Biomedical subjects

Jan Baan

Publications and source records attributed to Jan Baan.

16 recordsLinked to original sources

PubMed2006

Impact of multivessel coronary disease on long-term mortality in patients with ST-elevation myocardial infarction is due to the presence of a chronic total occlusion.

In acute ST-elevation myocardial infarction (STEMI), patients with multivessel disease (MVD) are considered to be a subgroup with an increased risk of mortality compared with patients with single-vessel disease (SVD). To evaluate the effect of MVD on 1-year mortality in patients with STEMI, we studied 1,417 consecutive patients with STEMI who were admitted between 1997 and 2002 and treated with primary percutaneous coronary intervention. Further, we hypothesized that the effect of MVD on mortality is due to the presence of a chronic total occlusion in a noninfarct-related artery. Patients with MVD and/or a chronic total occlusion had multiple differences in baseline and angiographic characteristics that were associated with worse outcome. Mortalities in patients with SVD, MVD, and a chronic total occlusion were 8%, 16%, and 35%, respectively. After correction for the baseline differences, MVD was an independent predictor of mortality (odds ratio 1.5, 95% confidence interval 1.1 to 2.1). However, when chronic total occlusion was included in the model, MVD was no longer an independent predictor for mortality, whereas chronic total occlusion was a strong and independent predictor for 1-year mortality in patients with STEMI treated with percutaneous coronary intervention (odds ratio 3.8, 95% confidence interval 2.5 to 5.8). In conclusion, patients with STEMI and MVD have a higher 1-year mortality rate compared with patients with SVD, which is mainly determined by the presence of a chronic total occlusion in a noninfarct-related artery. In the setting of primary percutaneous coronary intervention, the presence of a chronic total occlusion, and not the mere presence of MVD, is an independent predictor of mortality.

Age Factors↗

PubMed2006

Safety and feasibility of elective high-risk percutaneous coronary intervention procedures with left ventricular support of the Impella Recover LP 2.5.

Currently, the most used left ventricular (LV) support device is intra-aortic balloon counterpulsation. The percutaneous implantable Impella Recover LP 2.5 system is a novel LV (unloading) assist device. We studied the feasibility and safety of LV support with the percutaneous implantable Impella Recover LP 2.5 system in 19 consecutive high-risk patients with percutaneous coronary intervention. Procedural success using the device and percutaneous coronary intervention was achieved in all 19 patients, who were very poor candidates for surgery. The patients were elderly (84% were >60 years of age), 74% had previous myocardial infarction, 63% had LV ejection fractions of < or =25%, and all had LV ejection fractions of < or =40%. There were no procedural deaths and 2 device-unrelated in-hospital late deaths. Mean decrease in hemoglobin level was 0.7 +/- 0.4 mmol/L. The device did not induce or increase aortic valve regurgitation. There were no important device-related adverse events during LV support with the Impella Recover LP 2.5 system. However, these encouraging findings must be confirmed by larger studies, longer assist times, and in other patient categories.

Aged↗

PubMed2005

Suppression of physiological cardiomyocyte proliferation in the rat pup after neonatal glucocorticosteroid treatment.

BACKGROUND: Glucocorticosteroids (mostly dexamethasone) are widely used to prevent chronic lung disease in premature infants. Neonatal rats treated with dexamethasone have been shown to have reduced cardiac mass and cardiomyocyte hypertrophy, suggesting a lower number of cardiomyocytes at adult age, and a severely reduced life expectancy. In the present study we tested the hypothesis that a lower number of cardiomyocytes in later life is caused by a reduced cardiomyocyte proliferation and/or by early cell death (apoptosis). METHODS AND RESULTS: Rat pups received dexamethasone or saline control on day 1, 2 and 3 and were sacrificed at day 0, 2, 4, 7 and 21. The cardiomyocytes of dexamethasone treated pups showed a reduced proliferation as indicated by a lower mitotic index and reduced number of Ki-67 positive cardiomyocytes on day 2 and 4 as compared to day 0 and day 7 and also as compared to the age-matched saline pups. On day 7 and day 21 the mitotic index was not different between groups. From day 2 onward up to day 21 dexamethasone treated pups showed a lower number of cardiomyocytes. The cardiomyocytes showed no signs (<<1%) of apoptosis (Caspase-3 and cleaved-PARP) in any group. CONCLUSION: The temporary suppression of cardiomyocyte hyperplasia found in dexamethasone treated pups eventually leads to a reduced number and hypertrophy of cardiomyocytes during adult life.

Animals↗

PubMed2005

Neonatal glucocorticosteroid treatment causes systolic dysfunction and compensatory dilation in early life: studies in 4-week-old prepubertal rats.

Glucocorticosteroid treatment is widely used to prevent chronic lung disease in premature infants. Recent studies in adult rats, treated with dexamethasone in the neonatal period, report negative long-term effects on the heart and severely reduced life expectancy. We treated neonatal rats with dexamethasone and studied cardiac function after 4 wk (prepubertal age) to investigate whether the late effects as previously described are preceded by detectable alterations in cardiac function at a younger age. Male rat pups (n = 12) were injected intraperitoneally with dexamethasone on d 1, 2, and 3 (0.5, 0.3, and 0.1 mug/g) of life. Control pups (n = 10) received saline. At 4 wk the animals were anesthetized, and a pressure-conductance catheter was introduced into the left ventricle to measure pressure-volume loops. Cardiac function was measured and pressure-volume relations were determined to quantify intrinsic systolic and diastolic function. Subsequently, hearts were excised for histologic examination. Compared with saline-treated animals, dexamethasone-treated rats had a reduced ventricular weight (270 +/- 40 versus 371 +/- 23 mg, p < 0.001) and reduced systolic function (end-systolic elastance: 1.24 +/- 0.43 versus 2.50 +/- 1.39 mm Hg/muL, p = 0.028). Cardiac output was maintained and end-diastolic volume was increased (84 +/- 23 versus 59 +/- 19 microL, p = 0.012) indicating a state of compensatory dilatation. Heart rate, diastolic function, and systemic vascular resistance were unchanged. Neonatal dexamethasone treatment causes cardiac alterations that can be detected in the prepubertal period and that may precede severe cardiac dysfunction later in life. If our findings are confirmed in humans, this may have consequences for a large patient population and cardiac screening at young age may be indicated to enable secondary prevention.

Animals↗

PubMed2005

Left ventricular function and chronotropic responses after normothermic cardiopulmonary bypass with intermittent antegrade warm blood cardioplegia in patients undergoing coronary artery bypass grafting.

OBJECTIVE: Recent studies indicate that normothermic cardiopulmonary bypass (CPB) with intermittent antegrade warm blood cardioplegia (IAWBC) may have metabolic and clinical advantages, but limited data exist on its effects on myocardial function. Therefore, we investigated the acute effects of this approach on systolic and diastolic left ventricular function and on chronotropic responses. METHODS: In 10 patients undergoing isolated CABG we obtained on-line left ventricular pressure-volume loops using the conductance catheter before and after normothermic CPB with IAWBC. Steady state and load-independent indices of left ventricular function derived from pressure-volume relations were obtained during right atrial pacing (80-100-120 beats/min) to determine baseline systolic and diastolic function and chronotropic responses. RESULTS: The mean time of CPB was 105+/-36 min (median 103, range 60-167 min) with a mean aortic cross-clamp time of 75+/-27 min (median 69, range 43-129 min). Baseline (80 beats/min) end-systolic elastance (E(ES)) did not change after CPB (1.22+/-0.53 to 1.12+/-0.28 mm Hg/ml, P>0.2), while the diastolic chamber stiffness constant (k(ED)) significantly increased (0.014+/-0.005 to 0.040+/-0.007 ml-1, P=0.018) and relaxation time constant (tau) significantly decreased (61+/-3 to 49+/-2 ms, P=0.004). Before CPB, incremental atrial pacing had no significant effects on E(ES) and tau but significant negative effects on kED (0.014+/-0.005 to 0.045+/-0.012 ml-1, P=0.013). After CPB, atrial pacing had significant positive effects on E(ES), tau and kED (E(ES): 1.12+/-0.28 to 2.60+/-1.54 mm Hg/ml, P=0.021; tau: 49+/-2 to 45+/-2 ms, P=0.009; kED: 0.040+/-0.007 to 0.026+/-0.005 mm Hg, P=0.010), indicating improved systolic and diastolic chronotropic responses. CONCLUSION: On-pump normothermic CABG with IAWBC preserved systolic function, increased diastolic stiffness, and improved systolic and diastolic chronotropic responses. Normalization of the chronotropic responses post-CPB is likely due to effects of successful revascularization and subsequent relief of ischemia.

Aged↗

PubMed2005

Acute decrease of left ventricular mechanical dyssynchrony and improvement of contractile state and energy efficiency after left ventricular restoration.

OBJECTIVE: Surgical left ventricular restoration by means of endoventricular patch aneurysmectomy in patients with postinfarction aneurysm should result in acute improved left ventricular performance by decreasing mechanical dyssynchrony and increasing energy efficiency. METHODS: Nine patients with left ventricular postinfarction aneurysm were studied intraoperatively before and after ventricular restoration with a conductance volume catheter to analyze pressure-volume relationships, energy efficiency, and mechanical dyssynchrony. The end-systolic elastance was used as a load-independent index of contractile state. Left ventricular energy efficiency was calculated from stroke work and total pressure-volume area. Segmental volume changes perpendicular to the long axis were used to calculate mechanical dyssynchrony. Statistical analysis was performed with the paired t test and least-squares linear regression. RESULTS: Endoventricular patch aneurysmectomy reduced end-diastolic volume by 37% (P < .001), with unchanged stroke volume. Systolic function improved, as derived from increased +dP/dt(max), by 42% (P < .03), peak ejection rate by 28% (P < .02), and ejection fraction by 16% (P < .0002). Early diastolic function improved, as shown by reduction of -dP/dt(max) by 34% (P < .006) and shortened tau by 30% (P < .001). Left ventricular end-systolic elastance increased from 1.2 +/- 0.6 to 2.2 +/- 1 mm Hg/mL (P < .001). Left ventricular energy efficiency increased by 36% (P < .002). Left ventricular mechanical dyssynchrony decreased during systole by 33% (P < .001) and during diastole by 20% (P < .005). CONCLUSIONS: Left ventricular restoration induced acute improvements in contractile state, energy efficiency, and relaxation, together with a decrease in left ventricular mechanical dyssynchrony.

Aged↗

PubMed2004

Transcardiac conductance for continuous measurement of left ventricular volume: validation vs. angiography in patients.

OBJECTIVE: To test the feasibility of the transcardiac conductance (TCC) method for continuous, on-line measurement of absolute left ventricular (LV) volume and to validate the method by comparison with biplane angiography. DESIGN AND SETTING: Prospective clinical feasibility and validation study in a cardiac catheterization laboratory in a university hospital. PATIENTS AND INTERVENTIONS: Ten patients scheduled for electrophysiological studies ( n=5), percutaneous transluminal coronary angioplasty ( n=3), and left- and right-sided cardiac catheterization ( n=2) were enrolled in the feasibility study. Twenty patients scheduled for diagnostic left- and right-sided cardiac catheterization were included in the validation study. The latter were studied at baseline and during right atrial pacing 30 beats/min above baseline. MEASUREMENTS AND RESULTS: In the feasibility study satisfactory ventricular volume signals were obtained by TCC in eight of ten patients. In the validation study calibration factors (alpha and V(p)) for TCC were obtained by thermodilution and hypertonic saline dilution, to yield absolute LV volume. Results indicate a good linear correlation with angiographic volume ( R(2)=0.78) with an intercept of 10+/-15 ml, not significantly different from 0 and slope of 1.17+/-0.16. Mean calibration factors alpha and V(p) were 0.017+/-0.002 (interpatient variability 0.018) and 75.1+/-0.4 ml (interpatient variability 35.4 ml), respectively. CONCLUSIONS: The TCC method provides on-line and continuous LV volume signals in patients in a relatively noninvasive way. Calibration yields absolute LV volumes with a good linear correlation in comparison to biplane LV angiography. TCC appears to be a promising methodology for monitoring absolute LV volume in the ICU.

Aged↗

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↗

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

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

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

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↗