Internal reference: (b)(4).This case was reviewed and investigated according to the manufacturer's policy.Based on the previous assessment of this pa-pd shift complaint, the initial information available suggested that if pa-pd waveform shift occurs, inaccurate measurements could contribute to incorrect treatment decisions.The manufacturer's operator's manual requires use only by trained medical personnel and cautions that "federal law restricts this device to sale by or on the order of a physician (or properly licensed practitioner)." additionally, the operator's manual states that the ffr option on the manufacturer's system should be used only by physicians who are thoroughly trained in cardiac or peripheral vessel catheterization procedures.The fractional flow reserve (ffr) option on the manufacturer's system requires two pressure signals (pd and pa) to execute normalization and calculate results.The manufacturer's pressure wire, provides the distal pressure signal (pd).The physiologic aortic pressure signal (pa) comes from a sensor that is part of the hemodynamic monitoring system, a non-manufacturer's product.The aortic pressure sensor and attached guide catheter are set-up and positioned by the physician separate from manufacturer's pressure wire.Normalization is performed with the wire's pressure sensor located at the tip of the guide catheter within the coronary artery.Therefore, the physician initiates normalization once they have confirmed the placement of the pressure wire.Based on the above described factors (pd coming from volcano's pressure wire, pa coming from a non-manufacturer's product, and physician's initiation of normalization upon confirmation of placement of pressure wire), the physiologic aortic pressure signal can contain content that may cause a one cardiac cycle shift.Refer to manufacturer's operator's manual, section acquire ffr pressure measurements for warning on discontinuing use of the system, and contacting manufacturer's technical support if normalization fails to establish a pd/pa ratio of 1.0 after multiple attempts.Manufacturer's product manages such a shift by displaying the normalized waveforms so that the user can detect a one-cardiac cycle shift.Manufacturer's software (ffr v2.4 software) allows the user to evaluate the results of the normalization process and make adjustments if needed.The one-cardiac cycle shift is not caused by manufacturer's software and this not a product performance issue, as the product is working as designed the appropriate action is to review the presented waveforms and re-normalize with the goal of achieving a shift free normalization.Manufacturer's ffr v2.4 operator's manual has instructions in that if the user is unable to establish a post-normalization pd/pa ratio of 1.0 with overlapping waveforms after several attempts, they are instructed to contact manufacturer's technical support.As described in this document, ffr version v2.4 is performing as intended.
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