Ronald B. Tanke

Cardiac output measurement using an ultrasound dilution method: a validation study in ventilated piglets.

Objective: To assess agreement between a new method of cardiac output monitoring, using ultrasound dilution technology and ultrasound transit time-based measurement of pulmonary blood flow in a piglet model. Design: Prospective, experimental juvenile animal study. Setting: Animal laboratory of a university hospital. Subjects: Nine random-bred piglets. Interventions: After the animals received general anesthesia, we placed intravascular arterial and central venous catheters with the tip positioned in the abdominal aorta and the right atrium, respectively. The catheters were connected to the ultrasound dilution cardiac output monitor. An ultrasound transit time perivascular flow probe was positioned around the common pulmonary artery and served as the standard reference measurement. Cardiac output was manipulated during the experiment by creating hemorrhagic hypotension. Ultrasound dilution cardiac output was measured intermittently with injection volumes of 0.5 mL/kg and 1.0 mL/kg of isotonic saline at body temperature. Measurements and Main Results: Ultrasound dilution cardiac output (QUDCO) measurement was compared with pulmonary blood flow (QAPC). Bias, defined as QUDCO minus QAPC, was calculated for each measurement. Mean bias with standard deviation was calculated for measurements with volumes of injected saline, 0.5 mL/kg and 1.0 mL/kg, and compared using the Mann-Whitney U test. Mean bias (sd) between QUDCO and QAPC was 0.040 (0.132) and 0.058 (0.136) L/min for measurement with 0.5 mL/kg and 1.0 mL/kg of isotonic saline, respectively (no statistically significant difference). Conclusions: Ultrasound dilution cardiac output measurement is reliable in piglets with the use of a small volume of a nontoxic indicator (isotonic saline).

Long-term outcomes of transatrial-transpulmonary repair of tetralogy of Fallot

OBJECTIVES The surgical approach to repair of tetralogy of Fallot (ToF) has shifted over the years. We aimed to report the long-term follow-up after ToF repair with the transatrial-transpulmonary approach and to determine predictors of long-term outcomes. METHODS Retrospective analysis of patients operated on in two tertiary referral centres. Primary outcome measures were: death, pulmonary valve replacement (PVR), reintervention for other reasons, internal cardiodefibrillator and/or pacemaker placement. Kaplan-Meier assessment of overall and event-free survival as well as uni- and multivariate analyses of risk factors for outcomes were performed. RESULTS Four hundred and fifty-three patients were included. Median age at operation was: 0.6 years (range 0-19.6) and median age at the last follow-up was 14.3 years (range 0.1-42.1). Median age at repair decreased from 1.2 years (range 0.6-5.8) (1970-80) to 0.3 years (range 0-4.7) (2000-12). A transannular patch (TP) was used in 65% of all patients. The use of a TP showed a decline from 89% in the initial years of the cohort to 64% in 2000-12. Early mortality was 1.1% (5 patients) for the entire cohort and late mortality 2.4% (11 patients). Overall survival for the entire cohort was 97.3% (95% CI 95.7-98.8) and 91.8% (95% CI 85.9-97.7) at 10 and 25 years, respectively. For patients with a TP (n = 294) vs non-TP (n = 159), this was 97.2% (95% CI 95.2-99.2) vs 97.5% (95% CI 95.1-99.9) at 10-year and 91.0% (95% CI 83.9-98.1) vs 96.3% (95% CI 93.0-99.6) at 25-year follow-up (P = 0.958). Fifty-two patients underwent PVR, and in 5 a pacemaker was inserted. Event-free survival for TP versus non-TP patients was 80.2% (95 CI% 75.5-84.9) vs 81.7% (95% CI 75.2-88.2) at 10-year and 27.9% (95% CI 17.7-38.1) vs 78.5% (95% CI 71.4-85.6) at 25-year follow-up (P = 0.016). In multivariate analysis, both the use of a TP (HR 1.705, 95% CI 1.023-2.842) and the year of surgical repair of tetralogy of Fallot (HR 1.039, 95% CI 1.006-1.073) were associated with a higher probability of an event. CONCLUSIONS ToF patients corrected with the transatrial-transpulmonary approach have good long-term survival. PVR is a frequent event at longer follow-up, and other events are limited. The use of a TP is a predictor for poorer event-free outcomes, increasing the risk of the composite endpoint 1.7 times.

Difficulties generated by the small, persistently patent, arterial duct

Over recent years, echo-Doppler cardiography has shown that a small, sometimes silent, arterial duct exists in more patients than previously recognized. To know the incidence of an arterial duct subsequent to therapy, we studied retrospectively our patients undergoing open-heart surgery and surgical or catheter closure. Three groups of patients were studied: those with patency of the duct subsequent to open heart surgery without any sign of patency before or during surgery, those with persistent duct after surgical ligation and those with persistent patency after attempted catheter occlusion with the Rashkind device. In the first group (of 431 children) four (0.9%) had persistence of this duct, of which three were silent. In the second group, patency persisted in four of 100 patients (4%), three being silent. In the last group there were five persisting shunts, three producing no murmur, in 30 patients (17%). We compared our results with those reported in the literature and conclude that echo-Doppler cardiography is needed to detect persistent shunting across a duct after therapy, since most of the residual ducts in this study were silent. This means that clinical findings alone cannot be relied upon, and careful echo-Doppler cardiography is essential. Also, the process of closure of a persistent duct by surgical ligation or transcatheter intervention is no guarantee of success. The risk of infective endocarditis is important in such persistent ducts and, at present, it is unknown either for a small, silent duct or in a persistent duct that remains open after attempted transcatheter closure, but now is in association with a foreign body.

Management of children with dilated cardiomyopathy in The Netherlands: Implications of a low early transplantation rate

BACKGROUND The policy for listing and transplant for children with dilated cardiomyopathy (DCM) in The Netherlands has been conservative because of low donor availability. The effects of this policy on outcome are reported. METHODS This was a multicenter, nationwide study performed in 148 children with DCM. The primary outcome was death or heart transplant. RESULTS Overall, 43 patients (29%) died or were transplanted. Within 1 year of diagnosis, 21 patients died, and only 4 underwent transplantation (3 on mechanical circulatory support). The 1-year survival was 85% (95% confidence interval [CI] = 79-91), and 5-year survival was 84% (95% CI = 78-90). Transplantation-free survival at 1 year was 82% (95% CI = 75-88) and at 5 years was 72% (95% CI = 64-80). Within 1 year of diagnosis, with death as the main end-point (21 of 25, 84%), intensive care unit admission (hazard ratio = 2.6, p = 0.05) and mechanical circulatory support (hazard ratio = 3.2, p = 0.03) were risk factors (multivariable Cox analysis); inotropic support was longer in patients reaching an end-point. At >1 year after diagnosis, with transplantation as the main end-point (15 of 18, 83%), age >6 years (hazard ratio = 6.1, p = 0.02) was a risk factor. There were 56 (38%) children who recovered, 50% within 1 year of diagnosis. Recovery was associated with younger age; was similar in patients with myocarditis (43%) and idiopathic disease (41%); and was similar in patients initially admitted to the intensive care unit, admitted to the ward, or treated as outpatients. CONCLUSIONS The transplantation rate in our cohort in the first year was low, with 1-year and 5-year survival rates similar to other cohorts. Our results suggest that a conservative approach to list children for transplantation early after presentation may be justifiable except for patients with prolonged intensive care unit or mechanical circulatory support.

Mid-term results of the modified senning operation for cavopulmonary connection with autologous tissue

UNLABELLED The aim of this study was to determine the results and mid-term outcome of a modified Senning technique using autologous tissue for total cavopulmonary connection. The study involved 31 children, 8 with tricuspid atresia and 23 with complex congenital heart disease. In this operation, a flap of autologous atrial free wall tissue was used to tunnel inferior vena caval blood to the pulmonary arteries. An additional Damus-Kay-Stansel operation was required in 9 patients with subaortic obstruction. RESULTS the early mortality rate was 16% (5 out of 31 patients) and there were four late deaths. COMPLICATIONS Pleural effusions were encountered in 17 patients, of whom 4 had a concomitant pericardial effusion. Diaphragmatic paralysis was diagnosed in five patients, one of whom underwent surgical plication. Median hospital stay was 26 days. The 1- to 5-year actuarial survival was 68.6%. Follow-up ranged from 10 months to 7.1 years, mean 3.2 years. A serious atrial arrhythmia was diagnosed in one patient and another one died, possibly from rhythm disorders. Exercise tolerance and quality of life has improved in all but one of the survivors. Although follow-up is short, we have thus far witnessed a low incidence of hemodynamic and rhythm disturbances with this modification of the cavopulmonary connection.

Application of ultrasound dilution technology for cardiac output measurement: Cerebral and systemic hemodynamic consequences in a juvenile animal model

Objective: Analysis of cerebral and systemic hemodynamic consequences of ultrasound dilution cardiac output measurements. Design: Prospective, experimental piglet study. Setting: Animal laboratory. Subjects: Nine piglets. Interventions: Ultrasound dilution cardiac output measurements were performed in ventilated, anesthetized piglets. Interventions that are required for ultrasound dilution cardiac output measurement were evaluated for its effect on cerebral and systemic circulation and oxygenation. Measurements and Main Results: &Dgr;cHbD and &Dgr;ctHb, representing changes in cerebral blood flow and cerebral blood volume, respectively, were measured with near infrared spectrophotometry. Pulmonary artery (QMPA) and left carotid artery (QLCA) blood flow were assessed with transit time flow probes. Starting and/or stopping blood flowing through the arteriovenous loop did not cause relevant hemodynamic changes. Fast injection of isotonic saline caused a biphasic change in &Dgr;cHbD and &Dgr;ctHb. After injection of 0.5 mL/kg, the mean (sd) increase in &Dgr;cHbD and &Dgr;ctHb was 0.175 (0.213) &mgr;mol/L and 0.122 (0.148) &mgr;mol/L, respectively, with a subsequent mean decrease of −0.191 (0.299) &mgr;mol/L and −0.312 (0.266) &mgr;mol/L. Injection of 1.0 mL/kg caused a mean increase in &Dgr;cHbD and &Dgr;ctHb of 0.237 (0.203) &mgr;mol/L and 0.179 (0.162) followed by a mean decrease of −0.334 (0.407) &mgr;mol/L and −0.523 (0.335) &mgr;mol/L, respectively. QMPA and QLCA changed shortly with a mean increase of 5.9 (3.0) mL/kg/min and 0.23 (0.10) mL/kg/min after injection of 0.5 mL/kg and with 12.0 (4.2) mL/kg/min and 0.44 (0.18) mL/kg/min after injection of 1.0 mL/kg, respectively. The observed changes were more profound after an injection volume of 1.0 mL/kg compared with 0.5 mL/kg for &Dgr;cHbD (p = .06), &Dgr;ctHb (p = .09), QMPA, and QLCA (p < .01). No relevant changes in mean arterial blood pressure or heart rate were detected in response to the indicator injection. Conclusions: Cardiac output measurement by ultrasound dilution does not cause clinically relevant changes in cerebral and systemic circulation and oxygenation in a piglet model.

Low agreement between cardiologists diagnosing left ventricular hypertrophy in children with end-stage renal disease

BackgroundMonitoring of the appearance of left ventricular hypertrophy (LVH) by echocardiography is currently recommended for in the management of children with End-stage renal disease (ESRD). In order to investigate the validity of this method in ESRD children, we assessed the intra- and inter-observer reproducibility of the diagnosis LVH.MethodsEchocardiographic measurements in 92 children (0–18 years) with ESRD, made by original analysists, were reassessed offline, twice, by 3 independent observers. Smallest detectable changes (SDC) were calculated for continuous measurements of diastolic interventricular septum (IVSd), Left ventricle posterior wall thickness (LVPWd), Left ventricle end-diastolic diameter (LVEDd), and Left ventricle mass index (LVMI). Cohen’s kappa was calculated to assess the reproducibility of LVH defined in two different ways. LVHWT was defined as Z-value of IVSd and/or LVPWd>2 and LVHMI was defined as LVMI> 103 g/m2 for boys and >84 g/m2 for girls.ResultsThe intra-observer SDCs ranged from 1.6 to 1.7 mm, 2.0 to 2.6 mm and 17.7 to 30.5 g/m2 for IVSd, LVPWd and LVMI, respectively. The inter-observer SDCs were 2.6 mm, 2.9 mm and 24.6 g/m2 for IVSd, LVPWd and LVMI, respectively. Depending on the observer, the prevalence of LVHWT and LVHMI ranged from 2 to 30% and from 8 to 25%, respectively. Kappas ranged from 0.4 to 1.0 and from 0.1 to 0.5, for intra-and inter- observer reproducibility, respectively.ConclusionsChanges in diastolic wall thickness of less than 1.6 mm or LVMI less than 17.7 g/m2 cannot be distinguished from measurement error in individual children, even when measured by the same observer. This limits the use of echocardiography to detect changes in wall thickness in children with ESRD in routine practice.

Cardiac output measurement in ventilated lambs with a significant left-to-right shunt using the modified carbon dioxide fick method.

Background: It remains a great challenge to measure systemic blood flow in critically ill newborns. In a former study we validated the modified carbon dioxide Fick (mCO2F) method for measurement of cardiac output in a newborn lamb model. In this new study we studied the influence of a left-to-right shunt on the accuracy of the mCO2F method. Objective: To analyze the influence of a left-to-right shunt on the agreement between cardiac output measurement with the mCO2F method and ultrasonic transit time pulmonary blood flow in a lamb model. Methods: The study was approved by the Ethical Committee on Animal Research of the Radboud University Nijmegen and performed in 8 random-bred lambs. A Gore-Tex® shunt was placed between the left pulmonary artery and the descending aorta. This aortopulmonary shunt was intermittently opened and closed, while cardiac output was manipulated by creating hemorrhagic hypotension. Cardiac output measurement with the mCO2F method (QmCO2F) was compared with pulmonary blood flow obtained by a transit time ultrasonic flow probe positioned around the common pulmonary artery (QAPC). Results: Bias, defined as QmCO2F – QAPC, was calculated for each measurement. With an open shunt there was a significant left-to-right shunt (mean Qp/Qs ratio 2.26; range 1.56–3.69). Mean bias (SD) was –12.3 (50.4) ml·kg–1·min–1 and –12.3 (42.7) ml·kg–1·min–1 for measurements with a closed and open shunt, respectively (no statistical significant difference). Conclusions: Cardiac output measurement with the mCO2F method is reliable and easily applicable in ventilated newborn lambs, also in the presence of a significant left-to-right shunt.

Impaired longitudinal deformation measured by speckle-tracking echocardiography in children with end-stage renal disease

BackgroundLeft ventricular dysfunction is an important co-morbidity of end-stage renal disease (ESRD) and is associated with a poor prognosis in the adult population. In pediatric ESRD, left ventricular function is generally well preserved, but limited information is available on early changes in myocardial function. The aim of this study was to investigate myocardial mechanics in pediatric patients with ESRD using speckle-tracking echocardiography (STE).MethodsEchocardiographic studies, including M-mode, tissue Doppler imaging (TDI) and STE, were performed in 19 children on dialysis, 17 transplant patients and 33 age-matched controls. Strain measurements were performed from the apical four-chamber and the short axis view, respectively.ResultsThe interventricular and left ventricular posterior wall thickness was significantly increased in dialysis and transplant patients compared to healthy controls. No significant differences were found in shortening fraction, ejection fraction and systolic tissue Doppler velocities. Dialysis and transplant patients had a decreased mean longitudinal strain compared to healthy controls, with a mean difference of 3.1 [95 % confidence interval (CI) 2.0–4.4] and 2.7 (95 % CI 1.2–4.2), respectively. No differences were found for radial and circumferential strain.ConclusionsSpeckle-tracking echocardiography may reveal early myocardial dysfunction in the absence of systolic dysfunction measured by conventional ultrasound or TDI in children with ESRD.

Longitudinal Strain as Risk Factor for Outcome in Pediatric Dilated Cardiomyopathy.

In adults with dilated cardiomyopathy (DCM), it has been demonstrated that global longitudinal and circumferential strain have value in addition to left ventricular ejection fraction (LVEF) in predicting the risk of mortality, heart transplantation, and hospitalization for worsening heart failure [(