Final The Echo Manual DIGITAL

Chapter 12 Pericardial Diseases

CHAPTER 12 PERICARDIAL DISEASES

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than 40% in tricuspid E velocity, and increased diastolic flow reversal with expiration in the hepatic vein should be demonstrated to establish the diagnosis of constrictive pericarditis (1) (Fig. 12-20). Thus, the patterns of respira- tory variation in LV and RV filling are similar to those in cardiac tamponade, though the initiating event in the ventricular interdependence is different between two conditions (19). In up to 50% of patients with constrictive pericarditis, the respiratory variation in mitral E velocity may be less than 25% (36). This observation could reflect: 1) lower sensitivity of mitral E velocity variation in detecting more severe constriction when LA pressure is markedly increased and 2) mixed constriction and restriction physiology. When LA pressure is markedly increased from severe constriction, mitral valve opening occurs on the steep portion of the LV pressure curve, where respiration has little effect on the transmitral pressure gradient (37). Historically, Doppler echocardiography was repeated after preload reduction maneuvers, such as head-up tilt or assumption of the sit- ting position (37). However, this maneuver is rarely neces- sary now since the application of tissue Doppler imaging of mitral annulus longitudinal motion can identify con- striction in the absence of respiratory variation in mitral inflow velocities. As emphasized below, constrictive peri- carditis should be suspected when the mitral annulus early diastolic medial (e ′ ) velocity is preserved ( ≥ 8 cm/s) in patients with clinical evidence of heart failure, especially in the setting of a restrictive LV filling pattern (i.e., mitral E/A ≥ 1.5, deceleration time <160 milliseconds). Tissue Doppler imaging of mitral annular diastolic longitudinal velocity reveals contrasting findings in

Diastolic filling (or distensibility) of the LV and RV is mutually dependent because the overall cardiac volume is relatively fixed within the noncompliant and adher- ent pericardium. Hence, reciprocal respiratory changes occur in the filling of the LV and RV. With inspiration, the decreased filling in the LV described above allows for increased filling in the RV to accommodate augmented venous return. This increased ventricular interaction manifests itself by a leftward shift of the ventricular sep- tum and an exaggerated increase in the tricuspid inflow E velocity and hepatic vein diastolic forward flow veloc- ity (Fig. 12-20). With expiration, LV filling recovers and systemic venous return decreases, causing the ventricular septum to shift to the right, limiting RV filling. Tricuspid inflow E velocity decreases and hepatic vein diastolic forward flow decreases, with pronounced flow reversal during diastole. Typically, hepatic vein diastolic forward flow velocity is higher than systolic forward flow velocity, corresponding to the systemic y and x venous waveforms, respectively. Respiratory variation in the pulmonary valve regurgitation Doppler profile, arising from dissociation of pressures within the intrathoracic pulmonary artery and the encased RV, also occurs (35). An inspiratory decrease in pressure within pulmonary artery reduces the pulmo- nary artery − RV pressure gradient, resulting in early dia- stolic cessation of regurgitation during inspiration. This Doppler echocardiographic sign has relatively low sensi- tivity and specificity for the diagnosis of constrictive peri- carditis (35). Using the same formula for calculating percent veloc- ity change as in tamponade, a respiratory variation of greater than 25% in the mitral inflow E velocity, greater

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FIGURE 12-20 Typical mitral inflow and hepatic vein pulsed wave Doppler recordings in constrictive pericarditis along with simultaneous recording of respiration ( bottom ) (onset of inspiration at upward deflection and onset of expiration at downward deflection). Left: The first mitral inflow is at the onset of inspiration, and the fourth mitral inflow is soon after the onset of expiration. Mitral inflow E velocity is decreased with inspiration (1st and 6th beats). Right: With expiration, there is a marked diastolic flow reversal ( arrow ) in the hepatic vein (6th beat soon after the downward deflection of respirometer recording). Insp , inspiration; Exp , expiration.

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