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ABSTRACT: The current clinical standard for the analysis of intracoronary Doppler signals is the application of a zero-crossing (ZC) detector. However, the accuracy of the method is questionable, especially in areas of disturbed flow, as confirmed by in vitro studies, animal experiments, and intraoperative observations. The aim of this study is the comparison of a conventional ZC detector and a custom-designed spectral analyzer (fast Fourier transform, FFT) in the analysis of intracoronary Doppler signals obtained in 19 patients undergoing coronary angioplasty. A 3F catheter with an end-mounted Doppler ceramic crystal was placed over an 0.014" guidewire in a normal or near-normal segment proximal to the lesion to be dilated. The Doppler signal was recorded before and after intracoronary infusion of 12.5 mg of papaverine. In 9 patients high flow velocities could be recorded when the catheter was advanced across the stenosis. The blood flow velocity measurements obtained with ZC were significantly lower than the maximal FFT flow velocity measurements (16 +/- 12 cm/s vs. 29 +/- 18 cm/s, p < .001). In all the conditions of Doppler signal acquisition (baseline, hyperemia, stenosis) a large scattering of the signed differences between corresponding measurements was observed. The standard deviation of the difference ZC-FFT was +/- 11 cm/s and +/- 5 cm/s for the maximal and mean FFT flow velocity, corresponding in both cases to +/- 37% of the mean of the ZC and FFT measurements.(ABSTRACT TRUNCATED AT 250 WORDS)
Catheterization and Cardiovascular Diagnosis 02/1993; 28(1):56-64.
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Annales chirurgiae et gynaecologiae 02/1993; 82(2):101-8.
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ABSTRACT: The most feared complication of thrombolytic therapy is intracranial hemorrhage. Nevertheless, the benefits of thrombolysis far outweight the potential hazards of a cerebral bleed. In individual patients the expected benefit of thrombolytic therapy can be estimated by subtraction of the risk for intracranial hemorrhage from the predicted gain in survival. Accordingly, the net effect of thrombolysis will be beneficial in most patients who can be treated within the first 12 hours after symptom onset, even if one or two risk factors for intracranial hemorrhage can be identified. On the other hand, thrombolytic therapy is not warranted in elderly patients with a relatively small predicted infarct size and multiple risk factors for intracranial hemorrhage.
Zeitschrift für Kardiologie 02/1993; 82 Suppl 2:153-6. · 0.97 Impact Factor
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ABSTRACT: To study the immediate and long term clinical success of percutaneous transluminal coronary balloon angioplasty in patients over 70 years old.
Patients undergoing percutaneous transluminal angioplasty were prospectively entered in a specially designed database. The clinical and angiographic data of all patients over 70 were reviewed. Follow up data were collected by interview, during outpatient visits, by questionnaire, or through the referring physician.
A tertiary referral cardiac centre.
166 patients over 70 (median 73, range 70-84) underwent coronary angioplasty because of unstable angina (81 patients), stable angina (76 patients), or acute myocardial infarction (nine patients).
The initial clinical success rate was 86% (142 of 166 patients). A major procedural complication occurred in 10 patients (6%): four patients (2%) died, six patients (4%) underwent emergency bypass surgery, and five patients (3%) sustained an acute myocardial infarction. In 14 patients (8%) coronary angioplasty did not significantly reduce the diameter stenosis but there were no associated complications. A total of 226 lesions were attempted. The initial angiographic success rate was 192 out of 226 lesions (85%). The median follow up was 21 (range 0.5-66) months. Sixteen patients (10%) died during follow up, eight patients (5%) sustained a non-fatal myocardial infarction, 21 patients (13%) underwent a second or third balloon dilatation, and 17 patients (10%) underwent elective bypass surgery. Of the 146 survivors, 99 patients (68%) had sustained clinical improvement. The estimated survival at four years (Kaplan-Meier method) was 89 (SD 4)%. The event free survival at four years for the total study population was 61 (8)%. Multivariate logistic regression analysis showed that the extent of vessel disease was the only independent predictive factor for event free survival: the event free survival rate was 81 (10)% at four years for patients with single vessel disease, compared with 45 (12)% for patients with multivessel disease.
Coronary angioplasty in patients over 70 was a safe and effective treatment for obstructive coronary artery disease. The extent of vessel disease, and not the completeness of revascularisation, was the only independent predictive factor for event free survival.
Heart 03/1992; 67(2):138-43.
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ABSTRACT: This study reports the results from 3 European centers using rotary ablation with Rotablator, a device that is inserted into the coronary artery and removes atheroma by grinding it into millions of tiny fragments. Rotary ablation was performed in 129 patients. Primary success (reduction in percent luminal narrowing greater than 20%, residual stenosis less than 50%, without complications) was achieved by rotary angioplasty alone in 73 patients (57%). An additional 38 patients (29%) had successful adjunctive balloon angioplasty. Thus primary success was achieved in 111 patients (86%) at the end of the procedure. Acute occlusion occurred in 10 patients (7.7%). Recanalization was achieved by balloon angioplasty in 7: urgent bypass grafting was undertaken in 2. Q-wave and non-Q-wave myocardial infarction occurred in 3 and 7 patients, respectively. No deaths occurred. Follow-up angiography was performed in 74 patients (60%). Restenosis, defined as the recurrence of significant luminal narrowing (greater than 50%) occurred in 17 of 37 patients (46%) who underwent rotary ablation alone, and 11 of 37 patients (30%) who had adjunctive balloon angioplasty. The overall angiographic restenosis rate was 37.8%. In conclusion, rotary ablation is technically feasible, and relatively safe in the coronary circulation. The low primary success rate reflects the limited size of the device, which can be introduced through available guiding catheters, and limits the use of rotary ablation as a stand-alone procedure to lesions in small arteries or in distal locations. No reduction in restenosis was seen, but the role of this device combined with balloon angioplasty in larger arteries needs to be further defined.
The American Journal of Cardiology 03/1992; 69(5):470-4. · 3.37 Impact Factor
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ABSTRACT: The purpose of this study was to assess the early changes in stenosis geometry after implantation of the Medtronic Wiktor stent in human coronary arteries. Morphologic changes were evaluated by quantitative coronary angiography using automated edge detection. The hemodynamic significance of the morphologic changes were assessed by the calculation of the theoretical pressure drop across the dilated and stented stenosis derived from the Poiseuile and turbulent resistances assuming a coronary blood flow of either 0.5, 1, or 3 ml/sec. Fifty patients were studied before and immediately after stent implantation. The stented coronary artery was the left anterior descending artery in 26 patients, the circumflex artery in eight patients, and the right coronary artery in 16 patients. Stent implantation resulted in an additional increase in the minimal luminal cross-sectional area and minimal luminal diameter of the dilated vessel without changing the curvature of the stenosis. Furthermore, there was a significant reduction of the "plaque area." This was associated with a normalization of the calculated resistances to flow and pressure drop across the stenosis. To a minimal extent, recoil (0.1 +/- 0.36 mm) was observed after stent implantation.
Catheterization and Cardiovascular Diagnosis 01/1992; 24(4):237-45.
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ABSTRACT: Interventional cardiology has branched in two directions: devices that primarily dilate coronary stenoses and those that debulk coronary tissue. Presently the optimum coronary intervention has not been found. While patients are awaiting randomized trials, a comparison based on matched quantitative coronary analysis may be useful to evaluate results of new interventional techniques. Therefore we compared 51 patients undergoing atherectomy with individually matched patients who were undergoing balloon angioplasty and stenting. The lesions were matched according to location of stenosis and reference diameter. Atherectomy and stenting resulted in larger gains in minimal luminal diameter compared with conventional balloon angioplasty. The minimal luminal diameter was increased from 1.2 +/- 0.4 mm to 2.6 +/- 0.4 mm in the atherectomy group and from 1.2 +/- 0.3 mm to 1.9 +/- 0.4 mm in the angioplasty group (p less than 0.00001). Atherectomy and stenting resulted in similar gains in minimum luminal diameter (1.4 mm vs 1.3 mm, p = NS). In addition, atherectomy and stenting appear to be more effective in resisting elastic recoil because of tissue removal and an intrinsic dilating effect, respectively. In matched populations directional atherectomy and stenting appear to be more effective intracoronary interventional devices than balloon angioplasty based on the immediate results. However, atherectomy is limited in smaller coronary vessels because of its larger size.
American Heart Journal 10/1991; 122(3 Pt 1):836-43. · 4.65 Impact Factor
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ABSTRACT: Thirty three consecutive patients with clinically suspected endocarditis were studied by both precordial cross sectional echocardiography and transoesophageal echocardiography. The diagnostic value of both techniques was assessed. The data were compared with findings at operation in 25 patients. In 21 patients with native valve endocarditis precordial echocardiography showed evidence of vegetations in six patients and suggested their presence in nine. Transoesophageal echocardiography identified vegetations in 18 patients. Complications were seen in four patients at precordial echocardiography and in nine patients at transoesophageal echocardiography. Precordial echocardiography did not show vegetations in any of the 12 patients with prosthetic valve endocarditis whereas transoesophageal echocardiography showed vegetations in four. Complications were seen in four patients at precordial echocardiography and in 10 at transoesophageal echocardiography. Echocardiographic findings were confirmed at operation in all 25 operated patients. In two patients both echocardiographic techniques had missed the perforation of the cusps of the aortic valve that was seen at operation, but this had no effect on patient management. Transoesophageal echocardiography is the best diagnostic approach when infective endocarditis is suspected in patients with either native or prosthetic valves.
Heart 03/1990; 63(2):109-13.
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Progress in Cardiovascular Diseases 36(5):385-96. · 4.93 Impact Factor
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ABSTRACT: Thrombolytic therapy improves outcome in patients with myocardial infarction but is associated with an increased risk of intracranial haemorrhage. For some patients, this risk may outweigh the potential benefits of thrombolytic treatment. Using data from other studies, we developed a model for the assessment of an individual's risk of intracranial haemorrhage during thrombolysis. Data were available from 150 patients with documented intracranial haemorrhage and 294 matched controls. 49 patients with intracranial haemorrhage and 122 controls had been treated with streptokinase, whereas 88 cases and 148 controls had received alteplase. By multivariate analysis, four factors were identified as independent predictors of intracranial haemorrhage; age over 65 years (odds ratio 2.2 [95% Cl 1.4-3.5]), body weight below 70 kg (2.1 [1.3-3.2]), hypertension on hospital admission (2.0 [1.2-3.2]), and administration of alteplase (1.6 [1.0-2.5]). If the overall incidence of intracranial haemorrhage is assumed to be 0.75%, patients without risk factors who receive streptokinase have a 0.26% probability of intracranial haemorrhage. The risk is 0.96%, 1.32%, and 2.17% in patients with one, two, or three risk factors, respectively. We present a model for individual risk assessment that can be used easily in clinical practice.
The Lancet 342(8886-8887):1523-8. · 38.28 Impact Factor
