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Biomedical subjects

R W Koster

Publications and source records attributed to R W Koster.

At least 37 records · Page 2Linked to original sources
PubMed1997

Diagnostic accuracy of transesophageal echocardiography during cardiopulmonary resuscitation.

OBJECTIVES: We sought to establish the diagnostic accuracy of transesophageal echocardiography (TEE) during cardiopulmonary resuscitation. BACKGROUND: Because of its bedside diagnostic capabilities, excellent cardiac images and lack of interference with resuscitation efforts, TEE is ideally suited to determine the cause of a circulatory arrest that is not due to severe arrhythmia. However, the diagnostic accuracy of TEE during resuscitation is unknown. METHODS: TEE was performed in patients with prolonged circulatory arrest. The TEE diagnoses were compared with diagnoses from autopsy, surgery and clinical follow-up. RESULTS: Of the 48 study patients (29 male, 19 female, mean age +/- SD 61 +/- 20 years), 28 had an in-hospital cardiac arrest and 20 an out-of-hospital onset of arrest. Forty-four patients eventually died; four survived to discharge. The diagnoses made with TEE were cardiac tamponade (n = 6), myocardial infarction (n = 21), pulmonary embolism (n = 6), ruptured aorta (n = 1), aortic dissection (n = 4), papillary muscle rupture (n = 1), other diagnosis (n = 2) and absence of structural cardiac abnormalities (n = 7). A definite diagnosis from a reference standard was available in 31 patients. The TEE diagnosis was confirmed in 27 of the 31-by postmortem examination (n = 19), operation (n = 2), angiography (n = 2) or clinical course (n = 4). In the other four patients the TEE diagnosis proved incorrect by postmortem examination. The sensitivity, specificity and positive predictive value of TEE were 93%, 50% and 87%, respectively. In 15 patients (31%), major therapeutic decisions were based on TEE findings. CONCLUSIONS: TEE can reliably establish the cause of a circulatory arrest during cardiopulmonary resuscitation.

Adult↗
PubMed1997

Critical difference between serial measurements of CK-MB mass to detect myocardial damage.

To assess the critical difference in serial measurements of CK-MBmass and the ability of this critical difference to detect myocardial damage, we studied 110 patients in whom an acute myocardial infarction (AMI) had been ruled out. Blood samples were drawn at 3, 4, 5, 6, 7, 8, 12, 16, 20, and 24 h after onset of symptoms. With a critical difference of 72.6%, an increase of >2.0 microg/L between two CK-MBmass measurements was determined to be significant. Twenty-three of the non-AMI patients had an increase in CK-MBmass >2.0 microg/L, but five of these did not have an abnormal concentration of troponin T (i.e., not >0.1 microg/L). Also among the 110 non-AMI patients, 22 did have an abnormal troponin T value, 18 of whom (82%) also had CK-MBmass increased by >2.0 microg/L. In 20 of the 23 patients with an increase in CK-MBmass >2.0 microg/L, this increase was detected from the values for two samples collected at 5 and 12 h after onset of symptoms. In conclusion, using the critical difference for CK-MBmass defined as an increase >2.0 microg/L detected myocardial damage in patients without AMI.

Adult↗
PubMed1997

The clinical value of lactate dehydrogenase in serum: a quantitative review.

The aim of this article is to describe guidelines for rational use of lactate dehydrogenase and its isoenzymes, in the diagnostic processes and during follow-up, based on a systematic review of relevant literature. Sources of data for this study were English-language scientific publications, obtained from the database of the National Library of Medicine (Medline), concerning the clinical application (diagnosis, monitoring or treatment of disease) of lactate dehydrogenase and lactate dehydrogenase isoenzyme measurements in serum in the following main clinical fields: cardiology, hepatology, haematology and oncology. For acceptance in the present review, studies had to include: a proper definition of the tested patient population, diagnostic criteria, sampling time, sampling frequency, and test characteristics. Estimation of the relation between lactate dehydrogenase or lactate dehydrogenase isoenzymes and specific diseases expressed as sensitivity, specificity, survival or remission rate were extracted. The application of serum lactate dehydrogenase is relevant in the diagnosis of myocardial infarction (late detection), haemolytic anaemia, ovarian dysgerminoma and testicular germ cell tumor. For monitoring the progress of a disease lactate dehydrogenase is relevant in establishing the survival duration and rate in Hodgkin's disease and non-Hodgkin's lymphoma, and in the follow-up of ovarian dysgerminoma. Rational use of lactate dehydrogenase can be achieved when requests for its determination are limited to the above mentioned conditions. No rationale could be found for measuring lactate dehydrogenase isoenzymes.

Animals↗
PubMed1997

Effect of changes in liver blood flow on the pharmacokinetics of saruplase in patients with acute myocardial infarction.

BACKGROUND: The recombinant unglycosylated single chain urokinase-type plasminogen activator saruplase is cleared for a large part by the liver. A large interindividual variation in saruplase concentration is found in acute myocardial infarction (AMI) patients. The variable cardiac performance after an infarct may induce differences in liver blood flow that could explain the concentration diversity. This study was performed to investigate the relation between hepatic blood flow and the pharmacokinetic and pharmacodynamic properties of saruplase. METHODS AND RESULTS: Thirteen AMI patients were enrolled in this open label study. Patients received a bolus injection of 20 mg saruplase followed by a one-hour infusion of 60 mg saruplase. Concurrently 36 mg intravenous indocyanine green (ICG) was given over 1 h to measure hepatic blood flow. Blood samples were taken at regular time intervals to measure plasma levels of urokinase-type plasminogen activator (u-PA) antigen and activity, the two-chain form (tcu-PA) activity, indocyanine green, fibrinogen, fibrin and fibrin degradation products, alpha2-antiplasmin and thrombin antithrombin III complex. A correlation was seen between the clearance of ICG and both those of u-PA antigen (r = 0.62; p <0.05) and u-PA activity (r = 0.57; p <0.05). A negative correlation was seen between the area under the curve of tcu-PA activity and the areas under the effect curves of both fibrinogen and alpha2-antiplasmin (r = -0.84; p <0.01 and r = -0.65; p <0.05). CONCLUSIONS: Liver blood flow is an important determinant of the clearance of u-PA antigen and activity and reduction of flow in patients with heart failure will lead to an increase in plasma concentrations. High plasma concentrations of tcu-PA activity lead to increased systemic fibrinogenolysis. These results may be used to optimize saruplase treatment in patients with impaired cardiac function or after co-medication with drugs that affect liver blood flow.

Aged↗
PubMed1996

Pathogenesis of mitral regurgitation in acute myocardial infarction: importance of changes in left ventricular shape and regional function.

The pathogenesis of mitral regurgitation (MR) was determined by quantitative echocardiography in 188 patients with acute myocardial infarction (AMI) within 48 hours after admission. MR was classified, by using color Doppler, as significant (grades 3 to 4) or trivial (grades 0 to 2). Left ventricular (LV) function (global and regional), volume, and shape, as well as mitral valvular features, were measured and analyzed by stepwise logistic regression. Significant MR occurred in 25 (13%) patients. Univariately, recurrent infarction (p < 0.01), LV dilation (p < 0.001) and sphericity (p < 0.001), inferoposterolateral asynergy (p < 0.001), mitral annular dilatation (p < 0.005), and mitral leaflet restriction (p < 0.05) were associated with significant MR. In regression analysis, only recurrent infarction (odds ratio 5.08), LV sphericity index (odds ratio 1.12), and inferoposterolateral asynergy (odds ratio 6.07) were independently associated with significant MR, whereas none of the mitral valvular features examined had an independent association. In conclusion, changes in LV shape and regional function and not mitral valvular changes are prime determinants of significant MR after AMI.

Aged↗
PubMed1996

Prognostic value of troponin T, myoglobin, and CK-MB mass in patients presenting with chest pain without acute myocardial infarction.

OBJECTIVE: To assess the prognostic value of minor myocardial damage in patients presenting with chest pain without myocardial infarction. DESIGN: The relative risk of suffering a cardiac event in the next six months was assessed in patients with minor myocardial damage assessed by the cardiac markers CK-MB, myoglobin, and troponin T. SETTING: Emergency department of a large university hospital. PATIENTS: In 128 consecutive patients with chest pain, acute myocardial infarction (by WHO criteria) was ruled out; of these, 39 had a rise and fall of one or more markers, indicating minor myocardial damage. The presence of a documented history of coronary artery disease was assessed on admission. RESULTS: 24 patients had a subsequent event (cardiac death, acute myocardial infarction, percutaneous transluminal coronary angioplasty, coronary artery bypass grafting) in the next six months. An abnormal troponin T predicted a subsequent event while abnormal CK-MB or myoglobin did not. The relative risk for troponin T was 2.8 (95% confidence interval: 1.0 to 7.9), for myoglobin 1.0 (0.3 to 3.2), and for CK-MB 0.9 (0.2 to 3.4). A documented history of coronary artery disease predicted subsequent events with a relative risk of 3.9 (1.3 to 11.3). CONCLUSIONS: Troponin T was the only marker that predicted future events, but a documented history of coronary artery disease was the best predictor in patients in whom an acute myocardial infarction had been ruled out.

Aged↗
PubMed1996

Increase in hospital admission rates for heart failure in The Netherlands, 1980-1993.

OBJECTIVE: To study the trend in hospital admission rates for heart failure in the Netherlands from 1980 to 1993. DESIGN: All hospital admissions in the Netherlands with a principal discharge diagnosis of heart failure were analysed. In addition, individual records of heart failure patients from a subset of 7 hospitals were analysed to estimate the frequency and timing of readmissions. RESULTS: The total number of discharges for men increased from 7377 in 1980 to 13 022 in 1993, and for women from 7064 to 12 944. From 1980 through 1993 age adjusted discharge rates rose 48% for men and 40% for women. Age adjusted in-hospital mortality for heart failure decreased from 19% in 1980 to 15% in 1993. For all age groups in-hospital mortality for men was higher than for women. The mean length of hospital admissions in 1993 was 14.0 days for men and 16.4 days for women. A review of individual patient records from a 6.3% sample of all hospital admissions in the Netherlands indicated that within a 2 year period 18% of the heart failure patients were admitted more than once and 5% more than twice. CONCLUSIONS: For both men and women a pronounced increase in age adjusted discharge rates for heart failure was observed in the Netherlands from 1980 to 1993. Readmissions were a prominent feature among heart failure patients. Higher survival rates after acute myocardial infarction and the longer survival of patients with heart disease, including heart failure may have contributed to the observed increase. The importance of advances in diagnostic tools and of possible changes in admission policy remain uncertain.

Age Distribution↗
PubMed1996

Orthostatic hypotension due to suppression of vasomotor outflow after amphetamine intoxication.

Ten hours after ingestion of amphetamines, a previously healthy 17-year-old female adolescent experienced dizziness on standing. Examination revealed pronounced drowsiness and severe orthostatic hypotension. Assessment of arterial baroreflex function suggested that suppressed sympathetic vasomotor drive was the cause of the orthostatic hypotension. Within 3 days, the baroreflex failure resolved spontaneously. To our knowledge, suppressed vasomotor outflow after ingestion of amphetamines has been previously observed only in animal studies.

Adolescent↗
PubMed1995

Value of myoglobin, troponin T, and CK-MBmass in ruling out an acute myocardial infarction in the emergency room.

BACKGROUND: Ruling out acute myocardial infarction (AMI) on the basis of rapid assays for cardiac markers will allow early triage of patients and cost-effective use of available coronary care facilities. METHODS AND RESULTS: We studied the value of myoglobin, creatine kinase (CK)-MBmass, and troponin T in ruling out an AMI in the emergency room in 309 consecutive patients presenting with chest pain. The gold standard for AMI was the combination of history, ECG, and a typical curve of the CK-MB activity (CK-MBact). Myoglobin was the earliest marker, and its negative predictive value (NPV) was significantly higher than for CK-MBmass and troponin T from 3 to 6 hours after the onset of symptoms (myoglobin versus CK-MBmass, P < .03; myoglobin versus troponin T, P < .01). The NPV of myoglobin reached 89% 4 hours after the onset of symptoms. The NPV of CK-MBmass reached 95% 7 hours after the onset of symptoms. Troponin T was not an early marker for ruling out AMI, and NPV changed over time, together with CK-MBact. The early NPV was higher in a subgroup of patients with a low probability of the presence of AMI for the three markers. Cardiac markers rise earlier in patients with large infarcts than in patients with small infarcts as indicated by the cumulative proportion of the marker above the upper reference limit at each time point (myoglobin, P = .04; CK-MBmass, P = .013; troponin T, P = .016). CONCLUSIONS: For ruling out AMI in the emergency room, myoglobin is a better marker than CK-MBmass or troponin T from 3 until 6 hours after the onset of symptoms, but the maximal NPV reaches only 89%. At 7 hours, the NPV of CK-MBmass is 95%. The test characteristics are influenced by the probability of the presence of AMI in the patients studied and by the size of their AMI. Infarct size of AMI patients should be reported in studies evaluating cardiac markers.

Aged↗
PubMed1995

Doppler left ventricular flow pattern versus conventional predictors of left ventricular thrombus after acute myocardial infarction.

OBJECTIVES: The value of Doppler-derived left ventricular spatial flow patterns in predicting left ventricular thrombus formation after myocardial infarction was compared with that of conventional clinical and echocardiographic variables. BACKGROUND: Assessment of left ventricular thrombosis risk after myocardial infarction is important because of potential embolic sequelae that are reduced by oral anticoagulant agents. METHODS: Clinical, two-dimensional and Doppler echocardiographic data were prospectively obtained in 104 patients with acute myocardial infarction within 48 h of admission. Ventricular flow was assessed by Doppler echocardiography and considered normal when brisk ventricular inflow with simultaneous onset at the mitral valve and apical levels was present, together with alternating directions of apical flow throughout the cardiac cycle. In addition to normal flow, two abnormal flow patterns were recognized: apical rotating flow and vortex ring formation. Oral anticoagulant agents were prescribed only to patients with abnormal flow at admission. The incidence of left ventricular thrombosis was assessed by echocardiography during 9 months of follow-up. RESULTS: Abnormal flow pattern had a positive predictive value of 63% and a negative predictive value of 99%. On stepwise logistic regression analysis, only abnormal flow pattern had an independent relation to left ventricular thrombus (odds ratio 92). CONCLUSIONS: Left ventricular flow pattern derived by Doppler echocardiography soon after admission is superior to conventional clinical and two-dimensional echocardiographic assessment in estimating the risk of left ventricular thrombosis after myocardial infarction.

Blood Flow Velocity↗
PubMed1994

[Increase in the number of admissions due to heart failure in Dutch hospitals in the period 1980-1992].

OBJECTIVE: Determination of the trend in the occurrence of hospital admissions because of heart failure in the Netherlands. DESIGN: Descriptive investigation. SETTING: Dutch general and university hospitals. METHOD: Data on hospital admissions because of heart failure from 1980 to 1992, obtained from the National Medical Register, were analysed. Three ICD-9 CM diagnoses were combined (congestive heart failure 428.x, diseases of the heart due to hypertension 402.x and myocardial degeneration 429.I). RESULTS: From 1980 through 1992 the annual number of hospital admissions for heart failure increased by 69%, for both men and women, from 14,441 to 24,368. Age-adjusted admission rates increased by 43% for men, and by 30% for women. The admission rates were strongly age-related, with higher rates in the older age groups. Among men 89% of the patients in 1992 were older than 60 years, and 63% older than 70 years. Among women these figures were 94% and 79%, respectively. During the study period the age-specific admission rates rose in all relevant age groups. The rise was higher in the older age groups. In 1992 the average duration of stay in hospital was 14 days for men and 17 for women. CONCLUSION: Probable causes of the rise in the number of hospital admissions for heart failure were the increasing median age of the population, higher survival rates after acute myocardial infarction and longer survival of persons with heart disease. Demographic changes and medical progress will probably lead to a further rise in morbidity and mortality and of costs of heart failure.

Academic Medical Centers↗
PubMed1994

Telephone triage of cardiac emergency calls by dispatchers: a prospective study of 1386 emergency calls.

OBJECTIVES: To evaluate the handling of potential cardiac emergency calls by dispatchers, to determine their final diagnosis and urgency, and to determine the value of the main complaint in predicting urgency and the ability of the dispatchers to recognise non-urgent conditions. DESIGN: Prospective data collection and recording of main complaint of emergency calls placed via the 06-11 alarm telephone number with follow up to hospital when the patients were transported and the general practitioner when they were not. SETTING: Dispatch centres of the emergency medical services in Amsterdam (urban area) and Enschede (rural area). PATIENTS: 1386 consecutive adult subjects of emergency calls placed by citizens about chest problems or unconsciousness not caused by injury. MAIN OUTCOME MEASURES: Frequency of characteristics of the calls, outcome in diagnosis, and assessment of urgency. RESULTS: 69 (5%) patients were dead when the ambulance arrived. Diagnosis was established in 1071 patients (77%). The disorders most often reported were cardiac, with acute ischaemia in 15% of all subjects. In 28% of cases and for each presenting complaint no organic explanation was found. Overall 39% of all emergency calls were urgent; the urgency rate was lowest for calls for people with abdominal discomfort. Dispatchers correctly identified 90% of the non-urgent calls, but 55% of the calls that they identified as urgent proved to be non-urgent. CONCLUSION: Currently, direct dialling for an ambulance without the intervention of a general practitioner imposes a high work load on emergency systems and hospitals because triage by dispatchers is not sufficiently accurate. It may be possible to increase the accuracy of triage by developing and testing decision algorithms.

Acute Disease↗
PubMed1994

Pharmacokinetics and pharmacodynamics of saruplase, an unglycosylated single-chain urokinase-type plasminogen activator, in patients with acute myocardial infarction.

We examined in patients with acute myocardial infarction (AMI) the pharmacokinetics of saruplase, an unglycosylated, single chain, urokinase-type plasminogen activator (rscu-PA) by measuring urokinase-type plasminogen activator (u-PA) antigen and total u-PA activity, its conversion to active two-chain urokinase-type plasminogen activator (tcu-PA) and evaluated its effect on haemostatic parameters. Twelve patients were studied during and after administration of 20 mg bolus plus 60 mg continuous 1 h i.v. infusion of saruplase. For u-PA antigen and total u-PA activity (expressed as protein equivalents), where 234 U corresponds to 1 microgram, respectively, steady state plasma concentrations were 2.75 +/- 8.3 and 2.50 +/- 7.0 micrograms/ml (mean +/- standard deviation) and were reached within 20 min, t1/2 lambda 1 was 9.1 +/- 1.8 and 7.8 +/- 1.3 min, t1/2 lambda 2 1.2 +/- 0.2 and 1.9 +/- 0.5 h, and the total clearance was 393 +/- 110 and 427 +/- 113 ml/min. Inactivation of saruplase in plasma was negligible. After 15 min, tcu-PA was detected in plasma. From the ratio of the areas under the curve of tcu-PA and total u-PA activities it was calculated that 28 +/- 9.3% of the saruplase dose is converted into active tcu-PA. Systemic plasminaemia occurs as shown by a decrease in alpha 2-antiplasmin and fibrinogen and an increase in fibrinogen degradation products. Thrombin-antithrombin complex formation indicated activation of the clotting system. Saruplase is eliminated rapidly from plasma in AMI patients.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1991

Long-term efficacy of continuous and intermittent use of transdermal nitroglycerin in stable angina pectoris.

To assess efficacy of transdermal nitrate use, a randomized, placebo-controlled trial of continuous and intermittent use of nitroglycerin patches (10 mg/24 hours) was conducted in 127 patients with stable angina pectoris who discontinued exercise testing within 9 minutes because of angina. After a placebo run-in week, baseline (day 0) symptom-limited exercise testing was performed and repeated on day 1 and 14 before and after the administration of 0.5 mg of sublingual nitroglycerin. On day 0, total exercise duration was the same (within narrow limits) in all 3 groups and remained unchanged in the placebo group. On day 1, total exercise duration increased from 406 +/- 115 to 469 +/- 158 seconds (p less than 0.001) in the continuously treated group and from 396 +/- 105 to 475 +/- 171 seconds (p less than 0.001) in the intermittently treated group. In the intermittent group, exercise duration increased slightly to 483 +/- 140 seconds on day 14, and in the continuous group exercise duration decreased to 447 +/- 144 seconds. However, this decrease was not statistically significant. Similar treatment effects were seen for time to 1-mm ST depression. Sublingual nitroglycerin remained effective in all 3 groups and on all days. Eleven actively treated patients and 1 patient taking placebo discontinued the study because of headache. It is concluded that continuous use of transdermal nitroglycerin remains partially effective and intermittent therapy remains fully effective in improving long-term exercise capacity with acceptable adverse effects in patients with stable angina pectoris.

Administration, Cutaneous↗