Benign primary cardiac tumour.

• Female > Male
• Incidence of primary cardiac tumours 0.001 – 0.28%.
• 75% are benign tumours, of which 50% are myxomas (0.5 per million population per year).
• Any age group, higher in adults 3rd - 6th decade.
• Familial myxomas younger age in 2nd - 3rd decade.

• Sporadic – 90%.
• Familial – 10%. May form part of Carney's complex (Carney's, LAMB, NAME syndrome) or non-syndromic familial cardiac myxomas ^10,11.

• Originate from the endocardium. Composed of embryonic multipotential mesenchymal cells that persist during cardiac septation which can differentiate into angioblasts, fibroblasts, cartilage and myoblasts.
• Macroscopic – Polypoid > villous, papillary often with associated thrombus
  • Polypoid – Pedunculated > sessile. Smooth, round mass with low tendancy to fragment.
  • Villous - Gelatinous extensions, greater fragmentation and embolic risk.
• Sizes range from 1 – 15 cm, majority 5 – 6 cm with variable growth rate¹⁷

• LA (75 -80%) > RA (15-20%) > LV (3-4%) > RV (3-4%), fig. 1, 2a and 2b.
• LA myxomas origins: IAS at fossa ovalis border(75%) > posterior atrial wall > anterior atrial wall > atrial appendage
• Rare sites - Valvular myxomas (MV > TV > AV > PV) ^3,13, biatrial myxomas ^{1, 2, 12 ,} fig. 3
• Multiple tumours are more commonly seen among familial series.

• Depends on location, size and mobility. Masquerades as other intracardiac pathology, most commonly mitral valve disease¹.
• Embolism 30-40% patients
  • Left sided myxomas Cerebral (stroke), retinal arteries (visual loss)
  • Right sided myxomas Embolize to the pulmonary vasculature resulting in pulmonary hypertension or lethal pulmonary embolism.
  • Risk factors Include a villous surface and tumour vegetation^{1, 19}.
• Intracardiac obstruction LA, RA and ventricular tumours mimic symptoms of mitral stenosis, tricuspid stenosis, and outflow obstruction respectively. Presence of PFO and RA myxoma can cause cyanosis and systemic embolization.
• Valvular regurgitation From tumours impeding atrioventricular valve systolic closure or the to-and-fro movement of the myxoma can traumatize the valve or subchordal structures known as the 'ball wrecking' effect.
• Arrhythmias Atrial or ventricular arrhythmias seen within atrial and ventricular myxomas respectively
• Syncope Results from complete obstruction of MV, TV or arrhythmias
• Sudden cardiac death From MV or TV obstruction, coronary embolization, malignant arrhythmia
• General 40-50% patients experience constitutional symptoms of fatigue, fever, rash, arthralgia, myalgia, weight loss, anemia, raised ESR and CRP, haemolysis, polycythaemia, clubbing. Etiology of symptoms is associated with tumour embolization, complement activation and the secretion of IL6²⁵
• Frequency of symptoms Dyspnoea 80% > palpitations 26% > syncope 16% = pedal oedema 16% > chest pain 13%. Asymptomatic in 20%^{1, 12, 16, 18}
• Syndromes - Carney's Complex (Carney's Syndrome, Syndrome Myxoma)
  • Sporadic or autosomal dominant inheritance (chromosomes 2,12,17)
  • Multiple phenotypic variations expressed but commonly present with intracardiac myxomas, cutaneous disease (lentigines, ephelides, blue naevi), extracardiac myxomas (skin, breast, brain, testis, adrenal and thyroid gland), non-myxomatous tumours (pituitary adenoma, breast fibroadenoma, schwannoma), endocrinopathies (Cushing's syndrome, pituitary and thyroid dysfunction)
  • Multiple in 50% patients with atypical locations and higher incidence of recurrence
  • Present at a younger age, mean 25 yrs and exhibits no gender bias⁴
  • Previous acronyms include NAME (Naevi, Atrial myxoma, Myxoid neurofibroma and Ephelides) and LAMB syndrome (Cutaneous Lentigines, Atrial myxoma, Mucocutaneous myxoma and Blue naevi) which have been collated under Carney's complex¹⁰

• Exclude other intracardiac masses
  • Chest XRay Enlarged LA, tumour calcification, pulmonary edema
  • CT/MRI Good delineation of size, extent and solid/cystic tumour content
  • Angiography Not used for diagnosis. Tumour depicted by intracavity filling defect. Coronary angiography used to identify associated coronary disease in patients above 40 yrs, branches of the coronary system supplying the tumour, coronary tumour thrombosis and aneurysmal dilatations.
  • Echocardiograpy TEE provides better tumour definition, identifies multiple masses, location, extent of tumour attachment and associated thrombus compared to TTE. See below echo details.

• Exclude other intracardiac masses
  • Benign tumours Lipoma, papillary fibroelastoma, fibroma, angioma, rhabdomyoma
  • Malignant tumours Angiosarcoma, rhabdosarcoma, synovial sarcoma, others myofibroblastic differentiated sarcomas (fibrosarcoma, osteosarcoma, histiocytoma, leiomyosarcoma), lymphoma, metastases
  • Thrombus
    
  • Vegetation

• Curative (excisional biopsy)
• Prevent embolic complications

• Bicaval and aortic cannulation enables access of the RA or LA. Low or high lying RA tumours may necessitate SVC/brachiocephalic and femoral cannulation or deep hypothermic circulatory arrest, fig 5 and 6.
• Surgical excision of tumour and stalk with 5 mm margin of normal tissue is recommended to reduce the risk of recurrence with direct or pericardial/Dacron patch closure of ASD. Avoid tumour fragmentation on excision with good irrigation and suction to reduce the risk of distal embolization.
• Valvular damage will necessitate valve repair/replacement.

• Infected myxoma Rare complication with the formation of vegetations²⁰

• Malignant transformation Controversial. Associated with multiple distant metastasis of recurrent cardiac myxomas⁷

• Operative mortality 0 – 3%. Low risk of post-operative arrhythmias or permanent pacemaker.
• Recurrence
  • Sporadic myxomas 1 – 3%. Due to incomplete resection or intraoperative displacement of tumour material.
  • Familial Myxomas 12 – 22%. Due to multifocal genesis.
  • Monitoring IL6 could be used to follow patients for recurrence^6,25,26
  • Follow-up echocardiography recommended butinterval remains controversial. Closer follow-up required for familial tumours, atypical locations, younger patients, multiple lesions or altered genotype.

• Fig. 1a 2D midesophageal 4 chamber demonstrating a smooth polypoid left atrial myxoma.
• Fig. 1b 3D full volume of the MV LAX displaying a large left atrial myxoma prolapsing through the mitral valve.
• Fig. 1c 3D full volume of a left atrial myxoma viewed from the left atrium.
• Fig. 1d 3D full volume of the RV inflow demonstrating a left atrial myxoma attached to the interatrial septum.
• Fig. 2a 2D midesophageal RV in/outflow view demonstrating a myxoma adherent to the right ventricular free wall in a patient with Carney's complex.
• Fig. 2b 2D midesophageal RV in/outflow view demonstrating a myxoma adherent to the right ventricular free wall in a patient with Carney's complex. RA = Right atrium, RV = Right Ventricle, LV = Left Ventricle.
• Fig. 3 2D midesophageal 4 chamber view displaying a biatrial myxoma.
• Fig. 4 Coronal cardiac CT slice demonstrating a left atrial myxoma.
• Fig. 5 Hemorrhagic left atrial myxoma.
• Fig. 6a Intraoperative view of a large left atrial myxoma accessed through the right atrium whilst on cardiopulmonary bypass
• Fig. 6b Large polypoid left atrial myxoma
• Fig. 7 Left atrial myxoma with finger-like villous surface projections
• Fig. 8 2D midesophageal 4 chamber view of a left atrial myxoma with bright calcific and echolucent necrotic areas
• Fig. 9 Left atrial myxoma prolapsing through the mitral valve causing 'functional' mitral stenosis and incomplete mitral valve closure leading to mitral regurgitation
• Fig. 10 Transmitral pulse wave Doppler demonstrating mild mitral stenosis

• Single or multiple masses
• Location + size + mobility
• Attachment site + length/width stalk
• Smooth or villous surface appearance, fig. 1 and 7
• Calcified echogenic area
• Hemorrhagic (necrotic) echolucent areas, fig. 8
• Prolapse of myxoma through atrioventricular valve. Depends on size and presence of stalk. Tumours which do not prolapse have no stalk or are either too small or too large
• Trauma to valvular + subchordal structures

• Flow acceleration through stenotic valves
• Valvular regurgitation, fig.9

• Severity valvular stenosis peak/mean pressure gradients, PHT, DT, fig. 10
• Severity valvular regurgitation

• Benign, small, mobile mass located on atrioventricular or semilunar valves ^22,23.  Usually on left side of the heart of older patients and typically downstream of valve (LV side in MV PFE, aortic side in AV PFE)
• Associations – thromboembolic complications

• Benign, well encapsulated and homogenous tumours located at any position within the heart  and demonstrates no age or gender bias ^22,23.
• Subepicardial tumours may compress the heart and cause a pericardial effusion.
• Subendocardial tumours are usually found within the RA and LV and may lead to chamber obstruction.
• Fatty infiltration of IAS spares fossa ovalis producing a dumb-bell shaped septum which is > 1.5 cm thick.  Lipomas within IAS and myocardium may cause arrhythmias. IAS lipomas are more prevalent among elderly, women and obese patients.

• Benign intraventricular tumour, well demarcated mass with foci of calcification, 1-10 cm diameter
• Associations – childhood tumour, may lead to ventricular obstruction

• Benign, well circumscribed, pedunculated ventricular mass. Maybe multiple in number.

• Associations – commonest pediatric tumour, tuberous sclerosis (seizures, developmental delay, multiple solid end organ tumours) and may lead to ventricular obstruction

• Benign subendocardial nodules, 2-4 cm diameter, usually within interventricular septum,
• Associations – tumour blush on angiography ¹⁴

• Malignant tumour, broad base nodular or lobular mass, commonly located within the RA close to the IVC.  Locally invasive with spread to pleura, mediastinum and pericardium with associated effusion.
• Associations – male predominance, peak incidence in 4th decade, commonest sarcoma

• Located in any cardiac chamber
• Associations – male predominance, 2nd commonest cardiac sarcoma

• Commonest malignant cardiac tumour from distal solid organ and haematological malignancies.
• Frequency in descending order - leukaemia (54%) > melanoma (34%) > bronchogenic > sarcoma > breast > esophageal > ovarian > kidney > colonic ²²

• Vegetation adherent to myxoma.

• Secondary to left sided valvular obstruction/regurgitation.