Left ventricular end diastolic pressure (LVEDP), the pressure at the end of the filling phase of the heart, is elevated in congestive heart failure (CHF). Measurement of LVEDP may be useful in the management of patients with CHF; however, it requires cardiac catheterization by (i) direct measurement via placement of a catheter in the left ventricle, or (ii) indirect measurement by placement of a catheter in the pulmonary artery to measure the pulmonary capillary wedge pressure (PCWP).
The Vericor System (CVP Diagnostics, Boston, MA) involves the indirect measurement of left ventricular filling pressure (LVFP) by analysis of arterial waveform response to the Valsalva maneuver using a proprietary algorithm. The Vericor System was cleared by the U.S. Food and Drug Administration based on a 510(k) premarket notification.
To examine the relationship and the level of accuracy of a non-invasive system in directly determining LVEDP, Sharma et al (2002) assessed LVFP by measuring PCWP and LVEDP in 57 persons followed immediately by a Valsalva maneuver using the VeriCor System during elective right and left heart catheterization. The VeriCor and PCWP measurements were then compared with results from the catheter-measured LVEDP. VeriCor measurements correlated significantly with catheter-measured LVEDP (r = 0.86), comparable to the correlation of the PCWP with catheter-measured LVEDP (r = 0.81). VeriCor measurements were within 4 mm Hg of direct LVEDP measurements 84 % of the time and within 6 mm Hg of these measurements 93 % of the time, whereas the corresponding values for PCWP were 41 % and 67 %, respectively.
According to the American College of Cardiology/American Heart Association (ACC/AHA) Practice Guidelines on Heart Failure (2001), the role of periodic invasive or non-invasive hemodynamic measurements in the management of heart failure remains uncertain. The guidelines stated that, although hemodynamic measurements can be performed by non-invasive methods, these tests have not been shown to be more valuable than routine tests, including physical examination. Moreover, it is not clear whether serial non-invasive hemodynamic measurements can be used to gauge the efficacy of treatment or to identify patients most likely to deteriorate symptomatically during long-term follow-up.
There is inadequate evidence of the clinical utility of these indirect measurements of LVFP by computerized calibration of the arterial waveform response to the Valsalva maneuver. Clinical outcome studies published in the peer-reviewed medical literature are necessary to determine the value of this test in the clinical management of patients with CHF.
In a small, prospective study, Sharma and colleagues (2011) examined if non-invasive monitoring of LVEDP would reduce re-hospitalization rates in patients hospitalized for HF. A total of 50 patients admitted for HF were randomized to management guided by daily non-invasive estimated LVEDP monitoring (group I, open) to a target LVEDP of less than 20 mm Hg or management based on clinical assessment alone without knowledge of the estimated LVEDP (group II, blinded). Non-invasive estimated LVEDP was measured by the VeriCor monitor. The primary endpoints were the reduction of estimated LVEDP at discharge and the HF re-hospitalization rate on follow-up. Estimated LVEDP was significantly reduced at discharge in the open group compared with the blinded group (mean estimated LVEDP 19.7 +/- 1.3 mm Hg versus 25.6 +/- 1.5 mm Hg, respectively, p = 0.01). The re-hospitalization rates for HF on follow-up were significantly improved in the open group compared with the blinded group (at 1 month: 0 % versus 25 %, respectively [p = 0.05]; at 3 months: 0 % versus 32 % [p = 0.01]; at 6 months: 4 % versus 36 % [p = 0.01]; at 1 year: 16 % versus 48 % [p = 0.03]). The authors concluded that when HF is managed by clinical assessment only, estimated LVEDPs remain high at discharge, resulting in early and frequent re-hospitalization for HF. Therapy guided by estimated LVEDP monitoring optimizes filling pressures and reduces HF re-hospitalization rates. Findings of this small study need to be validated by well-designed studies.