Diagnosis of Constrictive Pericarditis
Diagnosis of Constrictive Pericarditis
Abstract & Commentary
By Michael Crawford, MD
Source: Talreja, DR, et al. Constrictive pericarditis in the modern era. J Am Coll Cardiol. 2008;51:315-319
The differentiation of constrictive pericarditis from restrictive cardiomyopathy can be difficult, but the treatment implications are great. Constrictive pericarditis (CP) can potentially be cured by surgery, whereas little can be done for restrictive cardiomyopathy (RCM). Thus, this group from the Mayo Clinic tested cardiac catheterization criteria in 100 sequential patients referred for cardiac catheterization to distinguish CP vs RCM. All the patients had symptomatic right heart failure, with elevated jugular venous pressure and no evidence of left heart disease. Sixty-one patients were referred for pericardiectomy and 23 were referred to right heart biopsy. The remaining 16 had an extensive evaluation and were diagnosed with other forms of heart disease. At catheterization, micromanometer catheters were used, and pressures in the right and left heart chambers were recorded simultaneously. Pressure wave form analysis was done with quiet and exaggerated respiration.
Results: In 59 patients, CP was confirmed by surgery; 58 showed hemodynamic improvement after pericardial stripping. The remaining 41 patients were thought to have RCM and, in 23, this was proved by biopsy. The remaining 18 patients had a variety of other cardiac diseases. Of the proven CP patients, only 60% had a thickened pericardium documented by CT or MR imaging, and echo Doppler evidence of CP was found in 73% (mitral inflow variation). Although there were statistically significant differences in conventional hemodynamic measurements between the CP and RCM groups, there was too much overlap to make these of diagnostic value. The area under the systolic ventricular pressure curves ratio (RV/LV) in inspiration vs expiration was called the systolic area index, and it had a 97% sensitivity and a 100% specificity for CP when it exceeded 1.1. Using peak systolic pressure rather than areas had a 59% sensitivity. Other indices had a relatively high sensitivity, but a lower specificity for CP such as RVEDP/RVSP > 0.33. Talreja and colleagues concluded that the ratio of RV to LV systolic pressure areas during inspiration and expiration is reliable for distinguishing CP from RCM
Commentary
Many cardiologists have recognized that evidence of ventricular discordance with respiration is a valuable diagnostic sign for CP. This study confirms that notion but demonstrated that using the area under the systolic ventricular pressure tracings is more sensitive than using peak pressure alone (97% vs 50%). In CP, the inspiratory increase in flow into the RV is accommodated at the expense of LV filling. Thus, RV pressure area increases during inspiration and LV pressure area decreases. During expiration, the reverse is true. In the index they devised, the greater the increase in RV pressure area compared to LV pressure area, the higher the index. For example, if the RV to LV pressure area ratio in expiration is one-quarter and in inspiration is one-half, then the index of RV/LV inspiration/expiration is 0.5/0.25 or 2. Values > 1.1 were considered diagnostic for CP.
The results of this study are only applicable to symptomatic patients referred for catheterization because clinical and non-invasive evaluations were inconclusive. A patient with right heart failure, Kussmaul's sign, a thickened pericardium on a CT scan, and marked respiratory variation in mitral and tricuspidal blood flow on echo Doppler would not have been included in this study because the diagnosis of CP is clear. Likewise, patients with obvious RCM were not studied. They diagnosed amyloid RCM in about 550 patients over the duration of the study, without cardiac catheterization. In fact, they did not biopsy everyone who went to catheterization in this study, which is a potential weakness.
The application of their results clinically could be problematic since they used micromanometer catheters, which are not routinely used in most laboratories. However, in my experience, high quality fluid filled catheter recordings clearly can demonstrate this pressure phenomenon. In fact, I am hesitant to send a patient to surgery for pericardial stripping without cardiac catheterization confirmation of the diagnosis. A thick pericardium on CT or MRI is useful, if positive, but a normal thickness does not exclude CP, as was shown in this study, where 40% of confirmed CP patients did not have a thickened pericardium. Most impressive about this study was that almost all of the CP patients sent to surgery improved. These heartening results make efforts to pin down this diagnosis worthwhile.
The differentiation of constrictive pericarditis from restrictive cardiomyopathy can be difficult, but the treatment implications are great.Subscribe Now for Access
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