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Biomedical subjects

N H Pijls

Publications and source records attributed to N H Pijls.

At least 55 records · Page 3Linked to original sources
PubMed1991

Concept of maximal flow ratio for immediate evaluation of percutaneous transluminal coronary angioplasty result by videodensitometry.

BACKGROUND: In the setting of percutaneous transluminal coronary angioplasty (PTCA), immediate information about the result of the intervention is important, whereas morphological parameters are often less reliable than in diagnostic coronary arteriography. Recently, a new videodensitometric method was introduced and validated in animal experiments, which allows accurate comparison of maximal myocardial perfusion between situations with different degrees of stenosis. This method uses mean transit time (Tmn) of the contrast agent at maximal hyperemia as a parameter for maximal flow and is strictly in accordance with indicated dilation theory. METHODS AND RESULTS: In 40 patients with angina pectoris, single-vessel disease, and a positive exercise test at the time of acceptance for PTCA, this approach was applied for evaluation of the improvement of maximal flow achieved by the PTCA. Maximal vasodilation was induced immediately before and 15 minutes after PTCA by intracoronary administration of papaverine, and digital angiographic studies were performed. By special breath-holding instruction, almost motionless, triggered image acquisition was possible during 15-20 heartbeats. Excellent subtraction images could be obtained, and reliable determination of Tmn at maximal hyperemia was possible in 33 patients both before and after PTCA. The ratio between maximal flow after and before PTCA, called maximal flow ratio (MFR), was represented by the ratio between Tmn before and after the intervention and compared with the results of exercise testing 24-48 hours before and 7-10 days after the procedure. After correction for pressure changes, MFR was 2.2 +/- 1.5 for the 33 dilated vessels and 1.0 +/- 0.2 for 25 normal vessels serving as a control. In 94% of all patients, an MFR value of more than 1.6 or less than 1.6 discriminated between presence or absence of reversal of exercise test result from positive to negative. If on-line judgment of success was based upon angiographic parameters or measurement of trans-stenotic pressure gradient, the relation with noninvasive functional improvement was present only in 66% and 74% of all patients, respectively. A definite range of what can be called normal Tmn at maximal hyperemia could be distinguished, and post-PTCA values for successfully dilated arteries returned completely to this normal range. CONCLUSIONS: Accurate comparison of maximal myocardial perfusion before and after PTCA is possible in man, improvement of maximal flow is highly related to functional improvement as indicated by exercise test results, and, therefore, this method provides a straightforward way for on-line evaluation of the result of the intervention.

Absorptiometry, Photon↗
PubMed1990

Mean transit time for videodensitometric assessment of myocardial perfusion and the concept of maximal flow ratio: a validation study in the intact dog and a pilot study in man.

Over the last decade it has become more and more obvious that besides anatomical information about the severity of coronary artery stenoses, information about coronary and myocardial blood flow is necessary to understand the functional significance of these obstructions and to evaluate the result of an intervention. Several methods have been proposed for this purpose, each of these having their particular limitations. In this study a new method is shortly described which allows the accurate calculation of relative maximal myocardial perfusion by ECG-triggered digital radiography (videodensitometry), using mean transit time (Tmn) as time parameter; this technique is based on the original physiologic principles of indicator dilution theory. This method was validated in 8 instrumented dogs in which an excellent linear relation was present between 1/Tmn and flow (r = 0.96 +/- 0.03). Although this method does not allow assessment of resting flow and therefore coronary flow reserve (CFR), it provides a means for the reliable comparison of maximal myocardial flow in different situations and it is independent of most factors affecting coronary flow reserve. The ratio between maximal flow after and before an intervention is called maximal flow ratio (MFR) and this concept was applied in a pilot study in man to evaluate PTCA results in 10 patients undergoing elective angioplasty. MFR was compared with the result of exercise testing 24 hours before and 10 days after the angioplasty. MFR greater than or equal to 1.5 was always accompanied by reversal of exercise test result from positive to negative. We conclude that the accurate calculation of relative maximal perfusion of the myocardium is possible by videodensitometry and suggest that comparison of maximal flow after and before an intervention can be valuable in man for functional evaluation of the result of the intervention.

Adult↗
PubMed1990

Cardiopulmonary resuscitation on the general ward: no category of patients should be excluded in advance.

In this study 91 consecutive CPR cases in 90 patients on general wards were evaluated during 18 months. Fifteen patients (16.5%) could be discharged, which is relatively favourable in comparison to the literature. Children proved to have a better chance to leave the hospital alive than adults (6/18 vs. 9/72; P less than 0.05). No factors with negative predictive value before the cardiopulmonary arrest could be isolated. Even oncological patients, often described as a prognostically poor category, with a success rate of 27% (6/22) did not differ from other categories. Patients with isolated respiratory arrest, ventricular tachycardia or ventricular fibrillation at the arrival of the CPR-team had a better chance to be discharged from the hospital. A rapid decrease in survival was noted if a CPR attempt lasted longer than 10 min (P less than 0.001). When there is no return of vital signs within 30 min the CPR attempt can be stopped. During follow-up period (mean 6 month) 2 of the 15 survivors (13.3%) died from a non-cardiopulmonary cause. It is concluded that no category of patients can be excluded from CPR in advance. Although ultimate success rate for CPR in the general wards will rarely exceed 15%, CPR has to be initiated in most cases of cardiopulmonary arrest.

Adolescent↗
PubMed1990

Mean transit time for the assessment of myocardial perfusion by videodensitometry.

The intrinsic limitations of coronary arteriography to predict the physiological effects of coronary obstructions are well known. Therefore, more direct assessments of the functional significance of coronary stenoses are becoming increasingly important. Study of contrast passage by electrocardiogram-triggered digital radiography has been proposed as a way of assessing changes in myocardial perfusion. The main problems in this approach are the limited time for motionless image acquisition, the potential alteration of vascular volume between different states, and the changing flow pattern induced by contrast agents. This has led to empiric substitution of mean transit time (Tmn) by other time parameters and to representation of vascular volume by maximal contrast intensity (Dmax). To avoid these problems, intact dogs were studied during almost motionless image acquisition of 20-25 consecutive paced heart beats obtained with synchronous radiographic pulses. In this way, unequivocal and reproducible determination of Tmn was possible. Constant and maximal vascular volume was created by continuous infusion of dipyridamole, and it was proved that coronary flow in this model was not influenced by contrast injections. Flow in the circumflex artery was measured by a ring mounted and calibrated Doppler probe. In each dog, flow in the circumflex artery was varied by a balloon occluder in 12 small steps (range, 0-174 +/- 42 ml/min). Inverse appearance time (1/Tapp), Dmax, Dmax/Tapp, inverse time of maximal intensity (1/Tmax), and 1/Tmn were calculated and the relations of these parameters to measured flow were investigated. Tmn proved to be the most reliable parameter for this purpose (r = 0.97 +/- 0.02; mean +/- SD), followed by Tmax (r = 0.93 +/- 0.04). Dmax failed to represent vascular volume but, in fact, showed a moderate correlation with flow (r = 0.78 +/- 0.22), as did Tapp (r = 0.64 +/- 0.18, 0.75 +/- 0.27, and 0.59 +/- 0.26 for the three definitions of Tapp used in this study). Dmax/Tapp correlated better with flow than either component separately. Our results indicate that the mean transit time calculated by videodensitometry can be used to accurately assess changes in myocardial perfusion strictly according to the original principles of indicator dilution theory.

Animals↗
PubMed1989

Kissing balloon angioplasty of a circumflex artery bifurcation lesion. A new approach utilizing two balloon-on-wire probes and a single guiding catheter.

A new approach to angioplasty of a coronary artery bifurcation lesion is described. Via a single guiding catheter, two ultra low-profile balloon-on-wire probes were advanced into the AV sulcus branch and a large obtuse marginal branch of the circumflex artery. The balloons were inflated simultaneously. The technique was easy to perform and remarkably effective.

Angioplasty, Balloon↗
PubMed1988

Is nonionic isotonic iohexol the contrast agent of choice for quantitative myocardial videodensitometry?

All currently used contrast media in coronary angiography induce a considerable hyperemic response interfering with the interpretation of circulation times derived from myocardial time-density curves. Aim of this study therefore, was to find a contrast agent with minimal hyperemic response. For this purpose 2, 4 and 6 ml of the nonionic isotonic low iodinated contrast agent iohexol (Omnipaque 140) and 6 ml of a similarly low iodinated but still hypertonic solution of the ionic diatrizoate (Urographin 30%) were administered into the left coronary artery of 8 anesthetized instrumented dogs. Heart rate was held constant by atrial pacing and left ventricular pressure, left ventricular dP/dt and mean and phasic coronary blood flow were recorded. To test the hypothesis that the hyperemic response to nonionic contrast media is partly due to an increase in inotropic state mediated by Ca++ion influx, all measurements were repeated 30 minutes after intracoronary administration of 0.5 mg verapamil. For iohexol the increase in coronary blood flow was small but significant: 12 +/- 7%, 25 +/- 11% and 38 +/- 16% for the 2, 4 and 6 ml administrations, respectively (mean +/- s.d.; p less than 0.01). For the diluted diatrizoate the increase in coronary blood flow was 65 +/- 23%. Increases for currently used contrast agents are on the order of 200-300%. After verapamil, the hyperemic response to iohexol decreased significantly to 9 +/- 5%, 20 +/- 8% and 29 +/- 12% for the 2, 4 and 6 ml administrations, respectively (p less than 0.01). The reaction to diatrizoate was not affected by verapamil. Moreover, there was a significant positive correlation between the increase in coronary blood flow and left ventricular dP/dt max under all conditions for all but one dog. We conclude that the isotonic, low iodinated nonionic contrast agent iohexol has only a moderate influence on coronary blood flow, which can be further attenuated by verapamil. By this approach, a more reliable assessment of circulation times from myocardial time-density curves obtained by digital subtraction angiography and videodensitometry becomes possible.

Angiography↗
PubMed1988

Prinzmetal's angina associated with alcohol withdrawal.

A 39-year-old woman developed critical anginal attacks 2-7 days after abruptly stopping long-lasting excessive alcohol drinking. The coronary angiogram demonstrated spasms in the left anterior descending and the right coronary artery without signs of preexistent stenosis. In previous reports alcohol-related coronary spasm always followed ingestion of alcohol several hours before. Because of the time delay in this case, we suggest that not the intake but the withdrawal of alcohol was the factor provoking coronary spasm in our patient.

Adult↗
PubMed1987

Vascular distribution of plasma catecholamines--pulmonary extraction, arterio-venous differences and effect of age.

In 19 normotensive patients undergoing cardiac catheterization, plasma samples were simultaneously collected from five different sites for measuring adrenaline and noradrenaline concentrations. Mean levels (+/- SEM) in pulmonary artery and aorta were 1.70 +/- 0.13 and 1.76 +/- 0.12 nmol/l for noradrenaline and 0.35 +/- 0.05 and 0.36 +/- 0.05 nmol/l for adrenaline, respectively. Thus, no pulmonary uptake of either catecholamine was demonstrated; this was independent of ventilatory lung function. Significant peripheral extraction was only found for adrenaline, and not for noradrenaline, so we found no evidence for the necessity of arterial blood sampling for noradrenaline determinations in this static study. Finally, a significant positive correlation of venous (r = 0.56; p less than 0.01), but not arterial noradrenaline concentration with age was found, as was a negative correlation of both arterial (r = -0.55; p less than 0.01) and venous (r = -0.62; p less than 0.005) adrenaline concentrations with age. The release of adrenaline by the adrenal glands proved to be significantly decreasing with increasing age (r = -0.53; p less than 0.02).

Adult↗
PubMed1986

Pancreatic mass due to Strongyloides stercoralis infection: an unusual manifestation.

A 30-year-old man returning from a trip through India complained of epigastric pain, diarrhea, loss of weight, and jaundice. Stool examination was positive for Strongyloides stercoralis. On ultrasonographic investigation, intravenous cholangiography, and endoscopic retrograde cholangiopancreaticography, stenosis of the distal common bile duct and enlargement of the pancreatic head were observed. The patient was treated for the Strongyloides infection. The jaundice disappeared within days, the laboratory finding normalized, and the patient recovered rapidly. However, the ultrasonographic examination showed a complete recovery in the course of about 2 years. From this report we conclude that in patients with obstructive jaundice and Strongyloides stercoralis infection, serious abnormalities resembling pancreatic tumour or pancreatitis can be found on ultrasonographic and radiological investigations, and this should be considered in the differential diagnosis of pancreatic mass in patients living in or returning from endemic areas.

Adult↗
PubMed1985

[The effect of beclomethasone dipropionate as inhalation therapy on the pituitary-adrenal axis in children].

The function of the pituitary-adrenal axis was investigated in ten asthmatic children (5-14 years of age) before and after administration of beclomethasone-dipropionate as inhalation therapy in a dose of 300-600 micrograms/24 hrs, during six months. Cortisol diurnal rhythm, excretion of free cortisol in 24 hours urine and stimulation of plasma-cortisol after ACTH-administration were determined. The same investigations were carried out in a comparable group of ten asthmatic children already using this inhalation therapy for more than one year. Significant differences were found comparing 08.00 h. cortisol values of the children from the first group and those who used medication for more than one year. In this first group, the ability of the adrenal glands to be stimulated by ACTH-administration after six months of medication, decreased significantly as well. These results indicate an impairment of the function of pituitary-adrenal axis during long-term treatment with inhaled beclomethasone-dipropionate. This implicates a decreased ability of the adrenal glands to react in an optimum way in stress-situations. In these patients oral or parenteral administrations of steroids should be considered earlier in stress situations like a severe asthma attack.

Adrenocorticotropic Hormone↗