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Biomedical subjects

R W Koster

Publications and source records attributed to R W Koster.

At least 19 recordsLinked to original sources
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↗
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↗
PubMed1991

The pharmacokinetics of recombinant double-chain t-PA (duteplase): effects of bolus injection, infusions, and administration by weight in patients with myocardial infarction.

The current mode of administration of recombinant tissue-type plasminogen activator (rt-PA) in acute myocardial infarction is rather complex, although the rationale for the different components of this scheme is not clearly established. We compared pharmacokinetics of a continuous infusion of 38.5 MU of Burroughs Wellcome t-PA (duteplase) over 90 minutes in nine patients (phase I) with a scheme including a 0.04 MU/kg bolus, a 60-minute 0.36 MU/kg lytic infusion and a 180-minute 0.21 MU/kg maintenance infusion in 15 patients with acute myocardial infarction (Phase II). t-PA activity and antigen were fitted in a one-compartment model from which model-dependent and model-independent parameters were derived. Clearance of t-PA activity was 1020 +/- 465 (mean +/- SD) ml/min in phase I and 1359 +/- 590 ml/min in phase II. Clearance of t-PA antigen was 666 +/- 230 ml/min in phase I and 704 +/- 199 ml/min in phase II. Clearance of activity was significantly (p less than 0.01) higher than of antigen. Clearance and steady-state plasma levels showed a large interindividual variability (coefficient of variation, 56.4%), but this was significantly reduced by dosing by weight (coefficient of variation, 28.9%; p = 0.031). A 10% bolus in phase II shortened the time to reach 75% and 90% of the steady-state plasma level by 4 and 5 minutes, respectively, not significantly different from phase I. A simulation study showed that a bolus should be approximately 15% of the lytic dose to achieve a maximal level in the shortest period.

Aged↗
PubMed1990

[Criteria for differential diagnosis in cardial symptoms; left- or right-sided chest pain?].

We studied the localization of pain in the acute phase of myocardial infarction in comparison with localization in non-cardiac chest pain. Myocardial infarction patients could not be differentiated from patients with non-cardiac chest pain in localization of pain on mid-chest, left side of the chest and left arm. However, myocardial infarction patients reported pain on the right side of the chest and in the right arm twice as often as non-cardiac chest pain patients. Results are similar when patients indicated the localization of the pain symptoms on attending the Emergency Coronary Care Unit, or when asked five days later. Pain symptoms on the right side of the chest and the right arm differentiate better between myocardial infarction and non-cardiac chest pain than the 'classical' symptom pattern.

Acute Disease↗
PubMed1990

[Acute Heart Care: what happens with patients who are not immediately hospitalized?].

The clinical course of the first six weeks after discharge after consultation was studied in 527 patient contacts in 460 patients who were evaluated for acute cardiac symptoms in a six-month period at the acute cardiac care facility 'Eerste Harthulp' in the Academic Medical Centre. Analysis revealed that the initial diagnosis of acute ischaemia (261 cases) was correct in 118 (45%) and the initial diagnosis of arrhythmia (114 cases) in 92 (81%). In 220 patients there was no cardiac history; in those instances the initial diagnosis of acute ischaemia was confirmed in only 40% but the initial diagnosis of arrhythmia in 78%. Three patients died within six weeks after evaluation and 28 patients were admitted within that period. Patients without cardiac history and without a clear cardiac diagnosis consulted their general practitioner moderately frequently in the first six weeks and used specialist care only rarely.

Academic Medical Centers↗
PubMed1990

A randomized dose-ranging study of rt-PA in acute myocardial infarction. Effects on coronary patency and fibrinolytic parameters.

This study was designed to examine the relationships between dose of Wellcome two-chain recombinant tissue type-plasminogen activator (BW rt-PA) and coronary patency and fibrinolytic parameters in acute myocardial infarction (AMI). In an open randomized study, patients with AMI (determined by ECG) and symptoms of less than 4 h duration without contraindications for fibrinolytic therapy were treated with rt-PA in nominal doses of 20 (7.7 MU), 50 (14.8-29.6 MU) or 100 mg (29.6-48.2 MU) administered over 90 min followed by intravenous heparin. Coronary patency was determined by coronary arteriography of the infarct-related artery and haematological parameters (fibrinogen, plasminogen, alpha 2-antiplasmin and fibrin(ogen) degradation products) measured at 90 min. Coronary patency increased in a dose-related manner to 53% (95% C.I. 37-69%) in the 100 mg/90 min group. Logistic regression demonstrated a relationship between dose (in MU kg-1) and coronary patency. Fibrinogen at 90 m was reduced to 74 (61.5-86.4%) of the pooled plasma standard in the nominal 100 mg group. Patients with a higher predose fibrinogen had higher reductions of fibrinogen. Serious bleeding occurred in three (3%) patients, and no intracranial bleeds were reported. BW rt-PA produces dose-related patency of the coronary arteries with moderate, dose-related reduction in fibrinogen.

Aged↗