Toshiyuki Katogi

Arterial haemodynamics in patients after repair of tetralogy of Fallot: influence on left ventricular after load and aortic dilatation

Background: Recent histological studies of the aortic wall of patients with tetralogy of Fallot (TOF) have shown massive degeneration of the tunica media of the aorta. Such changes in arterial wall structure may significantly alter arterial wall mechanical properties, and thus cause abnormal arterial haemodynamics. Objective: To test the hypothesis that after repair of TOF, there are abnormal arterial haemodynamics which are associated with aortic dilatation and which increased after load on the left ventricle. Methods and results: The subjects comprised 38 patients who had undergone complete repair of TOF, and 55 control subjects. Systemic arterial haemodynamics were investigated by measuring aortic input impedance during cardiac catheterisation. The patients with TOF had significantly higher characteristic impedance (158 (43) dyne.s.cm−5.m2 vs 105 (49) dyne.s.cm−5.m2) and pulse wave velocity (561 (139) cm/s vs 417 (91) cm/s) and significantly lower total peripheral arterial compliance (0.93 (0.39) ml/mm Hg/m2 vs 1.24 (0.58) ml/mm Hg/m2) than the controls (for all three variables, p<0.01 vs controls), suggesting that central and peripheral arterial wall stiffness are increased after TOF repair. Additionally, patients with TOF had significantly higher arterial wave reflection than the controls (reflection coefficient: 0.21 (0.12) vs 0.16 (0.06)). These abnormalities in patients with TOF increased the pulsatile load on the left ventricle and significantly contributed to decreased cardiac output, even when right ventricular function was taken into account by multivariate regression analysis. The increase in aortic wall stiffness was closely associated with the increase in aortic root diameter. Conclusion: These results indicating abnormal arterial haemodynamics after TOF repair highlight the importance of regular monitoring of the systemic arterial bed and potentially relevant cardiovascular events in long-term follow-up of TOF.

Ventricular-vascular stiffening in patients with repaired coarctation of aorta: integrated pathophysiology of hypertension.

Background— Despite successful repair, patients with coarctation of the aorta (COA) often show persistent hypertension at rest and/or during exercise. Previous studies indicated that the hypertension is mainly due to abnormalities in the arterial bed and its regulatory systems. We hypothesized that ventricular systolic stiffness also contributes to the hypertensive state in these patients in addition to increased vascular stiffness. Methods and Results— The study involved 43 patients with successfully repaired COA and 45 age-matched control subjects. Ventricular systolic stiffness (end systolic elastance) and arterial stiffness (effective arterial elastance) were measured invasively by ventricular pressure-area relationship during varying preload before and after &bgr;-adrenergic stimulation. The mean systolic blood pressure was significantly higher with concomitant increases in both end systolic elastance and effective arterial elastance in patients with COA compared with control subjects (113.2±16.8 versus 91.0±9.1 mm Hg, 44.5±17.0 versus 19.2±6.7 mm Hg/mL/m2, and 27.8±11.4 versus 20.2±4.8 mm Hg/mL/m2, respectively; P<0.01 for each). End systolic elastance and effective arterial elastance of patients with COA showed exaggerated responses to &bgr;-adrenergic stimulation, further amplifying blood pressure elevation. Quantification analyses assuming that ventricular systolic stiffness of patients with COA is equal to that of the control revealed that ventricular systolic stiffness accounts for approximately 50% to 70% of the elevated blood pressure in patients with COA. Furthermore, combined ventricular-arterial stiffening amplified systolic pressure sensitivity to increased preload during abdominal compression and limited stroke volume gain/relaxation improvement induced by &bgr;-adrenergic stimulation. Conclusions— Increased ventricular systolic stiffness, coupled with increased arterial stiffness, plays important roles in hypertension in patients with repaired COA. Thus, ventricular systolic stiffness is a potentially suitable target for reduction of blood pressure and improvement of prognosis of patients with COA.

Efficacy and safety of torasemide in children with heart failure

Objective: To examine the efficacy and safety of torasemide in children with chronic heart failure (HF). Methods: 102 children with chronic HF who had received oral torasemide were analysed. Of these, 62 (de novo group) were newly diagnosed as having HF and were given torasemide as a diuretic. The remaining 40 (replacement group) had been given furosemide for >3 months before the study, and furosemide was then replaced with torasemide. Clinical signs and symptoms of HF (assessed as the HF index), humoral factors and serum potassium concentrations before torasemide treatment were compared with those obtained 3–4 weeks after torasemide treatment. Patients were also monitored for adverse effects. Results: In the de novo group, torasemide significantly improved the HF index with concomitant improvement in plasma brain natriuretic peptide concentration (median (interquartile range) 52 (51) vs 43 (49) pg/ml). In a randomly selected group of 25 de novo patients with ventricular septal defect, echocardiography showed that torasemide significantly improved left ventricular geometry and function. In the replacement group, brain natriuretic peptide concentrations were also significantly decreased from 50 (104) to 45 (71) pg/ml after substitution of torasemide, but the HF index showed only a tendency for improvement (p = 0.07). Torasemide also had a potassium-sparing effect (de novo group, no change in potassium concentration; replacement group, significant increase from 4.2 (0.5) to 4.3 (0.5) mEq/l), and caused a significant rise in serum aldosterone concentration, consistent with the anti-aldosterone effect of this drug. Serum concentrations of sodium and uric acid had not changed after torasemide treatment, and there were no serious adverse events that necessitated drug withdrawal. Conclusion: Torasemide can be safely used, and appears to be effective for treatment of HF in children. Future clinical trials are warranted to verify the present results.

Successful bridge to resynchronization therapy with a left ventricular assist system in a patient with idiopathic dilated cardiomyopathy

Implantation of a left ventricular assist system (LVAS) in patients with idiopathic dilated cardiomyopathy (DCM) may improve cardiac function and allow explantation of the device. Generally, an ejection fraction of more than 40% is considered necessary for successful weaning from an LVAS, but less than 10% of DCM patients with an LVAS can achieve such a significant recovery of cardiac function. Cardiac resynchronization therapy, or atrial-synchronized biventricular pacing, has been found to treat congestive heart failure and ventricular dyssynchrony effectively. Here we report on a patient with an LVAS, in whom enough functional recovery could be obtained with resynchronization therapy for the device to be explanted successfully. A 32-year-old man was implanted with a Toyobo-NCVC paracorporeal LVAS to treat his intractable heart failure caused by idiopathic dilated cardiomyopathy. While on the LVAS for 8 months, his cardiac function recovered to some extent. The ejection fraction of his left ventricle (LVEF) improved from 9% to 41%. He chose explantation of the device rather than heart transplantation. Because he occasionally showed a wide QRS pattern on his ECG, epicardial biventricular pacing leads as well as a biventricular pacemaker were implanted on LVAS explantation surgery. An echocardiogram 2 weeks after explantation showed a marked difference in his LVEF by switching his biventricular pacing on and off (40% with biventricular pacing on and 29% with it off). Biventricular pacing may help recovery of cardiac function in selected LVAS patients and contribute to the increase in bridge to recovery cases.

Influence of Bidirectional Cavopulmonary Anastomosis and Concomitant Valve Repair on Atrioventricular Valve Annulus and Function

BACKGROUND The relationship between atrioventricular valve regurgitation (AVVR) and valve annulus after bidirectional cavopulmonary anastomosis (BCPA) and adequate indications for valve repair are unclear. METHODS We evaluated the size of the valve annulus and the grade of AVVR before and immediately after BCPA, and at the most recent follow-up before the Fontan operation in 37 patients with a functional single ventricle. RESULTS Nine patients underwent concomitant valve surgery. The mean z value of the valve annulus was significantly lower postoperatively than preoperatively in the 28 patients who were not treated by valve surgery (0.45 vs 1.51, p=0.01). However, mean regurgitation scores did not significantly change after BCPA (1.60 vs 1.78, p=0.08). The most recent assessment showed that the mean z value increased compared with that immediately after BCPA (1.36 vs 0.45, p=0.005). This increase was significant in the patients with moderate regurgitation. The mean z value of the valve annulus of the patients treated by concomitant valvuloplasty was significantly lower postoperatively than preoperatively (-0.25 vs 3.9, p=0.0001) and remained low at the latest evaluation. Mean regurgitation scores also significantly decreased after BCPA (2.25 vs 3.37, p=0.007). CONCLUSIONS Unloading the systemic ventricle by BCPA leads to a decrease in the relative size of the atrioventricular valve. However, this decrease does not improve the degree of AVVR in the absence of concomitant valve repair. Concomitant valve repair is justified in patients with moderate or worse AVVR and an abnormal valve structure.

Sedation of hypercyanotic spells in a neonate with tetralogy of Fallot using dexmedetomidine

OBJECTIVE Sedation is an important step in the management of patients with hypercyanotic spells associated with tetralogy of Fallot (TOF) to ameliorate and prevent recurrence of cyanosis. This case report illustrates the effectiveness of dexmedetomidine-induced sedation in the management of hypercyanotic spells in a neonate with TOF. DESCRIPTION An 8-day-old term newborn patient with TOF showed hypercyanotic spells, as indicated by an abrupt decrease in arterial saturation (SpO2) level measured by a pulse oximeter from 80% to as low as 50%, when the patient became irritable and agitated. We started continuous infusion of dexmedetomidine at a dose of 0.2 microg/kg/min without a loading bolus injection. About half an hour after commencement of dexmedetomidine infusion, the patient reached an acceptable level of sedation, together with a drop in heart rate by approximately 20 beats/min. There was no apparent respiratory depression or marked change in blood pressure. SpO2 was also stable during dexmedetomidine infusion. The patient underwent a successful Blalock-Taussig shunt operation on the next day of admission. COMMENTS Dexmedetomidine may be useful for the management of hypercyanotic spells in pediatric patients with TOF.

Extracardiac conduit Fontan procedure versus intra-atrial lateral tunnel Fontan procedure

The Fontan procedure has provided excellent surgical palliation for patients with various types of univentricular hearts, and it has evolved over time. Among many modifications, the lateral tunnel Fontan connection (LTF) and the extracardiac Fontan connection (ECF) are currently the most popular techniques for completing the total cavopulmonary connection. The advantages and disadvantages of both techniques are reviewed here. The advantages of the ECF includes adaptability to all types of univentricular hearts, ease of construction without aortic cross clamping and fewer atrial suture lines. The advantages of the LTF include the ability to complete Fontan circulation in young, very small patients with potential for growth. This review also compares post-operative arrhythmias and fluid dynamics associated with both techniques.

A case of ventricular septal defect and mitral insufficiency after blunt trauma

Few reports have described traumatic heart injury in children. We describe a case of acute mitral regurgitation associated with papillary muscle rupture, traumatic ventricular septal defect, and impending left ventricular free wall rupture due to blunt trauma in a 2-year-old girl. The papillary muscle was sutured to the left ventricular free wall. The septal defect and surrounding ruptured muscle were covered with a pericardial patch, and a Hemashield patch was used to close the ventriculotomy. A residual defect caused by dehiscence of the pericardial patch necessitated reoperation 10 months later. The patient is currently being observed on an outpatient basis.

Cardiopulmonary Bypass through a Left Thoracotomy Using Venous Drainage from the Innominate Vein in Congenital Heart Surgery

Cardiopulmonary bypass (CPB) through a left lateral thoracotomy is a useful approach for some congenital heart procedures, although vascular access for the arterial and venous cannulation can be challenging in the selective patients. Six patients underwent successful extracorporeal circulation through a left lateral thoracotomy using the innominate vein for venous drainage. No operative deaths or major complications occurred. Venous drainage solely from the innominate vein was adequate to establish partial bypass without the need for pericardiotomy. Total bypass was established with combined venous drainage from the innominate vein and the main pulmonary artery. Exposure of the systemic atrioventricular valve was excellent through a left thoracotomy. Venous drainage from the innominate vein without using atrial drainage can safely be used for extracorporeal circulation through a left lateral thoracotomy without compromising the procedure and it is a useful approach to congenital heart surgery in selected patients. doi: 10.1111/jocs.12165 (J Card Surg 2013;28:591–594)

Giant epicardial cyst presenting as acute cardiac tamponade in a 2-year-old boy

Cystic structures within the pericardial cavity are rare. They are divided into epicardial and pericardial variants. Pericardial and epicardial cysts rarely cause symptoms. This report describes a case of epicardial cyst with acute cardiac tamponade in a 2-year-old boy with no previous cardiac history who was transferred to our hospital because of hemodynamic instability. Emergency drainage of the pericardial effusion and complete excision of the cyst were performed through a median full sternotomy.