Balloon, Coronary↗
PubMed1989

[Balloon dilatation and coronary vascular stent implantation].

To avoid acute complications and restenosis after percutaneous transluminal coronary angioplasty coronary stents were developed. For the first time in 2 patients with severe lesions of the left anterior descending coronary artery 3 Palmaz-Schatz stents were implanted after application and fixation by balloon inflation. The vessels showed larger diameters with smoother surface and smaller gradients compared to balloon angioplasty as related to a blockade of the elastic properties of the vessel and suggested fixation of intima or media dissection. The implantation of the coronary stents was without complications. The control after 24 hours showed an open vessel with unchanged diameter. The patients were without symptoms during control after 4 weeks. Based on this and previous work the implantation of coronary stents seems to open a new dimension for percutaneous transluminal coronary angioplasty because vessel occlusions are prevented and restenosis possibly reduced. The newly designed stents show elementary constructive alternatives to currently used types.

Angioplasty, Balloon↗
PubMed1989

[High-frequency rotational atherectomy in coronary heart disease].

Percutaneous high frequency coronary rotational ablation (PTCR) was used in 10 patients with significant coronary artery disease. PTCR removes arteriosclerotic material from the vessel wall. A diamond-coated (60-80 micron) brass burr-drill, fastened to a flexible drive shaft rotating and tracking along a central coaxial guide wire, was used. The turbine rotates the drive shaft in excess of 150,000-190,000 revolutions per minute. PTCR was successful in all patients, but in three additional percutaneous transluminal coronary angioplasty (PTCA) was then successfully performed. Coronary dissection occurred only once, requiring surgery which was successful. No vessel perforation was observed. All vessels were open on the coronary angiograms performed after 24 hours. The main indication for PTCR seems to be a rigid and longer lesion which can not be dilated with the balloon catheter.

Angioplasty, Balloon↗
PubMed1989

High-frequency rotablation of occluded coronary artery during heart catheterization.

High-frequency rotation atherectomy of an occluded left circumflex coronary artery was performed in a 45-year-old man. Over a 0.009 inch flexible tip steel wire a diamond-coated brass burr fastened to a flexible drive shaft that rotates and tracks was advanced. The drive shaft was connected to a turbine and driven by compressed air with 150,000 rpm. After rotablation of the posterior lateral branch over 3 cm with a 1.5 mm burr and rotablation with a 1.75 mm burr of the posterior branch of the left circumflex coronary artery the vessel was reopened with a smooth surface without perforation and dissection. 24 h control and 6 mo control revealed an open coronary vessel. High frequency rotating coronary angioplasty seems to be a promising alternative method to PTCA in opening totally occluded coronary arteries.

Angioplasty, Balloon↗
PubMed1989

[Balloon dilatation and coronary vascular stent implantation].

To avoid acute complications and restenosis after percutaneous transluminal coronary angioplasty coronary stents were developed. For the first time three flexible Palmaz-Schatz stents were implanted after application and fixation by balloon inflation in two patients with severe lesions of the left anterior descending coronary artery. The vessels showed larger diameters with smoother surface and smaller gradients compared to balloon angioplasty as related to a blockade of the elastic properties of the vessel and suggested fixation of intima or media dissection. The implantation of the coronary stents was without complications. The control after 24 h showed an open vessel with unchanged diameter. The patients with the proximal lesion of the left anterior descending coronary artery six months later showed no restenosis and no luminal narrowing. The recanalized left anterior descending coronary artery, which was dilated, received two stents and was reoccluded after six months. Meanwhile, up to four stents were implanted successfully in an additional four patients with open vessels as the 24-h-control. Based on this and previous work the implantation of coronary stents seems to open a new dimension for percutaneous transluminal coronary angioplasty because vessel occlusions can be prevented. Whether or not the restenosis rate can be reduced has to be demonstrated in additional studies.

Adult↗