Graphical abstract
Keywords: Hypertension, Myxoid degeneration, Right coronary cusp prolapse, Transverse fold, Type II aortic regurgitation
Highlights
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Transverse fold of RCC causes type II AR, an underrecognized mechanism.
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Three-dimensional TEE identifies RCC fold when TTE is inconclusive.
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Myxoid degeneration in RCC causes transverse fold, likely linked to hypertension.
Introduction
Aortic regurgitation (AR) arises from various pathologies that affect the aortic valve (AV) leaflets and/or the aortic root, leading to valve malcoaptation. The Carpentier classification categorizes AR into 3 mechanisms based on aortic root and leaflet morphology, guiding reparability. Type II AR is characterized by excessive leaflet motion from cusp prolapse or commissural disruption.1 An underrecognized cause of prolapse is a transverse fold of a trileaflet AV coronary cusp, and limited literature exists on its multimodality imaging and histology. We present a case of severe type II AR resulting from a transverse fold causing right coronary cusp (RCC) prolapse in a 63-year-old hypertensive man. Multimodality imaging, intraoperative findings, and histopathology elucidate this rare pathology and its diagnostic challenges.
Case Presentation
A 63-year-old man with long-standing hypertension (>15 years), type 2 diabetes mellitus, and hyperlipidemia presented for evaluation of an incidental murmur. The patient reported dyspnea on exertion and fatigue that had progressively worsened over the previous 5 months. Physical examination revealed a blood pressure of 159/68 mm Hg, a diminished first heart sound (S1), a soft second heart sound (S2), grade 3/4 holodiastolic murmur heard best at the third left lower sternal border with a diastolic thrill, and a laterally and inferiorly displaced, sustained apical impulse.
Transthoracic echocardiography (TTE) showed a trileaflet AV with the RCC suspicious for prolapse versus flail, severe posteriorly directed AR, holodiastolic flow reversal in the descending aorta (time-velocity integral, 25 cm), and a dilated aortic root (4.9 cm; Videos 1-3). In addition, there was early closure of the mitral valve, severe left ventricular chamber dilatation (left ventricular end-diastolic volume index [LVEDI] of 145 mL/m2), severe concentric left ventricular hypertrophy (wall thickness, 17 mm; left ventricular mass index, 210 g/m2; relative wall thickness, 0.54), a normal left ventricular ejection fraction of 65%, and an abnormal left ventricular global longitudinal strain of –14%. Cardiovascular magnetic resonance, performed to assess left ventricular hypertrophy etiology, confirmed severe left ventricular dilation (LVEDI of 145 mL/m2), a thickened basal left ventricular wall (19 mm), mild myocardial late gadolinium enhancement with nonspecific and nonischemic changes along the basal lateral wall and inferior right ventricular insertion site, and severe AR.
Classified as American College of Cardiology/American Heart Association stage D with severe symptomatic AR, the patient was referred for cardiothoracic surgical evaluation. Transesophageal echocardiography (TEE), performed to confirm the AR mechanism, revealed a trileaflet AV with a transverse fold of the RCC causing distal prolapse. This resulted in severe, eccentric, posteriorly directed AR with a regurgitant volume of 76 mL, a regurgitant fraction of 61% (calculated via the continuity equation using left ventricular outflow tract and right ventricular outflow tract stroke volumes), holodiastolic flow reversal in the abdominal descending aorta, and diastolic fluttering of the anterior mitral valve leaflet with restricted opening (Figures 1 and 2, Videos 4-6). Blood cultures were negative, ruling out an active infective etiology. Genetic screening excluded connective tissue disorders. Cardiac computed tomography, performed for preoperative coronary assessment, showed minimal luminal irregularities and confirmed the transverse fold of the RCC (Figure 3).
Figure 1.
Two-dimensional TEE, midesophageal long-axis (144°) zoomed-in diastolic view of the AV, demonstrates (A) distal RCC prolapse (arrow) and (B) the W sign, where a transverse fold acts as the RCC's leading edge, causing true edge prolapse. Two-dimensional TEE, midesophageal short-axis diastolic view (45°) of the AV (C) and three-dimensional en face view (D), demonstrates the transverse fold (yellow arrows). Ao, Aorta; LA, left atrium, RA, right atrium.
Figure 2.
(A) Two-dimensional TEE, midesophageal long-axis (144°) zoomed-in diastolic view of the AV without (left) and with (right) color-flow Doppler, demonstrates distal RCC prolapse with the W sign, where a transverse fold acts as the RCC's leading edge, causing true edge prolapse, with posteriorly directed AR. (B) Pulsed-wave spectral Doppler display demonstrates holodiastolic flow reversal in the descending aorta (time-velocity integral, 25 cm) on TTE. (C) M-mode imaging on TEE demonstrates anterior mitral leaflet flutter (arrow) and restricted opening of the mitral valve. Ao, Aorta; LA, left atrium; LV, left ventricle.
Figure 3.
(A) Cardiac computed tomography, multiplanar reconstructed short-axis diastolic view of the AV, demonstrates a transverse fold of the RCC (yellow arrow). (B and C) Multiplanar reconstructed 3-chamber diastolic view demonstrates distal RCC prolapse with the W sign (yellow arrow), where the transverse fold serves as the leading edge of the cusp, causing true edge prolapse. (D) Three-dimensional volume-rendered image in the diastolic phase demonstrates normal coronary arteries and RCC prolapse (yellow arrow).
Intraoperative surgical findings revealed a prolapsed RCC with a transverse fold and redundant fibrotic valve leaflets. The patient underwent successful surgical AV replacement with a 27 mm bioprosthetic valve. Gross pathology of the RCC showed an elongated leaflet with a fold (Figure 4). Histopathology revealed myxoid degeneration affecting the RCC, with fibrosis (Figure 5). Six months postoperation, a follow-up TTE showed a well-seated valve with a mean gradient of 12 mm Hg, no prosthetic regurgitation, and significant symptom improvement.
Figure 4.
Gross pathology of the excised AV leaflets. (A) The RCC has an elongated cusp with a transverse fold (arrow) and focal degeneration. (B) The left coronary and noncoronary cusps reveal focal degeneration.
Figure 5.
Histological analysis of the RCC. Hematoxylin and eosin stain of the RCC of the AV at ×40 shows (A) a central band of myxoid degeneration (arrow) and (B) both myxoid degeneration (red arrowheads) and fibrosis (yellow arrows).
Discussion
This case of severe type II AR due to RCC prolapse with a transverse fold highlights an underrecognized mechanism identified through multimodality imaging and confirmed intraoperatively.
Type II AR, characterized by excessive leaflet motion, typically results from cusp prolapse or commissural disruption.1 In contrast, type I AR involves aortic dilatation or cusp perforation with normal leaflet motion, and type III AR results from leaflet restriction due to fibrosis or calcification (Table 1).2 Identifying these mechanisms is vital for presurgical planning and predicting AR recurrence.1
Table 1.
Classification of AR mechanisms
| Type | Cusp motion | Subtypes | Mechanism |
|---|---|---|---|
| I | Normal cusp motion | Ia | Distal ascending aorta and STJ dilatation, normal aortic root, causing central coaptation failure and central AR jet |
| Ib | Aortic root and STJ dilatation, leading to central AR jet | ||
| Ic | Isolated dilatation of aortic annulus resulting in central AR jet | ||
| Id | Aortic cusp perforation with AR jet originating in the cusp body | ||
| II | Excessive leaflet motion | Cusp prolapse leading to eccentric AR | |
| III | Restricted leaflet motion | Seen with congenitally abnormal valves, degenerative calcification, and any other cause of thickening/fibrosis or calcification of the leaflets leading to eccentric AR |
STJ, Sinotubular junction.
A prospective study of 2,000 patients reported a 1.2% prevalence of AV prolapse (24/1,788), primarily due to bicuspid valve prolapse (11/24), with trileaflet prolapse cases linked to mitral valve prolapse, marfanoid root dilatation, or endocarditis.3 In a retrospective study of 516 tricuspid valve AR surgical cases, cusp prolapse occurred in 46%, with 86% of these cases involving the RCC, although transverse folds were not reported.4 The prevalence and natural history of prolapse associated with a transverse fold in trileaflet AVs remain poorly documented, representing a gap in the literature.
Transverse fold–related AR predominantly affects hypertensive men, mirroring our patient's profile.5,6 Histology of the RCC revealed myxoid degeneration with no distinct fibrous band—often mislabeled as such—consistent with a prior report.5 Normal AV histology comprises a continuous endothelial layer and 5 connective tissue layers with collagen and elastic fibers organized in a honeycomb structure. Myxoid degeneration disrupts the fibrosa, replacing collagen with acid mucopolysaccharides, which leads to leaflet elongation, folding, and prolapse, likely driven by hypertension. Allen et al.7 noted myxoid degeneration in 36% of pure AR cases, often linked to hypertension (average age, 63 years; 85% male sex; 77% hypertensive), aligning with our patient's profile. The predisposition of the RCC to prolapse may stem from its unique anatomical support by the septal myocardium—unlike the noncoronary and left cusps, which are anchored to the heart's central fibrous skeleton—rendering it vulnerable to hypertension-related stress.
The diagnostic process required a broad differential diagnosis, including type I AR (root dilatation), leaflet fenestrations, perforation, endocarditis, and connective tissue disorders. Initial TTE identified severe AR, left ventricular remodeling, and a dilated aortic root (4.9 cm). Two-dimensional TEE revealed a W sign on the long-axis view, while three-dimensional TEE delineated the fold suspended by commissures, causing free-edge prolapse.6 The W sign is an echocardiographic finding observed on the long-axis TEE view, characterized by a W-shaped configuration of the prolapsing RCC owing to a transverse fold midway on the cusp acting as the effective leading edge and allowing the true free edge to prolapse distally. Weininger et al.6 reported that this sign was associated with successful AV repair via free margin shortening supported by valve-sparing aortic root replacement, yielding a symmetric repair. However, larger studies are needed to confirm this, since the valve could not be repaired in our patient, despite the presence of this sign. Preoperative TEE was instrumental in identifying the transverse fold of the RCC as the mechanism of severe AR, confirming the regurgitant volume and fraction, excluding valvular vegetation, and providing critical information for surgical planning, including the feasibility of AV repair. Cardiovascular magnetic resonance quantified LVEDI at 145 mL/m2 and assessed the left ventricular hypertrophy etiology, ruling out ischemic or infiltrative causes. Mild, nonischemic late gadolinium enhancement suggested a cause other than hypertrophic cardiomyopathy, likely related to hypertension and chronic valve disease. Cardiac computed tomography confirmed the transverse fold and excluded coronary artery disease. Negative blood culture and genetic screening results supported a primary degenerative etiology.
Intraoperative findings of leaflet redundancy, fibrosis, and myxoid degeneration precluded durable valve repair, necessitating surgical AV replacement. A 27 mm bioprosthetic valve was chosen for this 63-year-old patient with comorbidities (hypertension, diabetes, hyperlipidemia), aligning with 2020 American College of Cardiology/American Heart Association guidelines.8
This case prompts clinicians to consider transverse fold as a mechanism of AR in patients with hypertension. It challenges the “fibrous band” misnomer based on histological evidence of myxoid degeneration. The predominance of hypertensive men in reported cases highlights hypertension as a modifiable risk factor, emphasizing early blood pressure control. Clinicians should leverage multimodality imaging when TTE is inconclusive (Videos 1-3) and maintain a broad differential diagnosis. Further histopathological studies are needed to clarify this mechanism.
Conclusion
Transverse folds causing RCC prolapse are an underrecognized valve mechanism for type II AR. Multimodality imaging, particularly three-dimensional TEE, is essential for accurate diagnosis when TTE is inconclusive. The association with hypertension underscores the need for proactive blood pressure management. Further histopathological studies are vital to elucidate this mechanism and inform strategies for valve repair or replacement.
Ethics Statement
The authors declare that the work described has been carried out in accordance with the following guidelines: This work did not involve experimentation on humans or animals.
Consent Statement
The authors declare that informed patient consent was not provided for the following reason: Institutional policy does not require institutional review board approval or signed patient consent for de-identified reports of a single case.
Funding
The authors declare that this report did not receive any specific grant from funding agencies in the public, commercial, or not-for-profit sectors.
Disclosure Statement
The authors reported no actual or potential conflicts of interest relative to this document.
Acknowledgments
We thank Alex McCracken, RVT, RDCS, for acquiring the transthoracic images, Jennifer Pfaff and Sarah Kennedy for editorial preparation of the article, and Brian Schurrer for assistance with the figures.
Footnotes
Supplementary data related to this article can be found at https://doi.org/10.1016/j.case.2025.09.012.
Supplementary Data
Two-dimensional TTE, parasternal long-axis zoom view of the AV, demonstrates a dilated aortic root, RCC prolapse versus flail (green arrow), and reduced mitral valve opening.
Two-dimensional TTE, parasternal short-axis zoom view of the AV without (left) and with (right) color-flow Doppler, demonstrates a trileaflet AV (red arrow) with AR.
Two-dimensional TTE, apical long-axis view without (left) and with (right) color-flow Doppler, demonstrates a dilated left ventricular cavity with thick myocardium, normal global systolic function, and RCC prolapse versus flail (arrow) with posteriorly directed AR.
Two-dimensional TEE, midesophageal simultaneous orthogonal short-axis (50°; left) and long-axis (140°; right) zoomed views of the AV, demonstrates a transverse fold and RCC prolapse (arrow), respectively.
Three-dimensional TEE, midesophageal short-axis cropped view of the AV using light illumination technology, demonstrates a transverse fold (green arrow) on the RCC.
Two-dimensional TEE, midesophageal long-axis (144°) zoomed-in view of the AV without (left) and with (right) color-flow Doppler, demonstrates distal RCC prolapse (arrow), the W sign, where a transverse fold acts as the RCC's leading edge, causing true edge prolapse, with posteriorly directed AR.
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Associated Data
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Supplementary Materials
Two-dimensional TTE, parasternal long-axis zoom view of the AV, demonstrates a dilated aortic root, RCC prolapse versus flail (green arrow), and reduced mitral valve opening.
Two-dimensional TTE, parasternal short-axis zoom view of the AV without (left) and with (right) color-flow Doppler, demonstrates a trileaflet AV (red arrow) with AR.
Two-dimensional TTE, apical long-axis view without (left) and with (right) color-flow Doppler, demonstrates a dilated left ventricular cavity with thick myocardium, normal global systolic function, and RCC prolapse versus flail (arrow) with posteriorly directed AR.
Two-dimensional TEE, midesophageal simultaneous orthogonal short-axis (50°; left) and long-axis (140°; right) zoomed views of the AV, demonstrates a transverse fold and RCC prolapse (arrow), respectively.
Three-dimensional TEE, midesophageal short-axis cropped view of the AV using light illumination technology, demonstrates a transverse fold (green arrow) on the RCC.
Two-dimensional TEE, midesophageal long-axis (144°) zoomed-in view of the AV without (left) and with (right) color-flow Doppler, demonstrates distal RCC prolapse (arrow), the W sign, where a transverse fold acts as the RCC's leading edge, causing true edge prolapse, with posteriorly directed AR.