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Biomedical subjects

D O Williams

Publications and source records attributed to D O Williams.

At least 91 records · Page 5Linked to original sources
PubMed1988

Efficacy of a new angioplasty catheter for severely narrowed coronary lesions.

Conventional over the wire dilation catheters may be unsuccessful in crossing coronary lesions that are severely narrowed. Hence, a new, extremely low profile coronary angioplasty catheter specifically designed to dilate such lesions was investigated. The catheter features a 2.0, 2.5 or 3.0 mm (inflated diameter) balloon mounted on a guide wire. The deflated profile of the 2.0 mm balloon measures 0.020 +/- 0.001 in. (0.51 +/- 0.03 mm). The catheter can be used in conjunction with 7F angiographic or 8F guide catheters. The catheter was used in 61 patients, aged 43 to 86 years, with predominantly Canadian Cardiovascular Society class III-IV angina. Dilation was attempted in 77 lesions. Lesion length averaged 5.7 +/- 3.1 mm (mean +/- 1 SD), minimal diameter 0.51 +/- 0.25 mm and internal vessel diameter 2.27 +/- 0.43 mm. Sixty lesions (78%) were successfully dilated to less than 50% residual stenosis with this catheter alone; nine lesions were further dilated with a larger balloon catheter. The new catheter was unable to cross 13 lesions (17%); only 2 of these lesions were subsequently crossed with a conventional over the wire system. On the other hand, the catheter was used after failure of conventional dilating catheters in 21 lesions and was successful in 16. The new catheter was particularly valuable for distal lesions and those demonstrating 90 to 99% diameter reduction. For all lesions crossed, stenosis decreased from 76 +/- 11 to 29 +/- 12% after 2.9 +/- 2.7 inflations and peak inflation pressure of 8.0 +/- 2.9 bar. Complications were rare; coronary occlusion occurred in two lesions (3%) and dissection in three lesions (4%).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1988

The long-term followup results of coronary artery angioplasty.

The long-term efficacy of PTCA for the relief of angina pectoris and myocardial ischemia has been firmly established. Coronary angiography reveals sustained anatomic improvement in the majority, especially if PTCA is repeated in those patients who developed restenosis. Successful PTCA is associated with a low incidence of cardiac events such as myocardial infarction, elective cardiac bypass surgery, or death during late followup. The majority of patients are completely free of angina and demonstrate objective improvement with exercise testing. Patients with multivessel disease, if properly selected, may derive nearly as much long-term benefit from PTCA as patients with single-vessel disease.

Angioplasty, Balloon↗
PubMed1987

Angiographic findings when chest pain recurs after successful percutaneous transluminal coronary angioplasty.

Angiographic and clinical characteristics of 102 consecutive patients who underwent coronary cineangiography for assessment of recurrent angina pectoris after successful percutaneous transluminal coronary angioplasty (PTCA) were reviewed. Based on angiographic findings, patients were classified as having restenosis (n = 63), development of new, significant coronary stenosis (n = 15), incomplete revascularization (n = 9) or no significant coronary artery disease (n = 15). Eighteen clinical and technical characteristics of the study group were analyzed as predictors of angiographic outcome. The groups did not differ in terms of age, gender, number of inflations performed, peak inflation pressure or in the pre- or post-PTCA stenosis or gradient. The time from PTCA to onset of recurrent angina was the most powerful predictor of angiographic outcome. Patients in whom symptoms developed within 1 month of PTCA usually had incomplete revascularization or no coronary narrowing. Restenosis was the most common explanation for chest pain 1 to 6 months after PTCA. Angina recurring more than 6 months after PTCA was usually due to development of new, significant coronary artery narrowings.

Angina Pectoris↗
PubMed1987

Assessment of coronary flow reserve using digital angiography before and after successful percutaneous transluminal coronary angioplasty.

Important alterations of coronary blood flow and coronary flow reserve occur during percutaneous transluminal coronary angioplasty (PTCA). This study evaluated these alterations using digital subtraction angiography. Coronary flow reserve was determined before and after successful PTCA in 20 patients with 1-vessel coronary artery disease (CAD). Ten other patients with angiographically normal coronary arteries, normal exercise electrocardiographic responses and normal cardiac structure also were evaluated. Coronary flow reserve was calculated as the ratio of papavarine-induced hyperemic flow to basal flow. Flow reserve for the stenotic artery in patients who underwent PTCA was 1.6 +/- 0.2 (mean +/- standard error of the mean) (range 0.9 to 3.9, n = 20). After successful PTCA, flow reserve for this artery increased to 3.1 +/- 0.2 (range 1.7 to 5.2, n = 20) (p less than 0.0001 vs before PTCA). Flow reserve for adjacent nonstenotic, nondilated arteries was 2.6 +/- 0.2 (range 1.4 to 4.5, n = 13). Coronary flow reserve in the stenotic arteries before PTCA was far below normal. In addition, both successfully dilated arteries and nondilated, nonstenotic arteries in these patients with CAD had flow reserve values smaller than those in the patients with normal arteries (4.8 +/- 0.6, range 2.3 to 12.6, n =22) (p less than 0.01). These findings suggest that digital angiographic determinations of coronary flow reserve can reveal important alterations of individual artery vasodilatory capacity. The data suggest that although an epicardial coronary in a patient with CAD may appear angiographically normal, flow reserve remains impaired due to abnormalities as yet undefined.

Adult↗
PubMed1987

Superiority of intracoronary papaverine to radiographic contrast for measuring coronary flow reserve in patients with ischemic heart disease.

Measurement of coronary flow reserve has been suggested as an adjunct to anatomic assessment of coronary stenoses in patients with ischemic heart disease. We compared papaverine hydrochloride and radiographic contrast to determine which agent was superior for the determination of coronary flow reserve. Coronary flow reserve was determined during cardiac catheterization by means of digital coronary angiography and parametric imaging. Two groups of patients were studied. Among patients in group 1, coronary flow reserve was determined by means of both papaverine and contrast. In group 1 patients with normal coronary arteries, papaverine-induced flow reserve was greater than contrast-induced reserve in all but one vascular region (n = 9, 4.98 +/- 1.15 vs 3.56 +/- 0.89; p = 0.29). Group 1 patients with coronary disease also demonstrated significantly greater flow reserve with papaverine (n = 25, 2.57 +/- 0.20 vs 1.83 +/- 0.11, p less than 0.01). Group 2 included patients with single-vessel coronary artery stenoses. These patients were studied by means of either papaverine or contrast to determine coronary flow reserve for both the stenotic "ischemic" region and an adjacent nonstenotic, "nonischemic" region. Those patients in group 2 who were studied by means of contrast had a modest difference between flow reserve values in the nonischemic and those in the ischemic regions (n = 15, 1.78 +/- 0.10 vs 1.26 +/- 0.09; p less than .0001) with considerable overlap. Patients studied by means of papaverine had a much greater separation in flow reserve between nonischemic and ischemic regions (n = 22, 2.78 +/- 0.19 vs 1.46 +/- 0.14; p less than 0.0001).(ABSTRACT TRUNCATED AT 250 WORDS)

Blood Flow Velocity↗
PubMed1987

Thrombolytic therapy for prosthetic cardiac valve thrombosis.

To determine the efficacy and safety of thrombolytic therapy for prosthetic valve thrombosis, a composite series of 41 patients who received either streptokinase or urokinase intravenously for this disorder were analyzed. The series comprised 3 patients treated at Rhode Island Hospital and 38 previously reported on. Short-term success was achieved in 32 patients (78%). Prosthetic valve thrombosis recurred in seven (22%) of the successfully treated patients, four of whom were retreated with thrombolytic therapy. A favorable clinical outcome was observed in each. Fever and venipuncture bleeding were the most frequent side effects. Systemic embolization occurred in 4 (15%) of 26 patients with either aortic or mitral prosthetic valve thrombosis. None of these latter patients experienced a permanent neurologic or circulatory deficit. It is concluded that thrombolytic therapy is of value in the treatment of prosthetic valve thrombosis.

Adult↗
PubMed1987

Coronary angioplasty after recombinant tissue-type plasminogen activator in acute myocardial infarction: a report from the Thrombolysis in Myocardial Infarction (TIMI) Trial.

To assess the utility of percutaneous transluminal coronary angioplasty after successful thrombolytic therapy for patients with acute myocardial infarction, the outcome of 201 patients who received intravenous recombinant tissue-type plasminogen activator (rt-PA) was analyzed. Reperfusion of the infarct-related artery was observed in 132 patients who were assessed for potential coronary angioplasty at 18 to 48 hours after treatment. Coronary angioplasty was performed in 52 patients (39%). Reasons for not performing angioplasty included unsuitable coronary anatomy, presence of residual stenosis of less than 60% and the need to perform an earlier procedure. When attempted, coronary angioplasty was successful in 96% of patients and was associated with a decrease in coronary stenosis from 85 to 30%. No patient experienced a major complication associated with coronary angioplasty. Of 36 patients undergoing predischarge coronary angiography after successful angioplasty, the infarct-related artery remained patent in 97.2%. Thus, coronary angioplasty is feasible and safe in patients who achieve coronary reperfusion after intravenous rt-PA for acute myocardial infarction. Not all patients who achieve reperfusion, however, are suitable for coronary angioplasty. When attempted, angioplasty is usually successful and associated with sustained patency of the infarct-related artery.

Angioplasty, Balloon↗
PubMed1987

The effect of intravenous thrombolytic therapy on left ventricular function: a report on tissue-type plasminogen activator and streptokinase from the Thrombolysis in Myocardial Infarction (TIMI Phase I) trial.

In Phase I of the NHLBI trial of Thrombolysis in Myocardial Infarction (TIMI), 290 patients admitted within 7 hr after onset of acute infarction were randomly assigned to intravenous treatment with either streptokinase (SK) or recombinant tissue-type plasminogen activator (rt-PA). Left ventricular function was measured from contrast ventriculograms in 145 patients with both pretreatment and predischarge studies analyzable. Regional wall motion in the infarct site was measured by the centerline method and expressed in units of standard deviations (SDs) from the mean motion in 52 normal subjects. Patients treated with rt-PA (n = 77) achieved a significantly higher reperfusion rate after 90 min of treatment. Perfusion of the infarct-related artery improved from visual grade 0 or 1 (total occlusion or penetration without perfusion) to grade 2 or 3 (partial or full reperfusion) in 62% receiving rt-PA vs 31% receiving SK (n = 68) (p less than .001). However, the ejection fraction did not change significantly from before treatment to before discharge in either treatment group (+0.7 +/- 6.7% vs +1.0 +/- 8.3%, respectively). A small but significant increase in regional wall motion was observed in each of the two groups (+0.4 +/- 0.8 vs +0.3 +/- 0.8 SD/chord, respectively; each p less than .001 compared with baseline). This was countered by declines in the hyperkinesis of the noninfarct region (-0.3 +/- 1.0 SD/chord [p = .01] compared with baseline and -0.2 +/- 1.0 SD/chord [p = .23], respectively). Analysis of the combined groups revealed that the ejection fraction increased only in patients who achieved reperfusion by 90 min after onset of therapy or who had subtotal occlusions initially. There was greater recovery of left ventricular function in patients who achieved reperfusion earlier vs later than 4 hr after symptom onset and in patients with vs without some collateral circulation to the infarct-related artery.

Cardiac Catheterization↗
PubMed1986

Sustained efficacy of percutaneous transluminal coronary angioplasty.

To determine whether the immediate efficacy of percutaneous transluminal coronary angioplasty (PTCA) is sustained, follow-up data were obtained in 183 patients who had undergone PTCA at least 1 year earlier. The duration of follow-up ranged from 1 to 5 years. Subjective clinical information was obtained in each patient and objective functional information, determined by exercise stress testing, was obtained in 91. PTCA was initially successful in 141 patients (79%). Of the 42 patients in whom PTCA was unsuccessful, 26 underwent coronary artery bypass graft surgery (CABG), while 16 were maintained on medical therapy (MED). When compared to the MED patients at time of follow-up, successful PTCA patients experienced less angina (13% vs 47%; p = 0.003), used less nitroglycerin (25% vs 73%, p = 0.003), were hospitalized less often for chest pain (8% vs 31%; p = 0.02), and subjectively felt their condition had improved (96% vs 20%; p less than 0.001). Furthermore, during exercise testing, the prevalence of angina was reduced (9% vs 43%; p = 0.05), and exercise duration was greater (8.2 minutes vs 5.8 minutes, p = 0.05) among PTCA patients. There were no significant differences in the incidence of subsequent myocardial infarction, mortality, or need for coronary artery bypass surgery. For these variables, no differences were seen between the CABG and PTCA groups. Thus, successful PTCA results in long-term relief of subjective and objective manifestations of myocardial ischemia, superior to that of medical therapy and comparable to CABG.

Angina Pectoris↗
PubMed1986

Effect of intravenous and oral acebutolol in patients with bundle branch block.

We studied the effect of intravenous (1 mg/kg) and oral (400 mg) acebutolol on atrioventricular conduction in 22 patients with idiopathic bundle branch block and 1 to 1 atrioventricular conduction. Seven patients had previously symptomatic complete heart block (Group 1) and 15 were asymptomatic with bundle branch block only (Group 2). Following intravenous acebutolol heart rate decreased 82 +/- 16 to 63 +/- 16/min (P less than 0.01), A-H interval lengthened 98 +/- 22 to 121 +/- 30 msec (P less than 0.005) and H-V time was prolonged 60 +/- 13 to 70 +/- 17 msec (P less than 0.02) in those with previous heart block. The corresponding changes in the patients with no previous block were 74 +/- 14 to 61 +/- 8/min (P less than 0.01), 90 +/- 17 to 109 +/- 22 msec (P less than 0.05) and 48 +/- 15 to 56 +/- 14 msec (P less than 0.01). There was no difference between the basal or induced changes between these two groups. After intravenous acebutolol infusion 2 of 6 patients with previous spontaneous heart block and none of those without previous heart block developed atrioventricular block distal to His. The induced block was temporary (less than 10 min) and corresponded to the time of peak plasma acebutolol levels. Temporary atrioventricular block followed oral acebutolol administration in 4/7 patients with previous spontaneous heart block and 0/14 in those without block. In patients with bundle branch block intravenous acebutolol prolonged H-V conduction times in 19/20 patients and intravenous and oral acebutolol induced A-V block in 4/7 patients with previous spontaneous block.(ABSTRACT TRUNCATED AT 250 WORDS)

Acebutolol↗
PubMed1986

Coronary flow reserve provided by sequential internal mammary artery grafts.

Although internal mammary artery bypass grafts have a high patency rate, the adequacy of blood flow through such conduits, particularly if used sequentially, has been questioned. To evaluate this issue, coronary flow reserve was studied in 20 patients after coronary bypass surgery. Nine patients had sequential internal mammary grafts to the diagonal and left anterior descending coronary arteries; five had a single internal mammary graft to the left anterior descending artery and six had sequential saphenous vein grafts. Fifteen additional single vein grafts were also placed in these patients. Coronary flow reserve was measured after contrast-induced hyperemia by a digital subtraction angiographic technique an average of 25 days after surgery. There was no difference in coronary flow reserve between the proximal and distal anastomotic regions in either the sequential internal mammary graft group (2.14 +/- 0.50 versus 2.29 +/- 0.68, n = 8, p = NS) or the sequential vein group (1.77 +/- 0.49 versus 2.08 +/- 0.78, n = 6, p = NS). In addition, the flow reserve provided to either vascular bed of the sequential internal mammary graft was not different from that provided by a single internal mammary graft (1.64 +/- 0.39, n = 5), a single vein graft (1.95 +/- 0.95, n = 15) or nonstenotic native coronary arteries (2.04 +/- 0.87, n = 34). No cases of intracoronary steal were observed. Although some patients had unequal flow reserves between the proximal and distal anastomotic zones, these occurred in the setting of residual coronary stenoses distal to the site of graft insertion or prior myocardial infarction in the grafted distribution.(ABSTRACT TRUNCATED AT 250 WORDS)

Cardiac Catheterization↗
PubMed1986

Intravenous recombinant tissue-type plasminogen activator in patients with acute myocardial infarction: a report from the NHLBI thrombolysis in myocardial infarction trial.

The efficacy and safety of a 3 hr, 80 mg intravenous infusion of recombinant tissue-type plasminogen activator (rt-PA) were investigated in 47 patients with acute myocardial infarction. Coronary angiography, performed before the administration of rt-PA and for 90 min thereafter, demonstrated that 37 patients had total coronary occlusion before therapy. After 90 min of rt-PA (50 mg), reperfusion of the infarct-related artery was observed in 25 patients (68%). Continuous infusions of heparin for anticoagulation were administered for 8 to 10 days. Of 36 patients who underwent follow-up coronary cineangiography, 21 had initially presented with total occlusion and had experienced reperfusion at 90 min. Sustained perfusion of the infarct-related artery was observed in 14 (67%) of these 21 initially reperfused patients. Late angiography was performed in nine patients who initially demonstrated subtotal occlusion of the infarct-related artery; sustained perfusion was observed in eight (89%). Significant bleeding was observed in 15 patients (32%). A hematoma at the site of the acute catheterization accounted for most instances of significant bleeding (11/15, 73%). Administration of rt-PA resulted in a significant decline in fibrinogen and plasminogen while amounts of fibrin(ogen) degradation products rose. In no patient, however, did fibrinogen levels decline to less than 140 mg/dl. Thus, rt-PA, administered as a brief 80 mg intravenous infusion, is capable of restoring blood flow in a high proportion of patients with acute myocardial infarction due to total coronary obstruction. Declines in plasma fibrinogen and plasminogen are observed. If combined with heparin anticoagulation and invasive vascular procedures, significant bleeding is a common complication.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1986

Prediction of long-term clinical outcome with final translesional pressure gradient during coronary angioplasty.

The final translesional pressure gradient measured during coronary angioplasty correlates with immediate angiographic and clinical results. Whether the pressure gradient is of value in predicting late clinical outcome has not been determined. We therefore obtained complete follow-up information on 159 patients with single-vessel disease who underwent successful coronary angioplasty. Mean follow-up time was 15 +/- 10 months. The occurrence of repeat angioplasty, coronary bypass surgery, recurrent anginal chest pain, or a positive postangioplasty stress test were considered clinical events indicative of late failure. Of the variables age, gender, initial and final translesional pressure gradient, extent of initial and final arterial narrowing, site of dilatation, type of balloon catheter used, number of inflations, and maximal inflation pressure, only the final translesional pressure gradient was predictive of late failure when analyzed by multivariate techniques. Thus, the final translesional pressure gradient is of value in predicting both immediate and late outcome after coronary angioplasty.

Aged↗
PubMed1985

Elevated coronary vascular resistance in the presence of reduced resting blood flow distal to a severe coronary stenosis.

Vascular reserve in underperfused myocardium has recently been described. This seemingly paradoxical observation conflicts with older concepts of the coronary circulation which hold that flow deficits do not develop until reserve is fully exhausted. To examine this phenomenon in greater detail in an animal model mimicking a fixed human coronary artery stenosis, we analysed the records of 25 carefully selected, sedated pigs all instrumented with a rigid intralumenal coronary stenosis (82% lumenal diameter reduction). Each animal satisfied the following criteria: 1) perfused myocardial mass beyond the stenosis was within a narrow weight range (16 to 24 g); and 2) post stenosis (distal) epicardial (Epi) and endocardial (endo) flows were less than or equal to 90% of respective flows in a region perfused by the non-stenosed circumflex (CX) coronary artery. Accordingly, distal flow was reduced compared to circumflex zone flow (p less than 0.01) in the Epi (173 +/- 51 to 113 +/- 32 ml . 100g-1 . min-1), Endo (146 +/- 39 to 116 +/- 27) and transmural (Tm) regions (164 +/- 45 to 124 +/- 31). Despite a flow deficit and constant severity of stenosis, distal zone Tm resistance (0.55 +/- 0.21 mmHg/ml . 100 g-1 . min-1) exceeded the minimum level achievable with intravenous infusion of adenosine (0.25 +/- 0.07) in a separate group of eight animals without a stenosis. Distal transmural resistance also varied over a five fold range (0.27 to 1.33) and in 20/25 animals exceeded the highest level (0.37) seen in non-stenosis animals during adenosine infusion.(ABSTRACT TRUNCATED AT 250 WORDS)

Adenosine↗