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Biomedical subjects

R Erbel

Publications and source records attributed to R Erbel.

At least 145 records · Page 8Linked to original sources
PubMed2000

Preintervention lesion remodelling affects operative mechanisms of balloon optimised directional coronary atherectomy procedures: a volumetric study with three dimensional intravascular ultrasound.

AIMS: To classify atherosclerotic coronary lesions on the basis of adequate or inadequate compensatory vascular enlargement, and to examine changes in lumen, plaque, and vessel volumes during balloon optimised directional coronary atherectomy procedures in relation to the state of adaptive remodelling before the intervention. DESIGN: 29 lesion segments in 29 patients were examined with intravascular ultrasound before and after successful balloon optimised directional coronary atherectomy procedures, and a validated volumetric intravascular ultrasound analysis was performed off-line to assess the atherosclerotic lesion remodelling and changes in plaque and vessel volumes that occurred during the intervention. Based on the intravascular ultrasound data, lesions were classified according to whether there was inadequate (group I) or adequate (group II) compensatory enlargement. RESULTS: There was no significant difference in patient and lesion characteristics between groups I and II (n = 10 and 19), including lesion length and details of the intervention. Quantitative coronary angiographic data were similar for both groups. However, plaque and vessel volumes were significantly smaller in group I than in II. In group I, 9 (4)% (mean (SD)) of the plaque volume was ablated, while in group II 16 (11)% was ablated (p = 0.01). This difference was reflected in a lower lumen volume gain in group I than in group II (46 (18) mm(3) v 80 (49) mm(3) (p < 0.02)). CONCLUSIONS: Preintervention lesion remodelling has an impact on the operative mechanisms of balloon optimised directional coronary atherectomy procedures. Plaque ablation was found to be particularly low in lesions with inadequate compensatory vascular enlargement.

Adult↗
PubMed2000

Size of emptied plaque cavity following spontaneous rupture is related to coronary dimensions, not to the degree of lumen narrowing. A study with intravascular ultrasound in vivo.

OBJECTIVE: To identify any potential relations between the size of an emptied plaque cavity and the remodelling pattern, plaque or vessel dimensions, lumen narrowing, and other ultrasonic lesion characteristics. DESIGN: Intravascular ultrasound was used to examine prospectively 51 ruptured ulcerated coronary plaques. Cross sectional area measurements comprised lumen, vessel, plaque, and emptied plaque cavity. Lumen narrowing was calculated as 1 - (lesion lumen area/reference lumen area) x 100%. A remodelling index was calculated as lesion vessel area/reference vessel area, and plaques were divided into those with values > 1.05 (group A) and </= 1.05 (group B). RESULTS: Of the total of 51 plaques, 36 (71%) were assigned to group A and 15 (29%) to group B. In neither group was there a significant difference in reference dimensions and lumen narrowing. However, lesion vessel (mean (SD): 22.6 (8.1) mm(2) v 17. 5 (4.3) mm(2); p = 0.006) and plaque areas (15.8 (6.2) mm(2) v 12.8 (3.2) mm(2); p = 0.03) were greater in group A than in group B. The cavity inside the plaque was larger in group A than in group B (2.8 (1.6) mm(2) v 1.8 (0.9) mm(2); p = 0.007) and showed a positive linear relation with lesion and reference vessel size (r = 0.58 and 0.56, respectively; p < 0.001), but not with lumen narrowing. CONCLUSIONS: The size of the emptied cavity inside ruptured plaques is on average larger in lesions with adaptive vascular remodelling, and shows a linear relation with lesion plaque and vessel size and with the reference dimensions, but not with the degree of lumen narrowing.

Adult↗
PubMed2000

Coronary arterial stent patency: assessment with electron-beam CT.

PURPOSE: To evaluate electron-beam computed tomography (CT) for stent localization and noninvasive assessment of stent patency in patients with coronary arterial stents and coronary bypass stents. MATERIALS AND METHODS: CT in the single-section volume mode was performed in 202 patients with 321 coronary arterial stents in 221 vessels to localize the stents. Patency was evaluated in the multisection flow mode with an intravenous bolus injection of contrast material. All electron-beam CT images were reviewed by an observer who had no knowledge of the coronary angiographic results. Electron-beam CT findings were then compared with coronary angiographic findings. RESULTS: The stents could be visualized and related to the coronary arterial segments in 216 of 221 vessels with electron-beam CT. Of the 221 vessels, 207 were correctly evaluated with electron-beam CT. Compared with coronary angiography, electron-beam CT permitted the detection of 18 of 23 high-grade stenoses (sensitivity, 78%) and correctly depicted the absence of high-grade stenoses in 189 of 193 vessels with stents (specificity, 98%). Altogether, 18 stenoses were detected correctly at electron-beam CT; the interpretation was false-positive in four vessels (positive predictive value, 82% [18/22 vessels]) and false-negative in five (negative predictive value, 97% [189/194 vessels]). CONCLUSION: Electron-beam CT may be helpful in localizing intracoronary stents and assessing stent patency noninvasively to delay the intervals between catheterizations in an increasing number of patients.

Adult↗
PubMed2000

Perfusion-contraction mismatch with coronary microvascular obstruction: role of inflammation.

A close relationship exists between regional myocardial blood flow (RMBF) and function during acute coronary inflow restriction (perfusion-contraction matching). However, the relationship of flow and function during coronary microvascular obstruction is unknown. In 12 anesthetized dogs, the left circumflex coronary artery was perfused from an extracorporeal circuit. After control measurements, 3,000 microspheres (42 micrometer diameter) per milliliter per minute inflow were injected to cause a microembolism (ME, n = 6). With unchanged systemic hemodynamics and RMBF, posterior systolic wall thickening (PWT) decreased from 19.8 +/- 1.9% SD at control to 13.3 +/- 4.0, 10.3 +/- 3.8, and 6.9 +/- 4.7% (P < 0.05 vs. control) at 1, 4, and 8 h, respectively. For comparison, inflow was progressively reduced to match PWT to that of the ME group at 1, 4, and 8 h (stenosis, STE, n = 6). RMBF in the STE group was reduced in proportion to PWT. Infarct size was not different among groups (6.5 +/- 4.5 vs. 3.4 +/- 3.2%). However, the number of leukocytes infiltrating the area at risk was significantly greater in the ME group than in the STE group. Coronary microembolization results in perfusion-contraction mismatch and is associated with an inflammatory response.

Anesthesia↗
PubMed2000

Interaction of the ACE D allele and the GNB3 825T allele in myocardial infarction.

In polygenetic disorders, such as ischemic heart disease, the investigation of gene-gene interactions rather than determination of single gene effects is crucial to better understand the contribution of genetic factors. The 825T allele of the G-protein ss(3)-subunit gene (GNB3) associated with enhanced G-protein signaling is a candidate to interact with the angiotensin-converting enzyme (ACE) deletion/insertion (D/I) polymorphism to increase the risk for myocardial infarction (MI). The ACE D:/I variant affects the renin-angiotensin system hormones that activate G-protein-coupled receptors. Genotyping at the ACE and GNB3 loci was performed on 585 patients with coronary artery disease with (n=270) or without (n=315) previous MI. Logistic regression analysis demonstrated a significant interaction between the ACE D: allele and the GNB3 825T allele (P<0.001). The odds ratio for MI, associated with the 825T allele, was not increased in the presence of the ACE II genotype (OR 0.5; P=0.09) but was significantly higher in 825T allele carriers with the ACE DI genotype (OR 1.9; P=0.01) and further increased in individuals with the ACE DD genotype (OR 2.4; P=0.02). The highest odds ratio was found in homozygous 825T allele carriers with the ACE DD genotype (OR 7.5; P=0.006). Our data suggest a significant interaction of the GNB3 825T allele with the ACE D allele in MI. These hypothesis-generating data may justify larger prospective studies.

Aged↗
PubMed2000

Coronary calcification by electron beam tomography: comparison with coronary risk factors and angiography.

The development and progression of coronary artery disease is the result of exposure to a variety of different risk factors. In larger populations, strong associations exist between risk factors and the development of both angiographic and clinical coronary artery disease. But, this relationship is extremely variable in individual subjects. Coronary calcification is a specific marker of coronary artery disease. Its formation and progression is determined by largely identical risk factors compared with angiographic coronary artery disease. Coronary calcification quantitated by electron beam tomography (EBT) thus enables the non-invasive assessment of whether the risk factor exposure has actually led to the development of coronary atherosclerosis in an individual subject. Whereas other non-invasive tests focus on the physiological consequences of coronary obstruction, EBT represents anatomic disease itself. Because the propensity of plaques to cause coronary obstruction partly depends on the degree of arterial remodelling, large plaques may not necessarily appear as high-grade stenoses angiographically. Indeed, angiography and EBT evaluate two facets of atherosclerotic plaque disease, i.e. luminal obstruction and calcified plaque itself. Coronary calcification is strongly associated with the presence, extent, and severity of angiographic coronary artery disease. A number of studies have shown that it is clearly superior in this respect compared with conventional risk factors. However, because of the indirect relationships between plaque formation and luminal obstruction, EBT does not permit the site-specific prediction of coronary stenoses. Recent investigations have focused on the ability of EBT to represent the extent of anatomic coronary artery disease, which is an important predictor of future cardiac events. The availability of a simple, non-invasive test for the direct visualization of coronary artery disease holds great promise regarding improved definitions of the relationships between risk factors and coronary atherosclerosis as well as regarding the diagnosis of non-obstructive coronary disease, which can nevertheless result in acute events.

Calcinosis↗
PubMed1999

Usefulness of motion patterns indentified by tissue Doppler echocardiography for diagnosing various cardiac masses, particularly valvular vegetations.

This study sought to test whether anomalous cardiac and aortic structures can be differentiated from native tissue and artifacts by physical properties of tissue motion using transesophageal tissue Doppler echocardiography (TDE). TDE was employed in 85 consecutive patients after anomalous structures had been detected by conventional transesophageal echocardiography (TEE). The control group consisted of 40 randomized patients. Certainty of diagnosis was divided into 4 categories, and TDE signals were related to particular anomalous structures by a blinded second observer. A mechanical model of a beating ventricle was constructed and suspended in a water bath. Synthetic material was utilized to simulate anomalous intracavitary structures with varying shape, consistency, and attachment. Incoherent motion was present in endocarditic vegetations, freely oscillating thrombi, fourth-degree aortic plaques, Chiari network, valvular prolapse, tumors, and in normal valve leaflets and papillary muscles. Within 15 seconds vegetations could be detected in 17 patients (68%) using TDE versus 5 patients (20%) using only conventional imaging. Coherent motion with a phase difference occurred due to damped oscillation. This phenomenon occurred in 5 patients with thrombi of the left atrial appendage (100%), in 3 ventricular clots (75%), and in 2 hypernephroma in the right atrium (100%). Rapid identification of clots could be achieved in 15 patients (71%) versus 12 patients (57%). Concordant motion was shown in third-degree aortic plaques, postrheumatic valvular lesions, and aortic intramural hematomas, but diagnostic benefit could not be demonstrated. In 41 patients (48%) histopathologic and intraoperative results confirmed echocardiographic findings. Motion patterns could be reproduced independently of the heart rate by model experiments. This study demonstrates that TDE expedites the detection of vegetations in infective endocarditis. Diagnostic certainty can be increased as well for thrombus formations.

Adult↗
PubMed1999

G protein beta3 subunit 825T allele and enhanced coronary vasoconstriction on alpha(2)-adrenoceptor activation.

Recently, alpha(2)-adrenoceptor activation was shown to play an important role in the vasoconstriction of normal coronary arteries, whereas in the presence of atherosclerosis, the activation of both alpha(1)- and alpha(2)-adrenoceptors reduces coronary blood flow in humans. alpha(2)-Adrenoceptors activate pertussis toxin (PTX)-sensitive G proteins, whereas alpha(1)-adrenoceptors couple to PTX-insensitive G proteins. Thus, the 825T allele of the beta3 subunit of heterotrimeric G proteins, associated with enhanced PTX-sensitive G protein signaling, was expected to determine the alpha(2)-adrenoceptor-, but not the alpha(1)-adrenoceptor-, mediated reduction in coronary blood flow (CBF). Genotyping was performed on 48 individuals. Twelve of the 48 received the alpha(1)-adrenoceptor agonist methoxamine (MTX; 5 mg IC), and 12 received the alpha(2)-adrenoceptor agonist BHT 933 (BHT; 5 mg IC). Twenty-four additional individuals received both MTX and BHT during the same investigational procedure. CBF was calculated on the basis of coronary angiography and intracoronary Doppler flow velocity measurement. Drug-related ischemia was assessed on the basis of ST-segment changes and angina pectoris. In response to BHT, but not to MTX, CBF was reduced to a significantly greater extent in 825T allele carriers (58+/-4%, n=16) than in individuals homozygous for the C825 allele (28+/-4%, n=19, P=0.001). This finding was independent of cholesterol levels, mean arterial blood pressure, and the presence or absence of coronary artery disease. Ischemic events in response to BHT occurred more frequently in 825T allele carriers than in homozygous 825C allele carriers (P=0.01). alpha(2)-Adrenoceptor coronary vasoconstriction is genetically determined and significantly enhanced in GNB3 825T allele carriers.

Adrenergic alpha-Agonists↗
PubMed1999

M-mode analysis of mitral annulus motion for detection of pseudonormalization of the mitral inflow pattern.

Left ventricular (LV) diastolic dysfunction is a frequent cause of heart failure. Doppler echocardiography has become the method of choice for the noninvasive evaluation of LV diastolic dysfunction. However, pseudonormalization of mitral inflow often presents a diagnostic problem in clinical practice. We sought to define the role of mitral annulus motion in this setting. We performed echocardiography in 36 consecutive subjects (age 59 +/- 10 years). Eighteen had recently (within 3 months) been diagnosed with coronary artery disease, 18 had clinical suspicion of coronary artery disease, and 15 had symptoms of heart failure (New York Heart Association class 2.4 +/- 0.5). The amplitude (E(M)) and the slope (slope E) of early diastolic motion of the septal mitral annulus were derived from M-mode analysis. Left heart catheterization was performed for direct measurement of LV end-diastolic pressure. Pseudonormalization defined by an E/A ratio > 1 and a LV end-diastolic pressure > or = 16 mm Hg was found in 9 patients. All patients with pseudonormalization were symptomatic (New York Heart Association class 2.8 +/- 0.5). Patients with and without pseudonormalization did not differ with respect to the E/A ratio (1.29 +/- 0.44 vs 1.16 +/- 0.23, p = NS), deceleration time (182 +/- 38 vs 205 +/- 42 ms, p = NS), and isovolumic relaxation time (88 +/- 24 vs 92 +/- 18 ms, p = NS). In the group with pseudonormalization, a significant reduction of E(M) (3.9 +/- 1.6 vs 5.7 +/- 1.5 mm, p = 0.008) and slope E (24.5 +/- 11.8 vs 43.9 +/- 7.7 mm/s, p <0.001) was detected. Using E(M) <4.3 mm and slope E <35 mm/s as cut points, sensitivity and specificity for the detection of pseudonormalization were 66% and 82% for E(M) and 77% and 87% for slope E, respectively. There was no significant relation between LV end-diastolic pressure as a measure of preload and either E(M) (r = 0.44, p >0.5) or slope E (r = 0.30, p >0.2). Thus, E(M) and slope E may be preload-independent tools for assessing LV diastolic dysfunction in symptomatic patients with a pseudonormal mitral inflow pattern and elevated filling pressures.

Adult↗
PubMed1999

Augmented alpha-adrenergic constriction of atherosclerotic human coronary arteries.

BACKGROUND: Although adrenergic activation plays a major role in the initiation of experimental myocardial ischemia, the significance of alpha-adrenergic coronary constriction in humans has been questioned. The present study assessed the impact of selective alpha-adrenergic receptor activation in patients with normal or atherosclerotic coronary arteries. METHODS AND RESULTS: In 39 patients, coronary blood flow (CBF, mL/min) was determined from combined angiography and Doppler measurements. In 8 patients with normal coronary arteries (group 1) and 9 with single coronary artery stenosis (group 2), doses of 1, 2.5, 5, and 10 mg IC of the alpha1-agonist methoxamine (M) were injected. Identical doses of the alpha2-agonist BHT933 (B) were injected in 8 patients with normal coronary arteries (group 3) and 8 with single stenosis (group 4). In 6 additional patients with single stenosis (group 5), aortocoronary sinus lactate differences were measured in response to M and B. CBF remained unchanged in group 1. In contrast, CBF was decreased dose-dependently in group 2, with a maximum at 10 mg M (39.0+/-9.4 versus 15.2+/-7.0). In groups 3 and 4, CBF was also decreased dose-dependently, with a maximum at 10 mg B (63.3+/-24.8 versus 49. 1+/-27.9 and 41.5+/-19.0 versus 12.7+/-8.0, respectively). In group 5, there was more net lactate production with B than with M (-0. 34+/-0.11 versus -0.04+/-0.09 mmol/L). CONCLUSIONS: In normal coronary arteries, alpha1-adrenergic activation does not reduce CBF, whereas alpha2-adrenergic activation reduces CBF by microvascular constriction. Both alpha1- and alpha2-adrenergic epicardial and microvascular constriction are augmented by atherosclerosis and can induce myocardial ischemia.

Adrenergic alpha-Agonists↗
PubMed1999

Can right-sided atrioventricular sequential pacing provide benefit for selected patients with severe congestive heart failure?

This study reports on the methods and results of applying right-sided atrioventricular (AV) pacing in 26 patients with advanced cardiomyopathy. Ten of these patients had ischemic cardiomyopathy. Of the 16 patients with nonischemic cardiomyopathy, 10 were idiopathic and 6 were due to secondary causes. The patients had a mean age of 56 +/- 12 years and a left ventricular ejection fraction of 26 +/- 11%. Two transvenous stimulation electrodes were temporarily placed in the high right atrium and right ventricle, respectively. A Swan Ganz catheter was positioned into the pulmonary artery to determine cardiac output by the thermodilution method and to measure the pressure in the pulmonary artery and right atrium. In addition, aortic pressure was measured through a catheter sheath via the right femoral artery. Systemic and pulmonary vascular resistance were calculated. Stimulation was performed in VVI and DDD pacing modes using different AV intervals (40, 80, 125, 150, 175, 200, and 250 msec). No increase of cardiac output was observed for the overall study cohort (p = 0.51). At VVI pacing, stroke volume significantly decreased from 66 +/- 20 mL to 53 +/- 13 mL (p < 0.01). We distinguished between responders who developed an increase of cardiac output of > 1 L/min (n = 12, 46%) and nonresponders (n = 14, 54%). Etiology of either ischemic or nonischemic cardiomyopathy for responders, as well as conduction disturbances (first-degree AV block, LBBB, RBBB), were equally distributed among both groups. Using an AV delay of 150 and 175 msec, responders to DDD pacing derived a significant increase in cardiac output. An AV delay of 150 msec produced both a significant increase of stroke volume and decrease of systemic vascular resistance. In 46% of patients with dilated cardiomyopathy of either ischemic or nonischemic origin, right-sided AV-sequential pacing brought about an improvement of left ventricular function in terms of enhanced cardiac output. We suggest individual testing in all patients with severe left ventricular dysfunction to find responders.

Adult↗
PubMed1999

[Shy-Drager syndrome: a rare cause of orthostatic hypotension].

HISTORY AND ADMISSION FINDINGS: A 71-year-old man was admitted because of treatment-resistant orthostatic hypotension of unknown aetiology. When aged 64 years he developed some impotence and later urinary incontinence and urinary frequency. At 68 years he noted vertigo on physical activity, and a year later he had signs of reversible cerebral ischaemia. At this point the Schellong test demonstrated vasovagal circulatory dysfunction. After his 70th birthday the unsteadiness on walking and standing got worse and he had recurrent syncopes. He was in a wheel-chair when hospitalized and even the unsteady walk he could maintain for only a few seconds. INVESTIGATIONS: Plasma and urinary concentrations of catecholamines were at the lower limit of normal but failed to increase during orthostasis. Hormonal, cardiological and infectious causes of the orthostatic hypotension were excluded. Orthostatic tests after Schellong and with the tilting table showed orthostatic hypotension without increased sympathetic activity but hypertensive blood pressure levels during the recumbent period. Intravenous infusion of norepinephrine produced an excess rise in blood pressure (raised norepinephrine sensitivity). The recurrent urinary infection was shown to be due to a hypotonic bladder detrusor muscle. Neurological examination revealed cerebellar dysfunction, signs of pyramidal tract abnormality and sensory polyneuropathy. A Shy-Drager syndrome was diagnosed on the basis of the history, absent blood pressure rise and lack of catecholamine release during orthostasis with increased epinephrine sensitivity and characteristic neurological signs. TREATMENT AND COURSE: Physiotherapy and elastic stockings with administration of mineralocorticoids as well as of one direct (norfenefrine) and one indirect (amezinium) sympathomimetic drug failed to improve adequately the abnormal orthostatic response. But on additional administration of an alpha 2-receptor antagonist (yohimbine) the patient was able to stand and walk for a few minutes, but the urinary incontinence and the other neurological signs remained treatment-resistant. CONCLUSION: If orthostatic hypotension occurs together with neurological symptoms, a Shy-Drager syndrome should be taken into account.

Adrenergic alpha-Antagonists↗
PubMed1999

Stepwise intravascular ultrasound (IVUS) guidance of high-pressure coronary stenting does not result in an improved acute or long-term outcome: a randomized comparison to "final-look" IVUS assessment.

The objective of this study was to evaluate the potential benefit of stepwise intravascular ultrasound (IVUS)-guided coronary stent deployment compared to angiographic stent implantation with final IVUS assessment only. Acute procedural success and 6-month angiographic follow-up were compared in both groups. Intravascular ultrasound was performed using a 20- or 30-MHz mechanically rotated catheter in 85 patients who were prospectively randomized to group A (n=42; IVUS-guided) and group B (n=43; angiography +/- final IVUS assessment). There was no difference in the number of stents implanted (1.5+/-0.9 stents/lesion in group A and 1.3+/-0.6 stents/lesion in group B), the duration of the procedure, or the amount of contrast medium used. Defined criteria of optimal stent deployment (stent apposition, stent symmetry, complete coverage of dissections, >90% in-stent lumen area/reference lumen area) were achieved in 54.2% in group A and 56.6% in group B (NS). Angiographic follow-up was 87.1% at 6+/-2 months, and clinical follow-up was 100% at 8+/-1 months. There was no significant difference in restenosis rate (33.3% vs. 34.9%) applying a binary >50% diameter stenosis criterion for both groups. There was no significant difference in minimal in-stent lumen area at both baseline (7.91+/-2.64 mm2 vs. 7.76+/-2.21 mm2) and follow-up (5.84+/-2 mm2 vs. 5.52+/-1.87 mm2). With regard to immediate procedural lumen gain and rate of restenosis, multiple IVUS examinations during the procedure showed no advantage compared to final IVUS assessment only.

Coronary Angiography↗
PubMed1999

A new thrombectomy catheter device (AngioJet) for the disruption of thrombi: An in vitro study.

In this study we examined a new thrombectomy catheter device. Different kinds of in vitro generated thrombi and cadaver thrombi were disrupted in test tubes. The mean disruption rate (and disruption time for 1 g of thrombus) was 225 +/- 65 mg/sec (5 +/- 2 sec) for whole-blood, 117 +/- 60 mg/sec (12 +/- 9 sec) for fibrin, 41 +/- 18 mg/sec (30 +/- 18 sec) for mixed, 70 +/- 42 mg/sec (17 +/- 5 sec) for unorganized, 45 +/- 8 mg/sec (22 +/- 4 sec) for partly, and 5 +/- 1 mg/sec (216 +/- 29 sec) for completely organized cadaver thrombi (P < 0.05). More than 99% of fragmented particles of whole-blood thrombi were 0-12 microm in diameter. The particle size of fibrin, mixed, and cadaver thrombi was similar, with 25%-40% of particles between 0-12 microm, 55%-71% >12-24 microm, and 2%-7% >24 microm. The device may be effectively used in the therapy of massive pulmonary embolism or acute peripheral and coronary artery syndromes when medical thrombolysis is contraindicated and organization of thrombus is absent. Further studies need to be performed to investigate the potential effects of particle microembolization. Cathet. Cardiovasc. Intervent. 47:381-389, 1999.

Cadaver↗
PubMed1999

Early clinical experience with the implantation of a novel synthetic coronary stent graft.

Coating stents with autologous venous grafts has been suggested to prevent problems associated with conventional stenting, but the need for surgical vessel harvest hampered broad application. A novel synthetic coronary stent graft (CSG) overcomes this limitation by a synthetic membrane, fixed between two thin metallic stents. We successfully implanted 21 CSGs in 18 patients for treatment of acute coronary rupture, thrombus-containing lesions, and lesions with plaque rupture or adjacent pseudoaneurysm. Substantial residual angiographic diameter stenoses were seen in seven CSGs (25% +/- 10% vs. 8% +/- 6%; P < 0.01), which were implanted with relatively small balloon catheters (balloon-to-artery ratio 1.00 +/- 0.09 vs. 1.24 +/- 0.18; P = 0.01) and required postdilatation. Overall, the largest balloon catheter applied measured 4.0 +/- 0.7 mm (balloon-to-artery ratio 1.21 +/- 0.20) and the inflation pressure was 16 +/- 3 atm. Final intravascular ultrasound imaging demonstrated adequate and symmetrical expansion of the CSG (> or = 85% +/- 15% of the reference lumen). Elective implantation was associated with two small non-Q-wave myocardial infarctions, resulting from unavoidable occlusions of side branches. Thus, implantation of CSG is feasible and safe. Adequate expansion can be achieved by the use of relatively large low-compliant balloon catheters inflated with high pressure.

Angioplasty, Balloon, Coronary↗
PubMed1999

Minimally invasive evaluation of coronary stents with electron beam computed tomography: In vivo and in vitro experience.

We sought to describe the value of electron beam computed tomography (EBCT) to detect stent restenoses at follow-up and to identify characteristic EBCT features of coronary stents. Six coronary stents (GRII, Jostent, NIR, PS, Micro, Wiktor) were scanned in vitro (10 1. 5-mm-thick slices, 15-cm FoV, 100-ms AT) before and after inflation with 3.0-, 3.5-, and 4.0-mm balloons to study intensity values and different stent dimensions in comparison to caliper measurements. In 44 patients (60 +/- 10 years, 4 females) we prospectively compared EBCT findings [eight 8-mm-thick slices in the flow mode, 26-cm field of view (FoV), 50 ms acquisition time (AT)] with 6-month angiographic outcome after placement of 86 stents in 49 vessels. For the detection of significant angiographic luminal narrowing (>/=75%) that occurred in 17/49 vessels (35%), we found a sensitivity of 65%, a specificity of 84%, and a positive and negative predictive value of 69% and 82%, respectively. The in vitro data show significant differences in image intensity between the stents and a significant gradual decrease in image intensity with increasing stent diameters. The mean differences between EBCT and caliper measurements for the length and diameter were 0.17 +/- 0.18 mm and -0.32 +/- 0.25mm, respectively. EBCT is currently the only noninvasive technique that allows the assessment of stent dimensions and stent geometry, which may prove useful in patients when intravascular ultrasound cannot be performed. Contrast-enhanced EBCT is a promising tool for minimally invasive stent patency evaluation at follow-up, especially in patients that are unable to exercise. Cathet. Cardiovasc. Intervent. 48:39-47, 1999.

Coronary Angiography↗