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Biomedical subjects

B Meier

Publications and source records attributed to B Meier.

At least 433 records · Page 24Linked to original sources
PubMed1986

Effect of nifedipine on recurrent stenosis after percutaneous transluminal coronary angioplasty.

This double-blind, randomized study evaluated the effect of nifedipine on restenosis after coronary angioplasty. Two hundred forty-one patients with dilation of 271 coronary sites were randomized at the time of hospital discharge to receive nifedipine, 10 mg (123 patients), or placebo (118 patients) four times daily for 6 months. No patient was known to have coronary artery spasm. The mean duration of therapy was 4.4 +/- 2 (mean +/- SD) months for nifedipine and 4.3 +/- 2 months for placebo. A restudy angiogram was available in 100 patients (81%) in the nifedipine group and 98 patients (83%) in the placebo group. A recurrent coronary stenosis was noted in 28% of patients in the nifedipine group and in 29.5% of those in the placebo group (p = NS). The mean diameter stenosis was 36.4 +/- 23% for the nifedipine group and 36.7 +/- 23% for the placebo group (p = NS). By pill count, 78% of patients receiving nifedipine and 82% of those receiving placebo complied with the study drug regimen. Coronary stenosis recurred in 33% of patients in the placebo group and in 29% of patients in the nifedipine group who complied with the regimen and had angiograms (p = NS). In conclusion, the study did not demonstrate a significant beneficial effect of nifedipine on the incidence of recurrent stenosis after successful percutaneous transluminal coronary angioplasty.

Adult↗
PubMed1986

Trefoil balloon for aortic valvuloplasty.

A new balloon for valvuloplasty (Trefoil balloon) was successfully used in a 12 year old boy with congenital aortic stenosis. The Trefoil balloon consists of three angioplasty balloons mounted in parallel on a single shaft. When they are inflated simultaneously they produce a rosette that allows blood flow to continue through the valve. The aortic pressure only dropped to 75 mm Hg during a 15 s balloon dilatation at 4 bar (400 kPa). The procedure reduced the transvalvar gradient from 45 to 15 mm Hg.

Angioplasty, Balloon↗
PubMed1986

Restenosis after successful coronary angioplasty in patients with single-vessel disease.

To determine risk factors for restenosis, we studied 998 patients who underwent elective coronary angioplasty (PTCA) to native coronary arteries between July 1980 and July 1984. Restenosis, defined as a luminal narrowing of greater than 50% at follow-up, was present in 302 patients (30.2%). Univariate analysis of 29 factors revealed seven factors related to restenosis: vessel dilated (circumflex coronary artery 18%, right coronary artery 27%, left anterior descending artery 34%; p less than .01), final gradient of 15 mm Hg or less compared with greater than 15 mm Hg (27% vs 38%, p less than .01), duration of angina greater than 2 months compared with angina of shorter duration (27% vs 35%, p = .01), post-PTCA stenosis of 30% or less compared with 31% to 50% (28% vs 36%, p less than .025), stable vs unstable angina (26% vs 34%, p less than .05), presence vs absence of intimal dissection (26% vs 32%, p = .07), and female gender vs male gender (25% vs 32%, p = .08). Multivariate analysis revealed five factors independently related to increased risk of restenosis in the following order of importance: PTCA in the left anterior descending artery, absence of intimal dissection immediately after PTCA, final gradient greater than 15 mm Hg, a large residual stenosis after PTCA, and unstable angina. Restenosis after PTCA is a multifactorial problem. The hemodynamic and angiographic result at the time of PTCA significantly influences long-term outcome, but additional measures aimed at reducing the rate of recurrence of atherosclerotic plaque are required.

Adult↗
PubMed1986

Coronary dissection and total coronary occlusion associated with percutaneous transluminal coronary angioplasty: significance of initial angiographic morphology of coronary stenoses.

Coronary dissection and total coronary occlusion leading to emergency coronary surgery are the most frequent complications of percutaneous transluminal coronary angioplasty (PTCA) and their occurrence usually is unpredictable. To identify angiographic characteristics of coronary stenoses that may affect the incidence of these complications, the diagnostic pre-PTCA coronary angiograms of 38 consecutive patients (group I) undergoing emergency coronary surgery for dissection or occlusion were reviewed and compared with the angiograms of a random sample of 38 patients (stratified for left anterior descending and right coronary arteries) from a group of 1151 who did not need emergency coronary surgery (group II). Stenosis morphology before angioplasty was considered "complicated" if at least one of the following criteria was present: irregular borders, intraluminal lucency, and localization of stenosis in curve or at bifurcation. Baseline characteristics, maximum inflation pressures, types of balloon catheters used, and routinely registered angiographic stenosis properties (severity, length, eccentricity, and calcification) were similar in both groups. Irregular borders before PTCA were present in 22 of 38 patients in group I vs 10 of 38 in group II (p less than .05), intraluminal lucency in 22 of 38 vs nine of 38 (p less than .05), localization in curve in 27 of 38 pts vs 16 of 38 (p less than .05), and localization at bifurcation in 11 of 38 vs 15 of 38 (NS). Complicated angiographic morphology of coronary stenosis may represent a risk factor for dissection or occlusion. Therefore, although the predictive value of these findings is low, detailed evaluation of angiographic morphology of coronary stenoses may improve patient selection and reduce complication rates of PTCA.

Angioplasty, Balloon↗
PubMed1986

Percutaneous transluminal angioplasty of right and left internal mammary artery grafts.

Four patients with recurrent severe angina and evidence of myocardial ischemia two to six months after surgical coronary revascularization have been submitted to percutaneous transluminal angioplasty of the distal insertion of internal mammary artery grafts or of the recipient vessel distal to it. These cases illustrate the feasibility and safety of transluminal angioplasty of right and left internal mammary artery grafts, using the mammary artery as a way of access.

Adult↗
PubMed1986

Coronary artery dissection after transluminal angioplasty. Possible deleterious effects of treatment with intracoronary streptokinase.

Percutaneous transluminal coronary angioplasty (PTCA) is a nonsurgical alternative in the management of selected patients with coronary artery disease. Intimal dissection is the mechanism by which PTCA dilates coronary obstructions. Acute vessel occlusion is a rare but severe complication. Vessel patency can often be restored by fibrinolytic therapy when occlusion occurs immediately after angioplasty. A case of a patient with coronary dissection after PTCA and delayed obstruction, possibly aggravated by streptokinase is presented.

Adult↗
PubMed1985

[Multivessel percutaneous coronary angioplasty].

Between August 1983 and October 1984, 44 patients (39 male and 5 female, mean age 53 years) underwent multivessel percutaneous transluminal coronary angioplasty involving 2 vessels in 37 (84%), 3 vessels in 4 (9%), 4 vessels in 1 (2%) and coronary artery bypass graft plus 1 or 2 vessels in 2 (5%). A mean of 2.2 vessels per patient were attempted. Dilatations of multiple stenoses in the same vessel were not included. Primary success was achieved in 87 of 97 vessels (90%) and in 37 of 44 (84%) patients. Primary success per patient was defined as primary success in all or at least in the strategic lesions associated with clinical improvement of the patient. Complications included one death (2%), emergency coronary artery bypass surgery in one (2%) and myocardial infarction in 2 (4%) patients. Five other patients underwent elective coronary artery bypass surgery. Recurrence of lesion was 14% (5/37 patients) during a follow-up period of 3 to 12 months. Repeat angioplasty was successful in 4 patients (80%) and unsuccessful in 1 patient who underwent elective surgery. It is concluded that, in selected cases, multivessel percutaneous transluminal coronary angioplasty is a feasible alternative to coronary artery bypass surgery, with comparable risks. A satisfactory long-term amelioration without coronary artery surgery can be obtained in 2/3 of patients.

Adult↗
PubMed1985

[Intracoronary electrocardiography during transluminal coronary angioplasty].

To continuously record an intracoronary ECG during the crucial phase of percutaneous transluminal coronary angioplasty, the coronary guide wire was connected to an ECG recorder. In 25 patients the intracoronary ECG was recorded simultaneously with standard leads I, II and III during balloon occlusion of a coronary artery for 30-60 sec. The wire serving as electrode was positioned in the distal third of the coronary artery to be dilated, thus reflecting changes in the pertinent area of the myocardium. This was the left anterior descending coronary artery in 19 patients, the left circumflex coronary artery in 4 patients, and the right coronary artery in 2 patients. Electrocardiographic signs of ischemia were observed in 16 patients (62%). They were present in both the intracoronary ECG and at least 1 of the standard leads I, II or III in 11 patients, in the intracoronary ECG exclusively in 4 patients, and in the standard lead I exclusively in 1 patient. Sensitivity and specificity as an indicator for chest pain during balloon occlusion were 88% and 89% respectively for the intracoronary ECG and 63% and 78% respectively for the standard leads I, II and III. Sensitivity and specificity as an indicator for poor collateralization (coronary wedge pressure less than or equal to 25 mm Hg) were 100% and 69% respectively for the intracoronary ECG, and 60% and 62% respectively for the standard leads, I, II and III.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1985

Percutaneous perfusion of occluded coronary arteries with blood from the femoral artery: a dog study.

The idea of perfusing the distal coronary artery with arterial blood during balloon dilatation was implemented in early experimental coronary angioplasty but then abandoned. We pursued this concept in an animal model using a specially designed roller pump. The pump delivers blood from a femoral artery catheter through the central lumen of a balloon catheter occluding a coronary artery. Perfusion of large proximally occluded coronary arteries for at least 60 min was possible in 8 of 11 heparinized dogs. Hemolysis occurring in the pump system due to the small catheter lumen proved a minor problem. For a limited period of time, occluded coronary arteries can be adequately perfused with arterial blood by this percutaneous system that is readily applicable in any catheterization laboratory. Its use is conceivable not only for temporary treatment of acute complications during angioplasty but also for prolonged balloon dilatations of spastic or thrombosed coronary arteries.

Angioplasty, Balloon↗
PubMed1985

Non-selective intra-arterial digital subtraction angiography for the assessment of coronary artery bypass grafts.

Non-selective intra-arterial digital subtraction angiography (DSA) was performed immediately before selective coronary and bypass angiography in 33 consecutive symptomatic patients 48 +/- 30 months after coronary surgery, for the assessment of 75 coronary bypass grafts. Forty ml of non-ionic, low-iodine content contrast medium (iohexol) were injected into the ascending aorta at 10-20 ml/sec through a 7 or 8 F femoral pigtail catheter. Electrocardiogram-triggered images were acquired on a Siemens Digitron II apparatus in multiple projections in 24 patients and in a single projection in 9 patients. The results of this technique were compared by two independent angiographers with those of selective graft angiography in the same patients. Patency was shown by DSA in 45 of 54 grafts confirmed to be open by selective angiography (sensitivity 83%). Of 21 occluded grafts, stumps were clearly visible at selective angiography in 18 and at DSA in 9 (sensitivity for graft stumps = 50%, p less than 0.01). Of 54 patent grafts with selective angiography, the distal anastomosis could be visualized by DSA in 28 (52%), but the resolution was comparable to selective angiography in 20 grafts (37%) only. A non-significant difference in the sensitivity of DSA was observed between patent saphenous grafts to the left anterior descending coronary artery versus all other coronary arteries (95 vs 85%, respectively), while only 1 of 5 patent left internal mammary artery grafts to the left anterior descending coronary artery was visualized. In 16 of 50 grafts (32%) visualized in a second projection substantial additional diagnostic information was obtained. In conclusion, non-selective intra-arterial electrocardiogram-triggered DSA can visualize patent saphenous grafts with a high sensitivity and may be a useful screening tool for bypass grafts patency; false negatives, however, and poor visualization of distal anastomoses limit its routine clinical use.

Adult↗
PubMed1985

Transluminal coronary angioplasty--state of the art 1984.

Since its introduction in 1977 by Grüntzig, percutaneous transluminal coronary angioplasty (PTCA) has been increasingly applied to the treatment of coronary artery disease manifested by symptomatic ischemia. Initially only recommended for proximal short stenoses of one major coronary artery, the indication for PTCA has gradually been enlarged. Today even distally situated coronary stenoses in more than one vessel can be dilated successfully by using a steerable system. In experienced hands, an immediate improvement can be achieved in about 90% of the patients. In the realm of cost and morbidity PTCA offers obvious advantages over bypass surgery. However, indications for PTCA are more restricted than those for bypass surgery, specially in multi-vessel disease where the application of PTCA is still controversial. Moreover, long-term results are less favourable after PTCA since 25-30% of the patients show a recurrence within 6 to 12 months. Although PTCA will not replace coronary bypass surgery, it is already established as an alternative and complementary method for coronary revascularization.

Angioplasty, Balloon↗
PubMed1985

Thermoregulation in the slender loris (Loris tardigradus).

Thermoregulatory characteristics of slender lorises largely resemble those of other slow-moving Lorisidae: Body temperature is slightly below the normal mammalian level and basal metabolic heat production is only about half of the mass-specific standard. During cold exposure only a rather small body core is kept at a high temperature level whereas large parts of the body are allowed to cool. Contrary to the findings in other Lorisidae slender lorises are more tolerant against high environmental temperatures, largely due to the ability of considerably increasing evaporative cooling.

Animals↗
PubMed1985

Coronary pacing during percutaneous transluminal coronary angioplasty.

To avoid venous puncture, a new concept for standby cardiac pacing during percutaneous transluminal coronary angioplasty (PTCA) and diagnostic cardiac catheterization was developed. It uses an arterial guidewire as a unipolar pacing electrode with the second electrode attached to the skin. The system was tested in 25 coronary arteries of 22 patients undergoing PTCA and in the left ventricles of 10 patients undergoing diagnostic cardiac catheterization. Coronary pacing via the guidewire used for directing the balloon catheter was possible in all patients and in 24 of the 25 coronary arteries attempted. Maximum duration of pacing was 8 min. Threshold currents ranged from 1 to 15 mA (mean 5.7). Left ventricular pacing via the same wires or standard wires used for introduction of diagnostic or guiding catheters was possible in all patients and was maintained for up to 10 min. Threshold currents ranged from 1 to 7 mA (mean 3.9). Neither method for pacing produced adverse effects during these short applications. The setup for coronary pacing also allowed recording of an intracoronary electrocardiogram during PTCA. The presented system provides backup for the rare event of sustained bradycardia during PTCA or diagnostic cardiac catheterization. If applied cautiously, it may safely and reliably replace the standby of a conventional transvenous pacing catheter.

Adult↗
PubMed1985

[Redilatation of coronary stenoses. Effect on long-term results].

Subsequent to percutaneous transluminal coronary angioplasty (PTCA), with a primary success rate of between 84 and 94%, restenosis is reported to occur in 17 to 47%. Redilatation has been considered in about 30% of dilated patients and carried out in 20%. The experience presented is based on 608 consecutive patients who underwent PTCA at Emory University in Atlanta as well as 350 consecutive patients treated at the University of Genf. In general, the primary success rate of repeated PTCA is reported to be significantly better. Based on our data, the primary success of redilatation was 97%, as compared with an 87% success rate on initial dilatation. Associated with second and third dilatations, there is a substantially lower incidence of complications; in our patients, obstructive dissections occurred in 1% as compared with 7% at the time of initial dilatation and myocardial infarction was not observed (as compared with 1% initially). Emergency bypass surgery was required in only 1% as compared with 5% at initial dilatation. With regard to longterm results, the data reported shows some differences. While most of the figures indicate a rate of restenosis comparable to that seen after initial dilatation, a higher incidence of restenosis has been observed. In our patients, the rate of restenosis after repeat PTCA was essentially similar to that seen after initial PTCA; overall, however, that associated with LAD stenoses was notably higher. On use of redilatation, 78% of all patients, instead of only 63% after successful initial dilatation, had longterm benefits from this mode of therapy.

Angina Pectoris↗