Exploring energy loss by vector flow mapping in children with ventricular septal defect: Pathophysiologic significance.

BACKGROUND: Vector flow mapping is a novel echocardiographic flow visualization method, and it has enabled us to quantitatively evaluate the energy loss in the left ventricle (intraventricular energy loss). Although intraventricular energy loss is assumed to be a part of left ventricular workload itself, it is unclear what this parameter actually represents. The aim of the present study was to elucidate the characteristics of intraventricular energy loss. METHODS: We enrolled 26 consecutive children with ventricular septal defect (VSD). On echocardiography vector flow mapping, intraventricular energy loss was measured in the apical 3-chamber view. We measured peak energy loss and averaged energy loss in the diastolic and systolic phases, and subsequently compared these parameters with catheterization parameters and serum brain natrium peptide (BNP) level. RESULTS: Diastolic, peak, and systolic energy loss were strongly and positively correlated with right ventricular systolic pressure (r=0.76, 0.68, and 0.56, p<0.0001, = 0.0001, and 0.0029, respectively) and right ventricular end diastolic pressure (r=0.55, 0.49, and 0.49, p=0.0038, 0.0120, and 0.0111, respectively). In addition, diastolic, peak, and systolic energy loss were significantly correlated with BNP (r=0.75, 0.69 and 0.49, p<0.0001, < 0.0001, and=0.0116, respectively). CONCLUSIONS: In children with VSD, elevated right ventricular pressure is one of the factors that increase energy loss in the left ventricle. The results of the present study encourage further studies in other study populations to elucidate the characteristics of intraventricular energy loss for its possible clinical application.

Contributions of Respiration and Heartbeat to the Pulmonary Blood Flow in the Fontan Circulation.

BACKGROUND: In the Fontan circulation, driving forces with respiration, heartbeat, and lower limb muscle pump are relevant. However, the mechanics of these forces has not been proven, and their effects on the Fontan circulation remain unclear. METHODS: We performed catheter examinations and measured pressure and flow velocity simultaneously in the bilateral pulmonary arteries of 12 Fontan patients 1 year after the operation. The pulmonary pressure and flow velocity data were decomposed into respiratory and heartbeat components by discrete Fourier analysis. We then calculated respiratory and cardiac wave intensity (WI) based on the respiratory and heartbeat components of pressure and flow velocity data. RESULTS: Respiratory WI formed 2 negative peaks, a backward expansion wave during the inspiratory phase, and then a backward compression wave during the expiratory phase. In 2 phrenic nerve palsy cases and 1 case of a patient on a respirator, respiratory WI showed disturbed patterns and a negative pattern, respectively. Cardiac WI showed 2 or 4 negative peaks, the time phase of which matched that of the atrial contractions. CONCLUSIONS: WI analysis elucidated that inspiration acts as a sucking driving force and increases the pulmonary blood flow in the Fontan circulation. Respiratory complications compromise efficiency in the Fontan circulation. It was also revealed that the pulmonary blood flow was mutually dammed up and sucked in by increases and decreases in atrial pressure.

Fetal arrhythmogenic right ventricular cardiomyopathy with double mutations in TMEM43.

We herein describe a fetal case of arrhythmogenic right ventricular cardiomyopathy (ARVC) with double mutations in transmembrane protein 43 (TMEM43). RV aneurysm and ventricular arrhythmia were detected during the fetal period. After birth, electrocardiogram showed frequent premature ventricular contractions (PVC) of left bundle branch block morphology and epsilon waves in the right-sided chest leads. Echocardiography also indicated RV aneurysm with regionally decreased systolic function. PVC disappeared after treatment with amiodarone and mexiletin. Mutations in TMEM43, which was recently identified as the causative gene of ARVC type 5, were also confirmed in the present patient and in the patient's mother, and they were therefore diagnosed with ARVC. The present case confirms that symptoms of ARVC can emerge during the fetal period. Pediatricians need to keep in mind the possibility of ARVC when they encounter patients with RV aneurysm and arrhythmia.

Timing of Haemophilus influenzae type b vaccination after cardiac surgery.

BACKGROUND: The best time for vaccination in infants with congenital heart disease (CHD) after cardiopulmonary bypass (CPB) surgery is unclear, but it is important to prevent Haemophilus influenzae type b (Hib) infection in infants with CHD after CPB surgery. To identify the best time for Hib vaccination in infants with CHD after CPB surgery, we investigated the immunological status, and the efficacy and safety of Hib vaccination after CPB surgery. METHODS: Sixteen subjects who underwent surgical correction of ventricular septal defect with CPB were investigated. Immunological status and cytokines were analyzed before surgery, 2 months after surgery, and before Hib booster vaccination. Hib-specific IgG was also measured to evaluate the effectiveness of vaccination. RESULTS: Immunological status before and 2 months after surgery (e.g. whole blood cells and lymphocyte subset profile) was within the normal range and no subjects had hypercytokinemia. Additionally, all subjects who received Hib vaccination at 2-3 months after CPB surgery had effective serum Hib-specific IgG level for protection against Hib infection without any side-effects. CONCLUSIONS: CPB surgery does not influence acquired immunity and Hib vaccination may be immunologically safe to perform at 2 months after CPB surgery. Hib vaccination at 2-3 months after CPB surgery was effective in achieving immunization for infants with simple left-right shunt-type CHD.

Clinical utility of the plasma brain natriuretic peptide level in monitoring tetralogy of fallot patients over the long term after initial intracardiac repair: considerations for pulmonary valve replacement.

Clinicians are currently encountering an increasing number of patients in the long-term period after tetralogy of Fallot (TOF) repair presenting with pulmonary valve regurgitation (PR) or right ventricular (RV) dysfunction. The purpose of this study was to evaluate the clinical utility of the plasma brain natriuretic peptide (BNP) level and consider surgical indications and timing of pulmonary valve replacement (PVR). We examined 33 patients (21 males, 12 females, mean age 14.5 ± 2.8 years) who underwent TOF repair at Kitasato University Hospital. All patients were evaluated using echocardiography and blood sampling. The mean age at the time of initial repair was 1.3 ± 0.7 years. The patients with moderate-severe PR exhibited significantly higher plasma BNP levels than the patients with trivial-mild PR (mean 37.5 ± 33.1 vs. 17.3 ± 6.6 pg/ml, p = 0.013). The mean plasma BNP level with cardiac symptoms was higher than that observed in the patients without any symptoms (71.4 ± 46.1 vs. 25.0 ± 14.0 pg/ml, p = 0.005). The mean BNP level was significantly decreased after PVR (71.3 ± 46.1-26.1 ± 13.2 pg/ml, p = 0.009), and the plasma BNP level was found to be positively correlated with the RV end-diastolic pressure (r = 0.851; p = 0.008). The optimal BNP cut-off value for considering PVR was 32.15 pg/ml (sensitivity, 85.7 %; specificity, 83.3 %). The plasma BNP level may become a useful diagnostic tool for considering the indications and optimal timing of PVR over the long term after TOF repair.

Quantitative evaluation of hemodynamics in the Fontan circulation: a cross-sectional study measuring energy loss in vivo.

Flow energy loss (EL) at the Fontan anastomosis has been thought to reflect flow efficiencies and to influence on hemodynamics in the Fontan circulation and has been often discussed in numerical studies. However, in vivo EL measurements have to date not been reported. We directly measured EL in the Fontan circulation and examined the relationship between the structural configuration and EL, as well as the influence of EL, on the hemodynamics in the Fontan circulation. We performed a catheterization study measuring simultaneous pressure and flow velocity to calculate EL in nine patients (mean age 2.3 ± 0.3 years) 1 year after the Fontan procedure. The measured EL was 9.66 ± 8.50 mW. One patient with left pulmonary artery stenosis recorded the highest EL (17.78 mW), and one patient with bilateral superior vena cava and left phrenic nerve palsy recorded the second highest EL (14.62 mW). EL significantly correlated with time constant tau and weakly with max-dp/dt during the isovolumic diastolic phase (r = 0.795 and -0.574, respectively). EL also correlated with max-dp/dt during the isovolumic systolic phase (r = 0.842) but not with ejection fraction or systemic blood flow (r = 0.384 and -0.034, respectively). In conclusion, inefficient structural configuration and phrenic nerve palsy seem to be related with increased in EL at the Fontan anastomosis. Although these preliminary findings also suggest that EL is associated with an impaired relaxation of the ventricle, a long-term study with a large population is warranted to reach such a definitive conclusion.

Noninvasive assessment of pulmonary vascular resistance and pressure in patients with congenital heart disease: a new method using M-mode echocardiography.

BACKGROUND: The accurate evaluation of pulmonary vascular resistance (PVR) and mean pulmonary artery pressure is important to determine the optimal management and therapeutic strategy for patients with congenital heart disease (CHD). We evaluated the PVR and mean pulmonary artery pressure in 46 patients with several CHD types using the interventricular septum (IVS) motion determined by M-mode echocardiography. METHODS: We divided the patients into 2 groups according to the different IVS motions. We measured the maximum anterior displacement from the baseline during early systole (a) and the maximum posterior displacement from the baseline during early diastole (b). We defined type A to be a/b greater than or equal to 1.0, and type B to be a/b less than 1.0. RESULTS: The PVR and mean pulmonary artery pressure in type A patients were significantly higher than those in type B patients (p < 0.05). Type A IVS motion predicted patients with high PVR (>2.5 unit/m(2)) and high mean pulmonary artery pressure (>25 mmHg) (sensitivity 89%, specificity 89% and sensitivity 70%, specificity 91%, respectively). CONCLUSIONS: Our method can noninvasively separate high and low PVR among patients with CHD. This noninvasive method is therefore considered to be useful in the management of patients with CHD in a clinical setting.

The strategy of immune globulin resistant Kawasaki disease: a comparative study of additional immune globulin and steroid pulse therapy.

BACKGROUND: We compared the clinical utility of additional intravenous immune globulin (IVIG) therapy with the clinical utility of steroid pulse therapy in patients with IVIG-resistant Kawasaki disease. METHODS: We enrolled 164 patients with Kawasaki disease who were treated with a single dose of IVIG (2 g/kg) and aspirin (30 mg/kg per day). Twenty-seven of these patients (16%) were resistant to the initial IVIG treatment. We compared the effectiveness of treatment strategies for the initial IVIG-resistant 27 patients, 14 of these patients were treated with additional IVIG therapy, and the other 13 patients were treated with steroid pulse therapy (methylprednisolone 30 mg/kg per day for 3 days). RESULTS: Three patients in the group receiving additional IVIG treatment had coronary artery aneurysms (21.4%), no patients had coronary artery aneurysm in the steroid pulse therapy group; the difference in the incidence of coronary artery aneurysm was not statistically significant. The duration of high fever after additional treatment in the steroid pulse therapy group (1 ± 1.3 days) was significantly shorter than that in the additional IVIG treatment group (3 ± 2.4 days; P < 0.05). The medical costs were significantly lower in the steroid pulse therapy group than in the additional IVIG treatment group. CONCLUSION: Steroid pulse therapy was useful to reduce the fever duration and medical costs for patients with Kawasaki disease. Steroid pulse therapy and additional IVIG treatment were not significantly different in terms of preventing the development of coronary artery aneurysm.

Quantitative assessment of pulmonary vascular resistance and reactivity in children with pulmonary hypertension due to congenital heart disease using a noninvasive method: new Doppler-derived indexes.

We assessed the usefulness of transthoracic Doppler-derived indexes obtained in the proximal pulmonary artery (PA) branch for estimating pulmonary vascular resistance (PVR) in 45 children with congenital heart disease (CHD) and 23 normal control subjects. The acceleration time, inflection time (InT), deceleration index, and peak velocity, which were measured from the systolic PA flow velocity curve obtained at the sites of the main PA, and right and left PA, were compared with the PVR in patients with CHD. In addition, changes in either Doppler-derived indexes or PVR during 100% oxygen administration were compared in 22 patients showing a baseline PVR >or=4.6 U/m(2) (high PVR). The heart-rate-corrected InT (InTc) values obtained in the left PA in the high PVR group were significantly lower than those in the main PA (4.7 +/- 1.5 vs. 7.5 +/- 3.0; p < 0.001). The InTc obtained from the left PA separated patients with high and low PVR (4.7 +/- 1.4 vs. 9.9 +/- 2.4; p < 0.001) and no significant differences in InTc were found between the low PVR and the control groups. An increase in InTc to >6 during 100% oxygen administration for the high PVR group indicated good PA reactivity with a sensitivity of 93%, specificity of 100%, and agreement of 95% (kappa = 0.83). Moreover, this InTc index correlated inversely with PVR (r = -0.80). In conclusion, our method can noninvasively separate high and low PVR and assess the PA reactivity for high PVR in children with CHD.