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Biomedical subjects

B Meier

Publications and source records attributed to B Meier.

At least 451 records · Page 25Linked to original sources
PubMed1985

[Emergency cardiac pacing via a coronary vessel during percutaneous coronary angioplasty].

Percutaneous coronary angioplasty (PCA) is sometimes complicated by bradyarrhythmias necessitating emergency temporary cardiac pacing. This is usually performed by the classical transvenous endocardial approach. This experimental study investigated the possibility of using the metallic guide wire used during PCA as a monopolar electrode. Systematic electrical stimulation at different levels of the coronary arteries in 6 anaesthetised pigs showed threshold levels in the distal segments of 3 to 15 mA, close to the values observed in the right ventricule. Short periods of pacing were well tolerated. On the other hand, prolonged pacing (2 to 5 days) invariably led to the formation of a thrombus in the coronary segment occupied by the metallic guide wire and so should be avoided. This study shows that the metallic guide wire can be used as an emergency pacing electrode during PCA but this should be limited to a short period. This technique could replace the systematic introduction of classical transvenous pacing catheters.

Angioplasty, Balloon↗
PubMed1984

[Prevention of endocarditis using amoxycillin, clindamycin or erythromycin. Pharmacokinetic observations].

Current recommendations for antibiotic prophylaxis of bacterial endocarditis include oral amoxycillin, and erythromycin or clindamycin for the penicillin-allergic patient. The authors report the serum concentrations and side effects which may be expected after the recommended oral doses of these compounds. Single doses of 3 g amoxycillin and 600 mg clindamycin, and two doses of erythromycin (1.5 g and 0.5 g 6 h apart) were administered in a random sequence to each of 12 volunteers. After administration, peak serum concentrations of amoxycillin and clindamycin were 27 mg/l and 5.5 mg/l respectively. Amoxycillin was eliminated more rapidly than clindamycin. Serum concentrations of erythromycin were below the sensitivity limit of the assay (0.03 mg/l) in 3 volunteers at 1 h and in 2 at 2 h. The mean peak serum concentrations was 3.1 mg/l. Peak levels were associated with gastrointestinal side effects such as nausea, abdominal cramps and vomiting. The implications of these findings are discussed with respect to use of these antibiotics for the prophylaxis of bacterial endocarditis.

Amoxicillin↗
PubMed1984

Learning curve for percutaneous transluminal coronary angioplasty: skill, technology or patient selection.

As with all sophisticated techniques, operators who perform PTCA show a learning curve. It can best be visualized by observing changes in success rate with growing numbers of patients. Thus, the current success rate and complication rate of a particular operator may permit an estimate of the accumulated number of patients treated by that operator. Most likely, the learning curve is also reflected in the rate of long-term success, although it may be obscured by other factors in the variable natural course of CAD. The initial steep upslope of the learning curve is mainly caused by the growing skill of the particular operator. The later, flatter part appears to be secondary to improvements in technical equipment, which take more time. Patient selection has 2 effects on the learning curve that may be self-compensating. If lessons from the past are used for selection and conservatism is preserved, the learning curve will become more pronounced.

Angioplasty, Balloon↗
PubMed1984

Current status of dilatation catheters and guiding systems.

Both balloon catheters and guiding catheters for PTCA are high-quality instruments with an advanced degree of reliability and practicality. The standard set-up at Emory University consists of a steerable 3.0-mm balloon catheter and a Judkins-type guiding catheter.

Angioplasty, Balloon↗
PubMed1984

Risk of side branch occlusion during coronary angioplasty.

To assess the risk of side branch occlusion during percutaneous transluminal coronary angioplasty (PTCA), 600 consecutive procedures were analyzed. On the basis of pre-PTCA angiograms of 557 patients in whom the balloon was actually inflated, 365 side branches in 302 patients (54% of patients) were deemed in jeopardy. A total of 122 side branches in 102 patients (18%) originated from the lesion segment itself, i.e., their take-off was narrowed (Group I, 33% of side branches at risk), whereas 243 side branches in 214 patients (38%) originated from the immediate vicinity of the stenosis in a way that they were subjected to temporary occlusion during balloon dilatation (Group II, 67% of side branches at risk). Patency of side branches was determined by consensus of 2 observers. Criteria for occlusion were disappearance, filling by collaterals, or stagnation of flow. After PTCA, 20 of 365 side branches (5%) were occluded and associated with chest pain in 5 patients, creatine kinase increase in 6, left anterior hemiblock, septal Q waves and transient atrial fibrillation in 1 and non-sustained ventricular tachycardia in 1 of the 20 patients. Exercise tolerance did not decrease. No local predilection for side branch occlusion was evident. Seventeen of 122 side branches (14%) occluded in Group I, compared with 3 of 243 (1%) in Group II (p less than 0.001). Thus, more than half of the patients who underwent PTCA had side branches at risk for iatrogenic occlusion.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1984

Higher balloon dilatation pressure in coronary angioplasty.

The advent of improved balloon catheters for percutaneous transluminal coronary angioplasty (PTCA) in 1981 extended the theoretic pressure range available for dilatation from 7 atm to 13 atm. The impact of higher dilatation pressure on results of PTCA was studied. The last 100 consecutive patients treated exclusively with the old balloon type (low-pressure group) were compared to the first 100 consecutive patients treated exclusively with the new balloon type (high-pressure group). There was no difference in age, sex, artery distribution, initial degree of stenosis, and initial pressure gradient between the two groups. The mean peak pressure applied was 7.0 +/- 1.6 atm in the low-pressure group and 8.5 +/- 2.1 atm in the high-pressure group (p less than 0.001). The average balloon diameter used and the number and duration of balloon fillings were similar in both groups. Primary success, complications, and residual degree of stenosis were not different in the two groups. The residual pressure gradient, however, was significantly lower in the high-pressure group (11 +/- 7 mm Hg) than in the low-pressure group (16 +/- 10 mm Hg) (p less than 0.01). This indicates a better immediate hemodynamic result without increased risk. It is concluded that it is safe to perform PTCA with the new balloon types allowing for higher pressures. The increment in average pressure used for dilatation, which occurred incidentally, improved the average hemodynamic outcome. This may influence recurrence rate and deserves further investigation by randomized trials.

Angioplasty, Balloon↗
PubMed1984

Repeat coronary angioplasty.

The potential of repeat percutaneous transluminal coronary angioplasty as a mode of therapy for recurrence of stenosis after initially successful angioplasty was examined on the basis of data on all 514 patients with successful angioplasty at Emory University before April 1982. Recurrence was found in 171 (33%) of the 514 patients. Repeat angioplasty was attempted in 95 patients with a significantly higher primary success rate (97 versus 85%, p less than 0.001) and a lower complication rate (8 versus 15%, p less than 0.10) than those of initial angioplasty. Follow-up documentation was available in all 92 patients with successful repeat angioplasty. A second recurrence of stenosis was found in 26% (24 of 92). A third angioplasty was performed in seven patients; six procedures were successful and there have been no recurrences of stenosis. Repeat coronary angioplasty provides a means to treat recurrence of stenosis. It proved to be very successful and safe and yielded good long-term results. It also increased the percent of patients with documented lasting success after angioplasty from 63 to 78%.

Angioplasty, Balloon↗
PubMed1984

Coronary flow reserve measured during cardiac catheterization.

The degree of arteriographically visualized narrowing in coronary arteries has been the most important criterion for evaluating coronary disease for more than 20 years. Increasing data, however, suggest that anatomy alone does not predict the physiologic consequence of individual stenoses. We have applied a new digital arteriographic method for measuring coronary flow reserve (CFR) in patients undergoing diagnostic, postbypass, and postangioplasty catheterizations. All vessels with high-grade stenoses (greater than or equal to 70%) were found to have lower CFRs than those of normal arteries (1.01 +/- 0.15 v 1.84 +/- 0.36). However, considerable CFR variability was found in vessels of lesser stenoses. Coronary arteries that had undergone successful bypass surgery or angioplasty had intermediate CFR levels (1.44 +/- 0.18 and 1.51 +/- 0.16, respectively). Our study suggests that CFR assessed during cardiac catheterization may be useful for evaluating intermediate coronary lesions and the efficacy of interventions.

Adult↗
PubMed1983

Assessment of stenoses in coronary angioplasty. Inter- and intraobserver variability.

Three observers twice assessed coronary artery lesions of 10 patients in three oblique views using the films obtained before, immediately after, and six months after percutaneous transluminal coronary angioplasty. In order to improve accuracy of the interpretation, the stenoses were traced from the cine projector and the diameters measured with a calibrated magnifying glass. Interobserver and intraobserver variability of the commonly used method assessing only the projection showing the most severe stenosis was compared to that of a method assessing the mean of three projections. The interobserver coefficients of variation were 7.0% for using the one projection showing the most severe stenosis and 6.4% for using the mean of three projections (not significant). The intraobserver coefficient of variation was significantly reduced from 16.0 to 10.5% (P less than 0.0001) by using the mean of three projections. The assessment of three projections instead of one justifies the additional time needed by significantly increasing assessment reliability which is of great importance in evaluating and comparing anatomical results of percutaneous transluminal coronary angioplasty.

Angioplasty, Balloon↗