Direct Left Atrial Pressure (LAP)

Optimizing Mechanical Circulatory Support Devices

Left atrial pressure (LAP) is commonly measured indirecty by a referenced pulmonary capillary wedge pressure (PCWP). When compared to direct LAP pressure, PWCP derived pressures are characterized by dampened and out-of-phase signals. Figure 1 illustrates this characterization. In this example, true LAP peaks are consistently greater than 15 mmHg (15 to 17 mmHg).

Simultaneously, the PCWP peaks range from 7 to 10 mmHg or on average, across this sample, 60% less than the true LAP. Clearly, one can observe the true pressure reading in phase with the EKG and the distinct delay of the PCWP. Additionally, indirect LAP measurements in patients with tachycardia or arrhythmias further complicate the measurement, leading to unreliable results.

Direct and Reference (WPCP) Left Atrium Pressure Reading

Following Mechanical Circulatory Support (MCS) implantation, utilization of direct LAP using the Millar Mikro-Cath provides true pressure readings in phase with the cardiac cycle that can support optimization decisions.

During MCS speed change studies, the goal is to provide maximum benefit to the left ventricle through pressure and volume unloading via the MCS without worsening right ventricle failure. To do so, accurate hemodynamic readings are essential to achieve the ideal optimization. Integration of true, direct LAP can support this effort and may prevent suction events, lower inotrope usage, decrease incidence of acute kidney injury and occurence of dialysis and decrease overall length of stay.

The example data below shows true, direct LAP pressure measurements with the Millar Mikro-Cath used to determine the optimal vacuum settings for a total artificial heart patient. By combining direct left atrium and central venous pressures, clinicians were able to optimize the device to better manage the patient’s hemodynamics.

Left Atrial Pressure Measurement Post Total Artificial Heart

Based on experience of multiple MCS cases, assessment of direct LAP with the Millar Mikro-Cath enables accurate and convenient optimization of hemodynamics in left ventricular assist devices, provides necessary pressure resolution for left and right artificial ventricles in total artificial hearts and can be used to avoid suction events.


Data supporting LAP monitoring was presented at the 7th Annual Brano Heart Failure Forum in Opatija, Croatia September 2014 by members from the Center for Advanced Heart Failure, UT Health Science Center & Memorial Hermann Hospital, Houston, USA.