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Biomedical subjects

K J Beatt

Publications and source records attributed to K J Beatt.

At least 19 recordsLinked to original sources
PubMed1992

Angiographic risk factors of luminal narrowing after coronary balloon angioplasty using balloon measurements to reflect stretch and elastic recoil at the dilation site. The CARPORT Study Group.

Because many ongoing clinical restenosis prevention trials are using quantitative angiography to assess whether a drug is capable of reducing the amount of intimal hyperplasia, quantitative angiographic risk factors for angiographic luminal narrowing after balloon angioplasty were determined, including stretch and elastic recoil at the dilatation site. Quantitative analysis was performed on 666 lesions in 575 patients during angioplasty and at 6-month follow-up. Stretch was defined as balloon diameter minus minimal luminal diameter (MLD) before angioplasty/reference diameter, and recoil as balloon diameter minus MLD after angioplasty/reference diameter. Multivariate analysis was used to yield independent risk factors for luminal narrowing at follow-up. Predictors of absolute change in MLD were (1) relative gain at angioplasty (gain in millimeters normalized for reference diameter) and (2) lesion length. To allow risk stratification, logistic regression analysis was applied using the decrease in MLD as a binary outcome variable. A decrease in MLD at follow-up of greater than or equal to 0.72 mm was considered significant. Variables retained in the model were: relative gain greater than 0.3 mm (rate ratio 2.9), relative gain 0.2 to 0.3 (rate ratio 2.1), stenosis length greater than or equal to 6.8 (rate ratio 1.7), and thrombus after angioplasty (rate ratio 2.6). Although stretch was significantly related to luminal narrowing at univariate analysis, it was not retained in the multivariate models. A large gain in lumen diameter at angioplasty, dilation of long lesions, and angiographically determined thrombus after angioplasty were found to be accompanied by more severe luminal narrowing at follow-up.

Adult↗
PubMed1992

Stenting of venous bypass grafts: a new treatment modality for patients who are poor candidates for reintervention.

During a 2-year period, 136 self-expanding Wallstents were implanted in saphenous vein bypass grafts in 69 patients with end-stage coronary artery disease. All patients had severe symptoms and the majority were poor candidates for either repeat surgery or conventional bypass coronary angioplasty because of unfavorable native anatomy, impaired left ventricular function, or a high-risk bypass lesion anatomy for coronary angioplasty. All procedures were technically successful without major complications and a need for emergency bypass surgery. However, during the hospital stay acute thrombotic complications occurred in seven patients (10%) resulting in one death and acute myocardial infarction in five patients and necessitating emergency repeat PTCA in two patients and repeat CABG in four. Twenty-three patients had serious hemorrhagic complications directly related to the rigorous anticoagulation schedule. Two patients died of fatal cerebral bleeding. During follow-up, another five patients died accounting for a total mortality rate of 12%. At late angiographic follow-up (4.9 +/- 3.4 months, n = 53), 25 patients (47%) had a restenosis (greater than or equal to 50% DS) within or immediately adjacent to the stent, necessitating reintervention in 19 patients (PTCA, n = 12; repeat CABG, n = 7). In the group without stent-related restenosis (n = 28), 15 patients had progression of disease in either the native or bypass vessels leading to recurrence of major anginal symptoms within 1 to 24 months. Ten of these patients required further intervention (stent, n = 6; PTCA, n = 3; repeat CABG, n = 1). Stenting in saphenous coronary bypass grafts can be performed safely with excellent immediate angiographic and clinical results.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗
PubMed1992

Restenosis after coronary angioplasty: the paradox of increased lumen diameter and restenosis.

Restenosis after coronary angioplasty is the single complication that most limits this revascularization procedure in clinical practice. The process is largely unpredictable and the lesion-related factors predisposing to restenosis are poorly understood, with little consensus in published reports. In this study using detailed quantitative angiographic measurements to assess 490 lesions, the simple lesion characteristics associated with restenosis were defined and the relation to the restenosis process documented. Restenosis was defined as an absolute deterioration in the minimal lumen diameter by greater than or equal to 0.72 mm, a criterion based on the 95% confidence intervals for repeat angiographic measurements. This was chosen in an attempt to separate spurious changes due to a poor angiographic result and the variability of angiographic measurements from significant changes due to the restenosis process. The principal determinants of restenosis were found to be a large improvement in the minimal lumen diameter at the time of dilation (1.13 mm for the restenosis group compared with 0.86 mm for the no restenosis group [p less than 0.0001]) and an optimal postangioplasty result (minimal lumen diameter 2.28 mm in the restenosis group compared with 2.05 mm [p less than 0.001] in the no restenosis group, corresponding to a 25% and a 30% diameter stenosis, respectively [p less than 0.0001]). These observations reported for the first time suggest that the distinction needs to be made between a "clinical restenosis" of greater than or equal to 50% diameter stenosis and the "restenosis process" as measured by the absolute changes occurring during and after angioplasty.(ABSTRACT TRUNCATED AT 250 WORDS)

Angioplasty, Balloon, Coronary↗
PubMed1991

Comparative quantitative angiographic analysis of directional coronary atherectomy and balloon coronary angioplasty.

An attempt to assess the "utility" of directional atherectomy was made using a new quantitative angiographic index. This index can be subdivided into an initial gain component and a restenosis component. The initial gain index is the ratio between the gain in diameter during intervention and the theoretically achievable gain (i.e., reference diameter). The restenosis index is the ratio between the decrease at follow-up and the initial gain during the procedure. The net result at long-term follow-up is characterized by the utility index, which is the ratio between the final gain in diameter at follow-up and what theoretically could have been achieved. For this purpose, 30 coronary artery lesions were selected from a consecutive series of successfully dilated primary angioplasty lesions and were matched with the initial 30 successfully treated primary atherectomy lesions. Matching by location of stenosis and reference diameter resulted in 2 comparable groups with identical preprocedural stenosis characteristics. Atherectomy resulted in an increase in minimal luminal diameter 2 times larger than angioplasty (1.53 vs 0.77 mm; p less than 0.0001). However, at follow-up there was a significant decrease in minimal luminal diameter and a significant increase in percent diameter stenosis in the groups with atherectomy and angioplasty (1.69 +/- 0.58 vs 1.57 +/- 0.58 mm, p = not significant [NS], and 37 +/- 18 vs 47 +/- 18%, p = NS, respectively). The decrease in minimal luminal gain was more pronounced in the group with atherectomy than in that with angioplasty (0.92 +/- 0.69 vs 0.35 +/- 0.51 mm; p = 0.0005).(ABSTRACT TRUNCATED AT 250 WORDS)

Angioplasty, Balloon, Coronary↗
PubMed1991

Angiographic follow-up after placement of a self-expanding coronary-artery stent.

BACKGROUND: The placement of stents in coronary arteries after coronary angioplasty has been investigated as a way of treating abrupt coronary-artery occlusion related to the angioplasty and of reducing the late intimal hyperplasia responsible for gradual restenosis of the dilated lesion. METHODS: From March 1986 to January 1988, we implanted 117 self-expanding, stainless-steel endovascular stents (Wallstent) in the native coronary arteries (94 stents) or saphenous-vein bypass grafts (23 stents) of 105 patients. Angiograms were obtained immediately before and after placement of the stent and at follow-up at least one month later (unless symptoms required angiography sooner). The mortality after one year was 7.6 percent (8 patients). Follow-up angiograms (after a mean [+/- SD] of 5.7 +/- 4.4 months) were obtained in 95 patients with 105 stents and were analyzed quantitatively by a computer-assisted system of cardiovascular angiographic analysis. The 10 patients without follow-up angiograms included 4 who died. RESULTS: Complete occlusion occurred in 27 stents in 25 patients (24 percent); 21 occlusions were documented within the first 14 days after implantation. Overall, immediately after placement of the stent there was a significant increase in the minimal luminal diameter and a significant decrease in the percentage of the diameter with stenosis (changing from a mean [+/- SD] of 1.88 +/- 0.43 to 2.48 +/- 0.51 mm and from 37 +/- 12 to 21 +/- 10 percent, respectively; P less than 0.0001). Later, however, there was a significant decrease in the minimal luminal diameter and a significant increase in the stenosis of the segment with the stent (1.68 +/- 1.78 mm and 48 +/- 34 percent at follow-up). Significant restenosis, as indicated by a reduction of 0.72 mm in the minimal luminal diameter or by an increase in the percentage of stenosis to greater than or equal to 50 percent, occurred in 32 percent and 14 percent of patent stents, respectively. CONCLUSIONS: Early occlusion remains an important limitation of this coronary-artery stent. Even when the early effects are beneficial, there are frequently late occlusions or restenosis. The place of this form of treatment for coronary artery disease remains to be determined.

Angiography↗
PubMed1991

Coronary stenting with a new, radiopaque, balloon-expandable endoprosthesis in pigs.

BACKGROUND: Intracoronary stents may be effective when used as "bail-out" devices for acute complications after percutaneous transluminal coronary angioplasty. Furthermore, preliminary reports have demonstrated some promising results with stents with regard to the reduction of restenosis. Several stent devices are available for preclinical and clinical evaluation. The use of these stainless-steel stents has been limited by poor visibility during fluoroscopy and thrombogenicity during the first days to weeks after implantation. We therefore investigated the immediate and short-term effects on arterial patency of a new, radiopaque, balloon-expandable coil stent in normal coronary arteries of pigs. METHODS AND RESULTS: In 10 animals, a stent was placed in two of the three epicardial coronary arteries. During the implantation procedure, the animals received heparin; after the procedure, no antithrombotic drugs were administered. After 1 week (five animals and 10 stents) or 4 weeks (five animals and 10 stents), repeat angiography was performed, followed by pressure-fixation of the coronary arteries for light and electron microscopic examination. Angiographic analysis revealed that all stented coronary segments were patent and without signs of intraluminal defects. Scanning electron microscopy showed complete endothelial covering of all stents within 7 days. Light microscopy showed a reduced tunica media locally under the stent wires, which resulted from exerted pressure. The neointima on top of the stent wires measured 56 microns (range, 42-88 microns) after 1 week and 139 microns (range, 84-250 microns) after 4 weeks. CONCLUSIONS: Results from this study show that this radiopaque endoprosthesis can be safely placed in normal coronary arteries of pigs. After 4 weeks, all stents were patent and there was no need for additional antithrombotic treatment, whereas neointimal proliferation was limited.

Angiography↗
PubMed1990

Quantitative angiographic assessment of elastic recoil after percutaneous transluminal coronary angioplasty.

Little is known about the elastic behavior of the coronary vessel wall directly after percutaneous transluminal coronary angioplasty (PTCA). Minimal luminal cross-sectional areas of 151 successfully dilated lesions were studied in 136 patients during balloon inflation and directly after withdrawal of the balloon. The circumvent geometric assumptions about the shape of the stenosis after PTCA, a videodensitometric analysis technique was used for the assessment of vascular cross-sectional areas. Elastic recoil was defined as the difference between balloon cross-sectional area of the largest balloon used at the highest pressure and minimal luminal cross-sectional area after PTCA. Mean balloon cross-sectional area was 5.2 +/- 1.6 mm2 with a mean minimal cross-sectional area of 2.8 +/- 1.4 mm2 immediately after inflation. Oversizing of the balloon (balloon artery ratio greater than 1) led to more recoil (0.8 +/- 0.3 vs 0.6 +/- 0.3 mm, p less than 0.001), suggestive of an elastic phenomenon. A difference in recoil of the 3 main coronary branches was observed: left anterior descending artery 2.7 +/- 1.3 mm2, circumflex artery 2.3 +/- 1.2 mm2 and right coronary artery 1.9 +/- 1.5 mm2 (p less than 0.025). The difference was still statistically significant if adjusted for reference area. Thus, nearly 50% of the theoretically achievable cross-sectional area (i.e., balloon cross-sectional area) is lost shortly after balloon deflation.

Absorptiometry, Photon↗
PubMed1990

Assessment of the "long sheath" technique for percutaneous aortic balloon valvuloplasty.

A 100 cm-long 16.5 F valvuloplasty catheter introducer was assessed as an adjunct for percutaneous transluminal aortic valvuloplasty (PTAV) via the femoral artery in 31 patients with severe aortic stenosis. Observed improvements in peak systolic gradient (81.6 +/- 29.9 mm Hg vs. 35.5 +/- 16.0 mm Hg, P less than 0.000001) and aortic valve area (0.6 +/- 0.4 cm2 vs. 1.0 +/- 0.6 cm2, P less than 0.00001) were similar to those achieved in a control group (C) of 17 patients in which no femoral sheath was used. However, a shorter procedure duration (211 +/- 81 min vs. 117 +/- 30 min, P less than 0.001) and a reduced rate of vascular complications at the femoral puncture site (41% vs. 6.5%) were observed in patients in whom the long sheath (LS) technique was used. The frequency of other PTAV-related complications was comparable (C = 35%, LS = 29%, P = n.s.). Other technical advantages of this device are: 1) prevention of looping and bending of the balloon catheter in tortuous vessels and easy positioning of the balloon across the aortic orifice provided by the LS trackability, 2) stabilisation of the balloon during inflation, 3) monitoring of supravalvular aortic pressure provided by the side-arm of the LS and reliable measurement of systolic gradient, and 4) the ability to perform aortograms without the need of another catheter in the ascending aorta. Thus, in our experience, the long sheath technique is a valuable adjunct for PTAV.

Aged↗
PubMed1990

Aortic valvuloplasty of calcific aortic stenosis with monofoil and trefoil balloon catheters: practical considerations. An evaluation of balloon design and valvular morphology relationship, derived from experimental and clinicopathological observations.

In order to evaluate the relation between balloon design (monofoil, trefoil) and valvular configuration, experimental aortic valvuloplasty was performed in four post-mortem hearts with calcific aortic stenosis of various morphology. The degree of obstruction of the aortic orifice was assessed by computed axial tomography during inflation of monofoil 15 and 19 mm and trefoil 3 x 12 mm balloon catheters. We also evaluated the hemodynamic repercussion of balloon inflation (fall in systolic aortic pressure) in four elderly patients with acquired aortic stenosis who underwent a percutaneous transluminal aortic balloon valvuloplasty, with stepwise increasing balloon sizes of 15 mm, 19 mm and 3 x 12 mm, as during our in vitro experiments, and who underwent aortic valve replacement later on. In these patients, we correlated the anatomy of the excised aortic valves with the retrospective analysis of aortic pressure curves recorded during previous valvuloplasty procedures. Our experimental and clinicopathological observations showed that the degree of obstruction of the aortic orifice in post-mortem specimens and the tolerance to balloon inflation in live patients are dependent of the valvular configuration. Although trefoil balloons have the theoretical advantage to avoid complete obstruction of the aortic orifice during inflation, we observed that in presence of a tricuspid configuration, they could be potentially more occlusive than monofoil balloons since each of the 3 individual components of the trefoil balloon occupied the intercommissural spaces while inflated. However, they offered more residual free space when inflated in aortic valves with a bicuspid configuration (i.e. congenitally bicuspid valves or tricuspid valves with one fused commissure). In our opinion, these observations are relevant, since degenerative disease of the aortic valve (i.e. tricuspid valve without commissural fusion) is now recognized as the most common etiology of aortic stenosis in the elderly.

Aged↗
PubMed1990

Restenosis following coronary angioplasty.

The assessment of restenosis following angioplasty has become increasingly important in determining the clinical value of the procedure. Despite this there has been no uniformly accepted methodology for assessing the procedure and consequently the published results have often been misleading with little concensus. In this paper some of the irregularities are documented and practical ways for adapting methodology proposed.

Angiography↗
PubMed1990

Arterial stenting with self-expandable and balloon-expandable endoprostheses.

Coronary angioplasty is complicated by acute occlusion (within 24 hours) and late restenosis (within 6 months) in 2-5% and 20-40% of the cases, respectively. Vascular endoprostheses (stents) may provide the cardiologist with a solution to some of these complications. Several stent-devices are now available for experimental and clinical evaluation. In this study we describe our experience with two metallic stents in normal arteries of swine. Self-expandable, stainless steel stents (3.5 mm diameter) were implanted in 17 peripheral arteries, eight of which were deendothelialized by prior balloon angioplasty. Following implantation, the animals received antithrombotic therapy with acenocoumarol and aspirin (8 stents), or aspirin alone (9 stents). After 1 week repeat angiography was performed, which showed patency of all stented arteries. Microscopy showed complete covering by neointima, 80 microns in thickness. This self-expandable stent (SES) and a balloon-expandable stent (BES), constructed of tantalum, were implanted in normal coronary arteries. SES (3.0 and 3.5 mm) receiving animals were treated with coumadines (10 stents) or received no antithrombotic treatment (16 stents) after implantation. BES receiving animals were also not treated (10 stents). Three untreated animals with SES died suddenly within 48 hours. Postmortem examination showed partial or complete thrombosis of all six stents in these animals, resulting in a patency rate of 62% after 1 week. All animals with SES, which were treated with coumadines, and all animals with BES (untreated) had patent stents after one week. It is concluded that SES implanted in normal coronary arteries of pigs, which do not receive additional antithrombotic treatment, show a 38% occlusion rate within 48 hours, but show 100% patency after 1 week, when the animals are treated with coumadines. BES implanted in normal coronary arteries of pigs, which do not receive antithrombotic drugs, are 100% patent after 1 week.

Angioplasty, Balloon, Coronary↗
PubMed1990

Assessment of "silent" restenosis and long-term follow-up after successful angioplasty in single vessel coronary artery disease: the value of quantitative exercise electrocardiography and quantitative coronary angiography.

Exercise electrocardiographic (ECG) testing during follow-up after coronary angioplasty is widely applied to evaluate the efficacy of angioplasty, even in asymptomatic patients. One hundred forty-one asymptomatic patients without previous myocardial infarction underwent quantitative exercise ECG testing and quantitative coronary angiography 1 to 6 months after successful angioplasty in single vessel coronary artery disease to 1) determine the value of exercise ECG testing to detect "silent" restenosis, and 2) assess the long-term prognostic value of exercise ECG testing and coronary angiography. The prevalence of restenosis (defined as greater than or equal to 50% luminal narrowing at the dilation site) was 12% in this selected study group. Of 26 patients with an abnormal exercise ECG (ST segment depression greater than or equal to 0.1 mV), only 4 (15%) showed recurrence of stenosis. Sensitivity and specificity for detection of restenosis were 24% and 82%, respectively. One hundred thirty-four patients (95%) were followed up 1 to 64 months (mean 35) after exercise ECG testing and coronary angiography. Thirty-two patients (24%) experienced a cardiac event: in 25 patients (78%) the initial event was recurrent angina pectoris (New York Heart Association class III or IV) and in 7 patients (22%) it was myocardial infarction, although cardiac death did not occur. The mean interval between exercise ECG testing and the initial cardiac events was 14 months (range 1 to 55), whereas 47% of the initial events took place less than or equal to 6 months after exercise ECG testing.(ABSTRACT TRUNCATED AT 250 WORDS)

Angiography↗
PubMed1990

Restenosis after coronary angioplasty: new standards for clinical studies.

With the high initial success rates for coronary angioplasty that are reported regularly, it has become increasingly difficult to demonstrate methods or techniques that are able to provide more beneficial early results than can be achieved by conventional angioplasty. On the other hand, the incidence of late restenosis has remained much the same over the 10 years that angioplasty has been part of clinical practice, and there is still no proved intervention that modifies the restenosis process. Therefore, the problem of restenosis has assumed increasing relevance in determining the clinical value of coronary angioplasty and, accordingly, studies that address the problem of restenosis need to become more exacting. Although numerous articles have addressed the problem of restenosis in the clinical setting, many defining certain factors associated with restenosis and possible interventions to reduce the incidence of restenosis, there is surprisingly little consensus. Most of the discrepancies can be attributed to three factors: 1) the selection of patients, 2) the method of analysis, and 3) the definition of restenosis employed. This review shows how these three factors influence the outcome and conclusions of restenosis studies.

Angiography↗
PubMed1990

[Chronology and incidence of restenosis after coronary angioplasty. Comparison of patients with stable and unstable angina].

The aim of this prospective study was to compare the incidence of restenosis after percutaneous transluminal coronary angioplasty (PTCA) in patients with stable and unstable angina before the procedure. Between January 1984 and February 1986, 344 patients with stable angina and 228 patients with unstable angina underwent PTCA. The primary success rate was 86.3 per cent in patients with stable angina (297 patients) and 87.7 per cent in patients with unstable angina (200 patients). The patients were recalled for systematic control coronary arteriography at 30, 60, 90, 120 or 150 days, and was obtained in 83.8 per cent of patients with stable angina and in 86 per cent of patients with unstable angina. The degree of stenosis before and the angiographic changes after PTCA and at control coronary arteriography were evaluated by a computer-assisted automatic contour detection system. The three criteria of restenosis were: 1) over 50 per cent loss of the benefit of PTCA, 2) residual post-PTCA stenosis increasing from less than 50 per cent to more than 50 per cent at control arteriography, 3) a decrease in the minimum intraluminal diameter of at least 0.72 mm with respect to the immediate post-PTCA result. A comparison between the two groups of patients showed that the average age was slightly greater in patients with unstable angina (56 +/- 9 years vs 58 +/- 9 years, p = 0.047). Apart from this difference, the two groups were comparable with regards to the average number of lesions dilated per patient, the date of control arteriography, the severity of the coronary artery disease and previous bypass surgery, angioplasty and infarction.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗
PubMed1989

Short-, medium-, and long-term follow-up after percutaneous transluminal coronary angioplasty for stable and unstable angina pectoris.

The first 840 consecutive patients who underwent percutaneous transluminal coronary angioplasty (PTCA) performed in the same institution were retrospectively assessed at an average follow-up period of 25 months after the initial procedure. The study population consisted of 506 patients with stable angina pectoris (group 1) and 334 patients with unstable angina pectoris (group 2). Clinical end points were death, nonfatal myocardial infarction, recurrent angina pectoris necessitating bypass surgery or repeat PTCA, and event-free survival. The two groups were comparable with respect to age, sex, previous myocardial infarction, ejection fraction, and number of diseased vessels. PTCA was successful in 83.0% of group 1 and 87.1% of group 2. Follow-up rates were expressed as events per attempted PTCA in a patient group. No difference in survival was observed between the two groups, the mortality rate being approximately 2.8% at 25 months. In the group with stable angina pectoris there was a lower incidence of nonfatal myocardial infarction within the first 24 hours after angioplasty; 4.3% vs 9.0% (p less than 0.01). During long-term follow-up the increase in the incidence of nonfatal myocardial infarction was similar, resulting in an overall long-term follow-up infarction rate of 8.3% and 14.2%, respectively (p less than 0.01). A higher event-free survival was observed in group 1 within 24 hours after PTCA: 93.7% vs 84.2% (p less than 0.01). During subsequent follow-up the difference in event-free survival between the two groups was no longer significant: 68.5% vs 61.2%.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗