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Biomedical subjects

S G Ellis

Publications and source records attributed to S G Ellis.

At least 217 records · Page 12Linked to original sources
PubMed1989

Recurrent ischemia without warning. Analysis of risk factors for in-hospital ischemic events following successful thrombolysis with intravenous tissue plasminogen activator.

Ischemic events after successful thrombolysis have been reported to occur in 18-32% of patients treated for acute myocardial infarction with thrombolytic therapy, and previous studies in which patients received streptokinase suggest that risk of early recurrent ischemia is closely related to the presence of a high-grade residual stenosis. If these events are predictable after intravenous recombinant tissue-plasminogen activator (rt-PA) thrombolytic therapy, then further intervention after its use could be targeted at selected patients. One-hundred ninety-two patients from the Thrombolysis and Angioplasty in Myocardial Infarction (TAMI) I and TAMI III trials had successful rt-PA-mediated thrombolysis without immediate coronary angioplasty (PTCA). One-hundred seventy-four of these patients (92%) had prehospital discharge angiography. The mean age was 56 +/- 11 years; 81% were men; the infarct-related artery was the left anterior descending in 76 (39.8%), the left circumflex in 24 (12.6%), and the right coronary artery in 91 (47.6%). Thrombolysis with rt-PA resulted in a residual 73 +/- 13% diameter and 0.95 +/- 0.51 mm stenosis by quantitative coronary arteriography, and Thrombolysis in Myocardial Infarction (TIMI) flow grade 2 in 59.2% and 3 in 40.8% of stenoses as assessed on angiograms obtained 90 minutes after the initiation of rt-PA therapy. Recurrent ischemic events (ischemia requiring emergency percutaneous transluminal coronary angioplasty or urgent bypass surgery, reocclusion of the infarct-related artery, or cardiac death) occurred in 41 patients (21.3%).(ABSTRACT TRUNCATED AT 250 WORDS)

Angioplasty, Balloon, Coronary↗
PubMed1988

Presentation and late outcome of myocardial infarction in the absence of angiographically significant coronary artery disease.

To determine the natural history of myocardial infarction (MI) in the absence of angiographically significant (no lesion greater than or equal to 50% diameter stenosis) fixed coronary artery disease (CAD), clinical and angiographic data and late outcome were studied in 43 such patients. The mean age was 45 +/- 11 years; 32 patients (74%) were cigarette smokers. Mild fixed CAD, present in 38 patients (88%), was more frequent in the artery supplying the MI zone (p less than 0.01). Filling defects or serial angiographic resolution of obstruction in the artery supplying the MI zone were present in 14 patients (33%). At late follow-up, 14 major cardiac events occurred in 9 patients, including revascularization in 3, recurrent MI in 6 and cardiac death in 5. Of 35 patients undergoing catheterization within 1 year of the index MI, cumulative risk of a major cardiac event was 9 +/- 4, 12 +/- 5 and 20 +/- 7% at 3, 19 and 37 months, respectively. Myocardial infarction in the absence of significant fixed CAD tends to occur in young smokers with mild CAD in the artery serving the MI zone. Superimposed intracoronary thrombus can be frequently implicated. In these patients, subsequent major cardiac events may occur more frequently than previously reported.

Adolescent↗
PubMed1988

Coronary revascularization after intravenous tissue plasminogen activator for unstable angina pectoris: results of a randomized, double-blind, placebo-controlled trial.

To determine the role of intravenous tissue plasminogen activator (t-PA) in unstable angina, it was compared with placebo in a randomized, double-blind trial. Forty patients with angina at rest and provocable ischemia (pacing induced) had baseline coronary angiography, study drug infusion and then repeat angiography at 20 +/- 9 hours. All patients received diltiazem, nitrates, beta blockers, aspirin and intravenous heparin. During study drug infusion (150 mg over 8 hours), refractory ischemia necessitating emergency bypass surgery (CABG) or coronary angioplasty (PTCA) occurred in 4 of 20 t-PA patients compared with 1 of 20 placebo patients (p = 0.21). Before discharge, revascularization for persistent, provocable ischemia and a residual stenosis greater than or equal to 60% was as follows: t-PA patients, 8 PTCA and 7 CABG; placebo patients, 11 PTCA and 8 CABG (p = 0.39). Quantitative angiographic percent diameter stenosis of the culprit artery at baseline and follow-up was: t-PA 71 +/- 17 and 63 +/- 22; placebo 70 +/- 19 and 67 +/- 22 (difference not significant). However, 3 t-PA patients compared with no placebo patients demonstrated an insignificant (less than 60% diameter) residual stenosis and averted PTCA (p = 0.14). There were no complications of PTCA in the 8 t-PA patients; in contrast, 3 of 11 placebo patients had abrupt closure, necessitating emergency CABG in 2 (p = 0.23). Thus, intravenous t-PA in unstable angina can eliminate the need for PTCA in a few patients, does not appear to decrease the overall or emergency rate of revascularization procedures and may facilitate the safety of PTCA.

Angina Pectoris↗
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↗
PubMed1988

Predictors of success for coronary angioplasty performed for acute myocardial infarction.

To evaluate the predictors and likelihood of success for coronary angioplasty performed in the setting of acute myocardial infarction, 300 consecutive patients with 321 coronary stenoses were studied retrospectively. Success was defined as final diameter stenosis less than 70% and Thrombolysis in Myocardial Infarction (TIMI) flow grade greater than or equal to 2. Nine clinical variables and 15 angiographic variables were assessed. Seventy-nine percent of patients were men; the mean age was 56 +/- 11 years, and 54% of patients also received thrombolytic therapy. The mean left ventricular ejection fraction was 46 +/- 11%, and 18 patients (6%) were in cardiogenic shock. Angioplasty success in the infarct-related artery was achieved in 240 patients (80%). In 177 total occlusions (TIMI flow grade less than or equal to 1), the success rate was 75.7% and success was independently predicted by 1) an ejection fraction greater than 30% (p = 0.001); 2) no arterial bend greater than or equal to 45 degrees at the site of angioplasty (p = 0.008); and 3) no triple vessel disease (p = 0.014). In 144 subtotal occlusions (TIMI flow grade greater than or equal to 2), procedural success was achieved in 84.7% and was predicted by 1) absence of thrombus greater than 5 mm (p = 0.023), and 2) absence of other stenoses greater than or equal to 50% in the same artery (p = 0.043), whereas patency without further emergency intervention was achieved in 71.7% and was predicted only by patient age less than or equal to 60 years and absence of cardiogenic shock.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗
PubMed1988

Angiographic and clinical predictors of acute closure after native vessel coronary angioplasty.

To determine predictors of acute coronary closure after PTCA performed with steerable catheter systems, we compared 140 procedures complicated by acute closure and 311 representative successful attempts from 4,772 procedures performed between April 1982 and March 1986. Sixteen clinical, 35 angiographic, and seven procedural variables were analyzed. Multivariate analysis found seven independent preprocedural factors related to closure: stenosis length of 2 or more luminal diameters, female gender, stenosis at a bend point of 45 degrees or more, stenosis at a branch point, stenosis-associated thrombus (filling defect or staining), other stenoses in the same vessel, and multivessel disease. In addition, four procedural factors were found to be associated with closure by univariate analysis: post-PTCA percent stenosis (p less than .001), intimal tear or dissection (p less than .001), use of prolonged heparin infusion (p less than .001), and post-PTCA gradient of 20 mm Hg or more (p = .004). Multivariate analysis of both preprocedural and procedural variables found six factors independently related to closure: post-PTCA percent stenosis, dissection, prolonged post-PTCA use of heparin, branch point location, fixed bend point location, and other stenoses in the vessel dilated. The risk of coronary closure after PTCA has many determinants. While an estimation of risk can be made before performing PTCA, the most powerful predictors of closure can only be assessed during the procedure itself.

Acute Disease↗
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↗
PubMed1985

Relation between the transmural extent of acute myocardial infarction and associated myocardial contractility two weeks after infarction.

To characterize the relation between the transmural extent of acute myocardial infarction (AMI) and associated regional contractility after recovery from ischemia, 11 mongrel dogs underwent occlusion of the proximal left anterior descending coronary artery and were evaluated 2 weeks after infarction. Occlusion was permanent in 5 dogs, and reperfusion was allowed after 2 hours of occlusion in 6 dogs. All dogs had computer-assisted quantitative wall-thickening analysis by 2-dimensional echocardiography and infarct localization by the triphenyl-tetrazolium chloride technique. Percent systolic wall thickening was correlated with the transmural extent of AMI in 40 regions of interest, each measuring approximately 60 arc degrees in circumference. In 11 non-infarct-containing regions, the mean wall thickening was 59 +/- 16% (+/- standard deviation). In 29 infarct-containing segments (with transmural extent of infarction 11 to 100%) systolic wall thickening ranged from -4% to 47%. Wall thickening and transmural extent of AMI were inversely related. Least-squares regression analysis found the relation to be best described by the logarithmic function, percent wall thickening = 61 - 26 log (percent transmural extent of infarction +1), r = -0.87. The nature of this relation between structure and function suggests that salvage of small amounts of myocardium (transmural extent less than 30 to 40%) by coronary reperfusion or other means may have little effect on systolic myocardial function when compared with the function of transmural infarcts. Alternatively, salvage of more than 40% of the jeopardized myocardium should be expected to appreciably augment myocardial function.

Animals↗
PubMed1985

Detection of endocarditis-associated perivalvular abscesses by two-dimensional echocardiography.

The development of a perivalvular abscess as a complication of infective endocarditis adds appreciably to the expected morbidity and mortality of patients, but such abscesses are seldom recognized by available noninvasive techniques. Therefore, two-dimensional echocardiographic findings in 22 patients with perivalvular abscess found at surgery or necropsy were compared with those in 24 patients without abscess in a retrospective but blinded study. Forty-six valves were examined (31 aortic and 15 mitral, 35 prosthetic and 11 native); 4.0 +/- 2.4 days (range 0 to 7) elapsed between echocardiography and surgery or necropsy. Patients with perivalvular abscess had a somewhat higher incidence of serious complications (emergency repeat valve replacement or death) than did patients with endocarditis alone (63 versus 35%, respectively, p less than 0.05). No single echocardiographic finding was frequently seen with a perivalvular abscess. A "typical" echo-free abscess was noted in only one patient; however, the presence of one or more of the following had a positive predictive value of 86% and a negative predictive value of 87% for the presence of perivalvular abscess: prosthetic valve rocking; sinus of Valsalva aneurysm, anterior aortic root thickness of 10 mm or greater, posterior aortic root thickness of 10 mm or greater or perivalvular density in a septum of 14 mm or greater. These predictive values, of course, apply only to patients with infective endocarditis going to surgery, and may assist the surgeon in knowing whether or not to expect an abscess.(ABSTRACT TRUNCATED AT 250 WORDS)

Abscess↗
PubMed1985

Ultrasonic tissue characterization: detection of acute myocardial ischemia in dogs.

Ultrasonic tissue characterization is a new area of investigation in the field of cardiac ultrasound. The amplitude and frequency of the ultrasound signal are normally altered as the signal penetrates through tissue. It is assumed that the amplitude distribution and frequency shift of diseased or edematous tissue are different than those of normal tissue. A statistical approach to the analysis of the unprocessed radiofrequency signal in the amplitude domain was used to study the effect of acute myocardial ischemia on the parameter mean amplitude/standard deviation of the amplitude (MSR). Ten dogs were anesthetized and underwent left lateral thoracotomy. Baseline mean MSR from the interventricular septum was 1.99 +/- 0.05, but increased by 30 min after coronary artery occlusion and started to plateau at 1 hr (mean 2.24 +/- 0.06). Reproducibility in noninfarcted myocardium (left ventricular inferoposterior wall) was good, with a mean MSR of 2.00 +/- 0.05 at baseline and 1.98 +/- 0.04 3 to 4 hr later. There was no difference in mean MSR when data were obtained through chest wall and when they were obtained directly from the surface of the heart. We conclude that statistical analysis in the amplitude domain of the unprocessed radiofrequency signal can detect acute myocardial ischemia within 30 min after coronary artery occlusion, provides reproducible measurements, and is unaffected by chest wall filtering.

Animals↗
PubMed1984

Response of reperfusion-salvaged, stunned myocardium to inotropic stimulation.

The purpose of this study was to determine whether myocardium salvaged by reperfusion following coronary occlusion could respond to inotropic stimulation by dopamine. Mongrel dogs underwent a 2-hour occlusion of the proximal left anterior descending coronary artery, followed by reperfusion for 5 or 28 hours. Dopamine (5 to 10 micrograms/kg/min) or dextrose was administered 1 hour or 24 hours after the onset of reperfusion. Serial, computer-assisted, two-dimensional echocardiographic determination of percentage of systolic wall thickening (%SWT) and cross-sectional ejection fraction (% delta area) were used to evaluate the response to treatment. Myocardium in the region of central ischemia contracted poorly after 1 hour of reperfusion (mean %SWT = 1.3 +/- 13.3% [mean +/- SD] compared to preocclusion value of 43.6 +/- 18.5%, p less than 0.001) and tended to thin at 24 hours of reperfusion (mean %SWT = -6.0 +/- 12.3%, p less than 0.001). After 1 hour of reperfusion, dopamine produced a greater than fourfold improvement in %SWT within the reperfused zone (to 15.3 +/- 7.3%, p less than 0.05). After 24 hours of reperfusion, dopamine again produced an improvement in %SWT (to 5.8 +/- 12.5%, p less than 0.05). There were no significant changes in %SWT with dextrose infusion. Thus, dopamine stimulates the reperfusion-salvaged but noncontracting (stunned) myocardium to contract as early as 1 hour after reperfusion.

Animals↗
PubMed1984

Quantitative analysis of left ventricular function: pre- and postischemic two-dimensional echocardiography in dogs.

A quantitative technique that aligns the diastolic and systolic silhouettes was used to assess left ventricular function (wall thickening and endocardial wall motion) from two-dimensional echocardiographic studies for every 2 degrees of arc of the left ventricular circumference in canines. Thirty-two dogs were studied before and at specific intervals up to 14 days after either temporary or permanent occlusion of the left anterior descending coronary artery. Decreased systolic wall thickening and frank systolic thinning were observed in the ischemic/infarcted region 90 min and 6 hr after occlusion; endocardial motion showed the abnormally contracting segment less clearly. Partial recovery was seen in both groups of animals but to a greater degree in those with temporary occlusion. The technique was useful for assessing sequential changes in wall motion.

Animals↗
PubMed1983

Coronary reperfusion for the treatment of acute myocardial infarction: postischemic ventricular dysfunction.

There has been recent interest in treating acute myocardial infarction with coronary reperfusion by fibrinolytic therapy. Experimental studies have shown that myocardial infarct size can be reduced by coronary reperfusion. However, return of cardiac function, high energy phosphate metabolism, and cardiac ultrastructure may be delayed within tissue which is salvaged by coronary reperfusion. This postischemic ventricular dysfunction is transient and has been termed the 'stunned myocardium' phenomenon. Although reperfused infarcts are hemorrhagic, the hemorrhage is confined well within tissue which is already necrotic and does not appear to exacerbate the extent of necrosis. Clinical trials designed to assess the benefits of reperfusion for the therapy of acute myocardial infarction should concentrate on long-term rather than short-term changes in cardiac function.

Animals↗
PubMed1983

Studies of experimental coronary artery reperfusion. Effects on infarct size, myocardial function, biochemistry, ultrastructure and microvascular damage.

The present report is a review of recent experimental studies in a canine model of acute coronary occlusion. The questions addressed were: (1) Does coronary reperfusion reduce myocardial infarct size? (2) What is the relationship between microvascular damage and hemorrhage and the development of myocardial necrosis? (3) What are the biochemical, functional and ultrastructural characteristics of reperfused tissue salvaged from necrosis? Coronary occlusion followed by reperfusion in the dog resulted in significant subepicardial salvage of myocardium if reperfusion was instituted before 6 hours of ischemia. Because ultrastructural evidence of microvascular damage was found only after irreversible damage to myocytes, and because gross hemorrhage after coronary reperfusion was confined to zones of myocardium that were already necrotic, it does not appear that hemorrhage should serve as a deterrent to reperfusing reversibly injured myocytes. Severely ischemic myocardium that had been salvaged by coronary reperfusion required several days before it returned to normal from biochemical, functional and ultrastructural standpoints.

Adenosine Triphosphate↗
PubMedDate not supplied

Stenting for ischemic heart disease.

This article examines current indications to intracoronary stenting for percutaneous cardiac revascularization. The data sources are a review of the published English literature, with focus on clinical and randomized trails of coronary artery stenting. Stents reduce the need for emergency bypass surgery in the setting of acute or threatened vessel closure after percutaneous transluminal coronary angioplasty (PTCA). In selected cases, when deployed electively in large native vessels with focal stenosis, clinical and angiographic recurrence are significantly reduced. Preliminary studies have also suggested a potential role in the treatment of saphenous vein graft lesions and restenotic lesions, and in improving on suboptimal results in lesions refractory to balloon dilatation. To prevent stent thrombosis, adjunctive antiplatelet therapy has been shown to be more efficacious than anticoagulation, and optimal stent apposition to the vessel wall appears to be critical. A recent exponential increase in the use of coronary stents has revolutionized the contemporary practice of interventional cardiology. Although technical factors and feasibility have been well refined and shown, evidence-based practice is lacking for many patient subsets.

Angioplasty, Balloon, Coronary↗