Assessment of Right Heart Dilatation With Magnetic Resonance Imaging and Multidetector Computed Tomography Angiography: Spectrum of Disease Findings
Introduction
Right heart chamber enlargement can be due to a diverse and heterogeneous group of conditions with highly varied clinical symptoms and signs. The more common causes include smoking-related lung disease and thromboembolic disease. Causes of right heart enlargement can be broadly classified into congenital cardiac causes, acquired cardiac causes, and pulmonary vascular diseases. An appreciation of right atrial and ventricular enlargement on imaging studies is important as it may signify a previously undiagnosed cardiopulmonary disease or congenital anomaly. Right ventricular dilatation can be a precursor to right heart failure, and prompt diagnosis enables appropriate initiation of pharmacologic or surgical treatment strategies.
A number of imaging modalities can been used to evaluate the right heart, of which, cardiovascular magnetic resonance (CMR) imaging and multidetector computed tomography (MDCT) angiography are often the most useful for establishing a definite diagnosis. In this article, we review the spectrum of causes of right heart chamber enlargement in adults with particular focus on the role of CMR and MDCT.
Section snippets
Chest x-Ray
A chest x-ray is the first-line test in most cardiopulmonary diseases. Mild enlargement of the right atrium and ventricle is usually not appreciated, but more extensive ventricular enlargement causes elevation of the cardiac apex and bulging of the left heart contour. Elevated pulmonary artery pressures can cause enlargement of the pulmonary conus shadow.1 When the right atrium dilates, it causes prominence of the right heart border.
Transthoracic Echocardiography (TTE)
TTE is the first-line investigation for suspected structural
Congenital and Acquired Cardiac Shunts
A left to right shunt causes right heart dilatation via persistent elevation of right heart pressures secondary to remodeling of the pulmonary vasculature with arteriolar smooth muscle hypertrophy and development of plexiform lesions. A left to right shunt may reverse when the right heart pressure approaches or exceeds systemic vascular resistance.9 TTE has traditionally been the primary imaging tool for evaluation of cardiac shunts, but CMR is a useful adjunct in selected cases, for example,
Right Ventricular Muscle Abnormalities
There are a number of conditions that affect the right ventricular myocardium causing secondary dilation of the RV. These are usually best assessed by CMR as this modality gives the most comprehensive anatomical, morphologic, and functional assessment.
Lung Parenchymal Disease
MDCT is the modality of choice for assessment of the lung parenchyma. Lung disease is the most common cause of pulmonary arterial hypertension in adults, which can subsequently lead to right heart dilatation and dysfunction. Advanced pulmonary fibrosis and chronic obstructive pulmonary disease are the most common causes, and the MDCT features of these conditions have been well described.
The MDCT vascular features of pulmonary hypertension of any cause include dilation of the main pulmonary
Congenital Absence of Pericardium
Congenital absence of the pericardium is a rare condition where patients present with paroxysmal nonexertional stabbing chest pain. A small proportion of patients are asymptomatic. The absence of pericardium can be partial or complete and can be assessed on chest x-ray, TTE, or CMR. The pathognomonic feature on all imaging modalities is that there is a “tongue” of lung tissue interposing between the main pulmonary artery and thoracic aorta (Fig 13). Imaging can also demonstrate marked
Conclusion
Right heart dilatation is an important entity, and an appreciation of the pathophysiology, causes, and imaging features is paramount in recognizing and potentially ameliorating the development of right heart dysfunction or adverse cardiac events. Chest x-ray and TTE have traditionally been, and still are, the mainstay in initial evaluation of right heart dilatation; however, recent advances in both MDCT and CMR now permit a comprehensive assessment of the causes and consequences of right heart
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