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Biomedical subjects

M Haude

Publications and source records attributed to M Haude.

At least 91 records · Page 5Linked to original sources
PubMed1997

Prognostic value of intracoronary flow velocity and diameter stenosis in assessing the short- and long-term outcomes of coronary balloon angioplasty: the DEBATE Study (Doppler Endpoints Balloon Angioplasty Trial Europe).

BACKGROUND: The aim of this prospective, multicenter study was the identification of Doppler flow velocity measurements predictive of clinical outcome of patients undergoing single-vessel balloon angioplasty with no previous Q-wave myocardial infarction. METHODS AND RESULTS: In 297 patients, a Doppler guidewire was used to measure basal and maximal hyperemic flow velocities proximal and distal to the stenosis before and after angioplasty. In 225 patients with an angiographically successful percutaneous transluminal coronary angioplasty (PTCA), postprocedural distal coronary flow reserve (CFR) and percent diameter stenosis (DS%) were correlated with symptoms and/or ischemia at 1 and 6 months, with the need for target lesion revascularization, and with angiographic restenosis (defined as DS > or = 50% at follow-up). Logistic regression and receiver operator characteristic curve analyses were applied to determine the prognostic cutoff value of CFR and DS separately and in combination. Optimal cutoff criteria for predictors of these clinical events were DS, 35%; CFR, 2.5. A distal CFR after angioplasty > 2.5 with a residual DS < or = 35% identified lesions with a low incidence of recurrence of symptoms at 1 month (10% versus 19%, P=.149) and at 6 months (23% versus 47%, P=.005), a low need for reintervention (16% versus 34%, P=.024), and a low restenosis rate (16% versus 41%, P=.002) compared with patients who did not meet these criteria. CONCLUSIONS: Measurements of distal CFR after PTCA, in combination with DS%, have a predictive value, albeit modest for the short- and long-term outcomes after PTCA, and thus may be used to identify patients who will or will not benefit from additional therapy such as stent implantation.

Aged↗
PubMed1997

Coronary artery calcium in acute coronary syndromes: a comparative study of electron-beam computed tomography, coronary angiography, and intracoronary ultrasound in survivors of acute myocardial infarction and unstable angina.

BACKGROUND: Quantification of coronary artery calcified plaques by electron-beam CT (EBCT) may predict cardiovascular events. However, whereas advanced coronary atherosclerotic plaques can be identified, mildly stenotic lipid-rich (soft) plaques may be difficult to detect. The value of EBCT in a subgroup of patients has therefore been questioned. To investigate this, we evaluated patients with acute coronary syndromes by EBCT and compared the results with coronary angiography and, in patients with an indeterminate angiogram, intracoronary ultrasound (ICUS). METHODS AND RESULTS: EBCT was performed in 118 consecutive patients (57+/-11 years of age) with previous myocardial infarction (n=101) or unstable angina (n=17). A standard protocol requiring a CT density >130 Hounsfield units in an area > or =1.03 mm2 was used for the definition of coronary artery calcium. We found that 110 patients had moderate to severe coronary artery disease by coronary angiography, and 8 had either mildly stenotic plaques at a single site (4 patients, confirmed by ICUS) or nonatherosclerotic causes of the unstable coronary syndrome (4 patients). One hundred and five of the 110 patients (96%) with moderate to severe angiographic disease but only 1 of the 8 other patients (13%) had a positive EBCT. Patients with acute coronary syndromes and negative EBCTs were significantly younger than patients with positive EBCTs (46+/-12 versus 58+/-10 years, P<.001), and a higher percentage was actively smoking (100% of the smokers versus 46%, P<.05). CONCLUSIONS: The vast majority of patients with acute coronary syndromes and at least moderate angiographic disease have identifiable coronary calcium by EBCT. Those patients with negative EBCTs have minimal or no atherosclerotic plaque formation. They are younger and tend to be active cigarette smokers.

Acute Disease↗
PubMed1997

[Treatment of a large intracoronary thrombus with urokinase and a chimeric monoclonal platelet aggregation inhibitor].

HISTORY AND CLINICAL FINDINGS: 7 days after an operation for intervertebral disc prolapse a 43-year-old man was referred with the clinical and ECG signs of an acute posterior wall myocardial infarction. INVESTIGATIONS: Creatine kinase (CK) activity was raised to 204 U/I (myocardial-specific isoenzyme CKMB of 23.6 U/I, 11.6% of total) and glutamic-oxalate transferase (GOT) activity to 37 U/I. Emergency cardiac catheterisation, performed 4 hours after renewed onset of precordial pain showed no abnormal findings in the right coronary artery, despite the ECG signs, but a definite filling defect in the anterior interventricular branch, which on intravascular ultrasound was an echo-dense noncalcified structure. TREATMENT AND COURSE: After percutaneous transluminal coronary angioplasty in the area of the obstructing structure a free-floating mass was identified in the proximal part of the anterior interventricular branch, most likely a thrombus. Intercoronary thrombolysis was therefore undertaken with urokinase (bolus of 1 mill. IU) together with the chimeric monoclonal antibody c7E3, which inhibits platelet aggregation by blocking the platelet glycoprotein surface receptor IIb/IIIa. Coronary angiography 12 hours later revealed almost complete dissolution of the previously obstructing mass. CONCLUSION: Combining the platelet aggregation inhibitor c7E3 with a thrombolytic agent is an alternative treatment to the current management of intracoronary thrombi. Intravascular ultrasound is a suitable method for demonstrating angiographically inconspicuous or unclear but pathogenetically significant vessel changes.

Abciximab↗
PubMed1997

High-volume nonionic dimeric contrast medium: first experiences during complex coronary interventions.

Interventional cardiology is a rapidly developing field of medicine with annually increasing numbers of coronary interventions. Especially through the development of alternative techniques for coronary angioplasty, new indications have been found and more difficult lesions are tackled. Inevitably, such complex interventions are time-consuming and require high amounts of contrast medium. Newer, mostly nonionic agents have been developed with improved tolerability as well as fewer cardiac and renal side effects due to their nonionic, hydrophilic structure, and their osmolality isotonic to plasma. This study sought to investigate the effects of high-volume nonionic, dimeric contrast medium during coronary interventions with special emphasis on renal and hemodynamic side effects during routine hospital stays. Retrospectively, 25 consecutive patients (age 56 +/- 10 yr) with normal renal and cardiac function receiving > 500 ml of the nonionic dimeric contrast medium iodixanol during complex coronary interventions were analyzed. The analysis was based on serum creatinine levels 1 day before and 2 days after contrast medium administration for the monitoring of renal function. Additionally, heart rate and left ventricular pressures were evaluated before and after left ventricular angiography. Mean serum creatinine rose from 0.9 +/- 0.2 mg/dl to 1.1 +/- 0.2 mg/dl (P < 0.05) after 2 days of coronary intervention. Heart rate, left ventricular systolic pressure, and left ventricular end-diastolic pressure did not change significantly. No major side effects were encountered in the short follow-up period of 2 days. Based on this retrospective analysis, high-volume nonionic, dimeric contrast medium administration in patients without preexisting renal insufficiency is associated with little impairment of renal function, and has only minor hemodynamic and general side effects. Iodixanol 320 mg I/ml is well-tolerated and effective for the use of cardioangiography. Given the limitations of this retrospective analysis, future prospective studies should systematically address the effects of high-volume contrast medium administration in otherwise healthy patients as well as in high-risk patients undergoing coronary interventions.

Aged↗
PubMed1997

[Laser angioplasty and recanalization].

Percutaneous transluminal coronary balloon angioplasty (PTCA) still is the most frequently applied interventional technique for treatment of coronary artery disease. Plastic deformation of the obstructive plaque with creation of splits, intimal tears and dissections is the main mechanism of PTCA for lumen widening. As a result, acute complications due to flow limiting dissections and acute vessel closure can unpredictably occur resulting in myocardial infarction, urgent bypass surgery and death. Furthermore, long-term success of PTCA is limited by restenosis. In order to overcome these limitations of PTCA, alternative interventional techniques were developed, which instead of deforming the obstructive plaque ablate this tissue. These techniques include high and low speed rotational angioplasty, directional atherectomy, the transluminal extraction catheter, ultrasound angioplasty and laser (Light Amplification by Stimulated Emission of Radiation) angioplasty. 308 nm XeCl excimer laser angioplasty today is the laser technique of choice for clinical application. This pulsed laser requires direct contact to the obstructive plaque. It creates fast (< 200 microseconds) expanding gas bubbles which induce plaque ablation. Main indications for 308 nm XeCl excimer laser angioplasty are diffuse and long coronary lesions and total coronary occlusions. Despite promising initial results this technique showed no better acute and long-term results in comparison to PTCA for the treatment of these types of lesions ("Amsterdam-Rotterdam" Study, "Excimer Rotational Balloon Angioplasty Comparison" Study). As a result, this interventional technique was rarely applied for patient treatment. More recently, the concept of plaque ablation by 308 nm XeCl excimer laser angioplasty was renewed for the treatment of in-stent restenosis. This indication is being investigated in the "Laser Angioplasty of Restenosed Stents" trial. First results document the practicability and safety of this approach. Long-term results are awaited. With ongoing miniaturization, laser guidewires were developed for the recanalization of chronic total occlusions. The randomized multicenter "Total Occlusion Trial with Angioplasty assisted by Laser guidewire "Study documented a success rate of laser wire recanalization in up to 66% in contrast to 47.5% for mechanical wires only. Long-term results are still awaited. Technical and procedural progress including saline flush during laser application, homogeneous light distribution and the concept of smooth laser ablation is pushed foreward to make excimer laser angioplasty safer, more predictable and more effective.

Angioplasty, Balloon, Coronary↗
PubMed1997

[New developments in parameter-oriented roentgen densitometry perfusion analysis within the scope of heart catheter studies].

X-ray densitometric evaluation of digital subtraction coronary arteriograms allows a qualitative and quantitative detection of contrast medium propagation through the epicardial coronary arteries, the capillary system and the coronary venous system. So-called "time-density-curves" (TDCs) can be generated following Lambert-Beer's law similar to indicator dilution curves by using contrast medium as the indicator. Several time and density parameters can be derived from these TDCs, which are related to local myocardial perfusion. Different animal validation studies have shown the applicability of this concept for in-vivo evaluation of coronary blood flow and myocardial perfusion. Nevertheless, absolute measurement of volumetric coronary blood flow or myocardial perfusion failed. Therefore, relative changes in coronary blood flow or myocardial perfusion in response to pharmacologically induced maximum hyperemia were measured and coronary or myocardial perfusion reserve was calculated as the ratio of hyperemic flow or perfusion divided by baseline values. Despite theoretical attractions for an application during routine cardiac catheterization, this densitometric approach did not get a wide acceptance. Primary reason for this limited use in specialized centers was the time consuming process of densitometric evaluation of the subtraction coronary arteriograms, which require digital cine angiography and necessitates enormous computer hard ware. This main limitation has been overcome since more powerful computer hard ware (processor speed, hard disk space, digitization boards) has become rapidly available during the last years at more moderate pricing and digital techniques today are state of the art in cardiac catheterization laboratories. In addition, soft ware program packages allowed an automatization of the digitization and densitometric evaluation process. These programs include ECG triggered cine image digitization with improved temporal resolution, semiautomatic definition of regions-of-interest including definition of reference regions-of-interest for the detection of background density changes and quality-controlled densitometric parameter analysis. This progress made an application during routine cardiac catheterization feasible. In animal validation studies this improved X-ray densitometric approach for evaluation of local myocardial perfusion was validated versus colour-coded microsphere techniques. The time parameter "rise time", defined as the time from the start of local contrast medium induced density change to its maximum revealed a close correlation (r2 = 0.965) to the results of the microsphere technique over a wide range of perfusion. We have applied this technique before and after coronary interventions such as balloon angioplasty and stenting. Results documented an improvement of poststenotic myocardial perfusion reserve immediately after coronary balloon angioplasty and an additional improvement after adjunct coronary stenting. Only after stenting but usually not after coronary balloon angioplasty alone poststenotic myocardial perfusion reserve gained the intraindividual reference level, measured in a perfusion bed supplied by an epicardial coronary artery without stenoses. These results documented the functional benefit of coronary stenting on poststenotic myocardial perfusion in addition to the well known morphologic benefit with the creation of a larger and more circular conduit.

Absorptiometry, Photon↗
PubMed1997

[Emergency stent implantation in the area of extensive muscle bridging of the anterior interventricular ramus after post-interventional dissection].

In a 64-year-old male patient with severe angina pectoris (CCS III) a systolic compression caused by a coronary muscle bridging in the left anterior descending artery could be detected by coronary angiography. Intravascular ultrasound (IVUS) as well as intracoronary Doppler examination showed a significant systolic reduction of the cross-sectional luminal area of 35.9% and a reduced coronary flow velocity ratio (CFVR) of 2.6. Two highly significant stenosis were detected proximal and distal of the muscle bridge. Percutaneous transluminal coronary angioplasty was performed at the distal lesion, resulting in a flow reducing dissection, and therefore subsequently a stent implantation was performed. Since the transition between the stent and the muscle bridge showed a severe flexion with continued systolic compression of the vessel, two further stents were employed to reinforce the entire area of the muscle bridging. A fourth stent was implanted in the proximal lesion. In the following angiographic and IVUS examinations a systolic compression was not detectable and the CFVR increased to 3.3. In the 6 months follow-up coronary angiography a restenosis in the stented area by intimal hyperplasia could be observed. However, IVUS showed all stents to be circular and fully expanded without signs of compression by the muscle bridge.

Aortic Dissection↗
PubMed1997

Comparison of electron beam computed tomography with intracoronary ultrasound and coronary angiography for detection of coronary atherosclerosis.

OBJECTIVES: This analysis compared the results of electron beam computed tomography (EBCT) with those of coronary angiography and intracoronary ultrasound (ICUS) for the in vivo detection of coronary atherosclerotic plaques. BACKGROUND: EBCT is a new imaging modality for identification of coronary calcifications. Coronary angiography depicts advanced changes in coronary morphology, whereas ICUS is an established diagnostic tool that detects the early stages of coronary artery disease. METHODS: In 57 patients (54 +/- 9 years old), 267 coronary segments were analyzed with EBCT (3-mm slices, acquisition time 100 ms, threshold definition of coronary calcification at 130 Hounsfield units in an area > or = 1 mm2, Agatston calcium score), coronary angiography and ICUS. The analysis was based on the number and extent of coronary calcifications on EBCT, coronary lumen reduction on coronary angiography and plaque formation with and without ultrasound signs of calcifications on ICUS. RESULTS: Compared with coronary angiography, EBCT yielded a sensitivity of 66%, a specificity of 78%, a positive predictive value of 39% and a negative predictive value of 91%. Compared with ICUS, EBCT yielded an overall sensitivity of 66%, a specificity of 88% and an overall accuracy of 81%. For plaques with and without ultrasound signs of calcifications, the sensitivity of EBCT was 97% and 47%, specificity 80% and 75% and overall accuracy 82% and 69%, respectively. CONCLUSIONS: This in vivo correlation between ICUS and EBCT demonstrates that EBCT is a noninvasive method that helps to visualize the atherosclerotic process by localization and quantification of coronary artery calcifications. EBCT detects calcified plaques with high accuracy. Plaques without ultrasound signs of calcifications can be detected by EBCT but with lower sensitivity but equivalent specificity.

Adult↗
PubMed1997

Stress echocardiography: new techniques.

Stress echocardiography is frequently used to evaluate coronary artery disease, and also in quantitative assessment of right and left ventricular function or cardiac valve integrity in patients with cardiomyopathy or during chemotherapy. Various new ultrasound techniques in stress echocardiography are now playing a significant role in this important area of cardiological diagnostics. New methods of echocardiographic signal processing have been developed to provide more quantitative and reproducible information on cardiac function during stress. The most important are: (1) raw data analysis techniques for endocardial border detection (acoustic quantification, CK = colour kinesis), (2) tissue Doppler imaging for myocardial velocity analysis and (3) transpulmonary contrast agents (Albunex, Laevovist, BY 963) for improving endocardial border delineation and for future analysis of myocardial perfusion. Like all new techniques, they must first be subjected to comprehensive scientific assessment, and appropriate training should be given, taking into account physical and physiological limits. These limits will constantly be redefined as echocardiographic techniques continue to change presenting new challenges for the further development of ultrasound technology. In this review, the improved new techniques will be discussed in detail.

Animals↗
PubMed1997

A prognostic computer model to predict individual outcome in interventional cardiology. The INTERVENT Project.

It is not yet possible to predict an individual's outcome from percutaneous transluminal coronary angioplasty or alternative/adjunctive coronary interventional techniques. The purpose of the INTERVENT project is to redefine complications associated with coronary interventions, to set up a prognostic computer model to predict individual outcome and to compare the results to those of conventional statistical techniques. 2500 data items were analysed in 455 consecutive patients (mean age: 61.1 +/- 8.3 years; range 33-84 years; 80.4% male, 16.7% unstable angina, 5.1%/10.1% acute/subacute myocardial infarction) undergoing coronary interventions at three university centres. In-lab/out-of-lab complication rates were 0.4%/0.9% (death), 1.8%/0.2% (abrupt vessel closure with myocardial infarction) and 5.5%/4.0% (haemodynamic complications). Computer algorithms derived by applying techniques from artificial intelligence were able (1) to reduce the set of possible relevant risk factors from 2500 to about 40, (2) to predict individual risk with an accuracy of > 95% and (3) to explain the structural relationship between outcome and risk factors. Patient data from two centres were used to construct and test the algorithm. Data from a third centre were used to evaluate the algorithm. The most important predictors-were acute myocardial infarction, heart failure (NYHA class > II), unstable angina, complex lesions, high low density lipoprotein cholesterol and duration of coronary heart disease. Neither age nor gender impaired the percutaneous transluminal coronary angioplasty results in acute ischaemic syndromes; however, for stable angina, procedural risk increased with age. There was little risk from primary percutaneous transluminal coronary angioplasty in acute myocardial infarction in patients with NYHA heart failure classes I-II; however, the risk was high for patients in NYHA classes > II, either with or without additional thrombolysis. Alternative/adjunctive intervention techniques were no predictors for in-lab-, but were predictors for post-procedural complications.

Adult↗
PubMed1996

Comparison of myocardial perfusion reserve before and after coronary balloon predilatation and after stent implantation in patients with postangioplasty restenosis.

BACKGROUND: Stents provide a scaffold for coronary arteries after angioplasty and inhibit elastic recoil. METHODS AND RESULTS: In 25 patients with postangioplasty restenosis of the left anterior descending artery, ECG-gated digital subtraction coronary angiograms were recorded at baseline and during hyperemia (12 mg papaverine IC) before and after balloon predilatation (PTCA), after implantation of a Palmaz-Schatz stent, and after 6 months. Densitometric evaluation revealed different time and density parameters to calculate two definitions of myocardial perfusion reserve (MPR1 and MPR2) and maximum flow ratio (MaxFR). Poststenotic MPR1 increased from 1.57 +/- 0.14 to 2.59 +/- 0.86 after PTCA and to 3.10 +/- 0.41 after stenting, with 2.90 +/- 0.65 at follow-up (ANOVA, P < .05), while reference MPR1 remained unchanged at 3.10 +/- 0.40. Poststenotic MPR2 increased from 1.36 +/- 0.28 to 2.50 +/- 1.20 and to 3.40 +/- 0.58, respectively, with 3.20 +/- 0.92 at follow-up (ANOVA, P < .05), while reference MPR2 remained unchanged at 3.40 +/- 0.60. MaxFR was 2.13 +/- 0.53 after PTCA, elasticity 2.83 +/- 0.35 after stenting, and 2.73 +/- 0.58 at follow-up (ANOVA, P < .05). A good correlation was found between minimal stenotic luminal diameter and MPR1 or MPR2 (r = .87 and r = .94) and between luminal gain and MaxFR (r = .75). A negative correlation was measured between recoil and MPR1, MPR2, and MaxFR (r = -.80, r = -.86, and r = -.83). At follow-up, a steeper correlation was found between MPR and minimal stenosis diameter (MPR1: slope, 0.52 versus 0.91; MPR2: slope, 1.48 versus 1.95) and between MaxFR and net lumen gain (slope, 0.78 versus 1.27). CONCLUSIONS: Coronary stent implantation in patients with postangioplasty restenosis normalized poststenotic myocardial perfusion immediately as a result of a larger postprocedural lumen and a more pronounced inhibition of elastic recoil. After 6 months this benefit was sustained despite progressive lumen loss.

Absorptiometry, Photon↗
PubMed1996

Non-invasive assessment of coronary Palmaz-Schatz stents by contrast enhanced electron beam computed tomography.

UNLABELLED: The aim of the study was the evaluation of electron beam computed tomography as a non-invasive method to localize coronary stents and to document patency in stented vessel segments. METHODS: Twenty-two patients (16m/6f, 58 +/- 7.8 years) with coronary Palmaz-Schatz stents were examined. Contrast enhanced electron beam computed tomography using an Evolution scanner (Siemens) and coronary angiography were carried out within 7 days of each other. Stent localization was performed using the single-slice mode of the electron beam computed tomography scanner. Patency of the coronary target segment was assessed using the multi-slice mode after peripheral venous injection of a 40 ml bolus of contrast medium (Ultravist 370). Qualitative image analysis of a cine loop of 10 consecutive frames and quantitative analysis of densitometric curves in a region of interest distal to the stented vessel segment were performed. RESULTS: All stented vessel segments were identified. In 20 patients (91%), qualitative assessment of contrast enhancement patterns enabled stent patency to be evaluated. In 18 patients (90%), contrast medium was visualized distal to the stent. Quantitative coronary angiography confirmed that the stented vessel segments were not stenosed. Densitometric curves obtained in 16 of these 18 patients yielded contrast enhancement distal to the stented vessel segment of 63 +/- 6% compared to the aorta. In one patient, qualitative and quantitative analysis showed prolonged contrast enhancement of reduced density, which hinted at a stenosis related to the stented vessel segment. Coronary angiography revealed subtotal occlusion of the stented vessel directly distal to the stent. In another patient, no contrast visualization of the vessel distal to the stent was achieved. Coronary angiography revealed complete stent occlusion in this case. CONCLUSION: Electron beam computed tomography can reliably localize coronary stents and may become a useful tool for providing information on stented vessel segment patency.

Adult↗
PubMed1996

Value of intracoronary ultrasound and Doppler in the differentiation of angiographically normal coronary arteries: a prospective study in patients with angina pectoris.

BACKGROUND: A substantial proportion of patients undergoing heart catheterization for suspected coronary artery disease have normal angiograms. Coronary morphology and blood flow velocity can be assessed very accurately with intracoronary ultrasound and Doppler. The purpose of this study was to use both methods to classify further patients with suspected coronary artery disease but with coronary angiograms adjudged normal at the time. METHODS AND RESULTS: In forty-four patients with suspected coronary artery disease and normal coronary angiograms, intracoronary ultrasound and intracoronary Doppler were performed in the left anterior descending and left main coronary arteries. Coronary flow reserve was obtained by calculating the ratio of the maximal coronary flow mean velocity after the intracoronary administration of 10 mg papaverine to the coronary flow mean velocity at rest. Of 44 patients, 16 (36%) (group I) were found to have normal coronary morphology by intracoronary ultrasound and normal (> 3.0) coronary flow reserve (5.3 +/- 1.8). In seven patients (16%) (group II) there were normal intracoronary ultrasonic findings but a reduced coronary flow reserve (2.1 +/- 0.4). Plaque formation was found in a total of 21 (48%) of the 44 patients; mean plaque sizes were 3.6 +/- 1.6 mm2 for those in group III (normal coronary flow reserve) and 5.0 +/- 2.3 mm2 for those in group IV (reduced coronary flow reserve). Vessel area in both of these groups (16.3 +/- 8.0 mm2 and 19.2 +/- 6.1 mm2) was significantly larger than that of group I (14.6 +/- 5.7 mm2, P < 0.01). Plaque calcification was found in 25% of those in group III and 44% of those in group IV. Thus, only 36% of the patients with normal angiograms were true normal, 48% exhibited early stage of coronary atherosclerosis, and the other 16% might be considered as syndrome X. CONCLUSION: Intracoronary ultrasound and Doppler can be used to differentiate further heart disease in patients with normal coronary angiograms. Only a minority were true normal. Early signs of atherosclerosis cannot be detected by coronary angiography. This may have important therapeutic and prognostic implications.

Adult↗
PubMed1996

Intravascular ultrasound for evaluation of coronary arteries.

Intravascular ultrasound (IVUS) has emerged form a research tool to an intrinsic part of modern invasive cardiology. The main reason is the capability to obtain "in vivo" histology. For the first time it is possible to base decisions not only on lumenograms but also on vessel wall assessment. The capabilities of IVUS can be divided in its (a) diagnostic and (b) intervention associated potentials. Diagnostic strength of IVUS is the ability to monitor compensatory coronary artery enlargement as a response to arteriosclerosis, to assess intermediate lesions, to reveal occult left main stem disease, and angiographycally "silent" arteriosclerosis. The intervention associated potentials of IVUS are the ability to allow optimal device selection, i.e. rotablators in calcified lesions or atherectomy devices in large plaque burden. The effects of PTCA on vessel wall morphology can be studied in great detail and the effect on luminal gain can be assessed almost on-line. Several groups showed, that the residual plaque area even after angiographycally successful PTCA lies still in the range of 60%. A significant reduction of this number may influence longterm outcome after PTCA. Minimal luminal areas and residual plaque area after PTCA seem to be an indicator of restenosis, while the presence or absence of dissections seem to be less predictive. Intravascular monitoring of stent expansion led to high-pressure stent deployment with significant increase in post-procedural luminal diameters and finally the ability to withhold anticoagulation in patients with optimal stent deployment. In the future, integrated devices, like balloons on intravascular ultrasound catheters, steerable catheters, integrated flow and pressure transducers, tissue characterization, and 0.018 "intravascular ultrasound guide-wires will further enhance the usefulness of IVUS.

Angioplasty, Balloon, Coronary↗
PubMed1996

[Normalization of myocardial perfusion reserve after coronary stent implantation in comparison with balloon angioplasty alone].

Stents scaffold coronary arteries after angioplastic treatment and inhibit elastic recoil resulting in a larger and more circular focal lumen. In 25 patients with significant stenoses of the left anterior descending coronary artery, presenting no collaterals or myocardial infarction, EKG-gated digital subtraction angiograms were recorded at baseline and during hyperemia induced by intracoronary injection of 12 mg papaverine before and after balloon angioplasty, and after adjunct implantation of a single Palmaz-Schatz stent. Densitometric evaluation revealed the time parameters contrast medium appearance time (MCAT) rise time (RT) and mean transit time (MTT) and maximum intensity (Imax). Myocardial perfusion reserve (MPR1) was calculated as the ratio of baseline MCAT and hyperemic MCAT multiplied by the ratio of hyperemic Imax and baseline Imax while MPR2 was calculated as the ratio of baseline RT and hyperemic RT. Maximum flow ratio (MaxFR) was calculated as the ratio of preprocedural hyperemic MTT and postprocedural hyperemic MTT. Post-stenotic MPR1 increased from 1.36 +/- 0.28 to 2.50 +/- 1.20 and to 3.40 +/- 0.58 (ANOVA p < 0.05), while reference MPR1 remained unchanged with 3.40 +/- 0.60. Post-stenotic MPR2 increased from 1.57 +/- 0.14 to 2.59 +/- 0.86 after balloon angioplasty and to 3.10 +/- 0.41 after stenting (ANOVA p < 0.05), while reference MPR2 remained unchanged with 3.10 +/- 0.40. MaxFR was 2.13 +/- 0.53 after balloon angioplasty and 2.83 +/- 0.35 after stenting (p < 0.05). A good correlation was found between minimal stenosis diameter and MPR1 or MPR2 (MPR1: r = 0.94; MPR2: r = 0.87) and between luminal gain and MaxFR (r = 0.75). A negative correlation was measured between recoil, defined as the difference between inflated balloon diameter and resulting minimal stenosis diameter, and MPR1 and MPR2 and MaxFR (MPR1: r = -0.86; MPR2 r = -0.80; MaxFR r = -0.83). In conclusion, adjunct coronary stent implantation normalized post-stenotic myocardial perfusion immediately in contrast to balloon angioplasty alone resulting from a larger postprocedural lumen and a more pronounced inhibition of elastic recoil.

Adult↗