A 20-year-old man presented to us with confusion and generalised skin rash in April 2010. On examination, he was febrile and in shock. He was detected with a mitral regurgitation murmur and mild neck stiffness. His white cell count was elevated and platelet count was low. His liver function was mildly impaired. Chest X-ray showed acute pulmonary oedema. Computed tomography (CT) scan of brain showed multiple haematomas in his left occipital lobe and right parietal lobe, and subarachnoid haemorrhage (Fig 1a). Blood culture showed methicillin-sensitive Staphylococcus aureus (MSSA).

Transthoracic echocardiogram showed a huge vegetation measuring 4 cm x 2.22 cm attached to the base of anterior leaflet of mitral valve, resulting in perforation of the base of leaflet with severe mitral regurgitation (Fig 2a). The diagnosis was infective endocarditis due to MSSA, complicated by ruptured chordae tendineae with severe acute mitral regurgitation and multiple, septic cerebral emboli. The source of infection was suspected to be the skin. He was treated with high-dose intravenous cloxacillin and gentamicin. His heart failure was treated with frusemide.

Three weeks later, he complained of sudden onset of right lower limb pain and numbness. His CT angiogram showed a large saddle embolus in the lower abdominal aorta (Fig 1b). Emergent right-sided lower femoral and bilateral iliac artery embolectomy was performed.

On postoperative echocardiogram, the size of the vegetation was found to be decreased to 1.5 cm in diameter (Fig 2b). He then underwent mitral valvular replacement about 1 week later.

The incidence of community-acquired native-valve endocarditis in western countries ranges from 1.7 to 6.2 cases per 100 000 person-years, with a male-to-female ratio of 1.7:1.1 Recently, the incidence of S aureus infective endocarditis is on the rise. Infective endocarditis due to S aureus is more common among young adults, especially the intravenous injection drug users.1 Usually, the tricuspid valve is involved.2

Extra cardiac complications of infective endocarditis usually include embolic events. The rate of embolic events has a relationship with the initiation of antibiotic therapy. In one study, after the commencement of appropriate antimicrobial treatment, the rate of embolism fell from 13 per 1000 patient-days during the first week of treatment to fewer than 1.2 per 1000 patient-days 2 weeks after treatment.3 A review involving 281 patients with suspected infective endocarditis demonstrated that the incidence of embolic events was greater with mitral than aortic valve vegetations (25% vs 10%).4 For mitral valve vegetations, the rate of embolism was higher if these were attached to the anterior leaflet rather than posterior leaflet. Some studies showed that the rate of embolism correlated with the size of vegetation, with the risk being higher if the diameter of the vegetation was greater than 1 cm.1

Up to 65% of embolic events of infective endocarditis are associated with neurological involvement. Such neurological complications account for 20% to 40% of all patients with infective endocarditis.5 Saddle embolus is a large embolus that straddles the arterial bifurcation and, thus, blocks both branches of the aorta. Saddle embolisation at the aortic bifurcation is an uncommon but serious complication. From the literature search, only eight cases were reported and all were caused by fungal endocarditis.6

1. Mylonakis E, Calderwood SB. Infective endocarditis in adults. N Engl J Med 2001;345:1318-30. Crossref

2. Hecht SR, Berger M. Right-sided endocarditis in intravenous drug users. Prognostic features in 102 episodes. Ann Intern Med 1992;117:560-6. Crossref

3. Heiro M, Nikoskelainen J, Engblom E, Kotilainen E, Marttila R, Kotilainen P. Neurologic manifestations of infective endocarditis: a 17-year experience in a teaching hospital in Finland. Arch Inern Med 2000;160:2781-7. Crossref

4. Rohmann S, Erbel R, Görge G, et al. Clinical relevance of vegetation localization by transoesophageal echocardiography in infective endocarditis. Eur Heart J 1992;13:446-52.

5. Røder BL, Wandall DA, Espersen F, Frimodt-Møller N, Skinhøj P, Rosdahl VT. Neurologic manifestations in Staphylococcus aureus endocarditis: a review of 260 bacteremic cases in nondrug addicts. Am J Med 1997;102:379-86. Crossref

6. Kawamoto T, Nakano S, Matsuda H, Hirose H, Kawashima Y. Candida endocarditis with saddle embolism: a successful surgical intervention. Ann Thorac Surg 1989;48:723-4. Crossref

A 72-year-old woman presented with decreased exercise tolerance since 2007. Based on a transthoracic echocardiogram (TTE) in another hospital, the patient was diagnosed to have perimembranous ventricular septal defect (VSD) with pulmonary hypertension. Upon referral to our unit in 2013, a more meticulous TTE examination revealed a mid-cavitary stenosis in the right ventricle (RV) which was best appreciated in the parasternal short axis and the subcostal short axis view (Figs 1 and 2). The systolic pressure gradient measured by continuous-wave Doppler between the two RV chambers was markedly elevated to 80 mm Hg. There was also severe tricuspid regurgitation with a dilated RV. The findings were confirmed on a transoesophageal echocardiogram (TEE) and the diagnosis was revised as double-chambered right ventricle (DCRV) with perimembranous VSD (Fig 3). A right heart catheterization study showed a stenotic band over the right ventricular outflow tract (RVOT) [Fig 4]. The systolic pressure at the proximal RV chamber was markedly elevated to 75 mm Hg. However, we failed to manipulate the catheter across the stenotic band to measure the pressure gradient across the two chambers. The coronary angiographic results were normal. The patient was referred to cardiothoracic surgeons and open heart surgery was undertaken. After right ventriculotomy, the anomalous infundibular muscle bundle and a small perimembranous VSD were identified. The obstructive muscle bundle was resected and VSD was repaired. The tricuspid valve was repaired by means of annuloplasty. In postoperative TTE, the previously noted high pressure gradient across the RVOT was no longer present. The right ventricular systolic pressure normalised to 15 mm Hg.

Double-chambered RV is characterised by the presence of an anomalous muscle bundle (AMB), which divides the RV into two separate chambers, namely, the proximal high-pressure and the distal low-pressure chambers. The AMB is considered a hypertrophied moderator band or the accentuated septoparietal trabeculation.1 2 These congenital anatomical substrates and other acquired haemodynamic factors lead to the development of DCRV.

Double-chambered RV is an uncommon condition and it is only seen in 0.5% to 2% of all cases of congenital heart disease.3 Most cases are diagnosed in childhood or adolescence before the age of 20 years. The occurrence in adults is rare and has only been described in case reports and small case series. About 80% to 90% of DCRV cases are associated with VSD, or sometimes with other congenital cardiac anomalies. Patients with DCRV usually present with shortness of breath and decreased exercise tolerance, but they may also have atypical symptoms such as chest pain, dizziness, and syncope.

The irregular shape and retrosternal position of RV, and its close proximity to the precordium impose diagnostic difficulty by TTE, especially in adults. Quite often, the mid-cavitary turbulent jet on TTE is mistaken as an intracardiac shunt, and the high RV systolic pressure is falsely interpreted as pulmonary hypertension. In a case series, only 15.6% of patients with DCRV could be correctly diagnosed by TTE.3 A high clinical suspicion and awareness of this clinical entity are required for precise diagnosis. The subcostal view of TTE may sometimes provide better visualisation of the RV and RVOT. It also allows better alignment of the turbulent jet for pressure gradient measurement. When TTE is not confirmative, TEE and cardiac catheterization serve as complementary tools. The use of cardiac magnetic resonance imaging as non-invasive assessment is now emerging as an alternative diagnostic modality for DCRV.

Surgical repair of RV by resection of the AMB is indicated in symptomatic patients, and it yields excellent long-term haemodynamic and functional results.4 Surgical treatment is also suggested in asymptomatic patients who have significantly elevated midventricular pressure gradient, that is, >40 mm Hg as the obstruction can progress rapidly over just a few years.5

1. Wong PC, Sanders SP, Jonas RA, et al. Pulmonary valve-moderator band distance and association with development of double-chambered right ventricle. Am J Cardiol 1991;68:1681-6. CrossRef

2. Alva C, Ho SY, Lincoln CR, et al. The nature of the obstructive muscular bundles in double-chambered right ventricle. J Thorac Cardiovasc Surg 1999;117:1180-9. CrossRef

3. Hoffman P, Wojcik AW, Rozanski J, et al. The role of echocardiography in diagnosing double chambered right ventricle in adults. Heart 2004;90:789-93. CrossRef

4. Telagh R, Alexi-Meskishvili V, Hetzer R, et al. Initial clinical manifestations and mid- and long-term results after surgical repair of double-chambered right ventricle in children and adults. Cardiol Young 2008;18:268-74. CrossRef

5. Oliver JM, Garrido A, Gonzalez A, et al. Rapid progression of midventricular obstruction in adults with double-chambered right ventricle. J Thorac Cardiovasc Surg 2003;126:711-7. CrossRef