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Paul Steendijk

Publications and source records attributed to Paul Steendijk.

At least 73 records · Page 4Linked to original sources
PubMed2004

Assessment of parallel conductance for the trans-cardiac conductance method: can we use the hypertonic saline method with pulmonary artery injections?

The trans-cardiac conductance (TCC) method provides on-line left ventricular (LV) volume signals by determining the electrical conductance of blood in the LV using central venous and epithoracic electrodes. Conductive structures outside the LV cause a 'parallel conductance' offset term (Vp) that is determined by bolus injections of hypertonic saline in the pulmonary artery (Vp(saline)). Analysis of the increased conductance signal during passage of the bolus through the LV yields Vp(saline). Since TCC signals are picked up by epithoracic electrodes, concern has been raised that hypertonic saline remaining in the lungs might lead to overestimation. The decrease in blood conductivity induced by injection of non-ionic contrast medium during a LV angiogram may also be used to determine Vp (Vp(contrast)). Since the contrast is injected directly into the LV, lung conductance should be unaltered. Thus, we compared Vp(saline) with Vp(contrast) in six anaesthetized sheep during different hemodynamic conditions. Linear regression showed that Vp(saline) = 0.99 Vp(contrast) + 2.45 ml (r2 = 0.99). Bland-Altman analysis yielded a small non-significant bias (+/-2SD) of 1.8 (+/-6.8) ml. We conclude that parallel conductance for TCC can be accurately determined with the conventional hypertonic saline method.

Animals↗
PubMed2004

QRS duration and shortening to predict clinical response to cardiac resynchronization therapy in patients with end-stage heart failure.

Despite current selection criteria (NYHA Class III-IV, LVEF < 35%, QRS > 120 ms with LBBB), 30% of patients do not benefit from cardiac resynchronization therapy (CRT). The use of QRS duration as selection criteria for CRT has not been evaluated systematically yet. Accordingly, the value of QRS duration at baseline (and reduction in QRS duration after CRT) to predict responders was studied. Patients were evaluated at baseline and after 6 months of CRT for NYHA Class, quality of life score, and 6-minute walk test. QRS duration was evaluated before, directly after implantation, and after 6 months of CRT. Sixty-one patients were included; 45 (74%) patients were classified as responders (improvement of NYHA Class, 6-minute walking distance and quality of life score) and 16 (26%) as nonresponders. QRS duration at baseline was similar between the two groups: 179 +/- 30 ms versus 171 +/- 32 ms, NS. Directly after implantation, QRS duration was reduced from 179 +/- 30 ms to 150 +/- 26 ms (P < 0.01) in responders; nonresponders did not exhibit this reduction (171 +/- 32 ms vs 160 +/- 26 ms, NS). After 6 months of CRT, QRS shortening was only observed in responders (from 179 +/- 30 ms to 159 +/- 25 ms, P < 0.01). ROC curve analysis showed that a reduction in QRS duration > 10 ms had a high sensitivity (73%) with low specificity (44%); conversely, a > 50 ms reduction in QRS duration was highly specific (88%) but not sensitive (18%) to predict response to CRT. No optimal cutoff value could be defined. QRS duration at baseline is not predictive for response to CRT; responders exhibit a significant reduction in QRS duration after CRT, but individual response varies highly, not allowing adequate selection of responders.

Aged↗
PubMed2003

Left ventricular dyssynchrony predicts benefit of cardiac resynchronization therapy in patients with end-stage heart failure before pacemaker implantation.

We evaluated patients with end-stage heart failure who have a high likelihood of response to cardiac resynchronization therapy (biventricular pacing). It appears that 20% of patients do not respond to this expensive therapy despite the use of selection criteria (dilated cardiomyopathy, heart failure, New York Heart Association class II or IV, left ventricular ejection fraction <35%, left bundle branch block, and QRS >120 ms). The presence of left ventricular dyssynchrony is needed to result in improvement after cardiac resynchronization therapy.

Aged↗
PubMed2003

Quantification of left ventricular mechanical dyssynchrony by conductance catheter in heart failure patients.

Mechanical dyssynchrony is an important codeterminant of cardiac dysfunction in heart failure. Treatment, either medical, surgical, or by pacing, may improve cardiac function partly by improving mechanical synchrony. Consequently, the quantification of ventricular mechanical (dys)synchrony may have important diagnostic and prognostic value and may help to determine optimal therapy. Therefore, we introduced new indexes to quantify temporal and spatial aspects of mechanical dyssynchrony derived from online segmental conductance catheter signals obtained during diagnostic cardiac catheterization. To test the feasibility and usefulness of our approach, we determined cardiac function and left ventricular mechanical dyssynchrony by the conductance catheter in heart failure patients with intraventricular conduction delay (n = 12) and in patients with coronary artery disease (n = 6) and relatively preserved left ventricular function. The heart failure patients showed depressed systolic and diastolic function. However, the most marked hemodynamic differences between the groups were found for mechanical dyssynchrony, indicating a high sensitivity and specificity of the new indexes. Comparison of conductance catheter-derived indexes with septal-to-lateral dyssynchrony derived by tissue-Doppler velocity imaging showed highly significant correlations. The proposed indexes provide additional, new, and quantitative information on temporal and spatial aspects of mechanical dyssynchrony. They may refine diagnosis of cardiac dysfunction and evaluation of interventions, and ultimately help to select optimal therapy.

Aged↗
PubMed2003

Real-time MR imaging of aortic flow: influence of breathing on left ventricular stroke volume in chronic obstructive pulmonary disease.

PURPOSE: To assess real-time changes of left ventricular stroke volume (SV) in relation to the breathing pattern in healthy subjects and in patients with chronic obstructive pulmonary disease (COPD). MATERIALS AND METHODS: Real-time magnetic resonance (MR) imaging flow measurements were performed in the ascending aorta of 10 healthy volunteers and nine patients with severe COPD. Breathing maneuvers were registered with an abdominal pressure belt, which was synchronized to the electrocardiographic signal and the flow measurement. Healthy subjects performed normal breathing, deep breathing, and the Valsalva maneuver. Patients with COPD performed spontaneous breathing. Paired two-tailed Student t tests were used in healthy volunteers to assess significant SV differences between normal breathing and deep breathing or the Valsalva maneuver. The results of measurements in the patients with COPD were compared with the results during normal breathing in healthy subjects with the unpaired two-tailed Student t test. RESULTS: In healthy subjects, SV decreased during inspiration and increased during expiration (r2 = 0.78, P <.05). When compared with the SV during normal breathing, mean SV did not change during deep breathing but declined during the Valsalva maneuver (P <.05). The difference between minimal and maximal SVs (ie, SV range) increased because of deep breathing or the Valsalva maneuver (P <.05). In normal and deep breathing, velocity of SV elevation and velocity of SV decrease were equal (which resulted in a ratio of 1), whereas during the Valsalva maneuver, this value increased (P <.05). Spontaneous breathing in COPD resulted in SV changes (P <.05) similar to those observed in healthy subjects who performed the Valsalva maneuver. CONCLUSION: Real-time MR imaging of aortic flow reveals physiologic flow alterations, which are dependent on variations in the breathing pattern.

Adult↗
PubMed2003

End-diastolic and end-systolic volume from the left ventricular angiogram: how accurate is visual frame selection? Comparison between visual and semi-automated comnputer-assisted analysis.

BACKGROUND: End-diastolic (ED), end-systolic (ES) left ventricular (LV) volumes and LV ejection fraction (LVEF) are important parameters for clinical decision making in heart disease. In clinical practice the frames from cine-angiography with the largest and smallest opacified LV areas are visually selected and the endocardial borders traced as LVED and LVES contours, respectively. We compared the accuracy of this visual method using two frames with a semi-automated computer assisted frame-by-frame analysis of the complete opacified cardiac cycles. METHODS AND RESULTS: In 17 patients a biplane LV cine-angiogram was obtained at 25 frames/s. Complete frame-by-frame analysis was performed using semi-automatic border detection software. Experienced independent observers visually selected and manually traced LVED and LVES in the so-called visually assessed two-frame method in a consensus meeting. LV volumes were calculated by the area-length method. Mean LVEDV, LVESV and LVEF were 133 +/- 57, 56 +/- 40 ml and 61 +/- 16%, respectively, for the visually assessed two-frame method, and 117 +/- 49, 53 +/- 33 ml and 60 +/- 13%, respectively, for the semi-automated computer assisted frame-by-frame method. LVEDV was significantly higher in the visually assessed two-frame method (p < 0.01). Linear regression analysis showed an excellent correlation between semi-automated computer-assisted frame-by-frame and the visually assessed two-frame LVEDV (y = 1.2x - 2.9; r2 = 0.98), LVESV (y = 1.2x - 8.2; r2 = 0.97) and good linear correlation for LVEF (p = 1.2x - 3.6; r2 = 0.82). Bland-Altman analysis showed respectively a bias of 16.4, 2.4 ml and 5.0% with overall wide limits of agreement (-6.6 and 39.4 ml; -16.6 and 21.4 ml; -9.0% and 19.1%). CONCLUSION: Correlation is excellent when visually assessed LVED and LVES are compared with a semi-automated computer assisted frame-by-frame analysis. However, the visually assessed two-frame method tends to overestimate the volumes obtained by semi-automated computer-assisted frame-by-frame analysis, especially for LVEDV, indicating that visual selection will yield a higher LVEF, which may influence clinical decision making.

Angiocardiography↗
PubMed2003

Chronic and adjustable pulmonary artery banding.

OBJECTIVE: Banding of the pulmonary artery might be required to prevent pulmonary vascular damage in patients with increased pulmonary artery flow and to retrain the left ventricle in preparation for an arterial switch operation in patients with congenitally corrected transposition of the great arteries. Readjustment of the pulmonary artery band might be required in the postoperative period. In this study we aimed to test the feasibility of a novel device for bidirectionally adjustable pulmonary artery constriction. METHODS: A hydraulic main pulmonary artery occluder was implanted in lambs and gradually inflated to create right ventricular pressure overload at a systemic (aortic) level. During the following period (up to 12 weeks), this pressure overload was monitored by measuring aortic and right ventricular pressures by means of implanted subcutaneous reservoirs. If required to maintain the right ventricular pressure overload at a systemic level in the growing animals, the occluder was deflated through a third subcutaneous reservoir. RESULTS: After the banding period (average of 64 +/- 8 days), the main pulmonary artery cuff could still be adjusted, and the animals showed no clinical signs of heart failure. Histologic analysis of the pulmonary artery showed extensive fibrosis, a giant cell response around the device, and small areas of tissue necrosis; complete transmural necrosis was not detected. CONCLUSIONS: This device allows adjustment of the pulmonary artery cuff in a precise manner over a prolonged period of time without surgical reintervention. Potentially, the device might have applications for clinical use in children with congenital heart disease.

Animals↗
PubMed2003

Effects of acute left ventricular unloading on right ventricular function in normal and chronic right ventricular pressure-overloaded lambs.

OBJECTIVE: Right ventricular pressure overload occurs in several types of (congenital) heart disease, as well as in pulmonary disease. Clinical outcome in some of these patient groups might in part be related to left ventricular loading conditions. The effects of left ventricular unloading on the function of the hypertrophic right ventricle have not been studied. We aimed to study the effects of left ventricular unloading on right ventricular hemodynamics and contractility in an animal model of chronic right ventricular pressure overload. METHODS: In lambs the pulmonary artery was chronically banded to increase right ventricular pressure to systemic levels. After 8 weeks, right ventricular contractility and hemodynamic function were assessed in these lambs, as well as in age-matched control animals, by using a combined pressure-conductance catheter in the right ventricle during baseline conditions and during complete bypass of the left ventricle. RESULTS: In both groups acute left ventricular unloading significantly decreased left ventricular pressure to low levels while aortic pressure was maintained. In the right ventricle of the control group, both end-systolic and end-diastolic volumes increased with left ventricular unloading (P <.01) while end-systolic pressure was maintained. Cardiac output was unchanged despite decreased right ventricular contractility. In the banding group acute left ventricular unloading also decreased right ventricular contractility but increased cardiac output. During acute left ventricular unloading, diastolic stiffness was unchanged in the control group, whereas it was significantly decreased in the banding group. CONCLUSIONS: Both in normal hearts and in hearts subject to chronic right ventricular pressure overload, acute left ventricular unloading decreases right ventricular contractility. Although no effects on cardiac output are encountered in normal hearts during left ventricular bypass, cardiac output is improved in right ventricular pressure-overloaded hearts, most likely related to improved right ventricular diastolic compliance.

Acute Disease↗
PubMed2003

The trans-cardiac conductance method for on-line measurement of left ventricular volume: assessment of parallel conductance offset volume.

The trans-cardiac conductance (TCC) method provides on-line left ventricular (LV) volume signals by determining the electrical conductance of blood in the LV by means of central venous and epithoracic electrodes. Conductive structures outside the LV blood pool cause a "parallel conductance" offset term (Vp) that can be determined by bolus injections of hypertonic saline in the pulmonary artery (Vp(saline)), which cause a transient increase in blood conductivity. This study in anesthetized sheep evaluates the accuracy of the saline calibration method and the variabilities of Vp between animals, between hemodynamic conditions and during the cardiac cycle. The conventional intra-cardiac conductance catheter method was used to obtain independent estimates of Vp by the zero-volume method (Vp(zero volume)). Mean baseline Vp(saline) and Vp(zerovolume) were 104 +/- 6 ml and 106 +/- 6 ml, respectively. Bland-Altman analysis showed a small nonsignificant bias (-2.5 ml) and narrow limits of agreement (4.6 ml). Vp was not significantly different between hemodynamic conditions (baseline, dobutamine, volume load, propranolol), but had a substantial interanimal variability (IAV) (38%). Average variations during the cardiac cycle were < 10% of mean Vp. We conclude that the saline method can be applied to determine Vp for TCC. IAV is substantial, so that Vp must be determined in each animal, but within-animal variability is relatively small.

Animals↗
PubMed2003

Perioperative assessment of left ventricular function by pressure-volume loops using the conductance catheter method.

UNLABELLED: Interpretation of perioperative measurements of cardiac function during cardiac surgery is complicated by changes in loading conditions induced by anesthesia, cardiopulmonary bypass (CPB), and the surgical procedure itself. Quantification of left ventricular (LV) function by pressure-volume relations as obtained by the conductance catheter would be advantageous because load-independent indices can be determined. Accordingly, we evaluated methodological aspects of the conductance-catheter technique and documented LV function before and after CPB in eight patients undergoing coronary artery bypass grafting. LV pressure-volume loops by transesophageal echocardiography-guided transaortic application of the conductance catheter were obtained at steady-state and during preload reduction by temporary occlusion of the inferior cava. All patients remained hemodynamically stable, and no complications occurred. Complete data were acquired within 15 min before and after CPB. Cardiac output (5.2 +/- 1.3 L/min to 6.0 +/- 1.4 L/min) and LV ejection fraction (46% +/- 17% to 48% +/- 19%) did not change, but end-diastolic pressure increased significantly after CPB (8 +/- 2 mm Hg to 16 +/- 7 mm Hg; P < 0.05). Load-independent systolic indices remained constant (end-systolic elastance: 1.31 +/- 1.20 mm Hg/mL to 1.13 +/- 0.59 mm Hg/mL). Diastolic function changed significantly after CPB, as the relaxation time constant decreased from 64 +/- 6 ms to 52 +/- 5 ms (P < 0.05) and the chamber stiffness constant increased from 0.016 +/- 0.014/mL to 0.038 +/- 0.016/mL (P < 0.05). We conclude that the conductance catheter method provides detailed data on perioperative myocardial function and may be useful for evaluating the effects of new surgical and anesthetic procedures. IMPLICATIONS: Pressure-volume loops provide on-line quantification of intrinsic systolic and diastolic myocardial function in a load-independent fashion. This study shows the feasibility of perioperative pressure-volume analysis by use of the conductance-catheter method. This method provides detailed data about the immediate effects of surgery and may be used to evaluate complex cardiac procedures.

Adult↗
PubMed2002

Impact of pericardial restraint on right atrial mechanics during acute right ventricular pressure load.

Optimization of right atrial (RA) mechanics is important for maintaining right ventricular (RV) filling and global cardiac output. However, the impact of pericardial restraint on RA function and the compensatory role of the right atrium to changes in RV afterload remain poorly characterized. In eight open-chest sheep, RA elastance (contractility) and chamber stiffness were measured (RA pressure-volume relations) at baseline and during partial pulmonary artery (PA) occlusion. Data were collected before and after pericardiotomy. With the pericardium intact and partial PA occlusion, RA elastance increased by 28% (P < 0.04), whereas RA stiffness tended to rise (P = 0.08). However, after pericardiotomy, there was a significant fall in both RA elastance (54%, P < 0.04) and stiffness (39%, P < 0.04), and subsequent PA occlusion failed to induce a change in elastance (P > 0.19) or stiffness (P > 0.84). After pericardiotomy, RA elastance and stiffness fell dramatically, and the compensatory response of the right atrium to elevated RV afterload was lost. The ability of the right atrium to respond to changes in RV hemodynamics is highly dependent on pericardial integrity.

Animals↗
PubMed2002

Effectiveness of resynchronization therapy in patients with end-stage heart failure.

Biventricular pacing has been introduced to treat patients with end-stage heart failure, and short-term results of this technique are promising. Because data on longer follow-up are limited to 3-month follow-up, the sustained effect of biventricular pacing is unclear and long-term survival is unknown. Forty patients with end-stage heart failure in New York Heart Association (NYHA) functional class III or IV with left ventricular (LV) ejection fraction (EF) <35%, QRS duration >120 ms, and left bundle branch block morphology received a biventricular pacemaker. At baseline, and at 3 and 6 months after implantation, the following parameters were evaluated: NYHA class, Minnesota quality-of-life score, QRS duration on surface electrocardiogram, 6-minute walking distance, and LVEF. Long-term follow-up was obtained for up to 2 years. All clinical parameters improved significantly at 3 months and remained unchanged at 6-month follow-up. LVEF increased from 24 +/- 9% to 34 +/- 11%. Before implantation, patients were hospitalized (for congestive heart failure) an average of 3.9 +/- 5.3 days/year compared with 0.5 +/- 1.5 days/year after implantation. Long-term follow-up showed a survival of 87.5% at 2 years. Thus, biventricular pacing resulted in improvement of symptoms and quality of life, accompanied by improvement in 6-minute walking distance and LVEF. These effects were observed at 3 months after implantation and were maintained at 6-month follow-up. Moreover, 2-year survival was excellent.

Cardiac Pacing, Artificial↗
PubMed2002

Continuous on-line measurement of absolute left ventricular volume by transcardiac conductance: angiographic validation in sheep.

OBJECTIVE: Validation of the transcardiac conductance method for continuous, on-line measurement of absolute left ventricular volume by comparison with biplane angiography. DESIGN: Controlled, prospective animal study. SETTING: Catheterization laboratory of the Leiden University Medical Center. SUBJECTS: Six anesthetized sheep. INTERVENTIONS: Subjects were studied at baseline, during infusion of dobutamine, and during volume loading and beta blockade. In a pilot experiment, a coronary artery was occluded by a balloon, and the behavior of the transcardiac conductance signals during ischemia was tested. MEASUREMENTS AND MAIN RESULTS: Calibration factors alpha and V(p) were determined by thermodilution and hypertonic saline dilution, respectively. Calibrated transcardiac conductance volume was compared with angiographic volume in four different hemodynamic conditions, and transcardiac conductance measurements were registered during a period of ischemia. Results showed a good linear correlation between transcardiac conductance and angiographic volume (r =.77, p <.01) with an intercept of 12.5 +/- 5.6 mL (interanimal variability, 17.8 mL) and a slope of 1.49 +/- 0.15 (interanimal variability, 0.34). Mean alpha and V(p) were 0.12 +/- 0.01 (interanimal variability, 0.07) and 104 +/- 3 mL (interanimal variability, 38 mL), respectively. V(p) did not vary significantly between conditions, and alpha varied only during propranolol (p =.04). Transcardiac conductance enabled immediate visualization of acute left ventricular volume changes during coronary occlusion in a pilot experiment. CONCLUSIONS: Transcardiac conductance is a method to register an on-line, continuous, left ventricular volume signal, which correlates well with angiography. However, calibration factors need to be determined in individual subjects. The method appears promising to monitor absolute volume in the intensive care unit.

Angiography↗
PubMed2002

MR flow mapping in coronary artery bypass grafts: a validation study with Doppler flow measurements.

PURPOSE: To validate fast magnetic resonance (MR) flow mapping with intravascular Doppler flow measurements in vitro and in patients with nonstenotic and stenotic coronary artery bypass grafts. MATERIALS AND METHODS: MR and Doppler flow measurements were performed in a small-diameter flow phantom with physiologic flow conditions and at baseline and during adenosine stress in 27 grafts in 23 patients, who were scheduled for cardiac catheterization. At invasive analysis, the grafts were divided into those with stenosis of less than 50% (nonstenotic) and those with stenosis greater than or equal to 50% (stenotic). In vitro velocity values and velocity values in nonstenotic and stenotic grafts were compared with linear regression analysis, and the in vitro interstudy variability was determined. RESULTS: Excellent correlations in average peak velocity (r = 0.99, P <.001) and diastolic peak velocity (r = 0.99, P <.001) were demonstrated in vitro between MR and Doppler flow measurements, with less than 5% interstudy variability. MR and Doppler flow measurements revealed good correlations in peak velocity and velocity reserve both in nonstenotic (n = 20) (average peak velocity: r = 0.81, P <.001; diastolic peak velocity: r = 0.83, P <.001; velocity reserve: r = 0.56, P =.010) and stenotic (n = 7) (average peak velocity: r = 0.83, P <.001; diastolic peak velocity: r = 0.78, P =.001; velocity reserve: r = 0.70, P =.078) grafts. CONCLUSION: Fast MR flow mapping provides noninvasive measures of peak velocity and velocity reserve, which closely correlate with Doppler values both in vitro and in nonstenotic and stenotic grafts.

Adenosine↗
PubMed2002

Indexes of diastolic RV function: load dependence and changes after chronic RV pressure overload in lambs.

Diastolic function is a major determinant of ventricular performance, especially when loading conditions are altered. We evaluated biventricular diastolic function in lambs and studied possible load dependence of diastolic parameters [minimum first derivative of pressure vs. time (dP/dt(min)) and time constant of isovolumic relaxation (tau)] in normal (n = 5) and chronic right ventricular (RV) pressure-overloaded (n = 5) hearts by using an adjustable band on the pulmonary artery (PAB). Pressure-volume relations were measured during preload reduction to obtain the end-diastolic pressure-volume relationship (EDPVR). In normal lambs, absolute dP/dt(min) and tau were lower in the RV than in the left ventricle whereas the chamber stiffness constant (b) was roughly the same. After PAB, RV tau and dP/dt(min) were significantly higher compared with control. The RV EDPVR indicated impaired diastolic function. During acute pressure reduction, both dP/dt(min) and tau showed a relationship with end-systolic pressure. These relationships could explain the increased dP/dt(min) but not the increased tau-value after banding. Therefore, the increased tau after banding reflects intrinsic myocardial changes. We conclude that after chronic RV pressure overload, RV early relaxation is prolonged and diastolic stiffness is increased, both indicative of impaired diastolic function.

Aging↗
PubMedDate not supplied

Hemodynamic evaluation of saphenous vein coronary artery bypass grafts: relative merits of Doppler flow velocity and SPECT perfusion imaging.

BACKGROUND: Coronary angiography is considered the gold standard in evaluating vein graft disease; however, angiography does not allow assessment of hemodynamic consequences of lesions. In this study hemodynamic consequences of significant stenoses in vein grafts were evaluated by Doppler velocity assessment, and results were compared with single photon emission computed tomography (SPECT) perfusion imaging. METHODS AND RESULTS: Angiography was performed in 58 patients after coronary artery bypass grafting because of recurrent chest pain. During the procedure, Doppler velocity measurements were acquired before and after administration of adenosine. Of 58 patients (with 78 vein grafts), 20 patients (with 24 vein grafts) underwent SPECT perfusion imaging. Grafts were divided into those with nonsignificant percent diameter stenosis (< 50%) (n = 49) and those with significant percent diameter stenosis (> or =50%) (n = 29). When a cutoff value for coronary flow velocity reserve (CFVR) of 1.8 was applied, modest agreement (69%, kappa = 0.25, P < .05) between CFVR and angiography was shown. Agreement between SPECT and angiography was also modest (63%, kappa = 0.28, P = not significant). SPECT and CFVR provided comparable information in 20 of 24 grafts with available SPECT, illustrating good agreement (83%, kappa = 0.61, P = .001). CONCLUSIONS: Significant stenoses in vein grafts require further exploration to assess their hemodynamic significance. The Doppler velocity results agreed better with SPECT perfusion imaging than with percent diameter stenosis in the evaluation of vein graft function.

Aged↗