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K M Kent

Publications and source records attributed to K M Kent.

At least 19 recordsLinked to original sources
PubMed1992

Results of coronary angioplasty using the transluminal extraction catheter.

To assess the procedural results after coronary angioplasty using the transluminal extraction catheter (TEC) in patients with complex lesion anatomy, experience with 51 patients undergoing this procedure was reviewed. One or more adverse lesion morphologic features were present in 45 patients (88%) and > or = 2 adverse features were present in 38 (74%). Procedural success (< 50% final diameter stenosis and the absence of major complications) was obtained in 42 patients (82%); major complications occurred in 7 patients (death, 3; Q-wave myocardial infarction, 4; emergency bypass operation, 2). Distal embolization was noted in 5 patients with thrombus-containing saphenous vein graft stenoses. Only lesion thrombus correlated with an unsuccessful outcome. After TEC use, diameter stenosis was reduced from 76 +/- 13 to 50 +/- 22% (p < 0.001). Adjunct balloon angioplasty was used in 44 procedures (86%), further reducing the diameter stenosis to 32 +/- 22% (p < 0.001 compared with post-TEC). High-frequency intracoronary ultrasound was performed in 11 patients after TEC use. Plaque fissuring was present in all lesions and intraluminal dissection was noted in 4 (36%). Residual plaque after TEC use was found in virtually all lesions. During the 5.2 +/- 2.8-month follow-up period, 17 patients (40%) developed recurrent symptoms. Coronary bypass surgery was performed in 4 patients and repeat coronary angioplasty was required in 3. In addition, 3 patients died from cardiac causes. It is concluded that coronary angioplasty using the TEC may be a useful alternative to balloon angioplasty in patients with complex coronary anatomy, although distal embolization may still occur in thrombus-containing saphenous vein graft lesions.

Angioplasty, Balloon, Coronary↗
PubMed1992

Target lesion calcification in coronary artery disease: an intravascular ultrasound study.

OBJECTIVES: The purpose of this study was to evaluate the frequency, amount and distribution of target lesion calcification in patients undergoing transcatheter therapy for symptomatic coronary artery disease. BACKGROUND: Coronary artery target lesion calcification may be an important determinant of response to transcatheter therapy: balloon angioplasty causes dissections in calcified lesions, directional atherectomy cuts calcium poorly, rotational atherectomy causes preferential ablation of calcium and laser irradiation effect may vary. Intravascular ultrasound imaging is a highly sensitive technique for detection of plaque calcification in vivo. METHODS: We performed intravascular ultrasound imaging before or after, or both, various transcatheter therapies in 110 patients. These 84 men and 26 women had a mean age of 60 years and a duration of angina of 22 +/- 34 months. Forty-nine patients had one-vessel, 29 had two-vessel, 25 had three-vessel and 7 had left main coronary disease. Vessels treated and imaged were the left main (n = 7), left anterior descending (n = 47), left circumflex (n = 18) and right (n = 38) coronary arteries. RESULTS: Eighty-four patients (76%) had target lesion calcification; 29 patients had one-quadrant, 25 had two-quadrant, 17 had three-quadrant and 13 had four-quadrant calcification. The calcification was superficial in 42 patients, deep in 13 and both superficial and deep in 31. The axial length of calcium could be measured in 29 patients; it was < or = 5 mm in 11 and > or = 6 mm in 18. Fluoroscopy detected calcification in 50 patients (48%, p < 0.001 vs. detection by ultrasound); this proportion increased to 74% in patients with calcification of two or more quadrants and to 86% in patients with calcification > or = 6 mm in length of two or more quadrants. Calcification was more common in patients who smoked and tended to be more common in patients with multivessel disease or previous coronary artery bypass graft surgery. CONCLUSIONS: We conclude that target lesion calcification occurs in 75% of patients with symptomatic coronary artery disease requiring angioplasty. Target lesion calcification is best detected, localized and quantified by intravascular ultrasound. These observations may be important in selecting devices for transcatheter therapy.

Adult↗
PubMed1992

Prolonged intravenous urokinase infusion: an alternative pharmacologic approach in the treatment of thrombus-containing saphenous vein graft stenoses.

A subtotally occlusive saphenous vein graft stenosis resolved after rapid intracoronary and prolonged intravenous urokinase infusion. Additional therapy was unnecessary, avoiding the attendant risks of saphenous vein graft angioplasty. Combined intracoronary and intravenous urokinase infusion should be considered prior to coronary angioplasty of saphenous vein graft stenoses, particularly when diffuse degeneration is present or the risk of underlying thrombus is high.

Angioplasty, Balloon, Coronary↗
PubMed1992

Failure or success of complex catheter-based interventional procedures assessed by intravascular ultrasound.

Intravascular ultrasound provides high resolution cross-sectional images of vessel walls and may help to characterize atherosclerotic plaque morphology subtypes. This new imaging modality may have an important role in assessing the results of standard and investigational interventional therapeutic procedures. Four case histories of patients with coronary artery disease treated with different catheter-based therapies are presented. In each case, intravascular ultrasound added diagnostic information unobtainable from standard radiographic imaging techniques. These cases, involving PTCA (balloon dilatation), directional coronary atherectomy, high-speed rotational ablation, and balloon-expandable stent implantation, each represent an interesting example of procedure success or failure that could not be fully discerned without the use of intravascular ultrasound. Specifically, the distribution of intramural dissection, the presence and magnitude of intracoronary calcification, and morphologic patterns of intimal hyperplasia leading to restenosis, were accurately identified by ultrasound images. Thus intracoronary ultrasound imaging significantly enhances the understanding of failure modes, success, and complications after therapeutic interventions in patients with complex coronary disease.

Aged↗
PubMed1992

Arterial responses to balloon coronary angioplasty: an intravascular ultrasound study.

OBJECTIVES: The purpose of this study was to examine the coronary artery response to percutaneous transluminal coronary angioplasty by using intravascular ultrasound. BACKGROUND: The immediate effects of coronary angioplasty on arterial wall geometry and surface appearance are understood poorly. Most of the available data are derived from small necropsy series, inferred from animal models or extrapolated from in vitro studies. High frequency intravascular ultrasound provides transmural images of coronary arteries in vivo. METHODS: We used intravascular ultrasound to study 29 patients before or after, or both, successful coronary angioplasty. RESULTS: The angiographic diameter narrowing was 72 +/- 13% before and improved to 19 +/- 11% after angioplasty. Calcium was visualized in 7 (24%) of the 29 angioplasty sites by fluoroscopy versus 15 (52%) of sites by intravascular ultrasound (p = 0.022). Arterial dissection after angioplasty was observed in 8 (27%) of cases by contrast angiography versus 24 (83%) by intravascular ultrasound (p less than 0.001). Intravascular ultrasound detected extensive dissection at the angioplasty site in 11 (73%) of the 15 calcified plaques and in only 3 (21%) of the 14 noncalcified plaques (p = 0.024). Arterial expansion (defined as the area within the external elastic membrane at the angioplasty site greater than that of the proximal reference segment) occurred in 29% of calcified plaques compared with 86% of noncalcified plaques (p = 0.007). CONCLUSIONS: Intravascular ultrasound is more sensitive than angiography for identifying arterial calcium and dissection at the site of angioplasty. At the site of angioplasty, arterial dissection occurred more frequently in calcified plaques whereas arterial expansion occurred more frequently in noncalcified plaques. Successful angioplasty causes a continuum of arterial responses that vary importantly with plaque composition.

Angioplasty, Balloon, Coronary↗
PubMed1992

Morphological predictors of acute complications after percutaneous excimer laser coronary angioplasty. Results of a comprehensive angiographic analysis: importance of the eccentricity index.

BACKGROUND: Percutaneous excimer laser coronary angioplasty (ELCA) is a new technique for recanalization of arteries obstructed by coronary atherosclerosis. This study was conducted to assess the complication rate and determine the influence of clinical and angiographic characteristics on complications after ELCA. METHODS AND RESULTS: A detailed, quantitative, angiographic core laboratory analysis of patients undergoing ELCA was performed by two experienced angiographers who were not the primary laser angioplasty operators. Two hundred patients underwent 203 separate procedures on 220 lesions at three medical centers. Laser success was achieved in 180 lesions (81.8%) and procedural success in 199 (90.5%). Emergency coronary artery bypass graft (CABG) was required in five patients (2.5%). One patient suffered a Q wave myocardial infarction; there were no deaths. Also, acute closure and perforation occurred in 10 (4.5%) and three (1.4%) vessels, respectively. Coronary dissections after laser treatment were seen in 36 vessels (16.4%). Multivariate analysis found two independent preprocedural factors related to complications: eccentricity index, which is the percent deviation of the lesion lumen from the center of the artery (p = 0.0007), and proximal vessel diameter (p = 0.033). In addition, an abrupt proximal face of the lesion was associated with angiographic complications by univariate analysis (p = 0.051). Multivariate analysis showed the eccentricity index (p = 0.032) to be the only independent predictor for the occurrence of any one or more of the important complications (emergency CABG, perforation, acute closure, or Q wave myocardial infarction), whereas lesion angle greater than 45 degrees was a significant univariate predictor (p = 0.029). Other predictors of complications with balloon percutaneous transluminal coronary angioplasty, such as increased lesion length, rough edges, calcification, ulceration, and branch point, were not predictive of complications with the excimer laser. CONCLUSIONS: The degree of lesion eccentricity is the most powerful predictor of complications after ELCA. This and other morphological predictors may be of benefit in the selection of patients for ELCA as well as directing future development of this new technology.

Aged↗
PubMed1992

Intravascular ultrasound evaluation of the effect of rotational atherectomy in obstructive atherosclerotic coronary artery disease.

BACKGROUND: High-speed rotational atherectomy uses a diamond-coated, elliptical burr to abrade occlusive atherosclerosis, especially noncompliant calcified plaque. METHODS AND RESULTS: Intravascular ultrasound (IVUS) was used to analyze 28 patients after atherectomy. Arteries treated and imaged were left main (three), left anterior descending (12), left circumflex (five), right coronary (seven), and saphenous vein graft (one). Twenty patients had adjunct balloon angioplasty. Twenty-two (79%) target lesions were calcified; the intimal arc of calcium was 160 +/- 126 degrees (range, 0-360 degrees). After atherectomy, the intima-lumen interface was unusually distinct and circular. The lumen was larger than the largest burr used for both stand-alone (1.19 +/- 0.19-fold the largest burr size) and adjunct balloon procedures (1.30 +/- 0.15-fold the largest burr). Three-dimensional reconstruction of the ultrasound images showed a smooth lumen, especially in calcified plaque. Deviations from cylindrical geometry occurred only in areas of soft plaque or superficial tissue disruption of calcified plaque. Five patients were studied before and after rotational atherectomy. IVUS showed an increase in lumen size, a decrease in plaque-plus-media area and in arc of target lesion calcification, and no change in target lesion external elastic membrane cross-sectional area. CONCLUSIONS: Rotational atherectomy causes atheroablation with only moderate evidence of barotrauma in heavily calcified arteries, even after adjunct balloon angioplasty. The lumen is cylindrical, especially in areas of calcified plaque, and somewhat larger than the largest burr tip used.

Angioplasty, Balloon, Coronary↗
PubMed1991

Quantification of ST-segment changes during coronary angioplasty in patients with left bundle branch block.

Electrocardiographic manifestations of ischemia are difficult to interpret in the presence of left bundle branch block (LBBB). Recently developed techniques allow continuous computerized digital analysis of ST segments that can be zeroed to the patient's own baseline electrocardiogram even if that baseline is abnormal conduction. With use of this technology, ST-segment changes during balloon coronary occlusion were compared in 10 patients with LBBB versus an age-, sex-, and coronary anatomy-matched population of 20 control subjects with normal baseline conduction. ST-segment deviation of greater than or equal to 1 mm from baseline was present in 80% of patients with LBBB and in 75% of control patients (difference not significant). There was no significant difference between patients with LBBB versus control patients in maximal ST-segment deviation (2.6 +/- 1.7 vs 2.0 +/- 1.0 mm) or in ST-segment deviation measured after 60 seconds of occlusion (2.4 +/- 1.3 vs 1.8 +/- 1.1 mm). ST-segment deviation reached 1 mm more quickly in patients with LBBB (33 +/- 11 seconds) than in control subjects (60 +/- 36 seconds) (p = 0.003). It is concluded that ST-segment analysis is feasible in patients with LBBB using digital self-referenced ST analysis and may provide important clinical information regarding the presence of myocardial ischemia.

Angioplasty, Balloon, Coronary↗
PubMed1991

Relation of stenosis resolution pressure to long-term clinical outcome after successful percutaneous transluminal coronary angioplasty.

Variables associated with a poor long-term prognosis after successful percutaneous transluminal coronary angioplasty (PTCA) include a short duration of symptoms before PTCA, unstable angina and the presence of thrombus at the PTCA site. These imply a component of transient or dynamic obstruction as opposed to a pure fixed obstruction. It is postulated that resolution pressure (i.e., the pressure at which complete balloon inflation occurs) may also correlate with prognosis after successful PTCA. In 173 consecutive patients undergoing successful, elective, single-lesion PTCA, 48 (28%) were found to have narrowings that resolved at less than or equal to 2 atm (group 1) and 125 (72%) were found to have narrowings resolved at greater than 2 atm (group 2). There were no significant differences in baseline, anatomic or procedural variables between the 2 groups, except that angiographic coronary dissection occurred in 17% of group 1 patients versus 40% of group 2 patients (p less than 0.007). During a mean follow-up of 12.0 +/- 6.1 months, the incidence of cardiac events (repeat PTCA, coronary artery bypass grafting or myocardial infarction) was 29% in group 1 versus 15% in group 2 (p less than 0.05). The overall incidence of angina was similar between the groups (25 vs 28%), but Canadian Cardiovascular Association class 4 angina occurred significantly more frequently in group 1 than group 2 (21 vs 8%) (p less than 0.04). These data suggest that a low resolution pressure is associated with a higher incidence of unstable angina and recurrent cardiac events during follow-up than higher resolution pressures.

Aged↗
PubMed1991

Reduction of myocardial infarction after emergency coronary artery bypass grafting for failed coronary angioplasty with use of a normothermic reperfusion cardioplegia protocol.

Emergency coronary artery bypass grafting is necessary in 2.7% to 13.5% of patients undergoing elective percutaneous transluminal coronary angioplasty. Myocardial infarction develops in 11% to 49% of these patients, with 18% to 46% of infarcts resulting in new Q waves. Since February 1987 a revised protocol for myocardial preservation has been used in 19 patients undergoing emergency bypass grafting for failed angioplasty. Cardioplegia is induced with a normothermic blood cardioplegic solution. Multiple maintenance doses of cold (4 degrees C) blood cardioplegic solution are then delivered through the aortic root and vein grafts. Before the aortic crossclamp is removed, normothermic reperfusion cardioplegic solution is delivered through the aortic root and vein grafts. This group was compared with all patients undergoing emergency bypass grafting for failed angioplasty before February 1987. These 45 patients received cold induction of cardioplegic solution, multiple maintenance doses of cold cardioplegic solution, and no reperfusion cardioplegic solution. The prevalence of myocardial infarction in the group receiving cold cardioplegic solution was 65% versus 26% in the group receiving normothermic cardioplegic solution (p less than 0.007). Multivariate analysis identified the use of the normothermic cardioplegia protocol (p less than 0.005), nontotal occlusion of the angioplasty vessel (p less than 0.03), and presence of collateral flow to the angioplasty vessel (p less than 0.04) as being independently associated with absence of myocardial infarction.

Angioplasty, Balloon, Coronary↗