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Biomedical subjects

R K Myler

Publications and source records attributed to R K Myler.

At least 55 records · Page 3Linked to original sources
PubMed1990

Coronary angioplasty in young adults: initial results and late outcome.

The initial and late outcome of coronary angioplasty was studied in 148 patients less than 40 years of age (mean 36.4 +/- 3). Angioplasty was performed on a single vessel in 70% of patients and on multiple vessels in 30%; it was performed on a totally occluded vessel in 20%. Angioplasty was successful in 90.5% of patients, unsuccessful but uncomplicated in 7.4% and complicated by myocardial infarction in 0.7%, emergency bypass surgery in 0.7% and death in 0.7%. At late (mean 3.7 +/- 3 years; range 0.5 to 11.5) follow-up study after successful angioplasty, 94% of patients were alive, 79% were free of angina and 85% had returned to work; late myocardial infarction occurred in 4%. Actuarial survival at 5 years was 95%, and 85% of patients were free from death, infarction or bypass surgery. A second angioplasty was performed in 29 patients (22%) (mean 6.1 +/- 8.4 months) and was successful in 27 (93%), with no deaths. Elective coronary bypass surgery was performed in 8.5% of patients, with perioperative infarction in 9% and no deaths. By univariate analysis, late death was more likely to occur in hypertensive patients (15% versus 2.5%; p less than 0.01) and diabetic patients (21.4% versus 3.6%; p less than 0.01). Cox proportional hazard regression analysis identified hypertension (p = 0.007) and diabetes (p = 0.04) as independent time-related predictors of subsequent death. Thus, early and late results after coronary angioplasty in young adults are favorable, but certain risk factors are important predictors of outcome. Late revascularization procedures (repeat angioplasty or surgery) for restenosis or disease progression are common.

Actuarial Analysis↗
PubMed1990

Bidirectional crossover and late outcome after coronary angioplasty and bypass surgery: 8 to 11 year follow-up.

Between March 1978 and July 1981, 217 symptomatic patients underwent coronary angioplasty as an alternative to coronary bypass surgery. Angioplasty was successful in 143 patients (66%), unsuccessful but uncomplicated in 65 (30%) and complicated in 9 (4%) by one or more of the following criteria: Q wave myocardial infarction (2%), emergency surgery (4%) or death (0.5%). Late follow-up evaluation was obtained in 213 patients at a mean of 9 +/- 1 years. Of patients in whom angioplasty was successful, 59 (42%) of 140 required another revascularization procedure (repeat angioplasty in 26% and bypass surgery in 16%). The actuarial survival rate at 5, 9 and 10 years after successful angioplasty was 98%, 93% and 92%, respectively. Of the 65 patients with unsuccessful and uncomplicated angioplasty (usually as a result of technical factors), 58 underwent elective bypass surgery within 2 months and 56 survived. These 56 surgical patients were compared with the 140 patients with successful angioplasty. Univariate analysis of prognostic factors did not reveal significant differences between these two groups. At late follow-up study, the successful angioplasty and the successful surgical groups had similar rates of survival (93% versus 95%, p = NS) and of death or infarction, or both (11% versus 12.5%, p = NS). Repeat revascularization was required more frequently after successful angioplasty than after surgery (42% versus 18%, p less than 0.001). Crossover from angioplasty to surgery occurred slightly more often than from surgery to angioplasty (16% versus 12.5%, p = NS). The time to crossover from angioplasty to surgery occurred earlier than from surgery to angioplasty (mean 21 versus 76 months, p less than 0.001).

Angioplasty, Balloon, Coronary↗
PubMed1990

Coronary angioplasty after coronary bypass surgery: initial results and late outcome in 422 patients.

From 1978 to 1988, coronary angioplasty was performed in 422 patients with prior coronary artery bypass surgery (264 patients with native coronary artery angioplasty and 158 patients with graft angioplasty). Angioplasty was successful in 84%, unsuccessful but uncomplicated in 11% and complicated by one or more major cardiac events in 5% (myocardial infarction 5%, emergency bypass surgery 2% and death 0.2%). Follow-up data were obtained in 99% of 356 patients with successful angioplasty. At a mean of 33 +/- 26 months, 92% were alive, 73% had improvement in angina and 61% were free of angina. One or more of the following late events occurred in 67 patients (19%): myocardial infarction (6%), elective reoperation (13%) and cardiac death (6%). Repeat angioplasty was performed in 27%, with a success rate of 89% and no deaths. Initial success rates were equal in native vessel versus graft angioplasty, but late outcome was less favorable with the latter because of a higher rate of infarction (11% versus 4%, p less than 0.05) and need for reoperation (19% versus 10%, p less than 0.05). The initial success rate was higher in vein grafts less than 1 year old compared with grafts 1 to 4 years or greater than 4 years after operation (92% versus 85% versus 83%, respectively) and adverse late events were less frequent after angioplasty in recent vein grafts (less than 1 year 13%, 1 to 4 years 35%, greater than 4 years 29%; less than 1 versus greater than 1 year, p less than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Angina Pectoris↗
PubMed1990

Percutaneous transluminal aortic valvuloplasty--the acute outcome and follow-up of 149 patients who underwent the double balloon technique.

Double balloon percutaneous transluminal aortic valvuloplasty (PTAV) was performed on 149 patients (76 male (51%), mean age 76 +/- 11 years) whose symptoms included severe congestive heart failure in 127 cases (82%), syncope in 21 (14%) and angina in six (4%). Significant changes (P less than 0.05) in peak systolic (83 +/- 36 to 38 +/- 30 mmHg) and mean gradient (68 +/- 25 to 36 +/- 21 mmHg), and aortic valve area (0.6 +/- 0.2 to 1.0 +/- 0.4 cm2) were achieved in 130/149 patients (87%). Complications included an overall in-hospital mortality of 13%, (10.0% excluding the six deaths occurring in 18 moribund patients), a neurologic deficit incidence of 3%, and surgical arterial entry site repair 3.0% (14/47) of patients. Multivariate analysis identified congestive heart failure (NYHA Class IV), left ventricular ejection fraction, cardiac output and coronary artery disease as independent variables significantly affecting in-hospital mortality. Predictors of poor long-term survival were degree of heart failure, and coronary artery disease. The cumulative probability of survival at 24 months was 52 +/- 5% (excluding non-cardiac deaths, was 66 +/- 3%). Follow-up (mean time: 16 +/- 7 months) of 130 patients discharged alive revealed 41 late deaths (26 cardiac related). Sixty-two patients (70%) were symptomatically improved; 17 patients had symptom recurrence and underwent repeat valvuloplasty, and 10 patients valve replacement. Follow-up catheterization of 18 asymptomatic patients revealed that 11 patients had silently restenosed. These data indicate that aortic valvuloplasty is a palliative therapy for elderly patients, who are poor surgical candidates, with symptomatic calcific aortic stenosis with reasonable clinical success and long-term survival when considering their clinical status, but with a significant restenosis rate.

Aged↗
PubMed1990

Peripheral arterial occlusions: initial results from percutaneous angioplasty with a hybrid laser probe.

Percutaneous laser-assisted angioplasty performed with a laser-heated metal-capped fiber has been shown to be safe and effective. A hybrid probe was developed that allows a small percentage of laser light to emerge, converting the rest to heat. The probe was used to recanalize 37 peripheral arterial occlusions (10 in the iliac segment, 2-7 cm long, and 27 in the femoropopliteal segment, 1-35 cm long) in 37 patients. Primary success was defined as successful recanalization and continued patency during the first 24 hours, as assessed at physical examination. Primary success in the iliac segments was 70% and in the femoropopliteal segments was 85% (overall, 81%). The only complication was an arterial wall perforation, which had no sequelae. The probe is safe for use in peripheral arterial occlusions. There was no increase in the rate of perforation compared with the rate with the "hot-tip" laser probe, and the technique may have advantages over use of the original "hot-tip" laser probe.

Aged↗
PubMed1990

Incidence and consequences of periprocedural occlusion. The 1985-1986 National Heart, Lung, and Blood Institute Percutaneous Transluminal Coronary Angioplasty Registry.

Of 1,801 patients in the 1985-1986 Percutaneous Transluminal Coronary Angioplasty (PTCA) Registry, 122 (6.8%) had periprocedural occlusion (4.9% in the catheterization laboratory, 1.9% outside the laboratory). Baseline patient factors independently associated with increased occlusion rates included triple-vessel disease, high risk status for surgery, and acute coronary insufficiency. Lesion characteristics showing significant positive association included severe stenosis before PTCA, diffuse or multiple discrete morphology, thrombus, and collateral flow from the lesion. Intimal tear and dissection were also very strongly associated with occlusion. Sixty patients (49%) had a transient occlusion that was reopened with PTCA, 43 (35%) were not redilated and managed with bypass surgery, and 19 (16%) were not redilated and managed medically. In-hospital mortality was 5% in each of these treatment groups, compared with 1% in occlusion-free patients. In-hospital infarction rates ranged from 27% in patients with transient occlusion to 56% in the patients managed with surgery, compared with 2% in patients without occlusion. During 2 years of follow-up, somewhat increased mortality continued in patients with occlusion, whereas follow-up infarction rates were comparable for all patients regardless of occlusion. Patients with an occlusion that was reopened or managed medically had increased rates of surgery during follow-up. Rates of repeat PTCA were comparable (about 23% by 2 years) in patients with transient occlusion and those without occlusion. Occlusion remains a serious complication of angioplasty and is associated most strongly with major events and surgical procedures that occur during the in-hospital period.

Aged↗
PubMed1990

Percutaneous peripheral ultrasonic angioplasty.

We previously reported the initial use of percutaneous catheter delivered ultrasound energy for arterial recanalization in eight patients with peripheral vascular disease. All patients had severe claudication. There were four cases with total occlusion and four with high grade stenoses in a superficial femoral or popliteal artery. A prototype ultrasound probe, with a frequency of 20 kHz and a power output of 20 to 25 watts/cm2 was ensheathed in a 7F catheter and advanced to the occlusions with angiographic guidance. Three of four complete occlusions were recanalized in less than 120 s resulting in a 54 +/- 5% residual diameter stenosis. Ultrasound energy applied to isolated stenoses reduced them by 40%, from 77 +/- 14% to 37 +/- 21%. Further treatment with balloon angioplasty resulted in a mean residual stenosis of 20 +/- 9%. There was no angiographic or clinical evidence of arterial emboli, dissection, spasm, or perforation. Clinical follow-up and Doppler ankle-brachial indices were performed at one, three and six months after combined ultrasound and balloon angioplasty. Two occlusions recurred, both within the first three months, detected by return of claudication and an abnormal ankle/brachial index, and documented by angiography. Repeat balloon angioplasty of standard methods was performed in one, but the vessel again reoccluded. The other five patients with primary technical success have continued patency both clinically and by ankle/brachial index measurement. Percutaneous catheter delivered ultrasound energy appears promising in peripheral vessels to reduce arterial stenoses and recanalize complete arterial obstructions. The long-term findings from this pilot study were insufficient to assess if ultrasound has any effect on restenosis.

Aged↗
PubMed1990

Unstable angina and coronary angioplasty.

Of 2,122 consecutive patients undergoing elective coronary angioplasty from 1982 to 1985, 62% had stable angina pectoris (SAP), and 38% had unstable angina pectoris (UAP). There were differences between the two groups in clinical and morphological factors and in initial and late results of angioplasty. UAP patients were more likely than SAP patients to be smokers and to have had prior myocardial infarctions. Lesions in UAP patients were more severe, longer, more eccentric, more irregular, and more likely to have intracoronary thrombi than were lesions in SAP patients. Coronary angioplasty success was achieved in 84% of UAP and in 88% of SAP patients (p less than 0.05), and complications occurred in 6.7% of UAP and in 4.7% of SAP patients (p less than 0.05). Hospital death rates were low and similar, 0.2% for both groups. Follow-up (mean, 37 months) showed recurrent Canadian Cardiovascular Society (CCVS) class III/IV angina in 30.1% of UAP and in 25.2% of SAP patients (p less than 0.05). There was a return to work in 86% of UAP and in 91% of SAP patients (p less than 0.05). When UAP patients' durations of symptoms were further fractionated, it was found that the earlier angioplasty was performed after onset of angina, the lower was the success rate and the higher the complication rate and incidence of late follow-up untoward events. When coronary angioplasty was performed within 1 week of onset of angina ("early"), success was 79.1%; when angioplasty was performed 2 weeks or more after onset of angina ("later"), success was 86.3%. Major cardiac events occurred in 11.5% in the early group and in 4.8% in the later group (p less than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Angina Pectoris↗
PubMed1989

Percutaneous ultrasonic angioplasty:initial clinical experience.

Percutaneous catheter-delivered ultrasound energy for arterial recanalisation was applied in eight patients with peripheral vascular disease. Four patients had severe claudication with total occlusion and four high-grade stenosis in a superficial femoral or popliteal artery. A prototype ultrasound probe, with a frequency of 20 kHz and a power output of 20-35 W/cm2, was ensheathed in a 7F catheter and advanced to the occlusions under angiographic guidance. Three of four complete occlusions were recanalised in 120s or less, leaving a residual stenosis of mean (SD) diameter 54 (5)%. Ultrasound energy reduced the diameter of the isolated stenoses from 77 (14)% to 37 (21)%. All lesions were further treated with balloon angioplasty, resulting in a mean residual stenosis of 20 (9)%. There was no evidence of arterial emboli, dissection, spasm, or perforation. The major limitations of this ultrasound system are ease of steering and flexibility. Percutaneous catheter-delivered ultrasound energy appears promising for safe and effective use in atherosclerotic peripheral vessels to reduce arterial stenoses and recanalise complete arterial obstructions.

Angioplasty, Balloon↗
PubMed1989

Risk factors, time course and treatment effect for restenosis after successful percutaneous transluminal coronary angioplasty of chronic total occlusion.

Advances in technology and operator experience, and increased use of angiography early after myocardial infarction have led to greater use of percutaneous transluminal coronary angioplasty (PTCA) for chronic, total coronary artery occlusions. To better assess long-term outcome, 257 consecutive patients with successful PTCA of a total occlusion with late angiographic follow-up from 484 patients (53%) with PTCA success were reviewed. The mean +/- standard deviation patient age was 54 +/- 10 years, 79% were men, the duration of total occlusion was 11 +/- 15 weeks and the post-PTCA diameter stenosis was 24 +/- 12%. Eighty-two, 27 and 63% of patients received long-term aspirin, dipyridamole and warfarin therapy, respectively. Angiography at 8 +/- 8 months demonstrated restenosis (greater than or equal to 50% diameter stenosis) in 41% of patients restudied within 6 months and in 66% of patients restudied within 12 months by life table analysis. In multivariate regression analysis of 19 variables, 2 were independently correlated with the occurrence of restenosis: post-PTCA diameter stenosis greater than 30% (p = 0.02) and coronary artery dilated (left anterior descending and right coronary arteries greater than the left circumflex coronary artery) (p = 0.05). In log rank analysis that also considered the timing of angiographic detection of restenosis, dilatation of a proximal left anterior descending stenosis was also a significant predictor of restenosis (p = 0.01), and dilatation within 4 weeks of the presumed time of occlusion was only weakly predictive (p = 0.11).(ABSTRACT TRUNCATED AT 250 WORDS)

Angioplasty, Balloon↗
PubMed1989

Peripheral laser-assisted balloon angioplasty. Initial multicenter experience in 219 peripheral arteries.

In this multicenter clinical series of peripheral laser-assisted balloon angioplasty with an argon laser-heated, metallic-capped fiberoptic, angiographic and clinical success was achieved in a total of 155 (71%) of 219 attempted lesions. When the anatomy of the lesion was subjectively categorized by the angiographer into those considered possible or impossible to treat by conventional balloon angioplasty, clinical success was achieved in 116 (78%) of 149 lesions considered possible to treat with balloon angioplasty (39 [95%] of 41 stenoses and 77 [71%] of 108 occlusions). More importantly, clinical success was achieved in 39 (56%) of 70 lesions considered impossible to treat by conventional means. The incidence of complications, including vessel perforation (4.1%), with this new technique was equal to that reported for conventional balloon angioplasty, decreased with operator experience, and was less than that reported for argon laser angioplasty with bare fiberoptics. Thus, laser thermal angioplasty with a laser-heated, metallic-capped fiberoptic is a safe procedure that is easily learned by physicians skilled in interventional techniques. It allows for nonsurgical treatment of lesions considered difficult or impossible to treat by conventional balloon angioplasty.

Angioplasty, Balloon↗
PubMed1989

Coronary bifurcation stenoses: the kissing balloon Probe technique via a single guiding catheter.

A new technique employing two balloon probes via a single (large-lumen) guiding catheter is described. Examples involving the left anterior descending, diagonal, left main (protected), left circumflex-obtuse marginal, and atrioventricular branches and the right coronary artery-posterior descending and posterolateral branches are described and illustrated. This new technology (balloon probes and large-lumen guiding catheter) permits an effective and simplified alternative to the use of the single-guide/two-wire and double-guide/two-dilatation catheter-wire approaches in selected cases in which significant branch vessels (vis-a-vis myocardial regional blood supply) are at risk.

Aged↗
PubMed1989

Angioplasty of unusually large coronary arteries using the hugging balloon technique via a single guiding catheter.

Unusually large native coronary arteries, in particular those supplying expansive regions of myocardium, may not be adequately dilated using currently available coronary angioplasty catheters. The "hugging balloon" technique, in which two dilatation catheter balloons are simultaneously inflated side-by-side, has been previously described for lesions in large saphenous vein grafts using the double guiding catheter (and dual entry site) technique. With the development of large lumen guiding catheters and lower profile dilatation catheters, we report the initial use of the hugging balloon technique via a single guiding catheter in oversized native coronary arteries.

Angiography↗
PubMed1989

Treatment of coronary artery stenosis and coronary arteriovenous fistula by interventional cardiology techniques.

Complications associated with coronary arteriovenous fistulae (CAVF) include congestive heart failure, bacterial endocarditis, fistula rupture, and angina secondary to the "coronary steal" phenomenon. Traditional treatment of large CAVF is surgical ligation. In this report, we describe a modified microcoil embolization and guidewire technique for percutaneous closure of CAVF.

Angioplasty, Balloon, Coronary↗
PubMed1989

Silent ischemia: evaluation by exercise and redistribution tomographic thallium-201 myocardial imaging.

UNLABELLED: To compare the amount of myocardium jeopardized during silent ischemia and painful ischemia, 112 consecutive patients undergoing coronary arteriography with ischemia demonstrated by exercise and redistribution tomographic thallium-201 myocardial imaging (SPECT) were divided into two groups: 84 patients without anginal pain (silent ischemia) and 28 with pain (painful ischemia). The SPECT apical, mid and basal ventricular levels of the short-axis view and the apical portion of the long-axis view were divided into 20 segments. The results were 1) 7.4 +/- 4.7 ischemic segments in silent ischemia and 7.6 +/- 3.7 in painful ischemia (p = NS) with 4.7 +/- 3.6 segments in silent ischemia undergoing total redistribution compared with 5.4 +/- 3.4 in painful ischemia (p = NS); 2) no difference in the incidence of single, double or triple vessel disease between silent and painful ischemic groups; 3) similar anatomic distribution of ischemic segments between the two groups; 4) more positive exercise electrocardiographic (ECG) changes in painful ischemia (70%) than in silent ischemia (32%) (p less than 0.001) with equal amounts of ischemia associated with positive and negative exercise ECG findings. CONCLUSIONS: 1) Patients with silent and painful ischemia during exercise have similar amounts of ischemic myocardium demonstrated by tomographic thallium-201 imaging and similar extent of angiographically documented coronary artery disease despite the absence of pain and the lower incidence of positive exercise ECG findings in silent ischemia. 2) Positive and negative exercise ECG findings were associated with similar amounts of ischemic myocardium.

Angina Pectoris↗
PubMed1989

The setting of coronary angioplasty in multivessel disease: current status and future directions.

In summary, the use of coronary angioplasty in the setting of multivessel coronary disease has become more common in recent years. Reports indicate that, in carefully selected patients, a high initial success rate and low incidence of complications can be achieved. We have presented a schema for the triage of multivessel disease patients. Examples of each subgroup have been presented to illustrate the basis for this categorization. Our experience using this schema at the San Francisco Heart Institute has been valuable in understanding the initial and long-term results of coronary angioplasty in these patients. It is important that this paradigm (or a similar classification schema) be adopted to assist clinicians in making judgments about alternative approaches in patients with multivessel disease and to provide a common organization for the dissemination of research findings and collaboration among members of the medical community.

Angioplasty, Balloon, Coronary↗