Noriyasu Kawada

Reconsideration of Patient-Prosthesis Mismatch Definition From the Valve Indexed Effective Orifice Area

BACKGROUND The objective of this study was to reassess the validity of defining patient-prosthesis mismatch (PPM) in the aortic position on the basis of an indexed effective orifice area (iEOA) less than 0.85 cm(2)/m(2). METHODS From June 1996 to March 2008, 342 patients underwent aortic valve replacement with a Carpentier-Edwards Perimount valve. From the data collected, the transvalvular pressure gradient was determined by the modified Bernoulli equation, and EOA was calculated from the standard continuity equation. RESULTS The actuarial survival rate at 10 years after surgery was 84.0% +/- 8.2%. The prevalence of PPM was 6.1% when a projected iEOA less than 0.85 cm(2)/m(2) was defined as indicating significant PPM. There was no difference between patients with moderate PPM (85.2% +/- 9.8%) and patients without PPM (81.0% +/- 8.7%; p = 0.44). The relation between mean transvalvular pressure gradient and iEOA demonstrated a gentler slope than that reported previously. Postoperative mean transvalvular pressure gradient was 17.4 +/- 5.6 mm Hg and 14.5 +/- 5.6 mm Hg in patients with an iEOA less than 0.85 and 0.85 or greater, respectively. Most patients had a postoperative mean transvalvular pressure gradient more than 10 mm Hg regardless of PPM. CONCLUSIONS Our analysis suggested that an iEOA less than 2.0 cm(2)/m(2) might be the threshold for PPM, which should not be passed to achieve a low mean transvalvular pressure gradient (less than 10 mm Hg) with the Carpentier-Edwards Perimount valve. The implications of these findings include the necessity for reassessing the hemodynamic performance of each type of prosthesis when attempting to define PPM, to avoid residual significant transvalvular pressure gradient.

The Conduction System in Heterotaxy

Cardiac malformations associated with the syndrome of atriovisceral heterotaxy are among the most complex forms of congenital heart disease. Accordingly, the disposition of the specialized conduction tissue (the conduction system) is also variable and complex in these particular anomalies. The location of the conduction system and the degree of abnormalities of the conduction system correlate with the severity and location of the associated structural cardiac anomalies.

Mitral valve reconstruction: long-term results of triangular resection for degenerative prolapse

AbstractObjectives. Surgical treatment of a prolapsed anterior leaflet of the mitral valve is relatively difficult and controversial compared with management of a prolapsed posterior leaflet. The aim of this study was to assess the long-term results of mitral valve repair, focusing on triangular resection of the anterior leaflet. Methods. Between October 1991 and December 2006, surgical treatment for a prolapsed anterior leaflet was performed in 57 patients with degenerative mitral valve disease, including 49 patients who had anterior leaflet resection. Patients with mitral stenosis, ischemic mitral regurgitation, and congenital valvular disease were excluded. The mean age of the patients was 51.7 ± 15.9 years, and the mean follow-up period was 6.2 ± 3.8 years. Results. The overall actuarial survival rate and noreoperation rate at 10 years were 91.7% ± 4.1% and 92.3% ± 3.7%, respectively. Reoperation was performed in 2 (4%) of 49 patients who had anterior leaflet resection. All patients survived after reoperation, which involved mitral valve replacement. Postoperative echocardiographic studies showed that the mitral valve area was significantly smaller after repair in patients with anterior leaflet resection, but the area was still large enough for a functional valve. Among the 57 patients, 42 had no mitral regurgitation, whereas it was mild in 7 patients and moderate in 3 patients. Conclusion. Triangular resection of a prolapsed anterior leaflet of the mitral valve provides durable and reliable long-term results.

The role of a staged approach for high-risk Fontan candidates

The preoperative risk characteristics and surgical outcome were reviewed in 24 patients who underwent a one-stage Fontan procedure (One-stage Group) and in 16 patients who underwent bidirectional cavopulmonary shunt as an interim procedure prior to a subsequent Fontan procedure (Two-stage Group) to clarify the role of the staged approach for high-risk Fontan candidates. There were 2 hospital deaths after the one-stage Fontan, and another 2 after the takedown of the fenestrated Fontan to BCPS in patients considered to be less than ideal candidate because of the presence of 3 or more risk factors. In contrast, among the total of 16 patients in the Two-stage Group who had significantly more risk factors than those in One-stage Group (2.8 +/- 1.4, vs 1.1 +/- 1.2 p < 0.001), 14 patients survived after bidirectional cavopulmonary shunt, and a subsequent Fontan procedure was accomplished in 12 patients of these 14, with 2 operative deaths after the takedown to bidirectional cavopulmonary shunt. The rate of final Fontan completion in the Two-stage Group (10/16, 62.5%) was considered to be reasonable, considering the fact that this patient group essentially includes non-Fontan candidates. Additionally, in the category of high-risk with 3 or more risk factors, the rate of successful Fontan completion was higher in the Two-stage Group than in the One-stage Group (50% vs 25%). In the survivors of the Two-stage Group, the average number of risk factor decreased from 2.7 +/- 1.3 (range 0 to 5) to 1.0 +/- 1.0 (range 0 to 4) after bidirectional cavopulmonary shunt with concomitant procedures (i.e., extended pulmonary artery reconstruction in 8, and repair of atrioventricular valve regurgitation in 4), predominantly due to improved Fontan candidacy, relating to pulmonary and/or ventricular characteristics, and eliminated anatomical risks. In conclusion, the two-stage approach with bidirectional cavopulmonary shunt accompanied by concomitant repair of associated anomaly may be useful to lower the risk enough to allow subsequent Fontan completion in high-risk patients.

Right ventricular dynamic cardiomyoplasty for the univentricular heart with pulmonary hypertension

OBJECTIVES We conducted an acute experimental study to test the feasibility of dynamic cardiomyoplasty in a setting of modified Fontan procedure for univentricular heart with pulmonary hypertension to obtain a possible proxy for high-risk Fontan candidates. METHODS After electrical preconditioning of the left latissimuss dorsi for 6 weeks in 8 dogs, the right ventricular cavity was totally obliterated with concomittent closure of the tricuspid valve and right pulmonary artery. Modified Fontan circulation was established with the aortic homograft anastomosed between the right atrium and pulmonary trunk, incorporated with a pericardial pouch as a compression chamber (neoright ventricle) fixed onto the epicardial surface of the ventricle. After cardiopulmonary bypass termination, a latissimus dorsi was applied to wrap the pericardial pouch and ventricle clockwise and stimulated with a trained-pulse (25 Hz) at 1:1 synchronization ratio with cardiac beats. RESULTS Profound right heart failure was noted during Fontan circulation in increased pulmonary vascular resistance (11 +/- 3.2 Wood units), whereas graft pacing showed significant augmentation of systolic pulmonary pressure by 54 +/- 12%, the mean pulmonary flow by 68 +/- 23%, and aortic pressure by 23 +/- 5% at a physiological range of central venous pressure (13.2 +/- 0.7 mmHg). Right heart function curve analysis confirmed marked augmentation of right heart performance, restoring almost normal pulmonary circulation. These functional benefits were sustained up to 4 hours in 4 animals until experiments were terminated. CONCLUSIONS Dynamic cardiomyoplasty in a modified Fontan procedure is a viable surgical option for univentricular heart, not a Fontan candidate.

Redefinition of tricuspid valve structures for successful ring annuloplasty

Background: Although numerous reports have described suturing techniques for tricuspid annuloplasty, most studies were not based on a detailed anatomy of the tricuspid annulus. Thus, the definition of the tricuspid commissures remains unclear. This study aimed to clearly define the commissures and leaflets of the tricuspid valve and subvalvular structures, and to define a standard method for tricuspid annuloplasty. Methods: In 27 normal heart specimens without cardiac disease, the tricuspid commissure was defined using indentations of the leaflets as a point, not an area, and the length of each tricuspid annulus was measured. The relationships between the leaflets and the subvalvular structures were then examined. Results: In most specimens, the posterior leaflet had 2 (62.9%) or 3 (29.6%) scallops, providing further evidence of posterior leaflet diversity. In addition, the posterior leaflet had 1 or 2 indentations, which can be mistaken for true commissures. The annulus of the posterior leaflet was significantly longer than the annuli of the other 2 leaflets (P < .00428). The annuli of the septal and the anterior leaflets were supported by the interventricular septum and the supraventricular crest, respectively, whereas the posterior leaflet annulus was distributed largely along the right ventricular free wall. Conclusions: There was a structural gap between the tricuspid leaflet indentations and the subvalvular structures. The relationships among the leaflets, commissures, and subvalvular structures differed in the septal, anterior, and posterior leaflets. This new definition of the commissural point may aid the development of a clear‐cut methodology for prosthetic ring annuloplasty.

Extracardiac Direct Total Cavopulmonary Connection

We report a successful extracardiac direct total cavopulmonary connection without prosthetic materials performed in a 3-year-old boy with tricuspid atresia, infundibular pulmonary stenosis, and normally positioned great arteries. The transected pulmonary trunk was bought down posterolaterally with respect to the right atrium and was anastomosed end-to-end with the inferior vena cava.

Validity of identifying patient-prosthesis mismatch from the indexed effective orifice area.

The main problem that arises from patient-prosthesis mismatch after aortic valve replacement is a residual high transvalvular pressure gradient, resulting in left ventricular overload. It was demonstrated by Pibarot and Dumesnil that the indexed effective orifice area should be larger than 0.85–0.90 cm2/m2 to prevent any significant transvalvular pressure gradient after operation. However, we have encountered a higher residual transvalvular pressure gradient than expected in some patients with an aortic stented bioprosthesis with an indexed effective orifice area greater than 0.85 cm2/m2. Based on our data, an indexed effective orifice area of less than 1.25 cm2/m2 might be considered the threshold for patient-prosthesis mismatch in patients with a stented bioprosthesis because this indexed effective orifice area is associated with a low mean transvalvular pressure gradient (less than 10 mmHg). The practical implications include the necessity to consider the hemodynamic performance of each prosthesis type when seeking to define patient-prosthesis mismatch and abnormally or significant high postoperative gradients that lead to an increased left ventricular workload, so as to avoid residual significant transvalvular pressure gradients and higher rates of morbidity and mortality.

Technique of managing periprosthetic leakage due to mitral prosthetic valve endocarditis: report of a case

A patient with multiple leaks caused by active mitral prosthetic valve endocarditis with an annular abscess underwent repeat mitral valve replacement. To secure the new mitral prosthesis, sutures were placed through the healthy interatrial septal wall from right to left at the posteromedial region and then to the new prosthetic valve sewing cuff. In the anterolateral region, sutures were placed through the reconstructed annulus after debridement of the abscess and then reinforced with a pericardial xenograft patch. Postoperatively, the perivalvular leakage stopped and the patient recovered uneventfully.