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Biomedical subjects

P Kearney

Publications and source records attributed to P Kearney.

At least 55 records · Page 3Linked to original sources
PubMed1995

Microscopic evaluation of an occluded intracoronary Palmaz-Schatz stent removed before coronary artery bypass grafting.

Intracoronary implantation of stent devices is a new interventional technique with a promising role in the treatment of acute coronary occlusions caused by intimal dissection and suboptimal results of percutaneous transluminal coronary angioplasty. However, the prolonged presence of stent material embedded in the arterial wall may generate unknown late consequences. Major complications consist of subacute to chronic occlusion and restenosis. To elucidate the underlying cause we removed an angiographically occluded intracoronary artery Palmaz-Schatz stent before coronary artery bypass grafting. Scanning electron microscopy showed thorough coating of the metal struts of the stent by normal neoendothelial cells. Side branches arising at the level of the stent were patent. According the specific angiographic feature thrombotic occlusion originated distally of the stent.

Aged↗
PubMed1994

Aortic intramural hemorrhage visualized by transesophageal echocardiography: findings and prognostic implications.

OBJECTIVES: This study describes the transesophageal echocardiographic and follow-up findings in patients with aortic intramural hemorrhage. BACKGROUND: Localized aortic intramural hemorrhage resulting in layered thickening of the aortic wall seems to represent a variant of acute aortic dissection without communication or a typical moving intimal flap. In autopsy studies this variant, attributed to a rupture of the vasa vasorum, has been described in 5% to 10% of patients with dissection. METHODS: In a prospective transesophageal echocardiographic study in patients with aortic dissection performed between 1986 and 1991, the diagnosis of intramural hemorrhage was established in 15 of 114 patients and either confirmed anatomically (7 patients) with an additional diagnostic imaging technique or on the basis of clear follow-up changes (8 patients). RESULTS: Elderly patients (mean age 70 years) with a history of hypertension were affected by this variant of dissection. The ascending aorta was involved in 3 patients and the descending aorta in 12. The longitudinal extent varied between 3 and 20 cm, and wall thickness varied between 0.7 and 3 cm. Classic aortic dissection developed in five patients (33%) and rupture in four (27%). Regression of aortic wall thickening was noted in two patients, whereas three patients became asymptomatic without apparent wall changes (33%). Surgery was performed in 5 patients, whereas medical therapy was continued in 10. During a mean follow-up period of 11 months, eight patients (53%) died because of complications of the aortic disease. CONCLUSIONS: Intramural hemorrhage represents a variant of aortic dissection and may be an early finding in patients who develop classic aortic dissection or rupture. Transesophageal echocardiography is an excellent method for the detection of intramural hemorrhage and for monitoring these patients.

Aged↗
PubMed1994

Assessment of spontaneous coronary artery dissection by intravascular ultrasound in a patient with unstable angina.

We describe a case of spontaneous coronary artery dissection that gave rise to post infarction unstable angina. An ambiguous angiographic appearance was shown by intracoronary ultrasound to arise from an extensive coronary dissection. The dissection membrane separating true and false lumina and features to suggest sluggish flow and early thrombosis in the false lumen were observed. No increase in lumen calibre was evident on ultrasound after PTCA (probably a consequence of the relatively large ultrasound catheter blank), but coronary flow reserve measured with intracoronary Doppler did improve and the patient remained stable and free of angina following the procedure.

Angina, Unstable↗
PubMed1994

Spontaneous plaque rupture visualized by intravascular ultrasound.

An intravascular ultrasound examination was performed in order to evaluate an angiographically complicated lesion. Intravascular ultrasound was able to demonstrate spontaneous plaque rupture in a patient with recent acute subendocardial infarction. The inconclusive angiographic appearance was clarified by the intravascular examination and led us to conclude that the myocardial infarction was due to plaque rupture with subsequent thrombotic occlusion, which had spontaneously resolved by the time of the study.

Aged↗
PubMed1994

Vessel wall changes in the proximal non-treated segment after PTCA. An in vivo intracoronary ultrasound study.

Intimal disruption is known to induce prolonged intimal functional disturbance and is thought to be one of the mechanisms contributing to restenosis after PTCA. Although such damage can be induced by minimal trauma, the inevitable far greater disruption caused by passage of the PTCA apparatus through the stenosis does not appear to induce significant angiographically documented intimal proliferation. Pathological studies, however, have suggested that such a process might occur. Intravascular ultrasound allows in vivo study of vessel wall shape and constitution and is a far more sensitive detector of coronary atheroma than angiography. In this study we sought to determine the frequency of such functional disturbances and to assess their significance with respect to restenosis. The study group comprised 18 patients who underwent IVUS examination immediately after PTCA and at 6-months follow-up. They were analysed for luminal dimensions and vessel wall changes at the site of PTCA and at the level of the proximal non-treated segment. Seven patients (38%) had restenosed at follow-up IVUS examination; two patients had angiographically demonstrated luminal narrowing proximal to the PTCA site whereas seven had new intimal thickening in the proximal non-treated segment demonstrated by IVUS. Six patients had no intimal changes in either PTCA treated or untreated segments. Proximal intimal thickening was seen more frequently in those in whom increased intimal thickening at the PTCA site was noted. A trend (P < 0.1) was found towards an increased rate of new proximal vessel disease in those patients who had angiographically restenosed. IVUS demonstrates new intimal thickening in proximal non-treated segments in a considerable number of or patients undergoing PTCA.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗
PubMed1994

Aorta and aortic valve morphologies predisposing to aortic dissection. An in vivo assessment with transoesophageal echocardiography.

Predisposing factors for aortic dissection are well known from necropsy series. To evaluate the frequency of aortic and aortic valve disease in aortic dissection in vivo, 139 patients with acute aortic dissection (96 men, 43 women, mean age 60.5 +/- 15.7 years) were studied by transoesophageal echocardiography (TEE) using 3.5 and 5.0 MHz transducers. Left ventricular hypertrophy by TEE, defined as an end-diastolic wall thickness of the left ventricular septal wall over 1.5 cm, was found in 42 (67.7%) of 62 patients with type I, in 10 (58.8%) of 17 patients with type II and in 46 (76.7%) of 60 patients with type III dissection. The mean value for the aortic root diameter was 3.2 +/- 1.3 cm.m-2 in type I dissection and 2.8 +/- 0.9 cm.m-2(ns) in type II dissection. In the patient group with type III dissection this diameter was significantly smaller (1.8 +/- 0.9 cm.m-2; P < 0.001). Thickening of aortic valve leaflets was demonstrated in six (9.7%) of 62 patients with aortic dissection type I (two of them with mild aortic stenosis), in two (11.8%) of 17 patients with aortic dissection type II and in 15 (25.0%) of 60 patients with aortic dissection type III. A bicuspid aortic valve was diagnosed in five (6.3%) of 79 patients with aortic dissection types I and II and in one (1.7%) of 60 patients with type III dissection. By colour coded Doppler echocardiography, aortic regurgitation was found in 46 (74.2%) of 62 patients with type I, 13 (76.5%) of 17 patients with type II and 23 (38.3%) of 60 patients with type III dissection.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1994

Continuous coronary perfusion balloon catheters in coronary dissections after percutaneous transluminal coronary angioplasty. Acute clinical results and 6-months follow-up.

The purpose of the study was to evaluate prospectively the effect of a continuous perfusion balloon catheter ('High Flow CPC Mainz', Schneider/Pfizer Europe AG, CH-8052 Zurich, Switzerland) on tolerated inflation time during elective PTCA (n = 31), and its usefulness in cases of unsatisfactory morphological or functional results after PTCA (n = 42). Sixty-five patients were male, eight female; their mean age was 57.6 +/- 8.85 years. The target vessel was the LAD in 39 patients, the RCA in 29, the LCX in three, and bypass grafts in two. Seven patients had type A lesions, 44 type B and 22 type C, respectively. The target lesion was in the proximal third of the coronary artery in 41 patients, in the mid-third in 30, and in the distal third in two. Side branches were involved in 24 patients. The median size of the standard PTCA balloon was 3.00 mm and 3.5 mm for the CPC. Tolerated inflation time rose from 36 +/- 21 s to 213 +/- 108 s (P < 0.01). Additionally, the CPC catheter was used in 42 patients with symptomatic dissections (ST segment elevation, chest pain, or impaired contrast run-off) after PTCA. Wall wrapping by CPC was successful in 24 (57%) and unsuccessful in 18 (43%) patients. A significant difference was found for the inflation times tolerated between patients with successful (265 +/- 99 s) and unsuccessful wall wrapping (161 +/- 108 s; P < 0.01). Of the 18 patients with unsuccessful wall wrapping, 11 (61%) required an intracoronary stent, and six patients (30%) could be managed by medical treatment alone.(ABSTRACT TRUNCATED AT 250 WORDS)

Angioplasty, Balloon, Coronary↗
PubMed1994

Comparison of intravascular ultrasound and angiography in the assessment of myocardial bridging.

BACKGROUND: In autopsy, myocardial bridging is a common finding. With coronary angiography, a systolic compression, mainly of the left anterior descending coronary artery, is observed in 1% to 3% of the patients. Controversy exists concerning the functional importance of this finding. To obtain a functional insight into the myocardial bridging, intravascular ultrasound and intracoronary Doppler were performed. METHODS AND RESULTS: Intracoronary ultrasound and Doppler were performed in 14 patients with angiographic evidence of systolic vessel compression ("milking effect") in the left anterior descending coronary artery. The 4.8F, 20-MHz ultrasound catheter could not be advanced through the entire myocardial bridge segment in 6 of the 14 patients studied because the lumen was < 1.6 mm. In these patients, only the proximal parts of the bridge segment were scanned. The changes in cross-sectional shape during the cardiac cycle were determined for both the normal proximal segment and the bridge segment by use of a semiautomatic computer program. Intracoronary Doppler (20 MHz) was performed in 7 patients with a 3F catheter. A highly characteristic systolic eccentric or concentric compression with delayed relaxation in diastole of the myocardial bridging segment was clearly visualized in all patients. The cross-sectional lumen area variation was 40 +/- 25% in the bridging segments and 9 +/- 7% in the normal segments (P < .01). No atherosclerotic lesions were detected in the bridge or the distal segment in the 8 patients in whom the IVUS catheter was successfully advanced through the entire myocardial bridge. However, atherosclerotic plaques were found in the segments proximal to the bridge in 12 of 14 patients (86%). The resting mean flow velocity was 6.4 +/- 1.2 cm/s; the maximal mean flow velocity after intracoronary administration of 10 mg papaverine was 14.1 +/- 3.4 cm/s. The coronary flow velocity reserve was 2.2 +/- 0.7. A highly characteristic pattern showing a prominent peak in coronary velocity in early diastole was observed in 86% of patients, and this pattern was enhanced after injection of intracoronary papaverine. CONCLUSION: Intravascular ultrasound demonstrated a characteristic systolic compression of the bridge segments. The delayed compression release may explain the characteristic sharp early diastolic peak in coronary flow velocity found with intracoronary Doppler in vessels with myocardial bridging. Reduced coronary flow reserve may be related to this phenomenon, possibly explaining signs of ischemia detected in some of the patients, but may alternatively be a result of the presence of atherosclerosis in the segment proximal to the bridge in these patients.

Blood Flow Velocity↗
PubMed1993

Miniaturized pressure-guide-wire: evaluation in vitro and in isolated hearts.

UNLABELLED: The present study focused on the accuracy and reproducability of measurements performed with a miniaturized pressure guidewire system (PGWS) under standardized in vitro conditions and in an isolated pig heart model. We used a pressure guide wire system provided by Pressure Guide, Radi Medical Systems, Uppsala, Sweden. Pressures were recorded by a fiber optic pressure sensor located laterally and 3 cm from the distal end. The basic principle is that the element modulates an optical reflection by pressure induced elastic movements. The light source is an emitting diode in the control unit. The PGWS replaces a standard 0.018 in. guidewire. The PGWS was introduced through a Y-adapter in a recirculating perfusion model, consisting of tubing with internal diameters from 1.00 to 4.00 mm. Different perfusion pressures (range 20-140 mm Hg) were generated by a pressure controlled roller pump. RESULTS: Different lumen sizes from 1 to 4 mm had no influence on the measurements. a) In a range from 20 to 140 mm Hg no significant differences were found between the perfusion pressure and the pressures obtained by the PGWS, resulting in an r-value of 0.99 and an equation of y = 1.04x + 1.9. b) In pressure measurements proximal and distal of an artificial stenoses resulting in gradients from 0 to 100 mm Hg, the PGWS correctly identified the pressure difference with an equally high accuracy, 1, 2, and 3 cm behind the stenoses.(ABSTRACT TRUNCATED AT 250 WORDS)

Angioplasty, Balloon, Coronary↗
PubMed1993

A quantitative polymerase chain reaction assay for interleukin 5 messenger RNA.

The quantitation of low abundance messenger (m)RNA species such as that for interleukin 5 (IL-5) cannot be achieved by Northern blotting. Polymerase chain reaction (PCR) technology can be used to overcome this paucity of target molecules, but in its standard format it is semiquantitative. We describe the synthesis, purification, and use of a synthetic IL-5 mRNA (cRNA) molecule which, when included in the PCR reaction, enabled the amplification of IL-5 mRNA molecules from clinical samples to be made quantitative. A stringent protocol involving analysis of the purified transcript by PCR (to ensure its freedom from template molecules) is required. Preliminary experiments indicate that IL-5 mRNA levels are elevated in asthmatics.

Base Sequence↗
PubMed1993

Imaging in the catheterization laboratory.

Recent work confirms that visual assessment of the effect of widely employed coronary interventions is highly inaccurate. Rapid and reliable on-line angiographic quantitation is a useful advance, but problems in the application of the technique are encountered in a substantial number of cases. New algorithms have been devised to provide a comprehensive assessment of the geometry and likely functional significance of lesions as well as an objective evaluation of lesion morphology, and recent work has provided the framework for the quantitation of diffuse disease. Studies with intravascular ultrasound confirm the inadequate sensitivity of angiography in demonstrating mild to moderate atheromatous disease in the presence of vascular remodelling. The complex wall and lumen changes after percutaneous transluminal coronary angioplasty have been extensively studied; features often inadequately identified by angiography--including mural calcification and dissection--appear to affect short- and long-term outcome. The precise clinical utility of intravascular ultrasound is a critically important question that is being addressed by a number of multicenter studies. Current evidence suggests it will become part of a more comprehensive system of coronary assessment, both as the imaging modality of choice in selected indications (such as cardiac allograft arteriopathy) and as an important adjunct to angiography in certain coronary interventions.

Angioplasty, Balloon, Coronary↗
PubMed1993

Coronary artery remodeling in atherosclerotic disease: an intravascular ultrasonic study in vivo.

BACKGROUND: Pathologic studies have revealed that coronary arteries undergo compensatory enlargement in the presence of atherosclerosis. METHODS: In order to assess coronary artery remodeling in vivo, we used intravascular ultrasound to examine 46 patients (36 men and 10 women; aged 58.2 +/- 6.8 years) with non-calcified plaques. The vessel, lumen, and plaque areas of the atherosclerotic and of normal proximal and distal segments were determined. RESULTS: A total of 92 atherosclerotic segments were analyzed. The degree of stenosis ranged from 9.2 to 92.8% (mean 34.1 +/- 16.9%) and the plaque area from 2 to 19.6 mm2 (mean 6.3 +/- 3.6 mm2). The vessel area of the atherosclerotic segment (mean 20.4 +/- 7.3 mm2) was larger than that of the proximal segment (mean 18.7 +/- 7.3 mm2, P = 0.018). The vessel area increased in proportion to plaque area. This relationship can be described using the equation y = 23.5(1-e-0.35x). The difference between the vessel area in the atherosclerotic segment and that in the proximal normal segment correlated with the percentage of stenosis (r = 0.53, P < 0.005) until the degree of stenosis exceeded 45%. CONCLUSION: This study indicates that coronary artery remodeling, previously observed in pathologic studies, can be evaluated using intravascular ultrasound in vivo. As a result of the compensatory enlargement of the vessel, coronary angiography cannot be used to detect or exclude the early signs of coronary atherosclerosis.

Adult↗
PubMed1993

Spontaneous coronary artery dissection: a report of three cases and review of the literature.

We describe the clinical course of three patients who developed spontaneous coronary artery dissection. All patients were young women, one 9 weeks pregnant. All presented with chest pain; one died suddenly proving refractory to resuscitation, another developed unstable angina culminating in myocardial infarction, cardiogenic shock and death, and the third patient underwent coronary artery bypass grafting following diagnosis of a spontaneous coronary dissection of the left anterior descending artery at angiography. Pathological findings in the two fatal cases are reported. This condition, although rare, is a prominent cause of ischaemic coronary events in young women, when it is frequently associated with pregnancy or the puerperium. Most patients die suddenly, but a clinical spectrum is seen including stable and unstable angina, myocardial infarction and cardiogenic shock. The left anterior descending artery is most frequently affected. The classical histological finding is that of a large haematoma occupying the outer third of the media resulting in complete compression of the true lumen. The cause of spontaneous dissection remains unclear but theories of aetiology include a medial eosinophilic angiitis, pregnancy-induced degeneration of collagen in conjunction with the stresses of parturition, and rupture of the vasal vasorum. The diagnosis must be considered when a patient presents with a suggestive clinical profile. Urgent angiography should be undertaken to establish the diagnosis and consideration given to the need for coronary artery bypass grafting, which has been successfully employed in a number of patients. The uneventful long-term survival of cases treated conservatively has been reported.

Adult↗
PubMed1993

Ribozyme-mediated cleavage of the bcr/abl transcript expressed in chronic myeloid leukemia.

The bcr/abl transcript is specifically expressed in the hematopoietic cells of patients with chronic myeloid leukemia (CML). The Haseloff and Gerlach model was used to design a ribozyme targeted to this transcript. When tested against a synthetic substrate covering the translocation sequence, the ribozyme exhibited site specificity and an absolute requirement for divalent metal ions. Cleavage of the normal bcr was also noted but at a reduced efficiency compared to that exhibited for the bcr/abl substrate. Importantly, cleavage of the full-length bcr/abl mRNA was achieved at physiologic temperature, demonstrating effective ribozyme-mediated cleavage.

Base Sequence↗
PubMed1990

A physical map of the human PI and AACT genes.

We have used probes from the human genes PI, PIL, and AACT (alpha 1-antitrypsin, alpha 1-antitrypsin-related sequence, and alpha 1-antichymotrypsin) to make a pulsed-field map of the surrounding region of 14q31-32. We have discovered that the PI-PIL gene cluster is only 220 kb away from the AACT gene and that it is orientated in the opposite direction. The comparatively short distance between the genes comes as a surprise given previous estimates of the level of genetic recombination between them.

Bacterial Proteins↗
PubMed1987

The influence of viscosity on the migration of chloramphenicol and 4-hydroxybenzoic acid through glycerogelatin gels.

Migration of chloramphenicol and 4-hydroxybenzoic acid from solutions in 1-octanol into Glycerol Suppository Base, BP and soft gelatin capsule shells is reported. Rates of migration through the gels, quantified in terms of diffusion coefficients, are given. An electron spin resonance probing technique was used to determine the microscopic viscosity. The latter, rather than the bulk viscosity, was shown to be the major rheological influence on the rate of diffusion.

Chloramphenicol↗