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Biomedical subjects

R K Myler

Publications and source records attributed to R K Myler.

At least 73 records · Page 4Linked to original sources
PubMed1988

The balloon on a wire device: a new ultra-low-profile coronary angioplasty system/concept.

A new ultra-low-profile coronary angioplasty device, a "balloon probe," is presented. This device consists of a balloon on a coronary guidewire and is the lowest profile dilatation system presently available. The balloon material is polyethylene terephthalate, a new polymer with high inflation pressure limits and very low compliance. This report discusses this device and its usage in coronary artery disease.

Aged↗
PubMed1988

Transluminal coronary angioplasty in the treatment of silent ischemia.

Fifty-four asymptomatic patients with positive thallium exercise tests underwent coronary angiography followed by coronary angioplasty (PTCA), as the primary therapy for silent ischemia. The procedure was technically successful in 89% of these patients. Emergency bypass graft surgery was necessary in 2 (3.6%) and q-wave myocardial infarction occurred in 1 (1.8%) of these. All fifty-four patients have been followed for a mean of 35 months since angioplasty. Of the 48 patients with initially successful PTCA, 12 had either clinical restenosis (9/14 or 19%) or a new lesion (3/48 or 6%) during follow-up, which required a repeat PTCA. At the longest follow-up, 46 (85%) had been successfully treated with on or more PTCA procedures. Two patients (3.6%) had sustained late q-wave myocardial infarction and two additional patients reported angina pectoris. There were no deaths. Angioplasty as a primary therapy for silent ischemia appears efficacious, with success and restenosis rates comparable to those in the symptomatic population. Event-free survival is improved, compared with natural history data for patients with silent ischemia from other studies. Prudent risk/benefit analysis may help to define subgroups most likely to benefit from this intervention.

Adult↗
PubMed1988

In-hospital cardiac mortality after acute closure after coronary angioplasty: analysis of risk factors from 8,207 procedures.

Cardiac death consequent to acute vessel closure after coronary angioplasty occurred in 13 of 294 closures from 8,207 consecutive procedures performed at two centers since 1981 (0.16% cardiac mortality rate). To determine the predictors of cardiac death after acute coronary closure, 50 clinical, angiographic and procedural variables were analyzed by an observer unaware of the clinical outcome for each of the 13 patients who died and also 100 patients randomly chosen, in whom vessel closure after angioplasty did not result in death during hospitalization. Univariate analysis found female gender (p less than 0.0001), collateral channels from the vessel dilated (p less than 0.0001), use of balloon counterpulsation (p less than 0.0002), pre- and postprocedural hypotension (p = 0.0003 and p = 0.003, respectively), jeopardy score greater than or equal to 2.5 (p = 0.003), left ventricular hypertrophy (p = 0.013), hypertension (p = 0.02), diabetes (p = 0.02) and multivessel disease (p = 0.03) to be predictive of death. Multivariate analysis found collateral vessels, female gender and multivessel disease to be independent predictors of death. Thus, cardiac death after elective coronary angioplasty is very rare in experienced centers and occurs most often in women with a large amount of potentially ischemic myocardium. Hypotension often precedes the fatal closure event. Close attention to the amount of potentially ischemic myocardium and to the fluid volume status of these patients would seem to be especially warranted.

Adult↗
PubMed1987

Percutaneous transluminal angioplasty of stenotic coronary artery bypass grafts: 5 years' experience.

In a 60 month period (January 1981 to December 1985), 82 patients (79% male with a mean age of 60 years) had 83 saphenous vein grafts and 5 internal mammary artery grafts with a total of 101 stenotic sites treated with percutaneous transluminal coronary angioplasty. The mean time between bypass surgery and angioplasty was 51.2 months. The procedure was technically successful in 85% of patients, 86% of grafts and 85% of the sites attempted. In these cases, the mean diameter stenosis was reduced from 77 +/- 14 to 27 +/- 20% (p less than 0.001), the mean pressure gradient from 49 +/- 16 to 7 +/- 6 mm Hg (p less than 0.001). Emergency coronary artery bypass graft surgery was necessary in one patient (1.2%) whereas myocardial infarction occurred in three patients (3.6%). There were no hospital deaths. Clinical follow-up was obtained in all 82 patients. Before angioplasty, 23% were in Canadian Cardiovascular Society functional class II, 60% in class III and 17% in class IV. With a mean clinical follow-up period of 21.4 +/- 2.3 months, 71% are in class I, 17% in class II and 12% in class III. There were two deaths, 3 months or more after angioplasty, one probably due to graft closure. So far, angiographic follow-up (at 7.9 +/- 2.1 months) has been available in 26 patients. Ten patients (with 10 grafts) exhibited graft restenosis; six of them have had second successful repeat angioplasty. Among the many variables analyzed, statistically significant predictors of success were a higher measured balloon/graft ratio (p less than 0.001), smaller diameter graft (p less than 0.001), and shorter lesion length (p less than 0.01). The only predictor of complication was diffuseness of disease in the graft (p less than 0.05). The statistically significant predictors of recurrence were the residual stenosis after the initial angioplasty (p less than 0.01) and the measured balloon/graft ratio (p less than 0.01). Angioplasty of coronary artery grafts appears to be a feasible and efficacious procedure with a low complication rate. The technique is a satisfactory alternative to repeat surgery in selected patients.

Adult↗
PubMed1987

Multicenter study of percutaneous transluminal angioplasty for right coronary artery ostial stenosis.

Over a 5 year period at three centers, 53 patients underwent percutaneous transluminal angioplasty of a right coronary artery ostial stenosis. The procedure was successful in 42 patients (79%) and unsuccessful in 11, of whom 5 (9.4%) required emergency coronary artery bypass grafting because of abrupt closure. The right coronary ostial lesion had distinctive technical requirements to achieve success, including high pressure balloon inflation (10 +/- 4 atm) and the need for unconventional right coronary guide catheters. Technical factors that account for increased difficulty in these patients include: problems with guide catheter impaction and ostial trauma; inability to inflate the balloon with adequate guide catheter support; and need for increased intracoronary manipulation. The stenoses were quite discrete (4 +/- 5 mm) and calcified in the majority (40) of the 53 patients. Long-term follow-up (mean 12.5 months, range 4 to 60) of these patients demonstrated clinical recurrence of angina in 20 patients (48%) and angiographically proved restenosis in 16 (38%). Repeat coronary angioplasty was successful in three of six patients for relief of symptoms for over 6 months. In conclusion, angioplasty of the right coronary ostial lesion compared with nonostial dilation leads to a suboptimal early success rate; an apparent high risk of emergency bypass surgery; and a high restenosis rate. Careful assessment of the patient with this lesion and improved technology appear to be warranted.

Angiography↗
PubMed1986

Balloon angioplasty of coronary bifurcation lesions: the kissing balloon technique.

Initial experience with the technique of "kissing balloon" angioplasty is described in 52 patients undergoing coronary angioplasty. Guiding catheters employing both the femoral and brachial approach were used in all but two of the coronary angioplasties and, in addition, the bilateral femoral approach was used in the renal and peripheral angioplasties. Initial success was achieved in 51 (98%) patients. Abrupt closure requiring urgent coronary revascularization occurred in one patient six hours following the completion of the procedure. Another patient developed a new Q-wave on the electrocardiogram and moderate elevation of CPK-MB fraction following the procedure due to loss of a diagonal branch. No deaths occurred in this series. Angiographic restenosis developed in ten patients. In the recurrence group, five had repeat kissing balloon angioplasty, two had repeat single vessel angioplasty, and three patients chose elective surgical revascularization. Based on our experience, the technique of kissing balloon coronary angioplasty can be performed safely utilizing the brachio-femoral technique. The risk of major side branch occlusion can be minimized with this technique and the overall complication rate does not significantly differ from that of our experience in single vessel coronary angioplasty. Patient selection criteria are based upon the angiographic relationship of the major branch to the side branch and is important in determining the initial and long-term success of this technique.

Adult↗
PubMed1985

Selection of dilatation hardware for PTCA--1985.

Selection of the proper dilatation hardware in performing coronary angioplasty will facilitate the procedure, minimize its cost, and enhance its safety. Over the past 3 years, there has been an acceleration of growth in PTCA catheter and wire technology. We evaluated all currently approved dilatation systems as well as some investigational equipment and herein discuss their relative merits and disadvantages. To aid in operator selection of equipment, the concept of a risk: benefit ratio of potential for intimal trauma vs maximal back-up support is introduced. This information combined with objective data may be helpful in choosing the optimal dilatation equipment, which must be highly individualized for operator preferences and for each patient and his respective coronary anatomy.

Angioplasty, Balloon↗
PubMed1985

Percutaneous transluminal coronary angioplasty in left main stem coronary stenosis: a five-year appraisal.

Left main stem coronary stenosis is now uniformly treated with coronary artery bypass grafting. The advent of percutaneous transluminal coronary angioplasty has permitted a non-operative improvement in myocardial blood flow in many cases of single- and multi-vessel coronary atherosclerosis. The use of percutaneous transluminal coronary angioplasty in left main stem coronary stenosis has been sporadic and controversial. Twenty percutaneous transluminal coronary angioplasties were attempted in 19 patients as the treatment of choice for left main stem coronary stenosis in the past 66 months. The primary success rate was 95% (19/20 patients). The emergency surgery was performed only once (5%), and no death occurred secondary to percutaneous transluminal coronary angioplasty itself. In the follow-up (mean 41 months) period, 12 patients (63%) remained in satisfactory condition with no further need for surgical intervention. Seven patients (37%) ultimately required coronary artery bypass grafting. Although coronary artery bypass grafting will remain the fundamental treatment for left main stem coronary stenosis, this series delineates those anatomic and clinical exceptions wherein percutaneous transluminal coronary angioplasty may be utilized as the primary therapy for left main stem coronary stenosis.

Adult↗
PubMed1984

Baseline characteristics of patients in the National Heart, Lung, and Blood Institute Percutaneous Transluminal Coronary Angioplasty Registry.

The efficacy of PTCA was evaluated in several subgroups of patients. Of special clinical interest were the comparisons between subgroups of patients with multivessel disease vs 1-vessel disease, unstable angina vs stable angina, older age vs younger age, and female sex vs male sex. As a prerequisite for such comparisons, baseline characteristics of patients in the subgroups were examined. Compared with the subgroup with 1-vessel CAD, the subgroup with multivessel CAD had more elderly patients (age 65 years and older) and more of these patients had previous MI or CABG. PTCA was more often unsuccessful in patients with multivessel CAD because of inability to pass the catheter across the lesion. The subgroup of women tended to be older than men, and more women had severe and unstable angina, although fewer had multivessel CAD, previous MI or previous CABG. The PTCA success rate was 5% lower in women because of a greater frequency of inability to pass the lesion. Compared with younger patients, older patients had a higher prevalence of severe angina, multivessel CAD and lesions with larger diameters. The older patients had a 5% lower PTCA success rate, once again because of a greater frequency of inability to pass the lesion. The learning experience with PTCA was measured by the overall success rate as well as by the rate of ability to pass the lesion and the rate of dilating it once it was passed. These rates improved significantly by the investigators' case accumulations and independently by calendar year. Multivariate prediction of crossing the lesion and of overall success showed that favorable lesion characteristics and increasing physician experience were more important than the patient characteristics just discussed, although both female sex and multivessel CAD remained significant independent risk factors.

Age Factors↗
PubMed1984

Relative cost of coronary angioplasty and bypass surgery in a one-vessel disease model.

A national study was carried out to determine the relative costs of PTCA and CABG. Baseline clinical criteria for the 2 groups were similar. Data were collected in 186 sets for the PTCA group and 175 sets for the CABG group. Male patients make up 81% of the PTCA group and 80% of the CABG group. Mean hospital stay was 12 +/- 5 days in the CABG group, compared with 4 +/- 2 days in the PTCA group (p less than 0.001). The base charges for hospital and professional components of the CABG procedure were $15,580 +/- $2,159, whereas the same charges for the PTCA procedure were $5,315 +/- $2,159 (p less than 0.001). With an 80% primary success rate, which was the group mean success rate, the average dollar savings per PTCA procedure would be $7,149, or $7,149,000 per 1,000 cases. Thus, PTCA for revascularization in 1-vessel CAD is significantly more cost-effective than CABG in the short term.

Aged↗
PubMed1984

Complex coronary angioplasty: multiple coronary dilatations.

Selected patients underwent PTCA of multiple stenoses in different vessels or in the same vessel. Three hundred nine patients underwent 685 PTCA procedures in various combinations of arterial and vein graft stenoses. A multiple dilatation procedure was defined as successful when all lesions attempted were successfully dilated, or when the considered-critical-stenosis was successfully dilated and this resulted in a patient clinical improvement. Angiographic success was achieved in 599 of 685 lesions attempted (87.4%) and in 285 of 309 patients (92.2%). Complications included a mortality rate of 1.0%, an MI rate of 4.2% per patient and 1.9% per lesion attempted, and a 3.6% incidence of emergency CABG. Follow-up data show that 58 patients (20.4%) had clinical evidence of a lesion recurrence, and that 92.5% (37 of 40 patients) who underwent repeat angioplasty had a successful procedure. A sustained clinical improvement was obtained in 264 of 309 patients (85.4%). The data indicate that multiple dilatations are feasible with good success rates and acceptable complication rates. Further evaluation of this extended application of PTCA is needed to clearly establish its role in the therapy of CAD.

Adult↗
PubMed1984

Human coronary laser recanalization.

Five patients undergoing distal saphenous vein bypass had an attempt at intraoperative laser vaporization of a proximal coronary stenosis. Laser treatment of three patients was technically successful. One patient's successfully treated native vessel was competing with the graft at angiographic restudy 25 days after the procedure. This first human intraoperative laser recanalization trial generated questions regarding the energy source, power parameters, and catheter modifications required for satisfactory clinical laser therapy. The trial is directing future experiments toward more efficient and complete laser vaporization of atherosclerotic plaques in the human coronary vasculature.

Aged↗