Intracardiac masses include primary and metastatic tumours, as well as cysts and thrombi.Reference Kirklin and Barrat-Boyes1, Reference Bortolotti, Maraglino and Rubino2 Primary tumours have a frequency of 0.001–0.28% in post-mortem studies, of which 75% are benign and 50% are myxomas. Myxomas are seen in all age groups, but most often during the third and sixth decades of life.Reference Taşdemir, Emirogˇullari and Ceyran3 Some can become quite large, resulting in compression of cardiac chambers or vital structures such as conduction tissue or coronary vasculature, as well as obstruction of cardiac valves and outflow tracts. Right atrial myxomas are uncommon, but when present they often originate from the interatrial septum, and conduction disturbances – mainly tachyarrhythmias and atrioventricular block of first degree – are noted as an accompanying feature.Reference Ojji, Ajiduku and Omonua4, Reference Roberts and Ramsdale5 We report a myxoma in both left and right atrium associated with an atrioventricular dissociation in an 18-year-old boy.
Case report
An 18-year-old boy presented to his primary medical doctor with gradually increasing dyspnoea on exertion, worsening lower limb oedema and orthopnoea.
On physical examination, the patient had gallop rhythm, systolic murmur grade 3/6 heard at the apex, a diastolic murmur grade 2/6 at the mitral valve area, liver at plus 2 centimetres under the costal arch, and lower limbs with mild pitting oedema.
The electrocardiogram (Fig 1a) showed an atrioventricular dissociation with an accelerated junctional rhythm. On the bidimensional transthoracic echocardiogram, in the four-chamber view, two atrial masses were seen: a large pedunculated mass (30 millimetres × 42 millimetres) attached to the atrial septum in the region of the fossa ovalis, protruding in the left ventricle during diastole (Fig 1b), and another in the right atrium (45 millimetres × 55 millimetres), very mobile (Fig 1c), protruding in the right ventricle during diastole, causing moderate tricuspid stenosis. The myxoma in the right atrium was attached to the lower part of the interatrial septum. The right atrium and the right ventricle were dilated. The colour Doppler showed a mild mitral valve regurgitation. The left ventricle was not dilated, with good systolic function, and no pericardial effusion. The chest X-ray showed a mild cardiomegaly.
Figure 1 The electrocardiogram of the patient showing an atrio–ventricular dissociation. The left and right atrial myxomas and in the middle image and the left extreme image, respectively.
Pertinent laboratory findings were mild leukocytosis, mild elevated erythrocyte sedimentation rate, and normal room arterial blood gas.
The indication in this case was the immediate surgical resection of the masses. The patient was prescribed furosemide, 20 milligrams, twice a day, spironolactone, 25 milligrams, once a day with a good evolution. While waiting for the next surgical mission in our institution, the patient had a cardiac arrest and died 2 weeks after admission.
Discussion
Myxomas are the most common cardiac tumours in the adult population. They are believed to be derived from the mesenchymal cell precursors. They form intracavitary masses predominantly in the left atrium attached to the fossa ovalis. In children, they are also common in the right atrium. The bi-auricular localisation of the tumours is rare in the general population.Reference Kuroczyński, Peivandi and Ewald6–Reference DePace, Soulen and Kotler8 The symptoms and physical signs are diverse, and echocardiography has proved a sensitive method for their detection. Various electrocardiographic findings have been reported. Paroxysmal or sustained supraventricular arrhythmias occur infrequently and are presumably due to mechanical irritation by the tumour. Evidence of right atrial hypertrophy is not uncommon, but features of right ventricular hypertrophy are unusual.Reference Pinede, Duhaut and Loire9 Myers et alReference Myers, Wong, Tipple and Sanatani10 reported ventricular tachycardia and sudden death in children with intracardiac masses. The atrioventricular node lies in the lowest part of the right atrium, anterior to the ostium of the coronary sinus, and directly behind the attachment of the septal leaflet of the tricuspid valve. In our patient, the myxoma arose at this site, suggesting possible mechanical effects on the underlying conduction tissue or on its artery by vigorous movements of this large prolapsing tumour mass. Alternatively, marked pressure indentation/distortion of the interventricular septum by the prolapsing tumour may also be responsible for the slowing in atrioventricular conduction, and in our case for the atrioventricular dissociation.Reference Colucci and Braunwald11 As soon as an intracardiac mass is diagnosed, surgical intervention is essential, as the clinical picture may deteriorate rapidly to early sudden death. In our case, the absence of immediate surgical intervention led to the death of the patient. The treatment of choice is surgical resection, and the tumour should be resected together with a margin of tissue, to avoid recurrence. The deficit is closed primarily – as in our cases of myxoma – or using a pericardial or prosthetic patch – as in our patient with angiosarcoma. All intracardiac masses are potentially fatal and should be completely resected using proper protection techniques. Surgical treatment should be directed towards the elimination of mechanical obstruction and any other complication.Reference Al-Mateen, Hood and Trippel12
Conclusion
This report suggests that large myxomas originating low in the right atrium close to the atrioventricular node can affect electrical conduction. Immediate surgical treatment should be directed towards the elimination of mechanical obstruction and other complications, which is a challenge in an African context marked by financial limitation and lack of human resources.
