Yoshihisa Tanoue

Bidirectional Glenn Procedure Improves the Mechanical Efficiency of a Total Cavopulmonary Connection in High-Risk Fontan Candidates

BackgroundA total cavopulmonary connection (TCPC) is a widely performed surgical procedure for Fontan candidates. High-risk candidates who have undergone the bidirectional Glenn procedure (BDG) before TCPC have shown good results. The exact mechanism of this procedure, however, is still poorly understood. We hypothesized that a volume reduction with BDG improved ventricular contractility, thereby optimizing mechanical efficiency after TCPC. Methods and ResultsWe measured percent normal systemic ventricular end-diastolic volume (%N-EDV), contractility (end-systolic elastance; Ees), afterload (effective arterial elastance; Ea), and mechanical efficiency (ventriculoarterial coupling; Ea/Ees) on the basis of the cardiac catheterization data before and after TCPC. Eighteen patients who underwent staged TCPC after BDG (staged group) were compared with 29 patients who underwent primary TCPC (primary group). Ees and Ea were approximated as follows: Ees=mean arterial pressure/minimal ventricular volume, and Ea=maximal ventricular pressure/(maximal ventricular volume−minimal ventricular volume), and Ea/Ees was then calculated. The ventricular volume was normalized with the body surface area. A canine experimental model with conductance catheter was used to validate the accuracy of this approximation of Ees and Ea. %N-EDV decreased after TCPC in both groups. In the staged group, a smaller ventricular volume resulted in better contractility (Ees). Although afterload (Ea) increased in both groups, the increment of Ea was smaller in the staged group. These changes resulted in an improvement of Ea/Ees in the staged group, whereas Ea/Ees increased in the primary group. ConclusionsThe volume reduction of BDG preceding TCPC allows for any afterload mismatch to be corrected, thereby improving ventricular energetics after TCPC.

Midterm surgical results of total cavopulmonary connection : clinical advantages of the extracardiac conduit method

OBJECTIVE We evaluated the midterm surgical outcomes of intra-atrial lateral tunnel and extracardiac conduit total cavopulmonary connection to clarify the clinical superiority. METHODS Patients (n = 167) underwent total cavopulmonary connection (88 with lateral tunnel and 79 with extracardiac conduit) from November 1991 to March 1999. Survival, incidence of reoperation and late complications, exercise tolerance, hemodynamic variables, and plasma concentration of natriuretic peptide type A were compared. In the lateral tunnel group, time-related change in lateral tunnel size was investigated for its relationship to postoperative arrhythmias. RESULTS The 8-year survival was 93.2% in the lateral tunnel group and 94.9% in the extracardiac conduit group. Seven reoperations were performed in the lateral tunnel group but none in the extracardiac conduit group. Supraventricular arrhythmias developed in 14 patients (15.9%) in the lateral tunnel group and in 4 patients (5.1%) in the extracardiac conduit group (P =.003). Freedom from cardiac-related events was 72.5% in the lateral tunnel group and 89.8% in the extracardiac conduit group at 8 years (P =.0098). Hemodynamic variables and exercise tolerance were similar in both groups but plasma natriuretic peptide type A concentration, a parameter of atrial wall tension, was higher in the lateral tunnel group. In the lateral tunnel group, intra-atrial tunnel size increased by 19.4% during the 44.2-month interval and the percent increase in tunnel size was an independent predictor of supraventricular arrhythmias. CONCLUSIONS The midterm survival, hemodynamic variables, and exercise tolerance were similar and satisfactory in both lateral tunnel and extracardiac conduit groups; however, the incidence of cardiac-related events was significantly less frequent in the extracardiac conduit group. In the lateral tunnel group, careful observation is required to monitor the relationship of the dilating tendency of the intra-atrial tunnel and the development of late complications.

Comparative study of retrograde and selective cerebral perfusion with transcranial Doppler

BACKGROUND Retrograde cerebral perfusion (RCP) is a simple technique and is expected to provide cerebral protection. However, its optimum management and limitations remain unclear. Transcranial Doppler has been used to monitor cerebral perfusion. Using this Doppler technique, we compared cerebral blood flow for RCP with that for selective cerebral perfusion. METHODS Thirty-two consecutive patients underwent elective surgical repair of an aortic aneurysm involving the aortic arch at Kyushu University Hospital. Retrograde cerebral perfusion was used in 15 patients and selective cerebral perfusion, in 17 patients. Continuous measurement of middle cerebral artery blood flow velocities was performed by transcranial Doppler technique. RESULTS Retrograde middle cerebral artery blood flow velocities during RCP could be measured in only 3 patients, whereas middle cerebral artery blood flow velocities during selective cerebral perfusion could be measured in all but 1 woman. The increase in middle cerebral artery blood flow velocities after RCP was significantly greater than that after selective cerebral perfusion. CONCLUSIONS The measurement of middle cerebral artery blood flow velocities with transcranial Doppler technique is practicable during selective cerebral perfusion but difficult during RCP. The increase in middle cerebral artery blood flow velocities after RCP indicates reactive hyperemia and reflects the critical decrease in cerebral blood flow during this type of perfusion.

Ventricular mechanics in the bidirectional glenn procedure and total cavopulmonary connection

BACKGROUND The time course of ventricular efficiency in Fontan candidates who underwent both the bidirectional Glenn procedure (BDG) and total cavopulmonary connection (TCPC) were analyzed in this study. We previously reported that volume-load reduction of BDG preceding TCPC allowed for any afterload mismatch to be corrected, thereby improving ventricular efficiency after staged TCPC. METHODS We measured percent normal systemic ventricular end-diastolic volume (%N-EDV), contractility (end-systolic elastance [Ees]), afterload (effective arterial elastance [Ea]), and ventricular efficiency (ventriculoarterial coupling [Ea/Ees]) based on cardiac catheterization data before and after both BDG and staged TCPC in 30 patients. Ees and Ea were approximated as follows: Ees = mean arterial pressure/minimal ventricular volume, and Ea = maximal ventricular pressure/(maximal ventricular volume - minimal ventricular volume), and Ea/Ees was then calculated. Ventricular volume was divided by body surface area. RESULTS The %N-EDV decreased both after BDG and after staged TCPC, thus resulting in an improvement of Ees. Although Ea increased both after BDG and after staged TCPC, Ea decreased during the interval between BDG and staged TCPC. These changes resulted in an improvement in Ea/Ees during the interval period and after staged TCPC, although Ea/Ees worsened after BDG. CONCLUSIONS Correction of afterload mismatch during the interval period between BDG and staged TCPC is considered to be one of the most important factors for obtaining excellent clinical results when selecting a staged strategy to treat high-risk Fontan candidates.

Expression and subcellular localization of mammalian formin Fhod3 in the embryonic and adult heart

The formin family proteins play pivotal roles in actin filament assembly via the FH2 domain. The mammalian formin Fhod3 is highly expressed in the heart, and its mRNA in the adult heart contains exons 11, 12, and 25, which are absent from non-muscle Fhod3 isoforms. In cultured neonatal cardiomyocytes, Fhod3 localizes to the middle of the sarcomere and appears to function in its organization, although it is suggested that Fhod3 localizes differently in the adult heart. Here we show, using immunohistochemical analysis with three different antibodies, each recognizing distinct regions of Fhod3, that Fhod3 localizes as two closely spaced bands in middle of the sarcomere in both embryonic and adult hearts. The bands are adjacent to the M-line that crosslinks thick myosin filaments at the center of a sarcomere but distant from the Z-line that forms the boundary of the sarcomere, which localization is the same as that observed in cultured cardiomyocytes. Detailed immunohistochemical and immuno-electron microscopic analyses reveal that Fhod3 localizes not at the pointed ends of thin actin filaments but to a more peripheral zone, where thin filaments overlap with thick myosin filaments. We also demonstrate that the embryonic heart of mice specifically expresses the Fhod3 mRNA isoform harboring the three alternative exons, and that the characteristic localization of Fhod3 in the sarcomere does not require a region encoded by exon 25, in contrast to an essential role of exons 11 and 12. Furthermore, the exon 25-encoded region appears to be dispensable for actin-organizing activities both in vivo and in vitro, albeit it is inserted in the catalytic FH2 domain.

Ventricular energetics in endoventricular circular patch plasty for dyskinetic anterior left ventricular aneurysm

BACKGROUND The endoventricular circular patch plasty (Dor procedure) applies to patients with a left ventricular dysfunction due to an ischemic dilated ventricle. In the present study, we analyzed left ventricular energetics in patients who underwent the Dor procedure. METHODS We measured left ventricular contractility (end-systolic elastance; Ees), afterload (effective arterial elastance; Ea), and efficiency (ventriculoarterial coupling; Ea/Ees, and the ratio of stroke work and pressure-volume area; SW/PVA) based on the cardiac catheterization data before and after the Dor procedure in 8 patients with a postinfarction dyskinetic anterior left ventricular aneurysm. Concomitant procedures included coronary artery bypass grafting in all patients, mitral valve repair in one patient, and cryoablation in one patient. End-systolic elastance (Ees) and Ea were approximated as follows: Ees = mean arterial pressure/minimal left ventricular volume, and Ea = maximal left ventricular pressure/(maximal left ventricular volume-minimal left ventricular volume), and thereafter Ea/Ees and SW/PVA were calculated. The left ventricular volume was normalized with the body surface area. RESULTS End-systolic elastance (Ees) increased after the Dor procedure (from 1.15 +/- 0.60 to 1.86 +/- 0.84 mm Hg x m2 x mL(-1), p < 0.01), thus resulting in an improvement in Ea/Ees and SW/PVA (from 2.94 +/- 1.11 to 1.64 +/- 0.49, p < 0.01, and from 0.426 +/- 0.110 to 0.559 +/- 0.082, p < 0.01, respectively), even though Ea did not substantially change (from 2.96 +/- 0.78 to 2.74 +/- 0.55 mm Hg x m2 x mL(-1), p = 0.4). CONCLUSIONS Left ventricular contractility and efficiency improves after the Dor procedure in patients with a dyskinetic anterior left ventricular aneurysm. However, afterload does not change. The use of appropriate afterload-reducing therapy thus plays an especially important role in the management of patients who undergo the Dor procedure.

Inhibition of lipid peroxidation with the lazaroid U74500A attenuates ischemia-reperfusion injury in a canine orthotopic heart transplantation model☆☆☆★★★♢

BACKGROUND The lazaroid U74500A is a 21-aminosteroid that inhibits lipid peroxidation and attenuates ischemia-reperfusion injury. We examined the effect of U74500A on heart preservation with the use of a clinically relevant canine orthotopic heart transplantation model. METHODS AND RESULTS Six donor dogs (group L) were pretreated intravenously with U74500A (10 mg/kg), and the dogs without pretreatment served as a control (group C, n = 6). The donor heart was preserved in cold University of Wisconsin solution for 24 hours. The heart was then transplanted orthotopically. Myocardial biopsy was performed to measure the adenosine triphosphate level at the end of ischemia. Before reperfusion, recipients in group L received another dose of U74500A (10 mg/kg) intravenously. After 3 hours of reperfusion, left ventricular function was evaluated by left ventricular pressure-volume relations with the use of a Millar catheter and conductance catheter, thereby deriving the slope of the end-systolic pressure-volume relation, the slope of the stroke work-- end-diastolic volume relation, and the slope of the maximum dP/dt--end-diastolic volume relation. At the same time, serum creatine kinase MB isoenzyme and lipid peroxide levels were measured. The slopes of the end-systolic pressure-volume relation, the stroke work--end-diastolic volume relation, and the maximum dP/dt--end-diastolic volume relation for group L were significantly higher than those for group C. The adenosine triphosphate levels for group L were significantly higher than those for group C. Serum creatine kinase MB isoenzyme and lipid peroxide levels for group L were significantly lower than those for group C. CONCLUSIONS Inhibition of lipid peroxidation by the administration of U74500A was effective for 24-hour canine cardiac preservation. These results indicate that U74500A is a promising agent for heart allograft preservation.

Arresting donor hearts with extracellular-type cardioplegia prevents vasoconstriction induced by UW solution.

The effects of arresting donor hearts with University of Wisconsin solution was investigated. Donor dogs were divided into two groups according to the technique used for arresting the heart. In group I (n = 6) the heart was arrested with University of Wisconsin solution, whereas in group II (n = 6) extracellular-type cardioplegia (K+ = 20 mmol/liter) was used to induce cardioplegic arrest. Aortic root pressure was measured during the infusion of solution at constant flow. In both groups, the hearts were then flushed and stored in cold University of Wisconsin solution for 6 h. The hearts were transplanted orthotopically and disconnected from cardiopulmonary bypass. Left ventricular function was evaluated by pressure-volume relations using a conductance catheter. Peak aortic root pressure during the infusion was significantly higher in group I than in group II, although post-transplant left ventricular function was similar in both groups. Although there was no difference in cardiac function after implantation, donor hearts should be arrested by extracellular-type cardioplegia to prevent coronary vasoconstriction associated with preservation in University of Wisconsin solution.

Left ventricular performance in aortic valve replacement

We analyzed the mid-term left ventricular (LV) performance after aortic valve replacement (AVR). We measured LV contractility (end-systolic elastance: Ees), afterload (effective arterial elastance: Ea) and efficiency (ventriculoarterial coupling: Ea/Ees; ratio of stroke work and pressure-volume area: SW/PVA) based on transthoracic echocardiography data obtained before, after and approximately 1 year after isolated AVR in 263 patients with aortic stenosis (AS group; n=116), aortic regurgitation (AR group; n=93) or aortic stenosis and regurgitation (ASR group; n=54). The LV volume was calculated by the Teichholz M-mode method. Ees and Ea were approximated as follows: Ees=mean blood pressure/minimal LV volume; Ea=systolic blood pressure/(maximal LV volume-minimal LV volume). Thereafter, Ea/Ees and SW/PVA were calculated. Arterial blood pressure was measured using manchette methods. Ees and Ea decreased after AVR in the AS group, but increased in the AR group. Ea/Ees and SW/PVA worsened after AVR in the AR group, but improved during a 1-year period after AVR in all groups. Contrasting effects of AVR on LV contractility and afterload between AS and AR were clearly demonstrated. The mid-term LV contractility and efficiency after AVR were excellent and satisfactory. However, LV efficiency worsened early after AVR in AR patients.

Left atrial appendage aneurysm in a child

We report a case of left atrial appendage aneurysm in a 1-year-old child. The patient was asymptomatic, and a mediastinal liquid mass that was confirmed to be an aneurysm of the left atrial appendage was incidentally revealed by transthoracic echocardiography. Aneurysmectomy was performed during cardioplegic arrest under the support of cardiopulmonary bypass. The postoperative course was uneventful.