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Biomedical subjects

W Burger

Publications and source records attributed to W Burger.

At least 37 records · Page 2Linked to original sources
PubMed1998

Endothelium-dependent and endothelium-independent flow reserve in vascular regions supplied by the internal mammary artery before and after bypass grafting.

OBJECTIVE: It was the goal of this study to compare endothelium-dependent and endothelium-independent flow reserve in vascular regions supplied by the left internal mammary artery before and after bypass graft surgery. METHODS: The native internal mammary artery in situ was investigated in 13 patients (age 61.8 +/- 8.0 years) with angiographically proven coronary artery disease. The internal mammary artery after bypass grafting was investigated in ten patients (age 60.8 +/- 7.3 years) 3.5 +/- 2.8 years after the operation. Flow reserve was evaluated endothelium-dependent with acetylcholine (ACh 25 and 50 microg i.c.) and endothelium-independent with nitroglycerin (NTG 0.3 mg i.c.) followed by papaverin (10 mg i.c.). Flow indices were calculated from intraluminal Doppler blood flow velocity measurements and the vascular cross-sectional area as determined by quantitative angiography. An index for vascular resistance was defined as the ratio of pressure gradient and resting or peak flow. RESULTS: After endothelium-dependent stimulation with acetylcholine 25 microg (50 microg), flow in the internal mammary increased by 352.3 +/- 152% (412 +/- 145%) before surgery, whereas it increased only by 213 +/- 134% (193 +/- 120%) after surgery (P < 0.05). Endothelium independent stimulation with papaverin resulted in a flow increase of 391 +/- 234% before surgery vs. 315 +/- 135% after surgery (n.s.). The resistance index decreased after endothelium-dependent stimulation with acetylcholine 25 microg(50 microg) to 35 +/- 16.8% (28 +/- 8.9%) before surgery, whereas it decreased only to 59 +/- 26% (72 +/- 43%) after surgery (P < 0.05). Endothelium independent stimulation with papaverin resulted in a decrease of the vascular resistance index to 31 +/- 14% before surgery vs. 32 +/- 14% after surgery (n.s.). CONCLUSION: Vascular regions supplied by the internal mammary artery as a graft demonstrate a significantly reduced endothelium-dependent flow reserve but a preserved endothelium-independent flow reserve as compared to vascular regions supplied by the native internal mammary artery. The selective decrease in endothelium-dependent flow reserve may be due to microvascular changes in the myocardial region supplied by the internal mammary artery after bypass grafting.

Aged↗
PubMed1998

A randomized study of radiotherapy alone versus radiotherapy plus 5-fluorouracil and platinum in patients with inoperable, locally advanced squamous cancer of the esophagus.

Squamous cell cancer of the esophagus is the most common cancer among black South African males, and 60% of patients present with localized inoperable disease. Combined chemoradiotherapy has been reported to be superior to radiotherapy alone for localized inoperable esophageal cancer in North American patients. A study was carried out to determine if this was also applicable to South African patients, who present with more advanced disease. From September 1991 through June 1995, 70 patients with locally advanced (T3N0-1M0) squamous cancer of the esophagus were prospectively randomized to receive radiotherapy alone or radiotherapy combined with cisplatin and 5-fluorouracil. There was no statistically significant survival difference between the two groups. The median survival was 144 days in the group receiving radiotherapy alone, and 170 days in the group receiving radiotherapy combined with chemotherapy (p = 0.42). The degree of weight loss before initiation of therapy had a significant effect on survival regardless of the treatment arm. Radiotherapy in combination with chemotherapy, as administered in this study for South African patients with locally advanced, inoperable squamous cancer of the esophagus, is no better than radiotherapy alone.

Adult↗
PubMed1998

Urinary excretion of diethylstilbestrol in the ostrich.

Stilboestrol tablets (20 x 1 mg) were given to 4 ostriches. Urine was collected over a period of 8 days and stored frozen at-20 degrees C pending analysis. Analyses were performed on a gas chromatograph-mass selective detector for the presence of parent compound and/or metabolites. Diethylstilbestrol and its metabolite, dienestrol, were detected in urine; dienestrol only for 1 day but diethylstilbestrol for 8 days after administration. Residue analysis for the use of diethylstilbestrol as growth promoter can be performed on the urine of ostriches by scanning for parent compound only since it can be detected longer than the metabolite.

Animals↗
PubMed1997

Right ventricular function before and after percutaneous balloon mitral valvuloplasty.

Aim of this study was to evaluate right ventricular performance in patients with mitral stenosis and its modification by balloon valvuloplasty. Right ventricular volumes of 24 patients with postrheumatic mitral stenosis were determined by thermodilution 1 or 2 days before and 1 or 2 days after valvuloplasty. Right ventricular ejection fraction at rest was 43 (36-47)% (median and interquartile range). Right ventricular end-diastolic volume was 100 (86-119) ml/m2. Supine bicycle exercise (50 Watt) reduced right ventricular ejection fraction to 30 (29-37)% (P < 0.0001) and increased right ventricular end-diastolic volume to 124 (112-141) ml/m2 (P < 0.0001). At rest, right ventricular ejection fraction correlated inversely with pulmonary vascular resistance (r = -0.64, P < 0.0001), while no significant correlation with mitral valve area was found. Valvuloplasty increased right ventricular ejection fraction at rest to 48 (44-50)% (P < 0.005), and during exercise to 42 (38-45)% (P < 0.0001). This improvement of right ventricular ejection fraction correlated inversely with the value of this parameter before valvuloplasty (r = -0.88, P < 0.0001) and with the gain in stroke volume (r = 0.57, P < 0.01). The right ventricular function curve, disturbed before commissurotomy, was reestablished by the procedure. In conclusion, at the here investigated stage of mitral stenosis right ventricular function is reversibly impaired. This is predominantly caused by the hemodynamic consequences of the valvular defect and not by an impairment of right ventricular myocardial function.

Adult↗
PubMed1997

[Balloon dilatation of valvular pulmonary stenoses in adults].

Balloon valvuloplasty of pulmonary stenosis has become the treatment of choice in children and adults. This is a report about the long term results in adult patients. Forty-six patients (mean age 37 +/- 17 years) with pulmonary stenosis were treated between 1984 and 1994 by this method. Thirty-four of 46 patients were re-examined 3 months to 9 years (mean 3.4 years) later by right heart catheterization and echocardiography. These 34 patients were representative for the whole group concerning age, severity of the pulmonary stenosis, and acute results after the intervention. The pressure gradient was acutely reduced by balloon valvuloplasty from 86 +/- 35 to 38 +/- 17 mm Hg (p < 0.0001) (n = 46) and was 32 +/- 10 mm Hg (n.s.) (n = 34) at follow-up. Within 3 months after the intervention, 8 of 13 patients with a pressure gradient > or = 100 mm Hg, showed spontaneously further reduction of the gradient due to the resolution of the subvalvular muscular hypertrophy. During a bicycle exercise test with 9 patients, the gradient rose significantly from 29 +/- 10 to 53 +/- 23 mm Hg (p < 0.01) as determined by right heart catheterization. All of these patients had normal cardiac output at rest and during exercise. None had signs of right ventricular hypertrophy in the electro- or echocardiogram. It is concluded that balloon valvuloplasty of pulmonary stenosis is the first line treatment in adults.

Adult↗
PubMed1997

Variations of segmental endothelium-dependent and endothelium-independent vasomotor tone after cardiac transplantation (qualitative changes in endothelial function).

Endothelial dysfunction is a common phenomenon after cardiac transplantation. However, qualitative differences in endothelial vasoregulation at different coronary segments and at different postoperative times have rarely been explored. To uncover the functional variations of endothelium responses we infused the endothelium-dependent vasodilator acetyl-choline (50 micrograms) followed by the endothelium-independent vasodilator 3-morpholinosydnonimine (SIN-1) (1 mg; 16 patients) or nitroglycerin (0.3 mg; 14 patients) sequentially into the left coronary artery. We investigated the responses of 120 nonstenotic coronary segments (proximal and distal left anterior descending and right circumflex coronary arteries) in 30 patients with quantitative angiography (group 1: 13 patients, 12 +/- 1 months after cardiac transplantation; group 2: 17 patients, 55 +/- 3 months after cardiac transplantation). Continuous-flow measurement was performed to exclude significant reduction of microvascular response influencing epicardial dilation. Five responses to acetylcholine administration followed by nitrates were observed. On the one end of the spectrum, segments dilate to acetylcholine administration with no further dilation to exogenous nitric oxide, indicating completely preserved endothelial function. On the other end, segments constrict to acetylcholine with no change after endogenous nitric oxide, reflecting a defective endothelial and defective smooth muscle function. The different patterns of coronary vasomotor lone responses to endogenous nitric oxide followed by exogenous nitric oxide represent different degrees of endothelial function after cardiac transplantation. In addition, the functional assessment of endothelial integrity shows qualitative time-dependent differences between proximal and distal coronary parts. The existence of coronary segments with functioning endothelium indicates that the latter is not diffusely disturbed in all cardiac transplant recipients and that the endothelial damage is perhaps not irreversibly lost.

Acetylcholine↗
PubMed1997

Successful thrombolysis after prosthetic pulmonary valve obstruction under aspirin monotherapy.

In a 22-year-old woman with recent onset of left-sided chest pain and exertional dyspnea, echocardiography revealed obstruction of a St. Jude Medical bileaflet prosthetic valve (size 23 mm) in the pulmonary position. Oral anticoagulation had been replaced for the previous 7 years by aspirin as the sole antithrombotic treatment. The valve had been inserted 16 years ago for pulmonary atresia. Valve function was restored by systemic application of 9 million units of urokinase.

Adult↗
PubMed1997

New Y-TZP powders for medical grade zirconia.

There is interest in using zirconia for biomedical applications as ball heads for total hip prostheses. Two potential types are under discussion: partially stabilized zirconia (PSZ) and tetragonal zirconia polycrystals (TZP) materials. Because of its enhanced material properties, TZP stabilized with yttria is favourable. To eliminate high amounts of natural radioactive impurities, the precursors are purified. The kind of precursor and purification method determine the powder impurity level. The disadvantage of Y-TZP is that the hydrothermal decomposition reaction method is that it depends very strongly on the grain size and the distribution of the stabilizing yttria within the zirconia grains. Thermodynamical and kinetic investigations on high purity coprecipitated and yttria-coated zirconia powders show different behaviours. Y-TZP materials based on yttria-coated zirconia powders show excellent mechanical strength of more than 1000 MPa, a Weibull modulus of up to 20 a! nd a fracture toughness of 9 MPa radical m. The material properties of Y-TZP ceramics based on coprecipitated powders and prepared under the same conditions are less attractive. It is expected that materials based on yttria-coated zirconia will show enhanced properties compared to materials derived from coprecipitated powders. Therefore Y-TZP materials derived from yttria-coated powders are very attractive as medical grade zirconia.

Journal Article↗
PubMed1996

[Quality assurance in invasive cardiology. A prospective study for the evaluation of indications for coronary angiography and coronary dilatation using the "Rand Corporation" method].

OBJECTIVE: To assess the indications for coronary angiography and percutaneous transluminal coronary angioplasty (PTCA) according to the criteria of the RAND Corporation's expert panel ratings; to compare the results with those already published in the literature; and to examine the method with respect to its appropriateness as a measure of quality control. PATIENTS AND METHODS: The parameters necessary for rating according to the RAND Corporation's published criteria were prospectively obtained in 116 consecutive patients (89 men, 27 women; mean age 59.4 +/- 10.7 years) undergoing coronary angiography and 138 patients (112 men, 26 women; mean age 61.5 +/- 9.4 years) undergoing PTCA. RESULTS: For coronary angiography the >>inappropriate rate << was 22.4%, for >> uncertain indications << 15.5%, >> appropriate indications << 24.1%, and for >> necessary indications << 37.9%. 38.6% of coronary angiographies, performed in the course of angiographic control after PTCA, were >> inappropriate <<, but only 12.5% of other coronary angiographies (P < 0.01). In 48.6% of >> appropriate << or >> necessary << procedures invasive treatment followed, compared with 19.2% of those rated >> inappropriate << (P < 0.05). In 10.1% of patients the indications for PTCA were judged >> inappropriate <<, in 32.6% as >> uncertain <<, in 13.0% as >> appropriate << and 44.2% as >> necessary <<. There was no correlation between ratings and the acute results of PTCA. These findings pertaining to indications for coronary angiography and PTCA correspond to those reported in the literature. CONCLUSIONS: As the RAND criteria take inadequate account of individual peculiarities, they are not suitable for individual clinical decisions. But they are useful as screening method in a quality control project, because procedures for which indications have not been adequately proven are singled out by an unfavourable rating and can thus be thoroughly analysed in the individual case.

Angina Pectoris↗
PubMed1996

[Balloon mitral valve commissurotomy in pregnancy].

HISTORY AND CLINICAL FINDINGS: A 31-year-old woman with known postrheumatic mitral valve stenosis developed for the first time left heart failure in the 19th week of her fifth pregnancy. After intensive drug treatment she was in stage 3 (New York Heart Association classification). Apart from that the patient was in a good general condition and obstetrical status was according to the estimated duration of pregnancy. Auscultation revealed an apical diastolic murmur and mitral opening snap. INVESTIGATIONS: Echocardiography demonstrated a mitral valve opening area of 0.85 cm2 (pressure-half time method); the mean gradient was 19 mm Hg. TREATMENT AND COURSE: Because of the severity of the findings a percutaneous transvenous balloon valvotomy (according to Inoue) was performed in the 27th week of pregnancy, after careful lead shielding of abdomen and pelvis. Radiological screening time was 10 min. The invasively measured transvalvar pressure gradient was reduced from 28 to 4 mm Hg, echocardiographically determined mitral opening area increased to 1.5 cm2. Delivery was induced in the 36th week of pregnancy because of third-degree renal pelvis congestion. A healthy child, weighing 2850 g was delivered vaginally. CONCLUSION: High-grade symptomatic mitral stenosis can, if necessary, be treated with a low-risk to mother and child by percutaneous balloon valvotomy.

Adult↗
PubMed1996

13-Cis-retinoic acid and interferon alpha-2a in patients with advanced esophageal cancer: a phase II trial.

The aim of this study was to investigate the possible therapeutic effect of 13-cis-retinoic acid plus interferon alpha-2a in patients with inoperable squamous cancer of the esophagus. Patients with advanced, measurable, histologically confirmed squamous carcinoma of the esophagus with an Eastern Cooperative Oncology Group (ECOG) performance status of 0, 1 or 2 who had adequate bone marrow, liver, and renal function were eligible for study. Patients were given cis-retinoic acid 1 mg/kg/day per mouth continuously and interferon alpha-2a 3 Mu/day for 3 days followed by 6 Mu subcutaneously daily thereafter. Seventeen patients were entered on study. Fifteen patients were evaluable for toxicity. The most common toxicities were grade 1 and 2 cheilitis, dry skin and flu-like symptoms which occurred in all patients. Two patients had grade 3 toxicity (1 anorexia and 1 fatigue). No grade 4 toxicity occurred. Fifteen patients were evaluable for response. No objective response was documented. The median survival time was 15 weeks. With no response seen it is unlikely that the combination of treatment as used in this study will be of benefit in patients with advanced squamous cancer of the esophagus.

Administration, Oral↗
PubMed1996

Time course of endothelial function in epicardial conduit coronary arteries and in the microcirculation in the long-term follow-up after cardiac transplantation.

BACKGROUND: Endothelial dysfunction has been reported in epicardial conduit coronary arteries and in the microcirculation after cardiac transplantation. It has been assumed that endothelial dysfunction may precede hemodynamically relevant transplant vasculopathy. In this study the long-term course of endothelial function was investigated in conduit coronary arteries and in the microcirculation after cardiac transplantation. METHODS: Patients were stratified according to time after transplantation (group I, up to 2 years after transplantation; group II, 2 to 4 years after transplantation; group III, more than 4 years after transplantation). Changes of the diameter of proximal, mid and distal segments of the left anterior descending coronary artery and the circumflex branch of the left coronary artery were investigated after endothelium-dependent and endothelium-independent stimulation with acetylcholine (ACh, 50 and 100 micrograms i.c.) and nitroglycerin 0.3 mg i.c. Coronary flow changes were assessed endothelium-dependently (ACh 50 and 100 micrograms i.c.) and endothelium-independently (dipyridamole 0.56 mg/kg i.v.) utilizing an 8 F Judkins-style Doppler catheter. RESULTS: Application of 50 micrograms/100 micrograms ACh resulted in a reduction of coronary artery diameter in proximal, mid and distal vascular segments of the left anterior descending coronary artery and the circumflex branch of the left coronary artery. The vasoconstrictive effect did not differ significantly between groups I,II and III. Nitroglycerin 0.3 mg i.c. increased coronary artery diameters in groups I, II and III. ACh (50 micrograms/100 micrograms) increased coronary flow index by 217 +/- 70%/236 +/- 110% (P < 0.05 vs. baseline) in group I, 113 +/- 26%/77 +/- 22% (P < 0.05 vs. baseline) in group II and 108 +/- 26%/109 +/- 21% (P < 0.05 vs. baseline) in group III. Dipyridamole increased coronary flow index by 296 +/- 78% (P < 0.05 vs. baseline) in group I, by 63 +/- 16% (P < 0.05 vs. baseline and vs. group I) in group II and by 113 +/- 30% (P < 0.05 vs. baseline and vs. group I) in group III. CONCLUSION: A constant vasosonstrictor response to ACh was observed in epicardial coronary arteries after cardiac transplantation indicating endothelial dysfunction independent of the time course. Endothelial dysfunction in these vessels may not be an early indicator of hemodynamically relevant transplant vasculopathy. Endothelium-dependent and endothelium-independent flow reserves decreased 2 years after transplantation and remained constant thereafter.

Acetylcholine↗
PubMed1995

Role of pericardial constraint for right ventricular function in humans.

STUDY OBJECTIVE: To analyze the extent of pericardial constraint on right ventricular function in humans. PATIENTS AND METHODS: Twenty patients, 59 +/- 2 (mean +/- SEM) years old, undergoing coronary bypass surgery. Right ventricular volumes and pressures were evaluated using a rapid response Swan-Ganz thermodilution catheter. INTERVENTIONS: Parameters were determined before and after pericardiotomy, both before and during increased right ventricular systolic pressure by partial compression of the pulmonary artery (before pulmonary compression: 25 +/- 1 mm Hg; during: 39 +/- 1 mm Hg). RESULTS: Pericardiotomy alone did not significantly affect right ventricular end-diastolic volume (before: 79 +/- 4 mL m-2; after: 78 +/- 3 mL m-2), right ventricular ejection fraction (before: 48 +/- 1%; after: 48 +/- 2%), and right atrial pressure (before: 4.3 +/- 0.8 mm Hg; after: 4.3 +/- 0.7 mm Hg). Before pericardiotomy, the increase in right ventricular afterload significantly increased right atrial pressure (to 5.5 +/- 0.7 mm Hg, p < 0.05) and reduced right ventricular ejection fraction (to 43 +/- 2%, p < 0.01). Right ventricular end-diastolic volume remained unchanged. After pericardiotomy, the increase in right ventricular afterload significantly increased right ventricular end-diastolic volume (to 85 +/- 3 mL m-2, p < 0.01) and also reduced right ventricular ejection fraction (to 42 +/- 2%, p < 0.01), while right atrial pressure was not significantly changed. During increased right ventricular afterload, the right ventricular diastolic pressure-volume relation was shifted rightward. CONCLUSIONS: At normal levels of right ventricular diastolic filling, the pericardium does not exert constraining effects on right ventricular function. However, with increasing levels of right ventricular preload, pericardial constraint significantly influences right ventricular function in humans.

Aged↗
PubMed1994

Endothelium-dependent and endothelium-independent vasomotion in large coronary arteries and in the microcirculation after cardiac transplantation.

Endothelium-dependent and endothelium-independent vasodilation of the epicardial conduit vessels and the microcirculatory coronary vessels was investigated with cumulative doses of acetylcholine (ACh 50 micrograms and 100 micrograms i.c.), nitroglycerin (0.3 mg i.c.) and dipyridamole (0.56 mg.kg-1 i.v.) in 17 patients (3 female/14 male; age: 47 +/- 3.6 years) with angiographically normal coronary arteries 40 +/- 5.1 months after cardiac transplantation. The effect of ACh on large conduit arteries was evaluated angiographically. Coronary blood flow velocity changes were measured utilizing an 8F Judkins style 20 MHz Doppler catheter positioned in the left main coronary artery. A coronary flow index was calculated from the mean Doppler flow velocity and the computed cross-sectional vascular area. After 50 micrograms of ACh the diameter of proximal, middle and distal segments of the left anterior descending coronary artery decreased significantly by 7.6 +/- 2.06% (P < 0.05), 10.6 +/- 3.5% (P < 0.01) and 12.6 +/- 3.29% (P < 0.01) and after 100 micrograms ACh by 10.5 +/- 2.4% (P < 0.05), 13.0 +/- 3.7% (P < 0.01) and 15.3 +/- 3.9% (P < 0.01). The endothelium-independent vasodilator nitroglycerin (0.3 mg i.c.) induced an increase in vascular diameter of 14.4 +/- 3.1% (P < 0.01), 18.6 +/- 4.1% (P < 0.01) and 20.8 +/- 2.9% (P < 0.01) in proximal, mid and distal segments of the left anterior descending coronary artery.(ABSTRACT TRUNCATED AT 250 WORDS)

Acetylcholine↗
PubMed1994

Long-term glycemic control has a nonlinear association to the frequency of background retinopathy in adolescents with diabetes. Follow-up of the Berlin Retinopathy Study.

OBJECTIVE: To assess the influence of long-term glycemic control on the development of background retinopathy in adolescents followed longitudinally from the onset of insulin-dependent diabetes mellitus (IDDM). RESEARCH DESIGN AND METHODS: Repeated retinal fluorescein angiographies, in intervals of 1-2 years, were evaluated prospectively in 346 patients (190 males, 156 females; 19.8 [8.8-35.4] years of age; diabetes duration of 10.4 [1.1-27.4] years at their latest eye examination, median [range]). The influences of long-term HbA1c (mean of 18 [1-95] determinations per person) and microalbuminuria (> or = 2 of > or = 3 measurements > or = 15 micrograms/min x 1.73 m2) were studied by multiple linear regression, life-table analysis, and trend analyses. RESULTS: The rate of background retinopathy per 100 patient-years increased with poorer glycemic control from 0.7 (long-term HbA1c < 7% to 7.3 (HbA1c > 11%) following an exponential function. Life-table analysis after subdivision in HbA1c quartiles of equal sizes (HbA1c < 8, 8-9, 9-10, and > 10%) revealed an individual median expectation of background retinopathy after more than 25, 16.2, 12.7, or 12.0 years of diabetes, respectively. However, significant differences were found only between 8-9% and 9-10%, calculated either as prevalence, life-table analysis, or relative incidence, thus suggesting that a threshold model may also fit the data. After 12 years of diabetes, < 25% of those patients exhibiting microalbuminuria (n = 18) were expected to be free from retinopathy compared with 81% of those with normoalbuminuria (n = 86). CONCLUSIONS: Two statistical models are appropriate to explain the relationship between glycemic control and risk for background retinopathy: 1) a continuous exponential relationship as described by the DCCT or 2) the presence of a threshold HbA1c level at 9%. Thus, diabetes treatment in children should aim at long-term HbA1c levels < 9.0%, but every progress closer to normal may further reduce the risk.

Adolescent↗
PubMed1994

[Angiography follow-up after transluminal angioplasty of coronary bypass grafts].

Between January 1979 and October 1991, percutaneous transluminal angioplasty of stenosed or occluded coronary bypass grafts was attempted 180 times in 146 patients (180 lesions in 157 bypass grafts); 6/157 grafts were internal mammary grafts. The procedure was successful in 129/157 grafts (82%) and in 151/180 lesions (84%). Failures occurred almost exclusively in recanalization attempts. Cardiac complications occurred in 4/146 patients (2.7%). Three patients developed an acute myocardial infarction, another patient died after acute occlusion of a native vessel dilated during the same procedure. In successful attempts the severity of stenosis was reduced from 87 +/- 10% to 33 +/- 15%. 113/129 successfully dilated grafts had at least one (mean 2.7) control angiogram. 54/113 (48%) showed recurrence after a mean follow up of 6 months. An additional 15 grafts showed late restenosis in a second control angiogram (mean follow-up 23 months). The total restenosis rate was 61%. Restenoses were dilated again one to six times (mean 1.9) with comparable success and recurrence rate. Two patients died during the sixth angioplasty. Finally, 32/129 (25%) grafts were occluded or presumably occluded, and 97/129 (75%) were angiographically confirmed open without restenosis. Thus, angioplasty of bypass grafts is an alternative to a repeat revascularization surgery. The acute results are comparable to the results of angioplasty in native coronary arteries. The restenosis rate is high. One has to be aware of late restenosis. Restenosis can be dilated repeatedly with a comparable success rate and with no significant increase in restenosis rate.

Adult↗