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Biomedical subjects

M Fleisch

Publications and source records attributed to M Fleisch.

At least 19 recordsLinked to original sources
PubMed1998

Hemodynamic and coronary effects of the endothelin antagonist bosentan in patients with coronary artery disease.

BACKGROUND: Endothelin is a potent endothelium-derived vasoconstrictor peptide with proliferative properties. Elevated levels of the peptide occur in coronary artery disease; however, its pathophysiological role as a regulator of coronary tone and structure is uncertain. Endothelin-receptor antagonists are specific tools to clarify this issue and might be useful in the treatment of coronary artery disease. METHODS AND RESULTS: In a double-blind, placebo-controlled randomized study, we investigated the effects of the ETA/ETB endothelin-receptor antagonist bosentan or placebo on systemic and coronary hemodynamics in 28 patients with angiographically documented stable coronary artery disease by quantitative coronary angiography and an intracoronary Doppler guidewire. Bosentan 200 mg IV decreased systolic blood pressure (P<0. 05), whereas heart rate increased slightly (P<0.05). Coronary diameter increased, particularly in vessels with no or mild angiographic changes (P<0.01). Glycerol trinitrate did not further dilate these segments, whereas coronary diameter increased significantly after nitrate in the placebo group. The increase in coronary diameter after bosentan correlated inversely with plasma LDL-cholesterol levels (P<0.01) in both stenotic and angiographically normal coronary segments. Coronary flow velocity did not change. Bosentan was well tolerated. CONCLUSIONS: Endogenous endothelin exerts a vasoconstrictor tone in epicardial coronary arteries of patients with coronary artery disease, as evidenced by the vasodilation exerted by the combined ETA/ETB endothelin-receptor antagonist bosentan under acute conditions. Bosentan can safely be given to these patients. Hence, further long-term studies are necessary to determine the therapeutic potential of endothelin-receptor antagonists in patients with coronary artery disease.

Antihypertensive Agents↗
PubMed1998

[Pathophysiology of coronary collateral circulation in the human].

The functional relevance of coronary collaterals in humans has yet to be fully explored. Several studies demonstrated a protective role of collaterals in patients with coronary artery disease. On the other hand, negative aspects of well-developed coronary collaterals have been reported, e.g. a higher rate of restenosis following coronary angioplasty, or a redistribution of blood via collaterals away from the myocardial area in need towards normally perfused areas (coronary steal). In the past, the coronary collateral circulation has been assessed only qualitatively, using visual angiographic or nuclear imaging methods. With the recent advent of intracoronary Doppler and pressure-transducers, quantitative assessment of functional parameters of the coronary circulation has become feasible. This article reviews ongoing research in the field of coronary collaterals in humans, concerning their exact determination, the positive and negative aspects of their structure as well as their functional aspects.

Angioplasty, Balloon, Coronary↗
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

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↗
PubMed1997

Direct intracoronary evidence of collateral steal in humans.

BACKGROUND: Coronary steal is defined as a fall in blood flow toward a certain vascular region in favor of another area during arteriolar vasodilatation, ie, a coronary flow velocity reserve (CFVR) <1. The purpose of this study was to determine the frequency of steal in patients with a wide range of collateral supply to a vascular area of interest and to assess whether steal is associated with the amount of collateral flow. METHODS AND RESULTS: One hundred patients 57+/-9 years old with a coronary artery stenosis to be dilated were examined with intracoronary (IC) Doppler guidewires. IC adenosine-induced CFVR<1 obtained distal to the stenosis was defined as steal. An index for collateral flow was determined by positioning the Doppler guidewire in the collateral-dependent vessel distal to the stenosis and measuring the flow velocity time integral during (Vi(occl), cm) and after (Vi(ø-occl)) balloon occlusion. Vi(occl)/Vi(ø-occl) was determined without and with intravenous adenosine (140 microg x kg(-1) x min(-1)). Coronary steal occurred in 10 of 100 patients. Patients with steal showed superior collaterals compared with those without steal: Vi(occl)/Vi(ø-occl)=0.65+/-0.24 in patients with steal versus 0.29+/-0.18 in those without steal (P=.0001). In all patients with steal, there was a reduction in collateral flow during intravenous adenosine-induced hyperemia, whereas in the majority (70%) of patients without steal, collateral flow increased or remained unchanged during hyperemia. CONCLUSIONS: Coronary steal assessed by intracoronary Doppler flow velocity measurements occurs in 10% of patients with a wide range of coronary collaterals to the vascular area from which blood flow is redistributed. There is a direct association between the presence of steal away from and the amount of collateral flow toward the region under investigation. Collateral flow to the vascular region studied decreases during adenosine-induced hyperemia, which indicates a mechanism of steal via the extensive collaterals.

Aged↗
PubMed1997

[Measurements of intracoronary pressure and blood flow velocity].

Quantitative coronary angiography and new intracoronary imaging devices are not able to provide functional data for the assessment of the severity of coronary artery stenotic lesions. The functional characterization of coronary artery stenosis gives insight into whether it compromises myocardial perfusion under conditions of pharmacologic or physical stress, i.e., whether the stenosis has hemodynamic relevance. The measurement of trans-stenotic pressure gradients and/or post-stenotic blood flow velocities using very recently developed, miniaturized pressure- and Doppler-angioplasty guidewires (1/3 mm in diameter) provides a valuable alternative to traditional, non-invasive means for the functional assessment of coronary artery disease. The most widely employed parameters for the functional characterization of coronary artery stenoses are the ratio between flow velocities during pharmacologically induced hyperemia and at resting conditions (coronary flow velocity reserve), and the pressure-derived fractional flow reserve, i.e., the ratio of mean poststenotic to mean aortic pressure during hyperemia. Furthermore, poststenotic pressure and flow velocity measurements during and after occlusion of stenosis can be used for the quantitative assessment of collateral circulation among different vascular regions.

Angioplasty, Balloon, Coronary↗
PubMed1997

[Interventional treatment of heart valve diseases].

Percutaneous balloon valvuloplasty of stenoses has been introduced into medical practice in the late 70ies. Over the past decade, the method has evolved to a valid alternative to valve surgery in selected cases. Balloon valvuloplasty of isolated mitral stenosis is to date the therapy of choice and yields results comparable to those of surgery. It is even superior in only moderately diseased valves. However, the most frequent valve stenosis, that is aortic stenosis of the elderly, is not suitable for balloon dilatation. Dilatation of congenital aortic stenosis can be attempted if the valve is bicuspid or tricuspid. The recurrence rates for valvular stenoses after valvuloplasty are similar to those after surgical commissurotomy.

Aged↗
PubMed1997

[Myocardial revascularization in geriatric patients].

The results of percutaneous transluminal coronary angioplasty (PTCA) in 71 patients over 75 years of age were retrospectively analyzed and compared with those of 55 patients aged over 75 who underwent surgical revascularization (CABG) during the same time period (1992-1995). The main indication for revascularization was unstable angina. The clinical success in PTCA patients was 92%, with a lesion success rate of 93%. Major cardiac complications occurred in 5% of patients with an in-hospital mortality of 1%. The mean hospital stay was 4 days. During a follow-up period of 16 (range 1-36) months, 23% of patients treated with PTCA needed repeat revascularization (17% PTCA, 6% CABG) and 4 patients (6%) suffered nonfatal myocardial infarction. In-hospital mortality and complications were higher among the surgically treated patients (mortality 7%, major complications 45%), a fact probably related to their poorer clinical condition preoperatively. Repeat revascularization rate in the surgically treated group was 2%. The long-term mortality rate in both groups was 10%. Among long-term survivors, 92% of patients indicated that revascularization (PTCA or CABG) improved their quality of life. More than 80% led normal lives, and > 90% would undergo a second procedure if needed. In selected patients aged over 75, PTCA has a high immediate success rate with low complications and mortality. Long-term recurrence rate is high, however, and repeat revascularizations are frequent. Patient satisfaction after myocardial revascularization (PTCA or CABG) is excellent and the majority of elderly patients can lead an active and independent life.

Aged↗
PubMed1996

Low-dose thrombolysis for thrombosed prosthetic heart valve.

This report describes two cases of successful fibrinolysis of thrombosed tricuspid and mitral valve prostheses (Carbomedics; Austin, Texas) with low-dose urokinase therapy corresponding to only one third of the dose usually recommended.

Heart Valve Prosthesis↗
PubMed1995

[Management of patients with carotid stenosis and coronary heart disease].

Coronary and carotid atherosclerosis are often coexistent in the same patient. Therefore, patients presenting with carotid stenosis should be screened for coronary heart disease and vice versa. Patients with significant asymptomatic or symptomatic carotid stenosis have an elevated perioperative risk of cerebral ischemic attacks during operations with extracorporeal circulation and of myocardial infarction during carotid endarterectomy. The operations should be performed simultaneously, with carotid endarterectomy being done before sternotomy. This yields mortality and morbidity rates comparable with those for isolated operations on extracorporeal circulation. Medical therapy for such patients consists of platelet inhibitors with adequate cardiac medication.

Adult↗
PubMed1995

[Acquired heart diseases and pregnancy].

Understanding of the mechanisms of cardiovascular and hemodynamic adaptation during pregnancy helps to prevent or manage complications in cardiac patients during gestation. Manifestations of coronary heart disease are exceptional during pregnancy and delivery. The same is true of disorders of the pericardium. Peripartal cardiomyopathy is a myocardial disorder of undetermined cause occurring shortly before, during or after delivery, which may take a fatal course. Hypertrophic obstructive or non-obstructive cardiomyopathy is compatible with gestation and delivery without serious complications in most cases. Rheumatic mitral stenosis was the most common cardiac disorder until the 1950s. Nowadays it is rarely seen in this country. Surgical and other interventional therapies have greatly changed the outlook in pregnant women with valvular heart disease. A highly controversial issue is heart valve replacement in young women and management of anticoagulation during pregnancy. Like any other drug therapy, anticoagulation during gestation requires careful weighing of the benefit for the mother against toxic and teratogenic effects for the fetus. In women with heart disease the management of pregnancy should start, if possible, before conception. Thorough counseling and proper planning of pregnancy and of therapeutic measures is essential in order to avoid or manage complications.

Abnormalities, Drug-Induced↗