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Biomedical subjects

W Bay

Publications and source records attributed to W Bay.

At least 19 recordsLinked to original sources
PubMed1999

Cerebral microemboli during left heart catheterization.

BACKGROUND: The aim of this study was to describe the rate of microemboli signals (MES) during left heart catheterization (LHC). METHODS: A monitoring of both middle cerebral arteries using transcranial Doppler ultrasonography was performed to investigate cerebral microemboli during LHC. Seventy-two patients undergoing LHC and 29 patients with LHC followed by coronary intervention were studied. RESULTS: During a standardized LHC (n = 52), 95 +/- 45 MES were detected of which 67.5% occurred during injection of contrast media or saline solution, 30% during movements of wire and catheter, and 2% during catheter manipulation. During coronary interventions only, rotablation (n = 2) was followed by a massive increase in MES. The use of injection fluids prepared with minor gas content reduced the MES rate by 67% (P <.05). All MES were clinically silent. CONCLUSIONS: Cerebral microembolism is a current finding during LHC. The dependence of the MES rate during diagnostic LHC on the gas content of the injection fluids provides evidence that most of the MES are caused by microbubbles and not by solid emboli. The high rate of MES during coronary rotablation may be explained by the formation of cavitation bubbles. The clinical results of the MES during LHC appear to be benign.

Adult↗
PubMed1999

Early time course of heart rate variability after thrombolytic and delayed interventional therapy for acute myocardial infarction.

In 89 of 97 consecutive patients with myocardial infarction (MI) undergoing thrombolysis and delayed early coronary angiography with PTCA, if indicated, heart rate variability (HRV) in time domain was evaluable 40 +/- 11 h after the onset of chest pain using 24-hour ECG recordings. Patients with anterior MI (n = 40) had lower values for HRV and left ventricular ejection fraction (p < 0.05). The mean of all 5-min standard deviations of RR intervals (SDNNi) and the root-mean-square difference of successive RR intervals (rMSSD) decreased significantly (p < 0.001 each), whereas the standard deviation of all normal RR intervals and the percentage of absolute differences between successive RR intervals only showed a tendency to lower values 4 weeks after MI (p = 0.20 and 0.08, respectively). The decreases in SDNNi and rMSSD were more evident in inferior than in anterior MI. The time course of HRV following MI was similar in patients with and without PTCA. These results indicate an initial vagal hyperactivity in inferior MI, which is quickly predominated by sympathetic activation and a prolonged recovery of the cardiac autonomic imbalance after MI despite a successful combined reperfusion therapy.

Adult↗
PubMed1998

Primary lymphoma of the heart: report of a case with histological diagnosis of the transvenously biopsied intracardiac tumor.

Primary cardiac lymphoma is an extremely rare disease and is associated with a high mortality. In most cases, lymphomatous involvement of the heart and/or pericardium occurs as a late manifestation of disseminated disease. Primary cardiac lymphoma is treatable when appropriately diagnosed. We report the case of an immunocompetent 69-year-old patient who presented with signs of dyspnea and a transmural mass infiltrating the apical section of both ventricles. Examination of the tissue obtained by transvenous biopsy revealed high-grade non-Hodgkin's lymphoma of B-cell lineage. The patient was treated successfully with CHOP chemotherapy. This case demonstrates that early diagnosis and intensive chemotherapy might contribute to a better prognosis for patients with malignant lymphoma of the heart.

Aged↗
PubMed1998

Influence of thermal stress on the incidence of acute myocardial infarction in a temperate climate.

Using a Poisson regression model the relative incidence of acute myocardial infarctions (AMI) prospectively registered in 8 hospitals within a radius of 50 km during a 2-year period was correlated with the outside conditions characterized by a complete thermophysiological model (Klima-Michel Model) defining thermal stress. An increase in the incidence of AMI related to thermal stress could be demonstrated neither by splitting the study period into 12 equally sized 'felt-temperature' classes by months of the year nor by single days. This was confirmed by correlation of the AMI rate with the mean felt-temperature level during the preceding 14 days. Thermal stress caused by the atmospheric conditions in a temperate climate may be too weak to influence significantly the incidence of AMI.

Aged↗
PubMed1998

Experimental intracoronary stenting: comprehensive experience in a porcine model.

Appropriate animal models for intracoronary stenting are most important for improving understanding of the pathophysiology of acute occlusion and long-term re-stenosis, which currently limits the safety and efficacy of percutaneous transluminal coronary angioplasty in humans. Since the anatomy and physiology of swine coronary arteries closely resemble those of humans, the procine model should be ideal for testing of stents. This is a comprehensive report on an experimental set-up in pigs, communicating in detail the necessary techniques as well as some modifications facilitating safe intracoronary stent placement and successful follow-up studies for weeks or months. Stent procedure is performed in mechanically ventilated and haemodynamically monitored animals under balanced anaesthesia. Intracoronary application of flow wires allows the assessment of local flow conditions, flow properties and coronary flow reserve. Real-time intravascular ultrasonography (IVUS) provides detailed information on coronary morphology and enables the appropriate sizing of the coronary lumen. From our own experience, we like to propose that the use of the porcine model has the potential to gain new insights into the pathophysiology of intracoronary stent placement-associated complications and allows for the study of modifications in techniques and materials, and the development of novel pharmacological therapeutic strategies.

Angioplasty, Balloon, Coronary↗
PubMed1997

Coronary implantation of silicone-carbide-coated Palmaz-Schatz stents in patients with high risk of stent thrombosis without oral anticoagulation.

Coronary stenting in bail-out situations is effective but associated with increased stent thrombosis and bleeding rates. Silicone-carbide coating reduces fibrinogen activation on alloplastic surfaces and thus may also reduce stent thromboses. A total of 44 patients received 58 silicone-carbide-coated stents for threatened (80%) or abrupt (20%) closure. In addition to heparin, patients were treated with aspirin and ticlopidine (75%) or aspirin (25%) only. Two patients (4.5%) died in the hospital. The combined in-hospital complication rate including death, emergency revascularization, stent-related myocardial infarction, and stent thrombosis was 9% (4 of 44 patients). Major bleeding occurred in 4 patients (9%). Six-month follow-up angiography was obtained in all eligible patients (42 of 44), revealing a restenosis rate of 21% (9 of 42). Thus, coronary implantation of silicone-carbide-coated stents is feasible in bail-out situations without oral anticoagulation and with a low complication rate. Further studies are required to optimize the anticoagulation regimen with this type of coating.

Adult↗
PubMed1997

Trouser-like stenting: a new technique for bifurcation lesions.

We report on a new technique of stenting a bifurcation lesion. A manually bent 180 degrees hinged slotted tube stent was implanted using the kissing balloon technique (resembling two trouser legs). In addition, the proximal part of the main vessel was covered with a stent mounted on two balloons corresponding to the trousers' waist. This "trousers-like stent technique" ensures open accesses to both vessels not obstructed by stent struts and could be a promising solution for main bifurcation lesions.

Angioplasty, Balloon, Coronary↗
PubMed1996

Determinants of the natural course of ventricular late potentials after thrombolytic therapy for acute myocardial infarction.

The intraindividual changes of ventricular late potentials and their possible determinants were examined prospectively in 88 consecutive patients (male: 75; mean age: 58 +/- 9 years) after thrombolytic therapy for acute myocardial infarction. Late potential analysis was performed 4 weeks and 12 months after acute myocardial infarction. At the same time, a left heart catheterization was performed to assess the extent of coronary heart disease and left ventricular ejection fraction. The incidence of late potential 4 weeks after acute myocardial infarction was 15% (13/88 patients). Eighteen percent (16/88) of the patients revealed changing results of late potential analysis: 9 patients lost late potential (late potential pos./neg.) 1 year after acute myocardial infarction and 7 patients presented new formation of late potential (late potential neg./pos.). Preserved late potentials were found in four patients (late potential pos./pos.). Late potential analysis remained negative in 68 patients (late potential neg./neg.). There was no influence of age, gender, site of infarction, clinical course, and medical treatment on the natural course of late potential. Changing results of late potential analysis seemed to be correlated with the evolution of left ventricular ejection fraction and the dynamics of coronary heart disease. In the group late potential pos./pos., comparable values for left ventricular ejection fraction were measured at both examinations, whereas late potential neg./neg. had a significant increase in ejection fraction. In the group late potential pos./neg., a significant improvement in left ventricular function was also measured. In contrast, the late potential neg./pos. group tended to have lower left ventricular ejection fractions 1 year after infarction. In the late potential neg./pos. and late potential pos./pos. groups, the extent of coronary artery disease returned to conditions comparable to baseline despite an initial reduction after coronary revascularization performed 4 weeks after infarction. Late potential neg./neg. and late potential pos./neg. revealed a stable benefit gained from coronary revascularization with a persistent reduction in the number of diseased vessels. Dynamic changes in the results of the signal-averaged ECG 1 year after thrombolytic therapy for acute myocardial infarction were observed in 18% of the patients. These changes seem to be correlated with the evolution of left ventricular function and the dynamics of coronary artery disease.

Action Potentials↗
PubMed1995

Comparison of mortality from acute myocardial infarction in patients receiving anistreplase with those not receiving thrombolysis.

Within 1 year, 434 patients were admitted to 14 hospitals with suspected acute myocardial infarction (AMI) < or = 4 hours after the onset of symptoms. Group A consisted of 171 patients (39%) treated with thrombolysis, and group B consisted of 263 patients (61%) with contraindications. Patients in group A more likely had a "definite AMI" (92%; group A1) than patients in group B (67%; group B1). Group B1 had 277 contraindications (1.6/per patient) with increased risk for life-threatening bleeding being the most frequently recorded at admission. The in-hospital mortality in group A1 was 7% (11 of 158) and in group B1, 27% (47 of 177) (p < 0.0001). Age and type of therapy (thrombolysis or no thrombolysis) were identified as independent predictors of increased mortality (p < 0.0001 and < 0.05, respectively). Thus, although most patients with an AMI are excluded from thrombolytic therapy because of contraindications, our data suggest that their in-hospital mortality is unexpectedly high. Further evaluation of this group of patients is warranted to define the impact of contraindications as an independent factor of mortality.

Aged↗
PubMed1994

High resolution ECG and left ventricular volume after acute myocardial infarction.

The presence of ventricular late potentials (LPs) early after acute myocardial infarction (AMI) was recently reported to correlate with left ventricular dilatation subsequent to AMI. We assessed prospectively the relationship between LP (time domain) in the late phase of AMI and left ventricular end-diastolic volume (EDV) measured by equilibrium radionuclide angiocardiography 4 weeks and 12 months after AMI. In 80 consecutive patients 4 weeks and 12 months after thrombolytic therapy for AMI, LP and EDV were determined (EDV1, EDV2). There was no significant correlation between QRS duration (r = 0.18), RMS40 (r = 0.08), or LAS40 (r = 0.1) and EDV1 or EDV2 in patients with or without LP at baseline. In both groups (patients with [n = 15] and without LP [n = 65]), EDV1 and EDV2 were comparable (128 +/- 32 mL vs 126 +/- 35 mL; 114 +/- 40 mL vs 117 +/- 36 mL; P = NS). In addition, there was no significant difference between EDV1 and EDV2 in patients who developed new LP (n = 6) or lost LP (n = 9) 12 months after AMI. In contrast to LP in the very early phase after AMI, there seems to be no significant correlation between the high resolution ECG in the late phase after thrombolytic therapy for AMI and left ventricular EDV.

Electrocardiography↗
PubMed1993

Cineradiography for determination of normal and abnormal function in mechanical heart valves.

To determine the diagnostic value of cineradiography of mechanical heart valves, 112 cinefluoroscopic studies were performed in 76 patients with 95 valve prostheses (caged ball or disk valves, tilting disk and bileaflet valves). A patient group (n = 45) presenting with clinical or echocardiographic findings suggestive of valve-related complications was compared with a control group (n = 31) without such symptoms. Disk-opening angles (mean +/- SD) for Medtronic Hall aortic valves were found to be significantly smaller (62.8 +/- 11.1 degrees) in patients than in control subjects (73.9 +/- 1.6 degrees; p < 0.05). Tissue ingrowth or thrombus formation, or both, demonstrated in 3 patients on subsequent reoperation, are considered as the main cause of incomplete or asymmetric disk opening. Opening and closing times did not differ significantly between patients and control subjects. Besides abnormal valve motion, structural defects such as strut fracture or leaflet escape could be rapidly detected by cineradiography if x-ray projections according to the particular valve design were used. Together with quantitative Doppler echocardiographic and clinical data, this method can help to give specific answers if the question is to either confirm or exclude imminent or acute valve malfunction. Thus, modern cineradiography is a highly valuable noninvasive diagnostic tool for both rapid management of emergency cases and routine follow-up of patients with mechanical heart valves.

Aortic Valve↗
PubMed1993

Acute renal failure resulting from intravenous immunoglobulin therapy.

In idiopathic thrombocytopenic purpura, a known immune-mediated disorder, intravenous IgG is the treatment of choice. Success and the lack of side effects of intravenous IgG in the treatment of idiopathic thrombocytopenic purpura have encouraged consideration of its use in the treatment of neurologic disorders of presumed autoimmune pathogenesis. In this report, we describe two patients who developed acute renal failure following intravenous IgG treatment. The first patient had chronic inflammatory demyelinating polyneuropathy and was treated with intravenous IgG instead of prednisone because of preexisting diabetes. The second patient had idiopathic thrombocytopenic purpura and received intravenous IgG treatment as part of standard care. The patient with idiopathic thrombocytopenic purpura had unrelated bilateral high-grade renal artery stenosis. Both patients had a creatinine level of 140 mumol/L (1.6 mg/dL) prior to treatment. Renal biopsies performed during acute renal failure in each patient demonstrated marked swelling and vacuolization of the proximal tubular epithelial cytoplasm typical of high-solute-load-induced damage (similar to that associated with the use of mannitol). This report draws attention to the importance of screening for impaired renal function before intravenous IgG therapy is initiated. The patients we describe received standard doses of intravenous IgG at the recommended infusion rate yet developed oliguric renal failure. Awareness of serious side effects and recognition of predisposing factors provide means of avoiding known life-threatening complications of intravenous IgG therapy.

Acute Kidney Injury↗
PubMed1991

Stability of dobutamine hydrochloride in peritoneal dialysis solutions.

The stability of dobutamine hydrochloride in peritoneal dialysis solutions at 4, 26, and 37 degrees C was determined. Dobutamine (as the hydrochloride salt) was added to dialysis solutions containing 1.5% or 4.25% dextrose to concentrations of 2.5, 5.0, and 7.5 mg/mL. Samples were stored at 4, 26, and 37 degrees C to mimic refrigerator, room, and body temperature, respectively. At 0, 4, 8, and 24 hours, the samples were analyzed in triplicate by stability-indicating high-performance liquid chromatography to determine the percentage of drug remaining. More than 90% of the drug was retained under all storage conditions in 1.5% dextrose dialysate containing an initial dobutamine hydrochloride concentration of 5.0 or 7.5 micrograms/mL. The mean concentration in the samples containing an initial dobutamine hydrochloride concentration of 2.5 micrograms/mL and stored at room temperature remained greater than 90% of the initial concentration for the first four hours and then decreased to less than 90%. Dobutamine was stable in 4.25% dextrose dialysate regardless of the initial concentration or the storage condition. Dobutamine hydrochloride 5.0 and 7.5 micrograms/mL in 4.25% dextrose dialysis solution was stable under all the test conditions. Dobutamine hydrochloride 2.5 micrograms/mL was stable in 1.5% dextrose dialysate for only four hours at room temperature.

Dialysis Solutions↗
PubMed1987

Intracellular pH in quiescent and stimulated ventricular myocardium. Effect of extracellular chloride concentration.

In ventricular trabeculae from guinea pig and cat heart superfused with a modified Tyrode's solution (pHo = 7.4) containing either 137 mM or 103 mM Clo-, intracellular pH (pHi) was measured with H+-sensitive double-barreled microelectrodes. In quiescent preparations pHi was 7.26 +/- 0.017 when Clo- was 137 mM, and 7.38 +/- 0.02 in 103 mM chloride. In 103 mM Clo- containing saline stimulation of the preparation produced no acidification but in 137 mM Clo- acidification occurred. The acidification was completely reversible when chloride was reduced again. When HCO3-/Cl- exchange was blocked by 0.5 mM SITS, pHi was lowered similar to the effect of increasing extracellular chloride concentration. It was concluded that when Clo- is raised, the HCO3-/Cl- exchanger operates as a Cl-/Cl- exchanger.

Animals↗
PubMed1987

A unique familial lobular glomerulopathy.

Five members of a family (four brothers and their father) were found to have proteinuria and microhematuria. One of the affected brothers developed chronic renal failure. Although a renal biopsy was never performed, this brother has subsequently received a renal transplant from a clinically unaffected sister. Renal biopsy was performed on four of the siblings (three brothers and the sister). Renal tissue from all three brothers who underwent biopsy showed similar glomerular lesions, characterized by striking cloverleaf expansion of glomerular lobules by an acellular hyaline material and segmental mesangial cell proliferation. Electron microscopy showed massive mesangial and subendothelial deposits and occasional areas of glomerular basement membrane splitting with round inclusions. The renal biopsy specimen of the sister was normal on light and electron microscopy and negative for immunoglobulins and complement on immunofluorescent staining. Immunofluorescence microscopy on one of the male siblings was negative for immunoglobulins and complement. No other physical or serologic abnormalities could be established. To our knowledge, this is a unique form of familial glomerulopathy that has not been previously described.

Adult↗
PubMed1983

The significance of the monocyte crossmatch in recipients of living-related HLA identical kidney grafts.

Monocytes and vascular endothelial cells (VEC) carry a "cell specific" antigen system that has been found to play an important role in the pathogenesis of rejection. In a preliminary study utilizing a standard crossmatch technique with the peripheral blood monocyte as target, recipients of HLA identical living-related grafts who had either pretransplant or who developed posttransplant anti-monocyte antibody, had a high incidence of early graft rejection. This larger study of recipients of HLA identical living-related grafts represents the results of 21 patients from 13 separate transplant centers in the United States. Results from this study seem to indicate a positive monocyte crossmatch represented a degree of sensitization toward donor monocyte antigens which lead to a poor clinical course.

Antigens, Surface↗