Answers

Short answers

1 A transient loss of consciousness, chest pain on exertion, and a heart murmur are suspicious of a cardiac syncope.

2 The next diagnostic step should be transthoracic echocardiography.

3 Patients with a cardiac myxoma may be asymptomatic or they may present with one or more of the classic triad of cardiac, embolic, or systemic signs.

4 The treatment of choice is surgical excision. The survival rate is similar to that of the general population.

Long answers
1 Differential diagnosis
Syncope is a symptom, defined as a self limited loss of consciousness caused by a transient global cerebral hypoperfusion, that often leads to falling. Syncope may be neurally mediated, cardiogenic, cerebrovascular in origin, or caused by orthostatic hypotension. It must be differentiated from other "non-syncopal" conditions associated with a transient loss of consciousness. Cardiac syncopes can be caused by structural cardiac defects or cardiopulmonary disease, such as valvular heart disease, obstructive cardiomyopathy, myxoma, pulmonary embolism, or pulmonary hypertension; they can also be caused by primary cardiac arrhythmias, such as sinus node dysfunction, atrioventricular conduction system disease, or paroxysmal supraventricular and ventricular tachycardias (box).¹

Causes of a transient loss of consciousness Syncopal causes1    Neurally mediated (reflex) Vasovagal syncope (common faint) Carotid sinus syncope Situational syncope (for example, during micturition, defecation, cough, or after exercise)    Orthostatic hypotension Autonomic failure Drug induced Volume depletion    Structural cardiac disease or cardiopulmonary disease Cardiac valvular disease Obstructive cardiomyopathy Myxoma Pericardial tamponade Pulmonary embolus or hypertension    Cardiac arrhythmias Sinus node dysfunction Atrioventricular conduction system disease Paroxysmal supraventricular or ventricular tachycardias Inherited syndromes (such as long QT syndrome, Brugada syndrome) Malfunction of an implanted device (pacemaker or implantable cardioverter defibrilator)    Cerebrovascular Vascular steal syndromes Non-syncopal causes Metabolic disorders (such as hypoglycaemia, hypoxia) Epilepsy Intoxications (such as alcohol and drugs) Psychogenic disease

Epidemiological studies have shown that syncope is a common presenting problem, accounting for up to 5% of emergency room visits.¹ Initial evaluation of patients with a transient loss of consciousness consists of careful history taking and physical examination, a standard electrocardiogram, and measurement of supine and upright blood pressure.¹

Ask about the patient’s position and activity just before the attack and predisposing factors such as crowded warm places or prolonged standing, as well as vegetative symptoms like nausea, blurred vision, or sweating. Eyewitnesses can provide important information about duration, abnormal movements, changes in skin colour, and the period of time until complete reorientation.

Questions about personal and family medical history, especially cardiac disease or neurological disease, current drugs, and previous events complete the picture.

Several population based studies have shown that in as many as 45% of patients with a syncope, a cause can be identified from the history and physical examination alone. In most young patients without heart disease a definite diagnosis of neurally mediated or orthostatic syncope can be made without further investigations.¹

One year mortality is consistently higher (18-33%) in patients with a cardiac syncope than in those with a non-cardiac (0-12%) or unexplained syncope (6%).¹ Further investigation is therefore essential if the history, physical findings, or electrocardiography are suggestive of a cardiac syncope.

2 Next diagnostic step
The next diagnostic step is a transthoracic echocardiogram. This test and a subsequent transoesophageal echocardiogram showed a mobile pediculed mass measuring 4x3 cm that originated from the left ventricular septum. During systole it prolapsed almost entirely through the aortic valve into the aorta ascendens, causing a profound obstruction of the left ventricular outflow tract (fig 1).

View larger version (49K): [in this window] [in a new window] [PowerPoint Slide for Teaching]   Fig 1 Top: transthoracic echocardiographic images. Bottom: transoesophageal echocardiographic images. Both investigations show a mobile mass (arrows) prolapsing into the left ventricular outflow tract and through the aortic valve during systole. LA = left atrium, LV = left ventricle, RA = right atrium, RV = right ventricle, A = aorta

 
We made a presumptive diagnosis of a left ventricular myxoma on the basis of the morphological appearance and location of the mass. Potential differential diagnosis such as a massive vegetation (for example, in fungal endocarditis) or a papillary fibroelastoma seemed unlikely because the mass had no connection to the aortic valve or the mitral valve. Other conditions that may present with a syncope and a systolic heart murmur in a young patient, such as a valvular stenosis of a congenitally bicuspid aortic valve or hypertrophic cardiomyopathy, were definitely excluded. Transthoracic echocardiography is the screening test of choice for cardiac tumours, with a sensitivity reaching 95%.²

At present a multimodal imaging approach is recommended in patients with a suspected cardiac myxoma.³ Cardiac magnetic resonance imaging shows in detail the location, insertion site, and size of the tumour. Tissue characteristics and signs of neovascularisation provide important information if the differentiation between cardiac myxoma and cardiac thrombus is uncertain after echocardiography. Multidetector computed tomography or invasive coronary angiography are the investigations of choice to rule out concomitant coronary artery disease or anomalies before surgery.

3 Clinical signs, potential risks, and complications
Cardiac myxomas are the most common primary tumours of the heart. They are of endocardial origin, and about three quarters of them originate in the left atrium.^{4 5} Cardiac myxomas of the left ventricle are therefore extremely rare.

The clinical symptoms of cardiac myxomas are determined by their location, size, mobility, and surface.^{4 5} Patients may be asymptomatic or present with one or more of the classic triad of cardiac, embolic, or systemic signs.⁵

Cardiac signs such as cardiac failure, syncope, thoracic pain, palpitations, dyspnoea, or cough are the most common clinical presentations. Systolic, and more commonly diastolic, murmurs (because tumours are more often located in the left atrium) are heard in up to 89% of patients with a cardiac myxoma.^{2 4} Findings on electrocardiography are non-specific, but abnormalities such as left atrial hypertrophy, repolarisation, or conduction disorders may be found in up to 62% of patients.²

Embolism occurs in 30-40% of patients and significantly more often in cardiac myxomas with a villous surface.^{4 5} Several cases of myocardial infarction,^{6 7} stroke,^{8 9} retinal arterial occlusion,¹⁰ and sudden death¹¹ have been described.

Unspecific systemic signs such as fever, fatigue, arthralgia, myalgia, and weight loss are seen in 20-35% of cases.^{4 5} They are often accompanied by anaemia or a raised erythrocyte sedimentation rate. These symptoms are mediated by the production and release of interleukin 6 by the myxoma itself.^{12 13} Raised interleukin 6 concentrations return to normal and systemic symptoms disappear after excision of the tumour.^{14 15}

Cardiac myxomas can occur in all age groups but are particularly common between the third and sixth decade, and there is a female preponderance.⁵ Most cardiac myxomas are sporadic. However, familial myxoma occurs as part of the Carney’s complex. This complex is a multiple neoplasia syndrome characterised by spotty skin pigmentation, cardiac and cutaneous myxomas, schwannomas, and endocrine tumours.¹⁶

4 Management and prognosis
The treatment of choice is surgical removal. In our patient coronary artery anomalies could be excluded by multidetector computed tomography coronary angiography. Cardiac magnetic resonance imaging showed a left ventricular mass with signs of myxomatous tissue and neovascularisation. After cardiopulmonary bypass the tumour was excised via transaortic access in cardioplegic arrest (fig 2). Postoperatively, the diagnosis of a cardiac myxoma was confirmed histologically.

View larger version (79K): [in this window] [in a new window] [PowerPoint Slide for Teaching]   Fig 2 Intraoperative images showing transaortic access (Ao) and the myxoma (arrow)

 
Survival after resection of primary cardiac tumours is excellent. The survival rate of patients with sporadic cardiac myxomas is not significantly different from that of the general population.¹⁷

The risk of recurrence of a sporadic myxoma is low (1-3%). But in Carney’s complex, because of its multigrowth potential, recurrence ranges between 12% and 22%. Echocardiographic follow-up twice yearly is therefore recommended.⁴

Outcome
Six months after surgery our patient was free of any symptoms and echocardiography showed no signs of recurrence.

Cite this as: BMJ 2009;339:b3323