Manabu Takanashi

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.

The Clinical Utility and Safety of a New Strategy for the Treatment of Refractory Kawasaki Disease

Objective To assess the clinical utility and safety of a strategy for refractory Kawasaki disease, defined by Egami score ≥3. Study design First‐line treatment was with intravenous methylprednisolone (30 mg/kg, 2 hours, 1 dose) plus intravenous immunoglobulin (2 g/kg, 24 hours) treatment. Patients resistant to first‐line treatment received additional intravenous immunoglobulin as a second‐line treatment. Patients resistant to second‐line treatment who had received Bacillus Calmette‐Guérin vaccination 6 months earlier were treated with infliximab; otherwise, plasma exchange was performed. A total of 71 refractory patients with Kawasaki disease (median age: 2.4 years) of 365 patients with Kawasaki disease were treated according to our strategy from April 2007 to April 2016. Treatment resistance was defined as a persistent fever at 36 hours after treatment. We evaluated coronary artery lesions at the time of the diagnosis, at 1 month, and at 1 year after the diagnosis in accordance with the American Heart Association guidelines and the criteria of the Japanese Ministry of Health, Labour, and Welfare. Results First‐line therapy was effective for 58 of 71 patients (81.6%), and second‐line therapy was effective for 9 of 13 patients (69.2%). At third line, 3 patients were treated by infliximab, and 1 was treated with plasma exchange. Of the 18 patients with coronary artery abnormalities at diagnosis, 13 patients at 1 month and 6 patients at 1 year had coronary artery dilatation (median z score 3.0, 2.6, and 1.4, respectively). There were no patients with coronary artery aneurysm (CAA). Conclusions Our strategy for refractory Kawasaki disease was safe and effective in preventing CAA.

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.

Timing of Haemophilus influenzae type b vaccination after cardiac surgery

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.

FOUR-DIMENSIONAL MAGNETIC RESONANCE IMAGING (4D-MRI) FLOW ENERGY LOSS: NEW INSIGHT INTO FONTAN CIRCULATION IN ADULT PATIENTS

The purpose of this study was to evaluate the flow energy loss (EL) in Fontan circulation using four-dimensional magnetic resonance imaging (4D-MRI). Fourteen Fontan patients (11 males, 3 female, 24.5 ± 9.7 years of age) were examined. Ventricular volume was measured by cine MRI, and blood flow