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Biomedical subjects

B Meier

Publications and source records attributed to B Meier.

At least 145 records · Page 8Linked to original sources
PubMed1998

Quantitation of mitral regurgitation using the systolic/diastolic pulmonary venous flow velocity ratio.

OBJECTIVES: The purpose of this study was to test the hypothesis that pulmonary venous flow velocity ratios during systole and diastole in patients with mitral regurgitation (MR) correctly predict the quantitative degree of MR. BACKGROUND: Pulmonary venous flow velocity measurements have thus far been used only for the qualitative assessment of MR. Recent studies have evaluated this method using transesophageal echocardiography against semiquantitative references. METHODS: In 100 patients without aortic regurgitation or atrial fibrillation and with left ventricular (LV) ejection fraction >45%, MR was assessed by quantitative echocardiographic Doppler and color Doppler, providing forward and total LV stroke volume for the calculation of the mitral regurgitant fraction (RFstandard), the reference parameter, and also supplying mitral regurgitant orifice area (ROA) values and the RF by the flow convergence method (RFPISA [proximal isovelocity surface area]). Measurements of pulmonary venous flow velocity time integral values during systole to diastole (VTIs/VTId) were obtained and tested for their predictibility of ROA, RFstandard and RFPISA. RESULTS: There was an inverse and significant correlation between VTIs/VTId and ROA, RFPISA and RFstandard, respectively: RFstandard=49 - 20 VTIs/VTId, r=0.77, p=0.0001. A principal source of variability in the relation between VTIs/VTId and RFstandard was the presence of mitral valve prolapse as the cause of MR. Pulmonary venous flow reversal (VTIs/VTId <0) correctly identified severe MR with 52% sensitivity, 96% specificity and 80% positive and 87% negative predictive accuracy. CONCLUSIONS: The VTIs/VTId ratio allows a moderately accurate assessment of the severity of MR.

Adult↗
PubMed1998

Long-term physical exercise and quantitatively assessed human coronary collateral circulation.

OBJECTIVES: This prospective, cross-sectional study sought to determine an association between the level of long-term physical activity as well as other clinical and angiographic variables and an index of collateral flow to the vascular region undergoing percutaneous transluminal coronary angioplasty (PTCA). BACKGROUND: There is limited and conflicting information about the effect of physical exercise on the coronary collateral circulation in humans, partly because previous studies lacked a quantitative means of assessing collateral channels. METHODS: In 79 patients (mean [+/-SD] age 58 +/- 10 years) with coronary artery disease undergoing PTCA (no transmural myocardial infarction), a coronary collateral flow index was determined as the ratio between the intracoronary (IC) distal flow velocity time integral during (Vi(occl)[cm]) and after (Vi(occl) [cm]) PTCA of the stenosis. Vi(occl)/Vi(occl) was measured by a 0.014-in. Doppler guide wire, from which an IC electrocardiogram (ECG) was also recorded. Patients without ECG ST-T wave changes during PTCA were considered to have sufficient collateral channels (n = 29); those with ST-T wave changes were considered to have insufficient collateral channels (n = 50). The level of long-term physical activity was determined by a structured interview (score from 1 to 4). Univariate and multivariate analyses were used to find associations between physical activity as well as 30 other clinical and angiographic variables and the collateral flow index. RESULTS: Long-term physical activity during leisure time, but not during work hours, and the severity of the stenosis undergoing PTCA were found to be independently and directly associated with sufficient versus insufficient collateral channels and with Vi(occl) Vi(occl) (leisure time physical activity [LTPA] score 3.3 +/- 0.9 vs. 2.4 +/- 1.0, p = 0.0002; percent diameter stenosis 88 +/- 12% vs. 80 +/- 14%, p = 0.001; Vi(occl)/Vi(occl) = 0.1 +/- 0.1 LTPA score, p = 0.0002 for trend). CONCLUSIONS: In patients with coronary artery disease, the level of long-term physical activity during leisure time and the severity of the stenosis undergoing PTCA are directly associated with the quantitative degree of collateral flow.

Adult↗
PubMed1998

Coronary collateral quantitation in patients with coronary artery disease using intravascular flow velocity or pressure measurements.

OBJECTIVES: This study evaluated two methods for the quantitative measurement of collaterals using intracoronary (IC) blood flow velocity or pressure measurements. BACKGROUND: The extent of myocardial necrosis after coronary artery occlusion is substantially influenced by the collateral circulation. So far, qualitative methods have been available to assess the human coronary collateral circulation, thus restraining the conclusive investigation of, for example, therapies to promote collateral development. METHODS: Fifty-one patients with a coronary artery stenosis to be treated by percutaneous transluminal coronary angioplasty (PTCA) were investigated using IC PTCA guidewire-based Doppler and pressure sensors positioned distal to the stenosis. Simultaneous measurements of aortic pressure, IC velocity and pressure distal to the stenosis during and after PTCA provided the variables for calculating collateral flow indices (CFIv and CFIp) that express collateral flow as a fraction of flow via the patent vessel. Both CFIv and CFIp were compared with conventional methods for collateral assessment, among them ST-segment changes >1 mm on IC and surface electrocardiogram (ECG) at PTCA. Also, CFIv and CFIp were compared with each other. RESULTS: In 11 patients without ECG signs of ischemia during PTCA (sufficient collaterals), relative collateral flow amounted to 46% as determined by Doppler and pressure wire. Patients with insufficient collaterals (n=40) had relative collateral flow values of 18%. Using a threshold of CFI=30%, sufficient and insufficient collaterals could be diagnosed with 100% sensitivity and 93% specificity by IC Doppler, and 75% sensitivity and 92% specificity by IC pressure measurements. The agreement between Doppler and pressure measurements was good: CFIv=0.08 + 0.8 CFIp, r=0.80, p=0.0001. CONCLUSIONS: Intracoronary flow velocity or pressure measurements during routine PTCA represent an accurate and, at last, quantitative method for assessing the coronary collateral circulation in humans.

Angioplasty, Balloon, Coronary↗
PubMed1998

Accuracy of a new wrist cuff oscillometric blood pressure device: comparisons with intraarterial and mercury manometer measurements.

Accurate measurement of arterial blood pressure is of great importance for the diagnosis and treatment of hypertension. Because of the chronic nature of antihypertensive drug therapy, the involvement of the patient in blood pressure control is desirable. Such an involvement, however, is only feasible if simple, user-friendly, and precise blood pressure measurement devices are available. In this study we tested a new wrist cuff oscillometric blood pressure measurement device in 100 consecutive patients undergoing cardiac catheterization. Blood pressures were simultaneously taken intraarterially (axillary artery) and with a mercury manometer and stethoscope or noninvasive measurement device (OMRON R3). Intraarterial measurements were directly compared with two measurements taken in random order with either an arm cuff mercury manometer or the wrist cuff device. Systolic and diastolic blood pressure as assessed with the mercury manometer was higher, especially when compared with the intraarterial and the wrist cuff values, which were comparable. Correlations of blood pressure values with intraarterial measurement were 0.86 systolic and 0.75 diastolic (P < .01) for the wrist cuff and 0.84 systolic (P < .01) and 0.59 diastolic (P < .05) for the mercury manometer measurements. Reproducibility of both measurements was good for the wrist cuff device ([systolic/diastolic]: r = 0.94/0.92; P < .01) and the mercury manometer (r = 0.97/0.88; P < .01). Both methods overestimated high diastolic values, whereas only the wrist cuff underestimated high systolic values. Thus, the new oscillometric wrist cuff blood pressure measurement device measures arterial blood pressure with great accuracy and reproducibility. As compared with intraarterial values, the wrist cuff device overestimated high diastolic and underestimated high systolic blood pressure values. Blood pressure values as measured by the mercury manometer were higher than intraarterial values and those of the wrist cuff. Both noninvasive devices overestimated high diastolic values.

Blood Pressure Determination↗
PubMed1998

Endothelin-1 induces vasodilation in human skin by nociceptor fibres and release of nitric oxide.

AIMS: Endothelin is a peptide produced by endothelial cells with many biological properties. In the human skin microcirculation endothelin induces neurogenic vasodilation associated with burning pruritus. We investigated the mechanisms involved in this response. METHODS: The effects of prolonged pretreatment with capsaicin, a specific inhibitor of polimodal nociceptor fibres, and of the nitric oxide synthase inhibitor L-NMMA on endothelin-1-induced vasodilation were studied in 15 human subjects. Furthermore, we investigated the effects of the ET(A)-selective antagonist PD147953 on bradykinin-induced vasodilation. RESULTS: After local injection, endothelin-1 caused vasoconstriction at the injection site and a profound vasodilation in the surrounding area (flare reaction, P<0.01). This response was specific and not induced by saline, albumin, acetylcholine or an ET-antagonist. Prolonged capsaicin pretreatment inhibited endothelin-1 induced vasodilation in the area surrounding the injection site, but not the central vasoconstriction at the injection site. Bradykinin also induced a marked vasodilation in the area surrounding the injection site; this was not inhibited by an ETA-selective antagonist, while the flare reaction was. L-NMMA applied at the site of the flare reaction prevented endothelin-1-induced vasodilation. CONCLUSIONS: Endothelin-1 in the human skin microcirculation stimulates polimodal nociceptor fibres leading to the release of nitric oxide. This response may play a pathophysiological role in inflammatory processes in the human skin.

Adolescent↗
PubMed1998

Interventional cardiology in Europe 1994. Working Group Coronary Circulation of the European Society of Cardiology.

The working group Coronary Circulation of the European Society of Cardiology conducts an annual survey of cardiac interventions in Europe with the support of the national societies of cardiology. A detailed questionnaire about cardiac interventions performed during 1994 was mailed to all members of the European Society of Cardiology. Incomplete or absent data from eight national members precluded their inclusion in the final analysis. Thus, this report summarizes the cardiac interventions performed during 1994 in 29 of 37 members of the European Society of Cardiology, representing a total population of approximately 490 million inhabitants. CORONARY ANGIOGRAPHY: A total of 922,687 coronary angiograms were reported during 1994, representing an increase of 22% compared with 1993 and of 35% compared with 1992. The mean incidence of coronary angiograms was 1881/10(6) inhabitants, ranging from 4417/10(6) inhabitants in Germany to 35/10(6) inhabitants in Romania, Germany, France, Great Britain, and Italy with 50% of the European population performed 73% of all cardiac interventions. CORONARY ANGIOPLASTY: During 1994, a total of 224,722 coronary angioplasty (PTCA) procedures were reported in Europe, an increase of 22% compared with 1993 and of 52% compared with 1992. Adjusted per capita, the mean incidence of coronary angioplasty was 458/10(6) inhabitants, ranging from 1091/10(6) inhabitants in Germany to 6/10(6) inhabitants in Romania. On average, the ratio PTCA per coronary angiogram was 0.24, ranging from 0.37 in the Netherlands to 0.06 in Cyprus. Ad hoc PTCA accounted for 22% of all PTCA cases. The majority (81%) of PTCAs were restricted to a single vessel. Major complications were reported in 2% of patients undergoing PTCA, including death (0.3%), myocardial infarction (1.0%) and need for emergency coronary artery bypass grafting (0.7%). CORONARY STENTING: Coronary stents were utilized in 21,599 coronary interventions during 1994, an increase of 235% compared with 1993 and thus representing the fastest growth in interventional cardiology. The number of European countries employing stents during coronary angioplasty grew from 14 during 1993 to 24 during 1994. Elective use (38%) became the most frequent indication for coronary stenting during 1994, replacing bail-out stenting as the primary indication during 1993. OTHER NEW DEVICES: Other new interventional therapeutic devices were employed in 8827 cases. Only the Rotablator was used more frequently during 1994 as compared with 1993. All other new therapeutic devices showed a decline. Coronary ultrasound was utilized in 3032 interventions and coronary angioscopy in 304 cases during 1994. NON-CORONARY INTERVENTIONS: Valvuloplasty remained the most frequent non-coronary intervention in Europe during 1994 with a total of 2622 mitral. 609 pulmonary and 506 aortic valvuloplasties. CATHETERIZATION FACILITIES: The number of facilities per 10(6) inhabitants performing invasive cardiac procedures in Europe during 1994 ranged from 7.7 in Iceland to 0.2 in Romania (European mean 2.9). The number of trained operators per 10(6) inhabitants ranged from 24 in Germany to 0.4 in Romania (European mean 10). During 1994, a mean of 701 coronary angiograms and 170 PTCAs were performed per catheterization facility in Europe (range: 1052 coronary angiograms and 293 PTCAs per facility in Norway to 218 coronary angiograms and 37 PTCAs per facility in Romania). CONCLUSIONS: The number of both coronary angiograms and coronary angioplasties continues to grow at an annual rate of approximately 20% in Europe. There is a wide range in the amount of revascularization procedures performed between western and eastern European countries. However, countries with the lowest numbers of coronary angiograms and coronary angioplasties, e.g. Romania, also show the fastest annual growth. About one quarter of all patients undergoing coronary angiography are subsequently revascularized by coronary angioplasty. (ABSTRACT TRUN

Angioplasty, Balloon, Coronary↗
PubMed1998

Use of coronary angioplasty, bypass surgery, and conservative therapy for treatment of coronary artery disease over the past decade.

AIMS: There is a continuous increase in the number of percutaneous transluminal coronary angioplasty procedures performed per year per population in most industrialised countries. This analysis searches for trends in treatment decisions after diagnostic coronary angiography. METHODS AND RESULTS: The degree of coronary artery disease and the therapeutic strategy were determined retrospectively in consecutive patients undergoing coronary angiography at a Swiss university hospital during three different time periods in the past 11 years (n = 750 in 1994, n = 500 in 1990, and n = 545 in 1983). The indication for coronary angioplasty rose from 45% in 1983 to 78% in 1990 and 87% in 1994 in patients with one-vessel disease, from 25% to 38% and 71% in patients with two-vessel disease, and from 10% to 24% and 29% in patients with three-vessel disease. In contrast, the use of conservative therapy declined with time, independent of the severity of coronary artery disease. Indications for coronary artery bypass grafting decreased in patients with two-vessel disease, but did not change in patients with three-vessel disease over the 11 year period. CONCLUSIONS: The use of coronary angioplasty, bypass surgery, and conservative therapy changed drastically over the past decade, with an increasing use of angioplasty and a multivessel disease, and of bypass surgery in two-vessel disease. The expansion of coronary angioplasty is mainly related to increased use in patients previously treated conservatively.

Adult↗
PubMed1998

Prolonged heparin after uncomplicated coronary interventions: a prospective, randomized trial.

BACKGROUND: Continuous heparin infusion after percutaneous transluminal coronary angioplasty (PTCA) procedures prolongs the hospital stay and could increase the occurrence of bleeding complications. The aim of this randomized trial was to evaluate whether omission of heparin infusion after uncomplicated coronary interventions in patients with stable and unstable angina with or without stent implantation increased the incidence of acute cardiac complications. METHODS AND RESULTS: A total of 191 consecutive patients who underwent successful PTCA were randomly assigned to receive either prolonged heparin (heparin group) or no postprocedure heparin (control group). The 2 treatment groups were comparable with respect to clinical and angiographic characteristics. Stents were used in 36% of the control group and in 33% of the heparin group. Cardiac complications occurred in 8 (4%) patients. Four (4%) patients in the control group and 3 (3%) patients in the heparin group had a myocardial infarction. One patient in the control group died 3 days after the intervention. No patient in either group needed a repeat revascularization during the target hospitalization. Peripheral vascular complications in the control and heparin groups occurred in 1% and 3% of the patients, respectively. CONCLUSIONS: Omission of heparin after successful PTCA with or without stent implantation in patients with stable and unstable angina did not significantly increase the incidence of acute cardiac complications. It allows for early sheath removal and patient discharge and saves costs. This study, combined with other small studies in the field, provides strong evidence that heparin should not be used routinely.

Adult↗
PubMed1998

First clinical evaluation of a new concept for puncture-site occlusion in interventional cardiology and angioplasty.

UNLABELLED: Percutaneous transluminal angioplasties of coronary and peripheral vessels are frequently used and replace open surgery in a certain percentage. Hemostasis in most of these patients is reduced or inhibited and often leads to hemorrhage from the puncture track. Due to this fact, hospitalization is not only mandatory, but also surgical revision of the puncture site is often required. We designed and produced a coaxial delivery system, which is mounted on the indwelling guide-wire after withdrawal of the instrumentation for angioplasty. The delivery system is advanced down to the outer wall of the punctured vessel and 1 cc of human two-compound fibrin glue is released. Based on our experience with laboratory and animal research, which we already presented at the 7th International Symposium on Pediatric Surgical Research in Heidelberg, May 27-28, 1994, we conducted the first trials in interventional cardiology. In 1996, a first group of 10 patients, aged 49 to 80 years, underwent sealing of the right femoral artery after diagnostic evaluation (n = 3) of coronary balloon dilatation (n = 7). In patients, the local manual compression time was less than 5 minutes and 1 patient needed 10 minutes of digital compression. In one case, bleeding continued and a compression bandage was successful, whereas in another case the local hematoma formation needed surgical revision with suture of the ruptured vessel wall. CONCLUSION: Puncture-track sealing with locally applied fibrin glue seems to be an efficient tool to avoid bleeding after interventions of coronary and peripheral vessels. In the meantime, the device has been improved by a target system to optimize the delivery of the glue exactly at the outer wall of the vessel.

Aged↗
PubMed1998

Pseudoaneurysm of femoral artery after catheterisation: treatment by a mechanical compression device guided by colour Doppler ultrasound.

BACKGROUND: Femoral artery pseudoaneurysm is a significant complication in patients undergoing diagnostic or therapeutic catheterisation. First choice treatment for pseudoaneurysm is freehand ultrasound guided compression repair, which is time consuming and uncomfortable for the patient and operator. AIM: To explore a mechanical compression device (FemoStop) as an alternative treatment for iatrogenic femoral artery pseudoaneurysm. METHODS: Fourteen patients with pseudoaneurysm were considered for treatment with FemoStop after a brief freehand ultrasound guided compression repair to confirm the compressibility of the lesion. The FemoStop compression was applied for 20 minutes. The result was controlled with colour Doppler ultrasound, and a second cycle of 20 minutes followed if necessary. RESULTS: FemoStop compression was successful in 13 of the 14 patients. The mean compression time was 33 minutes (range, 20-60). The mean number of compression periods was 1.6 (range 1-3). FemoStop compression was successful in all 11 patients not taking anticoagulants and in two of three patients receiving anticoagulants. The mean compression time in patients given oral or intravenous anticoagulants was longer (50 v 27 minutes). Colour Doppler ultrasound 12 hours after the procedure indicated no recurrence of pseudoaneurysm in the 13 patients with initial success. CONCLUSIONS: FemoStop compression for iatrogenic pseudoaneurysm is feasible, and as safe and effective as freehand ultrasound guided compression repair. It is more comfortable for the patient and operator, and probably more economical than freehand compression.

Adult↗
PubMed1998

Nitrate induced coronary vasodilatation: differential effects of sublingual application by capsule or spray.

BACKGROUND: Sublingual nitroglycerin (glyceryltrinitrate, GTN) capsules or isosorbide dinitrate (ISDN) spray are routinely used to treat anginal attacks and to vasodilate maximally the epicardial coronary arteries during coronary angiography. OBJECTIVE: To compare the coronary vasodilatory effects of GTN capsules and ISDN spray with those induced by intracoronary GTN using quantitative coronary angiography. DESIGN: 96 patients (79 men and 17 women; median age 59 years) were randomised to four groups to receive either a sublingual capsule containing 0.8 mg GTN or two puffs of spray delivering 0.8 mg ISDN, followed or preceded by an intracoronary bolus of 0.2 mg GTN used as reference for maximal vasodilatation. RESULTS: There was a significant increase in the mean diameter of coronary arteries in angiographically normal segments in patients who received either intracoronary GTN (groups 1 and 2) or ISDN spray (group 4) as a first application (group 1, 0.46 mm, + 17%, (baseline vessel diameter 100%), p < 0.001; group 2, 0.45 mm, + 13%, p < 0.001; group 4, 0.47 mm, + 13%, p < 0.05). Patients who received a sublingual GTN capsule as the first application mode (group 3) had no significant change in epicardial vessel diameter (0.10 mm, + 5%, p = 0.3). CONCLUSIONS: Sublingual ISDN spray may be more efficacious than sublingual GTN capsules in certain patients with anginal attacks. ISDN spray should be preferred over capsules in coronary angiographic procedures.

Acute Disease↗
PubMed1998

Comparison of genetic variability in wild insular and mainland populations of Eulemur macaco: implications for conservation strategy.

DNA fingerprinting analysis was used to investigate genetic variability within and between three wild populations of Eulemur macaco living on two islands and on the mainland. The analyses revealed that the genetic variability of the population from the smaller island was, as expected, lower than that from the larger island. Surprisingly, on the larger island the genetic variability was greater than on the mainland. These results, in agreement with those previously obtained from blood markers, are discussed in relation to the history of these populations. In addition, the study suggests that settlement of the smallest island was not only by animals originating from the mainland, as previously proposed on the basis of blood marker data, but also by lemurs from the nearby, larger, island. Evidence is presented that reliable information about population structure can be derived only from studies using different genetic markers. This information is important to enable appropriate conservation programmes to be designed.

Animals↗
PubMed1998

Functional assessment of collaterals in the human coronary circulation.

The coronary collateral circulation is an alternative source of blood supply to a myocardial area jeopardized by the failure of the stenotic or occluded vessel to provide enough blood flow to this region. Until recently, only qualitative or semiqualitative methods have been available for the assessment of the coronary collateral circulation in humans, such as the patient's history of walk-through angina pectoris, the registration of intracoronary ECG signs for myocardial ischaemia or angina pectoris during coronary occlusion, or coronary angiographic classification (score 0-3) of collaterals. Studies of coronary wedge pressure measurements distal of a balloon-occluded coronary artery and the recent advent of ultrathin pressure and Doppler angioplasty guidewires have made it possible to obtain pressure or flow velocity data in remote vascular areas and, thus, to calculate functional variables for coronary collateral flow. Those coronary occlusive pressure- and flow velocity-derived parameters express collateral flow as a fraction of antegrade coronary flow during vessel patency of the collateral-receiving vessel. They are both interchangeable, and they have been validated in comparison to 'traditional' methods and against each other. The possibility of accurately measuring coronary collateral flow indices in humans undergoing coronary balloon angioplasty opens areas of investigation of the pathogenesis, pathophysiology and therapeutic promotion of the collateral circulation previously reserved for exclusively experimental studies. The purpose of this article is to review several clinically available methods for the functional characterization of the coronary collateral circulation.

Angina Pectoris↗
PubMed1998

Left heart bypass in the pig with a centrifugal pump using cannulae prepared for percutaneous placement.

A rapid and efficient circulatory support system may save a patient in cardiogenic shock. Left heart bypass with percutaneous and trans-septal placement of the aspiration cannula simplifies the circuit and eliminates the need for an oxygenator. In this pre-clinical study we assessed left heart bypass support with a centrifugal pump using new cannulae prepared for percutaneous placement (14 F arterial catheter and 16 F left atrial aspiration line) in 5 anaesthetized pigs. Animals were supported for two hours at a mean flow of 3.2 l/min (4,033 rpm), a mean haematocrit of 29% and low heparinisation (ACT double baseline). Hemodynamic measurements and blood samples were taken at baseline (A), 10 minutes (B), one hour (C) and 2 hours (D) on support. Results show maintenance of hemodynamic parameters throughout the 2 hour support period. Only systolic arterial and left ventricular pressure decreased by 12% and 20% respectively from baseline to the end of the support period with a 13% increase in cardiac output. When the pump was turned on (0-3 l/min) there was usually a decrease in heart rate, systolic pressure and left ventricular pressure, with unchanged cardiac output (non failing model). Potassium increased from 3.9 to 4.2 mmol/l (ns), and plasma hemoglobin from 6.0 to 18.2 mg/dl (p<0.05). Thrombocytes decreased from 187 to 155 10(9)/l (ns). In conclusion, this preclinical study demonstrated the feasibility of an efficient left heart bypass of short duration with a centrifugal pump using cannulae prepared for percutaneous placement. Left heart bypass was well tolerated hemodynamically and no significant laboratory change occurred within the two hours of support. This opens several possibilities for the short term support of patients in cardiogenic shock and eventually also for patients submitted to minimally invasive cardiac surgery.

Animals↗