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Biomedical subjects

F Zijlstra

Publications and source records attributed to F Zijlstra.

106 records · Page 6Linked to original sources
PubMed1988

Does intracoronary papaverine dilate epicardial coronary arteries? Implications for the assessment of coronary flow reserve.

Intracoronary papaverine is used as a means to induce a strong and short-lasting hyperemia in several recently developed methods to measure coronary flow reserve. Changes in stenosis geometry from papaverine would influence the measured coronary flow reserve. Therefore, we investigated the influence of intracoronary papaverine on stenosis geometry with quantitative analysis of the coronary angiogram and assessed the influence of papaverine on pressure-flow characteristics of the stenosis and coronary flow reserve. The cross-sectional areas (mean +/- SD) of the stenosis increased 18% +/- 7% after papaverine. The normal proximal and distal parts of the coronary artery dilated 5% +/- 2% after papaverine. This results in a decrease of the calculated pressure drop over the stenosis varying from 20% to 30%. Coronary flow reserve of a flow-limiting epicardial stenosis is overestimated by 16% when papaverine is used to induce hyperemia. These papaverine-induced changes can nevertheless be circumvented by maximal vasodilation of the major epicardial coronary artery with 3 mg intracoronary isosorbidedinitrate prior to the investigation of the coronary flow reserve with papaverine.

Angiography↗
PubMed1988

Value and limitations of intracoronary adenosine for the assessment of coronary flow reserve.

An ideal coronary vasodilator for studying coronary flow reserve should rapidly produce a maximal hyperemic response, be short acting to permit repeated measurements, and not alter systemic hemodynamics. We measured with a Doppler tip balloon catheter, in 12 patients before and/or after percutaneous transluminal coronary angioplasty the hyperemic response following 12.5 mg intracoronary papaverine and following gradually incremental bolus injections of intracoronary adenosine, starting from 0.05 mg until a maximal hyperemic response or side effects. The mean dose (+/- SD) of adenosine needed to produce maximal hyperemia was 0.23 (+/- 0.20 mg). Coronary blood flow velocity after adenosine increased to 1.6 +/- 0.3 times resting coronary blood flow velocity, comparable in magnitude to the hyperemia following intracoronary papaverine. The time from injection to peak effect after adenosine was 7.4 (SD +/- 2.2) sec and after papaverine 26 (SD +/- 7) sec. Adenosine resulted in a bradyarrhythmia in three patients. Intracoronary adenosine is a potent and very short acting vasodilator for studying coronary flow reserve, but the side effects and unpredictability of the dosage needed to produce maximal hyperemia may limit its applicability.

Adenosine↗
PubMed1988

Correlations between quantitative cineangiography, coronary flow reserve measured with digital subtraction cineangiography and exercise thallium perfusion scintigraphy.

The goal of this investigation was to establish which anatomical parameters of stenotic lesions correlate best with its functional severity. Therefore, thirty-eight patients with single vessel disease underwent coronary cineangiography and exercise/redistribution thallium-201 scintigraphy. Cross-sectional area at the site of obstruction (OA), percentage diameter stenosis (DS), the calculated pressuredrop over the stenosis (PD), as well as coronary flow reserve (CFR) derived from myocardial contrast appearance time and density were determined. The relations between CFR and the 3 anatomical parameters were described by the following equations: CFR = 4.6 - 0.053 DS, r = 0.82, SEE: 0.79, p less than 0.001 CFR = 0.5 + 0.75 OA, r = 0.87, SEE: 0.68, p less than 0.001 CFR = 3.6 - 1.5 log PD, r = 0.90, SEE: 0.62, p less than 0.001 The calculated pressuredrop was highly predictive of the thallium scintigraphic results with a sensitivity of 94% and a specificity of 90%. Therefore, the calculated pressuredrop is a better anatomical parameter for assessing the functional importance of a stenosis than percentage diameter stenosis or obstruction area. However, the 95% confidence limits of the relation between pressuredrop and coronary flow reserve are wide, making measurement of CFR a valuable addition to quantitative angiography, especially when determining the functional importance of moderately severe coronary artery lesions.

Adult↗
PubMed1988

Three-dimensional reconstruction of myocardial contrast perfusion from biplane cineangiograms by means of linear programming techniques.

The assessment of coronary flow reserve from the instantaneous distribution of the contrast agent within the coronary vessels and myocardial muscle at the control state and at maximal flow has been limited by the superimposition of myocardial regions of interest in the two-dimensional images. To overcome these limitations, we are in the process of developing a three-dimensional (3D) reconstruction technique to compute the contrast distribution in cross sections of the myocardial muscle from two orthogonal cineangiograms. To limit the number of feasible solutions in the 3D-reconstruction space, the 3D-geometry of the endo- and epicardial boundaries of the myocardium must be determined. For the geometric reconstruction of the epicardium, the centerlines of the left coronary arterial tree are manually or automatically traced in the biplane views. Next, the bifurcations are detected automatically and matched in these two views, allowing a 3D-representation of the coronary tree. Finally, the circumference of the left ventricular myocardium in a selected cross section can be computed from the intersection points of this cross section with the 3D coronary tree using B-splines. For the geometric reconstruction of the left ventricular cavity, we envision to apply the elliptical approximation technique using the LV boundaries defined in the two orthogonal views, or by applying more complex 3D-reconstruction techniques including densitometry. The actual 3D-reconstruction of the contrast distribution in the myocardium is based on a linear programming technique (Transportation model) using cost coefficient matrices. Such a cost coefficient matrix must contain a maximum amount of a priori information, provided by a computer generated model and updated with actual data from the angiographic views. We have only begun to solve this complex problem. However, based on our first experimental results we expect that the linear programming approach with advanced cost coefficient matrices and computed model will lead to acceptable solutions in the 3D-reconstruction of the myocardial contrast distribution from biplane cineangiograms.

Cineangiography↗
PubMed1988

Which cineangiographically assessed anatomic variable correlates best with functional measurements of stenosis severity? A comparison of quantitative analysis of the coronary cineangiogram with measured coronary flow reserve and exercise/redistribution thallium-201 scintigraphy.

The goal of this investigation was to establish which measured anatomic variable of stenotic coronary lesions correlates best with functional severity. Therefore, 38 patients with single vessel disease underwent coronary cineangiography and exercise/redistribution thallium-201 scintigraphy. The computer-based Cardiovascular Angiography Analysis System was used to determine the cross-sectional area at the site of obstruction (OA) and percent diameter stenosis (DS), and to calculate the pressure drop over the stenosis (PD) with use of fluid dynamic equations. Coronary flow reserve was measured radiographically. Myocardial perfusion defects on thallium scintigrams were analyzed quantitatively and by visual interpretation. The relations between coronary flow reserve (CFR) and the three anatomic variables were described by the following equations: 1) CFR = 4.6 - 0.053 DS, r = 0.82; SEE: 0.79, p less than 0.001. 2) CFR = 0.5 + 0.75 OA, r = 0.87; SEE: 0.68, p less than 0.001). 3 CFR = 3.6 - 1.5 log PD, r = 0.90; SEE: 0.62, p less than 0.001. The calculated pressure drop was highly predictive of the thallium scintigraphic results with a sensitivity of 94% and a specificity of 90%. The calculated pressure drop is a better anatomic variable for assessing the functional importance of a stenosis than is percent diameter stenosis or obstruction area. However, the 95% confidence limits of the relation between pressure drop and coronary flow reserve are wide, making the measurement of coronary flow reserve an indispensable addition to quantitative angiography, especially when determining the functional importance of moderately severe coronary artery lesions.

Adult↗
PubMed1988

Atrial wall stress rather than pressure per se might be responsible for the increased secretion of atrial natriuretic factor after heart transplantation.

Plasma atrial natriuretic factor (ANF) concentrations were measured, and relationships to intracardiac pressures and atrial dimensions were assessed in a series of 17 heart transplant recipients undergoing cardiac catheterization during their annual evaluation. Despite excellent cardiac function (normal filling pressures, adequate cardiac output, ejection fraction above 60%), plasma levels of ANF were elevated. Step-up levels across the heart were consistent with increased cardiac secretion, whereas both the metabolic clearance rate and plasma half-life were normal. Correlations between plasma concentrations of ANF at different cardiac sites and atrial filling pressures were low. However, right and left atrial dimensions in our patients were greatly enlarged. These findings suggest that increased atrial size (by virtue of the atrial anastomoses) and augmented wall stress (law of Laplace) rather than pressure per se are responsible for the increased ANF production after heart transplantation.

Atrial Natriuretic Factor↗
PubMed1988

Assessment of immediate and long-term functional results of percutaneous transluminal coronary angioplasty.

Assessment of the functional significance of coronary artery lesions during cardiac catheterization has recently become possible by calculating coronary flow reserve from both myocardial contrast appearance time and density in the resting and hyperemic states determined from digitized coronary cineangiograms. However, the interobserver and intraobserver variabilities, as well as the short-, medium-, and long-term variabilities of the coronary flow reserve measurements, have to be established before this technique becomes an acceptable means of assessing the immediate and long-term functional results of revascularization procedures such as percutaneous transluminal coronary angioplasty (PTCA). Variability was defined as the mean difference and standard deviation of the difference between duplicate determinations of coronary flow reserve. The intraobserver variability (mean difference +/- SD) in the measurement of coronary flow reserve was -0.01 +/- 0.07. Interobserver variability by two observers was +0.08 +/- 0.52. Short-term variability based on the analysis of two coronary cineangiograms taken 5 minutes apart was -0.02 +/- 0.26. Medium-term variability (coronary cineangiographies repeated 1-3 hours apart) was found to be -0.06 +/- 0.52. Long-term variability (coronary cineangiographies repeated 3-5 months apart) was 0.11 +/- 0.63. Having established the reproducibility of this radiographic method, we studied the prospective changes in coronary flow reserve in 25 patients undergoing PTCA for single vessel coronary artery disease. Coronary flow reserve measurements and quantitative coronary cineangiography were performed before, immediately after, and 3-5 months after PTCA. PTCA resulted in an immediate increase in coronary flow reserve from 1 +/- 0.3 to 2.3 +/- 0.6 with a concomitant increase in obstruction area from 0.9 +/- 0.3 to 3.3 +/- 0.7 mm2. Nine of the 25 patients developed restenosis defined as a diameter stenosis greater than 50% at follow-up. The other 16 patients had a coronary flow reserve of 3.3 +/- 0.6, which was measured 3-5 months after PTCA. Coronary flow reserve measurement from digitized coronary cineangiograms is a reproducible method for the assessment of the physiological importance of coronary artery obstructions. Short-, medium-, and long-term investigations of the functional results of interventions such as pharmacological therapy or revascularization can be performed reliably with this technique.

Adult↗
PubMed1987

Diabetes insipidus associated with dysplastic pancytopenia.

This case report describes a 60-year-old man who presented with a three-year history of generalized malaise, decreased libido, polyuria, and polydipsia. He had been previously investigated for pancytopenia, and found to have a hypoplastic bone marrow. A diagnosis of central diabetes insipidus was established; the patient was also found to have a number of other defects in his hypothalamic-pituitary function. Hematologic studies again revealed peripheral pancytopenia associated with a hypoplastic megaloblastic bone marrow. Computed axial and nuclear magnetic resonance tomography failed to establish the nature of the morphologic lesion in the hypothalamus. A possible relationship between the hematologic and endocrine disturbance is discussed.

Bone Marrow↗
PubMed1987

Does the quantitative assessment of coronary artery dimensions predict the physiologic significance of a coronary stenosis?

To study the relationship between the quantitatively assessed coronary artery dimensions and the regional coronary flow reserve as measured by digital subtraction cineangiography, we investigated 17 coronary arteries with a single discrete proximal stenosis and 12 normal coronary arteries before and after intracoronary administration of papaverine. Coronary flow reserve was found to be curvilinearly related to minimal luminal cross-sectional area (r = .92, SEE = 0.73) and to percentage area stenosis (r = .92, SEE = 0.74). Normal coronary arteries had a coronary flow reserve of 5.0 (+/- 0.8 [SD]), which differed significantly from the coronary flow reserve of the coronary arteries with obstructive disease, in which values ranging from 0.5 to 3.9 were found. Coronary arteries with a percentage area stenosis between 50% and 70% and a minimal luminal cross-sectional area between 2 and 4.5 mm2 differed significantly (p = .001), with respect to the coronary flow reserve, from coronary arteries with a percentage area stenosis in excess of 70% and a minimal luminal cross-sectional area less than 2 mm2. With the use of hemodynamic equations that describe the pressure loss over a stenosis, a theoretical pressure-flow relationship can be inferred that characterizes the severity of the stenosis. Based on this theoretical pressure-flow relationship, coronary arteries that have a limited coronary flow reserve and critical stenosis (distal coronary perfusion pressure below 40 mm Hg at coronary flow of 3 ml/sec) can be identified with high sensitivity (83%) and specificity (82%). Thus, in coronary artery disease the consequent reduction in coronary flow reserve can be predicted with reasonable accuracy by quantitative assessment of coronary artery dimensions.

Adult↗
PubMed1987

[Intracoronary blood flow velocity during angioplasty. Functional guide and indicator of the success of dilatation].

In order to assess the value of a new Doppler-fitted dilatation catheter, changes in blood flow velocities in the coronary arteries were recorded at various stages of transluminal angioplasty in 15 patients with isolated proximal coronary stenosis. A pulsed Doppler probe (emission frequency 20 MHz, recurrence frequency 62.5 MHz) attached to the distal end of the balloon catheter was used to measure blood flow velocities with a Doppler frequency/velocity relationship of about 3.75 cm/s per KHz. During each angioplasty the balloon was inflated 4 times on average, with successive increases of pressure from 7 to 12 atmospheres. Flow velocities were measured before and after each inflation and also when maximum hyperaemia occurred after temporary occlusion by the inflated balloon. Computer-assisted analysis of the coronary stenosis was carried out before and after the procedure. Patient's mean age was 53 years. Angioplasty was performed in the anterior interventricular artery (12 cases), the circumflex artery (2 cases) or the right coronary artery (1 case). Anatomical success was assessed by an increase of minimum luminal section area from 1.3 +/- 0.0 to 3.0 +/- 1.2 mm2. Functional success was assessed by a progressive and significant increase of the velocities measured during the first 3 dilatations. No further increase of velocity was observed between the last 2 inflations. Coronary reserve at the end of angioplasty was 2.1, corresponding to the theoretical value calculated taking into account the residual stenosis and the presence of the catheter in situ.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1986

Papaverine: the ideal coronary vasodilator for investigating coronary flow reserve? A study of timing, magnitude, reproducibility, and safety of the coronary hyperemic response after intracoronary papaverine.

A potent, short-acting vasodilator that induces a maximal hyperemic response of the coronary vascular bed is needed to determine coronary flow reserve. In 12 patients, we measured coronary sinus blood flow by thermodilution over a period of 2 min during which a bolus of 10 mg papaverine was given into the left main coronary artery. This was repeated after 5 min to assess the reproducibility of the changes. The maximal hyperemic response lasted from 24 until 37 sec after papaverine administration. There was no significant difference between the two consecutive hyperemic responses (Student's t-test for paired observations). The mean difference between first and second hyperemic responses at 30 sec was 7.0% (SD +/- 6.2%). In conclusion, 10 mg of intracoronary papaverine is a short-lasting and reproducible means of inducing a maximal hyperemic response in the coronary vascular bed and therefore appears to be the ideal agent for investigating coronary flow reserve.

Aged↗
PubMed1986

Diagnosis of tricuspid regurgitation: comparison of jugular venous and liver pulse tracings with combined two-dimensional and Doppler-echocardiography.

The clinical diagnosis of tricuspid regurgitation is difficult in patients after mitral valve replacement. We therefore studied the value of the jugular venous pulse tracing, liver pulse tracing and right atrial size estimated from a two-dimensional echocardiogram for diagnosing tricuspid regurgitation in 57 patients with a Björk-Shiley prosthesis in the mitral position and compared them with Doppler echocardiography. Liver pulse tracings have a higher diagnostic yield than jugular venous tracings which often have carotid pulse artifacts. The liver pulse has a sensitivity of 0.91, a specificity of 0.80. Right atrial dilatation has a sensitivity of only 0.50, but a specificity of 0.88. Likelihood ratios calculated on the basis of the combination of these two methods allow an accurate prediction of the presence or absence of tricuspid regurgitation.

Adult↗
PubMed1986

Echocardiographic demonstration of free wall vegetative endocarditis complicated by a pulmonary embolism in a patient with ventricular septal defect.

A defect in the muscular part of the interventricular septum in a 19 year old man was complicated by infective endocarditis caused by Staphylococcus aureus. The lesion was a large right ventricular free wall vegetation which embolised to the lungs. The vegetation was displayed by cross sectional echocardiography, which also confirmed the clinical diagnosis of ventricular septal defect. This case confirms the concept that the jet stream causes endocarditis at its point of impact. After six weeks' treatment with antibiotics the ventricular septal defect was repaired at operation.

Adult↗