Introduction
Shone complex is a rare congenital cardiac anomaly characterized by multiple obstructive lesions in the left heart, first described by Shone et al. in 1963.Reference Shone, Sellers and Anderson1 It classically includes four components: parachute mitral valve, supramitral ring, subaortic stenosis, and aortic coarctation. Cases with all four lesions are termed complete Shone complex, while those with two or three lesions are classified as partial Shone complex.Reference Brown, Ruzmetov and Vijay2 Partial Shone complex is usually diagnosed in childhood, and adult cases are uncommon.Reference Mierop, Alley and Kausel3–Reference Truong, Kutty and Broberg6 This report describes an adult patient with partial Shone complex who developed infective endocarditis and a saccular aneurysm at the site of coarctation of the aorta.
Case presentation
A 25-year-old male presented with a one-month history of high fever reaching 40°C. Previous antibiotic regimens, including ceftriaxone, cefuroxime, and moxifloxacin for suspected atypical pneumonia, were ineffective. Physical examination identified murmurs at the aortic and mitral valves and a radial-femoral pulse delay. Laboratory findings included leukocytosis (WBC 23,290/mmReference Mierop, Alley and Kausel3), elevated C-reactive protein (307 mg/L), and procalcitonin (2.38 µg/L). Blood cultures confirmed methicillin-sensitive Staphylococcus aureus, establishing the diagnosis of infective endocarditis.
Abdominal CT revealed hypodense lesions that were consistent with septic emboli. Transthoracic echocardiography showed concentric left ventricular hypertrophy and a bicuspid aortic valve with fusion of the right and left coronary cusps, classified as Type 1. The patient exhibited mild aortic stenosis, with peak/mean gradients of 28/13 mmHg, and an aortic valve area of 1.6 cm.Reference Brown, Ruzmetov and Vijay2 The ascending aorta was dilated to 4.1 cm. Moderate aortic regurgitation was present, with a pressure half-time of 408 ms. The mitral valve demonstrated anterior leaflet doming and a hypoplastic posterior leaflet, findings consistent with parachute mitral valve morphology. Mitral stenosis was confirmed with peak and mean transmitral gradients of 22 and 11 mmHg, respectively, and a valve area of 1.5–1.6 cmReference Brown, Ruzmetov and Vijay2 assessed by three-dimensional planimetry. Mild eccentric mitral regurgitation was also noted (Figure 1).
Transthoracic echocardiography. (a) Parachute mitral valve morphology. (b) Parasternal long-axis view showing congenital mitral valve abnormality. (c) Short-axis view demonstrating bicuspid aortic valve with right–left cusp fusion. (d) Three-dimensional planimetry showing reduced mitral valve area.
Suprasternal imaging demonstrated turbulent flow distal to the left subclavian artery, indicating coarctation of the aorta with a peak gradient of 53/29 mmHg. The narrowest portion of the descending aorta measured 12 mm. Notable tissue thickening at the coarctation site warranted further assessment using positron emission tomography. This imaging revealed focal fluorodeoxyglucose uptake, suggestive of active infection, and identified a saccular aneurysm located distal to the coarctation (Figure 2).
(a) Three-dimensional CT reconstruction demonstrating coarctation of the aorta distal to the left subclavian artery. (b) Saccular aneurysm distal to the coarctation site, associated with focal tissue thickening and suspected infectious involvement.
Empiric therapy with ceftriaxone and vancomycin was initiated and subsequently switched to cefazolin two days later following the identification of methicillin-sensitive Staphylococcus aureus. A multidisciplinary evaluation by the cardiology and cardiovascular surgery teams led to the decision for urgent surgical intervention due to coarctation-associated infective endocarditis and saccular aneurysm formation. The patient underwent surgery and completed a total of 44 days of cefazolin therapy.
The early postoperative period was initially uneventful. However, seven months later, the patient presented again with high-grade fever. Diagnostic assessment revealed infection involving the aortic graft. Empiric therapy with meropenem and teicoplanin was initiated but discontinued on the third day, after blood cultures once again yielded methicillin-sensitive Staphylococcus aureus. Antimicrobial therapy was subsequently adjusted to cefazolin and rifampicin.
Positron emission tomography demonstrated intense hypermetabolic activity consistent with active infection, extending from the posterior aortic arch to the descending aorta.
Repeat TTE and transesophageal echocardiography confirmed vegetation on the aortic graft and perforation of the mitral valve. The patient received 41 days of intravenous cefazolin and rifampicin, followed by discharge on oral amoxicillin 625 mg for suppressive therapy.
At nine months postoperatively, follow-up transesophageal echocardiography demonstrated the characteristic features of a parachute mitral valve, including a single papillary muscle visualized in deep gastric views. A perforation measuring approximately 5 mm was identified on the anterior mitral leaflet (A2 scallop). A filamentous, mobile structure measuring 0.6 cm extended intermittently into the left ventricle, raising suspicion of residual perforated tissue or persistent vegetation. Moderate-to-severe posteriorly directed eccentric mitral regurgitation was present, accompanied by systolic flow reversal in the pulmonary veins. The peak and mean transmitral gradients measured 23 and 14 mmHg, respectively, with a calculated mitral valve area of 1.7 cmReference Brown, Ruzmetov and Vijay2. The aortic valve remained bicuspid (Type 1 morphology) without evidence of vegetation. Grade 2 eccentric aortic regurgitation was also observed.
Discussion
Shone complex comprises a spectrum of left-sided obstructive lesions, classically including parachute mitral valve, mitral stenosis, subaortic obstruction, and coarctation of the aorta.Reference Shone, Sellers and Anderson1 In our patient, the coexistence of a parachute mitral valve, mitral stenosis, and coarctation of the aorta was consistent with a partial form of this complex anomaly.
Bicuspid aortic valve coexists in approximately 71% of Shone complex cases and can exacerbate hemodynamic burden.Reference Aslam, Khairy and Shohoudi7 In this case, mild aortic stenosis contributed to additional left ventricular outflow tract obstruction, potentiating the effects of coarctation.
Parachute mitral valve is frequently misdiagnosed as rheumatic mitral valve disease on TTE. In individuals with bicuspid aortic valve or unexplained murmurs, suprasternal imaging is essential to evaluate for aortic coarctation. Moreover, in febrile patients without evident vegetations, clinicians should maintain a systematic approach to identifying congenital lesions such as coarctation and patent ductus arteriosus, which may serve as potential infection sites.
Infective endocarditis is a major source of morbidity in CHD.Reference Murdoch, Corey and Hoen8 In this patient, methicillin-sensitive Staphylococcus aureus infection localized at the coarctation site resulted in systemic manifestations and septic embolism. Vegetations in this region may be challenging to visualize using standard TTE or transesophageal echocardiography. Suprasternal echocardiography raised suspicion, while positron emission tomography imaging confirmed infection and identified a saccular aneurysm, which is associated with a higher risk of rupture and mortality.Reference Bansal, Forbes and Aggarwal9 These observations underscore the clinical value of multimodality imaging in the assessment of infective endocarditis in adults with complex CHD.Reference Roque, Pizzi and Cuéllar-Calàbria10
As outlined in Table 1, previously documented adult cases of Shone complex demonstrate substantial anatomical and clinical heterogeneity. Most patients exhibit partial rather than complete forms, and outcomes vary widely based on the specific combination of lesions and associated comorbidities. While some individuals remain clinically stable after corrective or staged interventions, others develop significant complications such as dissection, hypertension, or recurrent infective endocarditis, illustrating the unpredictable natural history of the condition in adulthood. The present report expands the limited adult literature by describing a rare constellation of partial Shone complex complicated by coarctation-site methicillin-sensitive Staphylococcus aureus infection and saccular aneurysm formation. This reinforces the necessity of comprehensive multimodality imaging, meticulous hemodynamic assessment, and coordinated multidisciplinary management in optimizing diagnostic accuracy and clinical outcomes for such complex presentations.
Previously documented cases of Shone complex in adults
Abbreviations: PMV = parachute mitral valve; CoA = coarctation of the aorta; BAV = bicuspid aortic valve; SAS = subaortic stenosis; MS = mitral stenosis; IV = intravenous.
This case illustrates an uncommon adult presentation of partial Shone complex complicated by coarctation-site infective endocarditis and aneurysm formation. Timely diagnosis requires comprehensive echocardiographic assessment, multimodality imaging when indicated, and coordinated multidisciplinary management.
Take-home message
This case highlights the importance of multimodality imaging, early multidisciplinary evaluation, and long-term follow-up in adults with complex CHD, especially those with potential for recurrent infective complications.
Financial support
This research received no specific grant from any funding agency, commercial or not-for-profit sectors.
Competing interests
None.
Patient consent
Written informed consent for publication of this case and accompanying images was obtained from the patient.
