5.1. Imaging Modalities
Initial non-specific investigations such as ECG (electrocardiogram) and
CXR (chest x-ray) serve as preliminary tools in the diagnostic workup of
CaHD. The ECG might reveal low-voltage QRS complexes more frequently in
CaHD patients than in those without the disease, alongside non-specific
ST-T changes, PR prolongation and sinus tachycardia, hinting at the
underlying cardiac involvement.20 Conversely, CXR may
show an enlarged cardiothoracic ratio, indicative of cardiomegaly,
primarily due to right-sided chamber enlargement, although these
findings are not sensitive or specific to CaHD.21
Ultimately, transthoracic echocardiography is most commonly used in the
diagnosis of CaHD, offering more tangible insights into the valvular and
subvalvular apparatus affected by the disease. Echocardiographic
hallmarks of CaHD include thickening and reduced mobility of the
tricuspid and pulmonary valve leaflets, leading to regurgitation and
stenosis.22 A distinctive ”dagger-shaped”
continuous-wave Doppler profile is emblematic of severe tricuspid
regurgitation, illustrating the equalisation of right atrial and
ventricular pressures23. Such echocardiographic
features are pathognomonic, especially in the absence of exposure to
appetite suppressants or ergot-derived agents that could mimic similar
valvular abnormalities. The echocardiographic evaluation should
encompass multiple views of each valve, especially the tricuspid valve
visualised through various echocardiographic windows, to ensure a
comprehensive assessment.16 The right atrium and
ventricle typically exhibit enlargement due to volume overload, with
paradoxical motion of the interventricular septum observable in advanced
stages.15 Despite these significant structural
changes, right ventricular function often remains preserved until the
late disease phase.
TOE (Transoesophageal echocardiography) is subsequently recommended if
transthoracic echocardiography fails to provide adequate visualisation
of the cardiac structures, offering superior images of the valve
leaflets and subvalvular apparatus.2 Similarly,
cardiac magnetic resonance imaging (MRI) and 64-slice computed
tomography (CT) are also used as critical adjuncts, particularly for
evaluating the pulmonary valve when echocardiographic visualisation is
challenging.24 These modalities excel in providing
clear anatomic and functional information, facilitating the assessment
of right ventricular function and aiding in the evaluation of myocardial
metastases, which although rare, can present as homogenous
well-circumscribed masses. Table 3 summarises the advantages,
disadvantages, and key notes of primary and secondary imaging modalities
employed in diagnosing CaHD.