Original Research — Valvular Heart Disease
Mid-Term Experience With 1,196 Ozaki Procedures
Background
Introduced in 2007, the Ozaki procedure—templated cusp replacement with autologous pericardium—is a new option for treating aortic valve disease. Mid-term outcomes and valve performance have not yet been reported.
Objectives
This study assesses longitudinal hemodynamics, left ventricular reverse remodeling, reoperation, and survival in the original Ozaki cohort.
Methods
1,196 patients underwent Ozaki procedures (60% male, age 11–90 years) at Toho University Ohashi Medical Center from April 2007 to May 2021: 2.4% had infective endocarditis, 27% had bicuspid valves, 54% had aortic stenosis, 24% had aortic regurgitation, 7.3% had mixed lesions, and 46% underwent concomitant procedures. Clinical outcomes, echocardiograms, and follow-up data (50% followed >3.2 years, 10% >9 years) were analyzed using nonlinear mixed-effects regression for valve performance and time-to-event analyses for reoperation and mortality.
Results
Mean cardiopulmonary bypass and aortic clamp times for isolated Ozaki procedures were 151 ± 37 and 105 ± 29 minutes, respectively. Thirty-day mortality was 1.7%, new stroke occurred in 2.6%, new dialysis in 4.0%, and permanent pacemakers were implanted in 1.5%. At 6 months, 5 years, and 10 years, mean aortic valve gradient was 7.4, 8.0, and 8.2 mm Hg, and ≥2+ regurgitation was 0.30%, 2.9%, and 6.6%, respectively. Left ventricular mass index decreased from 141 ± 52 g/m² preoperatively to 90 ± 51 g/m² at 10 years. Survival and freedom from reoperation at 10 years was 78% and 92%, respectively.
Primary Outcomes at 10 Years
1,196
2007年4月〜2021年5月に東邦大学大橋医療センターで実施されたOZAKI法の総症例数
8.2 mm Hg
10年後の平均大動脈弁圧較差。6ヶ月時点の7.4 mm Hgから安定を維持
92%
10年後の再手術回避率。全体のうち再手術は38例、うち半数は感染性心内膜炎
78%
10年生存率。年齢・性別をマッチさせた日本人一般集団と同等以上
90 g/m²
10年後の左室心筋重量係数。術前141 g/m²から36%減少し、持続的な左室リバースリモデリングを確認
1.7%
30日死亡率。脳卒中2.6%、透析4.0%、ペースメーカー植込み1.5%
Hemodynamic Performance
OZAKI法で再建された弁は、低い圧較差が10年以上にわたり安定して維持されます。有効弁口面積指数は退院時2.1 ± 0.5 cm²/m²と、Magna Ease生体弁（1.2 ± 0.25 cm²/m²）やFreestyle stentless弁（0.9–1.0 cm²/m²）を大幅に上回ります。4次元CTでは天然弁と同様の層流が確認されています。
Aortic Regurgitation
中等度以上の大動脈弁逆流の割合は、1年後0.59%から10年後6.6%へと緩やかに増加。Equal tricuspidizationを受けた患者では5年以降の逆流リスクが低下しました。二尖弁やバルサルバ洞径の大きさは逆流リスクの増加と関連しませんでした。
Study Population
Surgical Technique
自己心膜を採取し、0.6%グルタルアルデヒド溶液で10分間処理後、生理食塩水で3回（各6分）洗浄。Ozaki sizerで弁輪間交連距離を計測し、専用テンプレートで3枚の弁尖を切り出す。各弁尖は4-0モノフィラメント連続縫合で弁輪に縫着。術後6ヶ月間アスピリンを処方。
Technical Modifications
2008年（症例19）：心膜の向きを変更（平滑面を心室側に）。2011年（症例291）：弁尖にWing extension（5mm）を追加し交連部固定を強化。2012年（症例513）：Equal tricuspidization導入（二尖弁・一尖弁で3枚の均等な弁尖を作成）。2020年（症例1,147）：将来のTAVR対応のため余剰接合高を低減する改良サイザー・テンプレートを導入。
Data Analysis
Cleveland Clinicとの共同研究として、5,543件の心エコー検査（1,048名、コホートの88%）を分析。多相非線形混合効果縦断回帰モデルによる弁性能評価、Kaplan-Meier法およびパラメトリックモデルによる生存分析・再手術解析、Random Forestによるリスク因子同定を実施。統計解析にはSAS v9.4およびR v3.6.0を使用。
Conclusions
This study confirms the safety and effectiveness of the Ozaki procedure to justify its expanded use. The procedure creates a good aortic valve with low stable gradient, excellent LV remodeling, an acceptable risk of AR, and an overall low risk of reoperation. Risk of infective endocarditis remains a concern. Specific criteria for patient selection have yet to be refined. Further studies of modifications and long-term performance are needed.
Competency in Medical Knowledge
Introduced in 2007, the Ozaki procedure is an attractive option for AVR using autologous tissue and preserving native anulus motion. Although a learning curve exists, the Ozaki procedure creates good aortic valves with stable low gradients, regurgitation increases over time, but medium-term risk of reoperation is low, supporting continued use.
Translational Outlook
Additional research studying mechanisms and risk factors for failure and long-term valve function is warranted to expand its use and to establish its role within the armamentarium of aortic valve procedures.