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Biomedical subjects

N H Pijls

Publications and source records attributed to N H Pijls.

At least 37 records · Page 2Linked to original sources
PubMed1996

Simultaneous coronary pressure and flow velocity measurements in humans. Feasibility, reproducibility, and hemodynamic dependence of coronary flow velocity reserve, hyperemic flow versus pressure slope index, and fractional flow reserve.

BACKGROUND: To assess coronary lesion severity in the catheterization laboratory, several guide wire-based methods have been proposed. The purpose of the present study was to compare the feasibility and the reproducibility of coronary flow velocity reserve (CFVR), instantaneous hyperemic diastolic velocity-pressure slope index (IHDVPS), and pressure-derived myocardial fractional flow reserve (FFRmyo). METHODS AND RESULTS: From distal coronary pressure and flow velocity signals (0.014-in guide wires), CFVR, IHDVPS, and FFRmyo were computed in 15 stenoses (13 patients) under the four following pairs of conditions: (1) twice under baseline conditions; (2) during atrial pacing at 80 and 110 bpm; (3) before and during intravenous infusion of nitroprusside; and (4) before and during intravenous infusion of dobutamine. A total of 104 measurements were obtained. Both CFVR and FFRmyo could be calculated in all cases. IHDVPS could be calculated in only 79% of cases. The mean value of CFVR did not change between the two baseline measurements and during infusion of nitroprusside but decreased from 1.85 +/- 0.41 to 1.66 +/- 0.45 (P < .05) during atrial pacing and from 1.90 +/- 0.50 to 1.41 +/- 0.28 (P < .05) during dobutamine infusion. The mean values of IHDVPS and FFRmyo remained similar, whichever the changes in hemodynamic conditions. The coefficient of variation between two consecutive measurements was significantly lower for FFRmyo (4.2%) than for CFVR (17.7%) and for IHDVPS (24.7%). CONCLUSIONS: CFVR is easy to measure but sensitive to hemodynamic changes. IHDVPS can be measured only in < 80% of cases and is highly variable even without changes in hemodynamic conditions. FFRmyo is easy to measure and almost independent of hemodynamic changes.

Aged↗
PubMed1996

Measurement of fractional flow reserve to assess the functional severity of coronary-artery stenoses.

BACKGROUND: The clinical significance of coronary-artery stenoses of moderate severity can be difficult to determine. Myocardial fractional flow reserve (FFR) is a new index of the functional severity of coronary stenoses that is calculated from pressure measurements made during coronary arteriography. We compared this index with the results of noninvasive tests commonly used to detect myocardial ischemia, to determine the usefulness of the index. METHODS: In 45 consecutive patients with moderate coronary stenosis and chest pain of uncertain origin, we performed bicycle exercise testing, thallium scintigraphy, stress echocardiography with dobutamine, and quantitative coronary arteriography and compared the results with measurements of FFR. RESULTS: In all 21 patients with an FFR of less than 0.75, reversible myocardial ischemia was demonstrated unequivocally on at least one noninvasive test. After coronary angioplasty or bypass surgery was performed, all the positive test results reverted to normal. In contrast, 21 of the 24 patients with an FFR of 0.75 or higher tested negative for reversible myocardial ischemia on all the noninvasive tests. No revascularization procedures were performed in these patients, and none were required during 14 months of follow-up. The sensitivity of FFR in the identification of reversible ischemia was 88 percent, the specificity 100 percent, the positive predictive value 100 percent, the negative predictive value 88 percent, and the accuracy 93 percent. CONCLUSIONS: In patients with coronary stenosis of moderate severity, FFR appears to be a useful index of the functional severity of the stenoses and the need for coronary revascularization.

Adult↗
PubMed1996

Comparison of intravenous adenosine to intracoronary papaverine for calculation of pressure-derived fractional flow reserve.

For calculation of fractional flow reserve (FFR), simultaneous registration of both aortic pressure (Pa) and transstenotic distal coronary pressure (Pd) is necessary at steady-state maximum coronary hyperemia. The aim of the present study was to compare the maximum transstenotic gradient (delta Pmax) and pressure-derived myocardial fractional flow reserve (FFRmyo), observed during intravenous adenosine infusion, to delta Pmax and FFRmyo induced by intracoronary papaverine, which is considered to be the gold standard for induction of coronary hyperemia, but acts too short for steady-state hyperemic pressure recordings and is associated with QT-prolongation. In 24 patients with coronary stenoses of various degrees, Pa and Pd were measured simultaneously by the diagnostic catheter and a high fidelity 0.018" fiberoptic pressure monitoring guide wire, respectively. Excellent steady-state phasic intracoronary pressure recordings were obtained in all patients within 1 min after start of intravenous adenosine infusion at a rate of 140 micrograms/kg/min, and compared to delta Pmax obtained 30 sec after intracoronary administration of papaverine (12 mg LCA, 10 mg RCA). Delta Pmax was 24 +/- 15 mmHg during adenosine infusion and 24 +/- 15 mmHg after papaverine administration. Myocardial fractional flow reserve, calculated from these pressure recordings, was 0.75 +/- 0.16 and 0.75 +/- 0.15, respectively, with an individual difference of 0.02 +/- 0.01 between both values (r = 0.99). No important side effects by intravenous infusion of adenosine were observed. Thus intravenous adenosine infusion at a rate of 140 micrograms/kg/min is an excellent and safe alternative for induction of steady-state maximum coronary hyperemia and therefore is an ideal vasodilator for determination of fractional flow reserve based upon pressure recordings.

Adenosine↗
PubMed1996

[Intracoronary pressure and its significance in the clinical evaluation of patients with ischemic heart disease].

Assessment of coronary artery disease is a highly relevant problem in current cardiology. Although, coronary angiography still remains the ultimate diagnostic test to prove the presence of coronary narrowings, it is increasingly becoming obvious that a refine understanding of the atherosclerosclerotic lesions and its consequences on perfusion of the underlying myocardium requires much more than just the silhouette of the arterial lumen provided by contrast angiography. This knowledge together with the current therapeutic invasive approaches has led to the introduction of new invasive methods to demonstrate the haemodynamic significance of a given lesion. In this brief review we describe the importance, feasibility and usefulness of transstenotic pressure gradient measurements. Furthermore, we provide the description of myocardial fractional flow reserve as a new functional index for the assessment of the coronary stenosis severity and its effects on maximal myocardial perfusion. This index, by interpreting the transstenotic pressure gradient in combination with mean aortic and central venous pressure offers a complex and easy assessment of coronary haemodynamics. On the basis of our recent experience we discuss the applications of the presented concept in daily clinical practice. (Tab. 3, Fig. 4, Ref. 25.).

Blood Pressure↗
PubMed1995

Fractional flow reserve. A useful index to evaluate the influence of an epicardial coronary stenosis on myocardial blood flow.

BACKGROUND: Fractional flow reserve (FFR), defined as the ratio of maximum flow in the presence of a stenosis to normal maximum flow, is a lesion-specific index of stenosis severity that can be calculated by simultaneous measurement of mean arterial, distal coronary, and central venous pressure (Pa, Pd, and Pv, respectively), during pharmacological vasodilation. The aims of this study were to define ranges of FFR values, whether associated with inducible ischemia or not, and to investigate FFR in normal coronary arteries. METHODS AND RESULTS: In 60 patients accepted for percutaneous transluminal coronary angioplasty (PTCA) of single-vessel disease, with a positive exercise test (ET) < 24 hours before PTCA, FFR was determined during adenosine-induced hyperemia just before and 15 minutes after angioplasty. Pa was measured by the guiding catheter, Pd by an 0.018-in fiber-optic pressure-monitoring wire, and Pv, by a multipurpose catheter. The ET was repeated after 5 to 7 days, and only if this second ET had reverted to normal was the pre-PTCA value of FFR definitely considered to be associated with inducible ischemia and the post-PTCA value not. Myocardial FFR (FFRmyo) increased from 0.53 +/- 0.15 before PTCA to 0.88 +/- 0.07 after PTCA. Coronary FFR increased from 0.38 +/- 0.19 to 0.83 +/- 0.12. In all patients, values of FFRmyo definitely associated with ischemia were < or = 0.74, whereas all except two values not associated with inducible ischemia exceeded 0.74. Moreover, FFRmyo in 18 coronary arteries in 5 normal patients equaled 0.98 +/- 0.03. CONCLUSIONS: A value of FFRmyo of 0.74 reliably discriminates coronary stenosis, whether associated with inducible ischemia or not. Therefore, FFRmyo is a useful index to determine the functional significance of an epicardial coronary stenosis and may facilitate clinical decision making in patients with an equivocal coronary stenosis.

Adenosine↗
PubMed1995

Damage to the collateral circulation by PTCA of an occluded coronary artery.

In this report, a patient is described with an occluded left circumflex artery, in whom the corresponding myocardium was protected at rest by sufficient collateral circulation. Because of angina pectoris class III, a PTCA of that occluded vessel was performed, complicated by a large dissection. Recruitable collateral flow, assessed from pressure calculations by a new technique, suddenly decreased at the very moment of dissection. This was accompanied by resting pain and ischemia on the ECG. This case report confirms the hypothesis that the collateral circulation can be damaged by PTCA and emphasizes that every PTCA implies a definite risk, even in case of an occluded coronary artery filled by collaterals.

Angina Pectoris↗
PubMed1995

Quantification of recruitable coronary collateral blood flow in conscious humans and its potential to predict future ischemic events.

OBJECTIVES: The present study was designed to evaluate the applicability of a pressure-flow equation for quantitative calculation of recruitable collateral blood flow at coronary artery occlusion in conscious patients and to investigate the value of that index to predict future ischemic events. BACKGROUND: Recent experimental studies have indicated that recruitable collateral blood flow at coronary artery occlusion can be expressed as a fraction of normal maximal myocardial blood flow by simultaneous recordings of mean arterial, coronary wedge and central venous pressures, respectively. This index is called the pressure-derived fractional collateral flow and is independent of hemodynamic loading conditions. METHODS: In 120 patients undergoing elective coronary angioplasty, mean arterial, coronary wedge and central venous pressures were measured at balloon inflations of 2 min. All patients had a recent exercise electrocardiogram (ECG) with positive findings showing clearly distinguishable, reversible ECG abnormalities, enabling recognition of ischemia at balloon inflation. Fractional collateral blood flow at angioplasty was calculated by coronary wedge pressure minus central venous pressure divided by mean arterial pressure minus central venous pressure and correlated to the presence or absence of ischemia at balloon inflation. Ischemic events were monitored during a follow-up period of 6 to 22 months. RESULTS: In 90 of the 120 patients, ischemia was present at balloon inflation, and in 82 of these patients, fractional collateral blood flow was < or = 23%. By contrast, in 29 patients, no ischemia was present, and fractional collateral blood flow was > 24% in all 29. During the follow-up period, 16 patients had an ischemic event. Fifteen of these 16 patients were in the group with insufficient collateral flow (p < 0.05). CONCLUSIONS: To our knowledge, this study presents the first method for quantitative assessment of recruitable collateral blood flow in humans in the catheterization laboratory. Sufficient and insufficient collateral circulation can be reliably distinguished by this method. Use of this method can also help to provide more insight into the extent and behavior of the collateral circulation for investigational purposes and may have potential clinical implications.

Angina Pectoris↗
PubMed1995

Quantitative coronary angiography in predicting functional significance of stenoses in an unselected patient cohort.

OBJECTIVES: This study investigated the value of quantitative coronary angiography for predicting coronary flow reserve, as calculated from the transstenotic pressure gradient in a large, unselected patient cohort. BACKGROUND: In patients with extensive coronary artery disease, quantitative coronary angiographic findings fail to correlate with functional variables of coronary stenoses. New developments in pressure-monitoring wire technology permitted validation in humans of the concept of myocardial fractional flow reserve as assessed from coronary pressure measurements. METHODS: One hundred ten patients with normal left ventricular function were studied in the setting of coronary angioplasty. Quantitative coronary angiography was performed on-line using the ACA system. Myocardial and coronary fractional flow reserve were calculated from aortic and distal coronary pressures during maximal coronary hyperemia. RESULTS: When data before and after angioplasty were pooled, a curvilinear relation was found between myocardial fractional flow reserve and both diameter stenosis (r = 0.79) and minimal lumen diameter (r = 0.82), and a linear relation was found between myocardial fractional flow reserve and angiographic stenosis flow reserve (r = 0.78). Correlations between quantitative angiographic and pressure-derived indexes, although significant, were characterized by a large dispersion of the values of myocardial fractional flow reserve for a similar angiographic degree of stenosis. Nevertheless, the sensitivity and specificity of a minimal lumen diameter < 1.5 mm to predict myocardial fractional flow reserve < 0.72 were 96% and 89%, respectively. The corresponding values for a diameter stenosis > 50% were 93% and 85%, respectively. CONCLUSIONS: 1) In an unselected patient cohort, geometric indexes of stenosis severity derived from quantitative coronary angiography correlate significantly with physiologic variables, although these relations are imprecise in individual patients. 2) Nevertheless, the diagnostic accuracy of quantitative coronary angiography in predicting myocardial fractional flow reserve < 0.72 is high and allows its use for clinical decision making in the individual patient during diagnostic or interventional procedures.

Aged↗
PubMed1994

Rationale and application of coronary transstenotic pressure gradient measurements.

Presence, extent, and evolution of atherosclerotic coronary narrowings, as well as the anatomic possibilities for revascularization, can be reliably defined at (and only at) selective coronary angiography. The latter remains, therefore, the pivotal diagnostic tool for patients with suspected coronary artery disease. However, in spite of the increasing availability of on-line quantitative coronary angiography, it still holds that the functional (physiologic) consequences of an epicardial coronary narrowing cannot be completely derived from geometric (anatomic) information. Clinical decision making can be particularly difficult in lesions of intermediate severity (40-70% diameter reduction), in postinterventional segments, and in some particular anatomic settings, namely, ostial stenoses, bifurcation lesions, and diffuse atherosclerotic disease. This has led to an explosive growth of new methods for assessing the physiological significance of coronary narrowings documented at angiography. Among them, Doppler blood flow velocitometry and transstenotic pressure gradient measurements have emerged as the only techniques easily applicable in most catheterization laboratories. Here, we briefly review the clinical interest of measuring transstenotic pressure gradients.

Blood Flow Velocity↗
PubMed1994

Resuscitation skills of lay public after recent training.

STUDY OBJECTIVE: To investigate the ability of laypeople to apply basic CPR techniques after recent training. DESIGN: Cross-sectional assessment of practical CPR skills. TYPE OF PARTICIPANTS: 151 laypeople who were trained twice in the preceding 20 to 24 months. MEASUREMENTS AND MAIN RESULTS: Practical skills were tested using six primary recorded variables that describe the quality of CPR techniques in a training situation. A total score on the skills of each participant was computed on the basis of a predefined scoring system. Thirty-three percent of the participants were able to perform adequate CPR. The compression:relaxation ratio, the breathing volume, and the breathing interval were points of concern. CONCLUSION: Practical skills in basic CPR after a 12-month training interval, though better in this study than in many previous studies, are insufficient in the majority of laypeople. The results of this study could be used to design a better tailored (re)instruction program, with an emphasis on regular, frequent refresher courses.

Adolescent↗
PubMed1994

Coronary flow reserve calculated from pressure measurements in humans. Validation with positron emission tomography.

BACKGROUND: Experimental studies have shown that fractional flow reserve (defined as the ratio of maximal achievable flow in a stenotic area to normal maximal achievable flow) can be calculated from coronary pressure measurements only. The objectives of this study were to validate fractional flow reserve calculation in humans and to compare this information with that derived from quantitative coronary angiography. METHODS AND RESULTS: Twenty-two patients with an isolated, discrete proximal or mid left anterior descending coronary artery stenosis and normal left ventricular function were studied. Relative myocardial flow reserve, defined as the ratio of absolute myocardial perfusion during maximal vasodilation in the stenotic area to the absolute myocardial perfusion during maximal vasodilation (adenosine 140 micrograms.kg-1 x min-1 intravenously during 4 minutes) in the contralateral normally perfused area, was assessed by 15O-labeled water and positron emission tomography (PET). Myocardial and coronary fractional flow reserve were calculated from mean aortic, distal coronary, and right atrial pressures recorded during maximal vasodilation. Distal coronary pressures were measured by an ultrathin, pressure-monitoring guide wire with minimal influence on the trans-stenotic pressure gradient. Minimal obstruction area, percent area stenosis, and calculated stenosis flow reserve were assessed by quantitative coronary angiography. There was no difference in heart rate, mean aortic pressure, or rate-pressure product during maximal vasodilation during PET and during catheterization. Percent area stenosis ranged from 40% to 94% (mean, 77 +/- 13%), myocardial fractional flow reserve from 0.36 to 0.98 (mean, 0.61 +/- 0.17), and relative flow reserve from 0.27 to 1.23 (mean, 0.60 +/- 0.26). A close correlation was found between relative flow reserve obtained by PET and both myocardial fractional flow reserve (r = .87) and coronary fractional flow reserve obtained by pressure recordings (r = .86). The correlations between relative flow reserve obtained by PET and stenosis measurements derived from quantitative coronary angiography were markedly weaker (minimal obstruction area, r = .66; percent area stenosis, r = -.70; and stenosis flow reserve, r = .68). CONCLUSIONS: Fractional flow reserve derived from pressure measurements correlates more closely to relative flow reserve derived from PET than angiographic parameters. This validates in humans the use of fractional flow reserve as an index of the physiological consequences of a given coronary artery stenosis.

Coronary Angiography↗
PubMed1993

Histological study of the internal mammary artery with emphasis on its suitability as a coronary artery bypass graft.

The internal mammary, musculophrenic, and superior epigastric arteries were unilaterally harvested from 11 individuals (aged 49 to 83 years; mean age, 67 years) and were examined histologically at 1-cm intervals. In 2 individuals the media of the entire internal mammary artery was elastic, whereas in the other 9 individuals we observed an alternating histological pattern in the media of the internal mammary artery, that of the proximal and distal segments being elastomuscular and that of the mid segment being elastic. In 4 of the latter 9 individuals the distal 10% to 20% of the media of the internal mammary artery was muscular with rare elastic lamellae. The media of the first 1 to 2 cm of the musculophrenic and superior epigastric arteries was elastomuscular or muscular with rare elastic lamellae, whereas more distally the media was purely muscular. The degree of intimal hyperplasia was significantly greater in arterial segments with a purely muscular media (25.6%) than in those with elastic (16.7%), elastomuscular (15.3%), and muscular (with rare elastic lamellae) (17.5%) types of media (p < 0.01). The mean cross-sectional luminal area of the elastic segment (1.9 mm2) and proximal and distal elastomuscular segments (1.9 and 1.2 mm2, respectively) of the internal mammary artery was significantly greater than that of the muscular segments of the musculophrenic artery (0.9 mm2) and the superior epigastric artery (0.7 mm2) (p < 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗
PubMed1993

Noninvasive hemodynamic assessment of the internal mammary artery in myocardial revascularization.

Using transthoracic B-mode imaging and Doppler spectrum analysis it was found that the luminal diameter of the internal mammary artery and its hemodynamics were not significantly different among 15 preoperative patients (64 +/- 10 years) who underwent myocardial revascularization using the left internal mammary artery and young and older control groups (25 +/- 3 years and 61 +/- 9 years, respectively). These data indicate that older age does not significantly adversely influence the degree of intimal thickening and compliance in the internal mammary artery. Doppler spectrum analysis of the internal mammary artery in the patients who were operated on revealed conversion from a triphasic systolic waveform preoperatively to a unidirectional combined systolic/diastolic waveform at 1 week and 2 and 6 months postoperatively, characterized by a significant increase in the diastolic blood flow velocity and a significant decrease in the systolic blood flow velocity and the pulsatility and resistance indices. This study indicates that transthoracic B-mode imaging and Doppler spectrum analysis are promising noninvasive techniques in the preoperative assessment of internal mammary artery morphology and physiology. In addition, Doppler spectrum analysis can also be used in the long-term serial assessment of the internal mammary artery conduit after myocardial revascularization.

Adult↗
PubMed1993

Transstenotic coronary pressure gradient measurement in humans: in vitro and in vivo evaluation of a new pressure monitoring angioplasty guide wire.

OBJECTIVES: The present study was designed to investigate 1) the feasibility and accuracy of coronary pressure measurements with a novel 0.015-in. (0.038 cm) fluid-filled guide wire, and 2) the effect of the guide wire itself on stenosis hemodynamics. BACKGROUND: To assess the functional results of coronary angioplasty, measurements of the transstenotic pressure gradient have been advocated. However, this gradient is no longer routinely measured because it is not reliable when determined with the angioplasty catheter. METHODS: A fluid-filled 0.015-in. guide wire to be connected to a conventional pressure transducer was developed. Five wires were tested for their frequency response characteristics and for their accuracy in measuring hydrostatic pressure. In an in vitro model of stenosis (reference diameter 4 mm), the pressure gradient was determined at incremental flow levels for varying stenosis severity with and without a 0.015-in. guide wire through the narrowing. In 37 patients, the transstenotic pressure gradient was measured before and after angioplasty and compared with obstruction area and percent area stenosis as determined by quantitative coronary angiography. RESULTS: The correlation between the actual pressure and the pressure recorded by the guide wire was excellent (r = 0.98) despite a slight underestimation (-3 +/- 5%). Phasic pressure recordings were precluded by a long time constant of 16 +/- 4 s. The presence of the guide wire produced a significant overestimation (> 20%) of the pressure decrease only in cases of tight stenosis (> 90% area reduction). Furthermore, a theoretic model based on the fluid dynamic equation predicted that this overestimation was inversely proportional to the reference diameter of the vessel, yet was only slightly influenced by the flow. The lesion was crossed in all but one patient (97%) and pressure gradient was recorded throughout the study in 34 (94%) of 36 patients. The mean pressure gradient decreased from 30 +/- 19 before to 3 +/- 5 mm Hg after angioplasty (p < 0.01). A curvilinear relation was found between the pressure gradient and both percent area stenosis (r2 = 0.67) and obstruction area (r2 = 0.72). A sharp increase in pressure gradient was noted once the stenosis exceeded 75% area reduction. CONCLUSIONS: Mean transstenotic pressure gradients can be easily and reliably recorded with a 0.015-in. fluid-filled guide wire. This ability should facilitate the functional assessment of coronary stenoses of intermediate severity and of immediate postangioplasty results.

Adult↗
PubMed1993

Experimental basis of determining maximum coronary, myocardial, and collateral blood flow by pressure measurements for assessing functional stenosis severity before and after percutaneous transluminal coronary angioplasty.

BACKGROUND: Severity of coronary artery stenosis has been defined in terms of geometric dimensions, pressure gradient-flow relations, resistance to flow and coronary flow reserve, or maximum flow capacity after maximum arteriolar vasodilation. A direct relation between coronary pressure and flow, however, may only be presumed if the resistances in the coronary circulation are constant (and minimal) as theoretically is the case during maximum arteriolar vasodilation. In that case, pressure measurements theoretically can be used to predict maximum flow and assess functional stenosis severity. METHODS AND RESULTS: A theoretical model was developed for the different components of the coronary circulation, and a set of equations was derived by which the relative maximum flow or fractional flow reserve in both the stenotic epicardial artery and the myocardial vascular bed and the proportional contribution of coronary arterial and collateral flow to myocardial blood flow are calculated from measurements of arterial, distal coronary, and central venous pressures during maximum arteriolar vasodilation. To test this model, five dogs were acutely instrumented with an epicardial, coronary Doppler flow velocity transducer. Distal coronary pressures were measured by an ultrathin pressure-monitoring guide wire (0.015 in.) with minimal influence on transstenotic pressure gradient. Fractional flow reserve was calculated from the pressure measurements and compared with relative maximum coronary artery flow measured directly by the Doppler flowmeter at three different levels of arterial pressure for each of 12 different severities of stenosis at each pressure level. Relative maximum blood flow through the stenotic artery (Qs) measured directly by the Doppler flowmeter showed an excellent correlation with the pressure-derived values of Qs (r = 0.98 +/- 0.01, intercept = 0.02 +/- 0.03, slope = 0.98 +/- 0.04), of the relative maximum myocardial flow (r = 0.98 +/- 0.02, intercept = 0.26 +/- 0.07, slope = 0.73 +/- 0.08), and of the collateral blood flow (r = 0.96 +/- 0.04, intercept = 0.24 +/- 0.07, slope = -0.24 +/- 0.06). Moreover, the theoretically predicted constant relation between mean arterial pressure and coronary wedge pressure, both corrected for venous pressure, was confirmed experimentally (r = 0.97 +/- 0.03, intercept = 9.5 +/- 13.3, slope = 4.4 +/- 1.2). CONCLUSIONS: These results provide the experimental basis for determining relative maximum flow or fractional flow reserve of both the epicardial coronary artery and the myocardium, including collateral flow, from pressure measurements during maximum arteriolar vasodilation. With a suitable guide wire for reliably measuring distal coronary pressure clinically, this method may have potential applications during percutaneous transluminal coronary angioplasty for assessing changes in the functional severity of coronary artery stenoses and for estimating collateral flow achievable during occlusion of the coronary artery.

Angioplasty, Balloon, Coronary↗
PubMed1992

Variation in the quality of cardiopulmonary resuscitation.

During instruction in basic cardiopulmonary resuscitation (CPR) skills, cardiac massage and mouth-to-mouth ventilation are applied without interruption for no longer than a few minutes. The aim of this study was to see if the quality of technique during the first 2 min of CPR reflects the resuscitators ability to perform CPR over a 15 min period. Assessments were done with a resuscitation mannequin from which recordings of several variables were made at 2, 5, 10, and 15 min after the start of CPR. 60 lay volunteers who had received CPR training were studied, and six variables that describe the quality of CPR technique were recorded and scored with a predefined scoring system. No deterioration in CPR skills was seen during 15 min. We conclude that the initial 2 min assessment reflects the resuscitators ability to perform CPR over a longer period.

Adult↗
PubMed1992

A scoring system for basic cardiac life support skills in training situations.

A valid and reproducible system for determining basic cardiac life support (BCLS) skills can help to evaluate the effect of instruction courses and to estimate the results of educational activities. The aim of this study was to develop and test such a system in accordance with the Standards and Guidelines of the American Heart Association (AHA). Five criteria were defined in advance towards such a system (1) Inadequate techniques must be reflected by a fail score. (2) Skilled persons should achieve a pass score. (3) The effect of training must be reflected by an improvement of the score. (4) Inter- and intra-observer variability must be negligible. (5) The system should be simple to apply. The system was developed, and in order to test the system, the BCLS skills of 40 ambulance nurses were tested once and those of 148 lay people twice. All cardiopulmonary resuscitation (CPR) attempts were performed on a mannequin. The relevant parameters of the attempt were continuously recorded and printed. Penalty points were assigned in a predefined way for aberrations of the techniques advised in the Standards and Guidelines. The system satisfied the five criteria mentioned above. It therefore offers a reliable and reproducible evaluation of BCLS skills.

Allied Health Personnel↗