Right Ventricular Diastolic Collapse by Cardiac Magnetic Resonance Imaging
Although the detection of pericardial effusion is relatively easy with 2-dimensional (2-D) echocardiography, the noninvasive physiological assessment of pericardial tamponade is more difficult. Pericardial tamponade is best assessed by simultaneous measurement of right atrial or ventricular pressure and intrapericardial pressure. In order to justify invasive pericardiocentesis, noninvasive data are usually acquired before pursuing a potentially risky invasive procedure. One of the earliest signs of tamponade is diastolic collapse of the right ventricle (RV), usually in early diastole, indicating that intrapericardial pressure is transiently exceeding RV filling pressure during diastole. This finding on 2-D echocardiography has been correlated with a decrease in cardiac output and impending tamponade.1–3 However, complete visualization of the RV free wall is frequently difficult with 2-D echocardiography because of the limitations of the intercostal echo “window.” Imaging of RV free-wall motion can be accomplished in true anatomic planes with cardiac magnetic resonance imaging (MRI) in multiple projections with relative ease, enhancing the ability of this technique to detect abnormalities of RV free-wall motion.
The value of cardiac MRI in detecting early diastolic collapse of the RV was demonstrated in a 66-year-old woman with metastatic breast cancer. She was admitted to the hospital with progressively worsening dyspnea, fatigue, and weakness. Her chest x-ray demonstrated an enlarged cardiac silhouette. The 12-lead ECG demonstrated low voltage (Figure 1). Cardiac examination revealed moderate distention of the jugular venous pulsation but no pulsus paradoxus. A 2-D echocardiogram revealed a moderate-sized pericardial effusion but no anatomic or Doppler evidence of tamponade. The free wall of the RV was not completely visualized in the short-axis and apical 4-chamber views, despite multiple attempts by multiple experienced echocardiographers (Figures 2 and 3⇓).). Doppler interrogation of the tricuspid and mitral inflow tracts during respiration did not demonstrate exaggeration of inflow to suggest tamponade, although inspiratory effort was poor (Figure 4). A cardiac MRI study was performed within 24 hours of the 2-D echocardiogram/Doppler study and demonstrated a circumferential pericardial effusion. The cardiac MRI 2-chamber views of the ventricles revealed early diastolic collapse of the RV free wall along the midsegment of the RV (Figure 5). This finding was also evident in the sagittal view through the pulmonary outflow tract (Figure 6) but not as clearly in the 4-chamber view (Figure 7). Pericardiocentesis was performed under fluoroscopy, and 400 mL of pericardial fluid was aspirated. The systemic blood pressure increased from 110/66 to 140/68 mm Hg, and the patient noted complete relief of her symptoms. A follow-up 2-D echocardiogram showed resolution of the pericardial effusion, but the free wall of the RV could still not be well visualized (Figure 8).
Cardiac MRI is capable of acquiring true short-axis views of the ventricles from base to apex, allowing detection of segmental RV diastolic collapse that is not evident with 2-D echocardiography because of its thoracic window limitations. The more-limited spatial resolution of echocardiography relative to MRI caused the size of the pericardial effusion in this case to be underestimated by the 2-D echo. In addition, 2-D echocardiography is usually not capable of visualizing the RV outflow tract in the sagittal view, which is easily accomplished with cardiac MRI. This case demonstrates the value of cardiac MRI in the assessment of patients with pericardial effusion. Although not used for this patient, MRI phase-velocity mapping of the tricuspid and mitral valves can offer further physiological data in the evaluation of patients with suspected pericardial disease.4
The online-only Data Supplement is available with this article at http://circ.ahajournals.org/cgi/content/full/118/8/e122/DC1.
Leimgruber PP, Klopfenstein HS, Wann LS, Brooks HL. The hemodynamic derangement associated with right ventricular diastolic collapse in cardiac tamponade: an experimental echocardiographic study. Circulation. 1983; 68: 612–620.
Shabetai R. Pericardial effusion: haemodynamic spectrum. Heart. 2004; 90: 255–256.
Sagrista-Sauleda J, Angel J, Sambola A, Alguersuari J, Permanyer-Miralda G, Soler-Soler J. Low-pressure cardiac tamponade. Circulation. 2006; 114: 945–952.