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The optimal hemodynamic assessment of an aortic valve gradient is performed with simultaneously acquired aortic and left ventricular pressures. Ideally, we would like to make these measurements in the safest and most accurate way, and for years, cath labs around the world used a femoral artery sheath with a pigtail catheter (1 French [Fr] size smaller) passed through the sheath to the left ventricle (LV).
Although two left heart pressures were obtained simultaneously, the transmission of aortic pressure to the femoral artery resulted in delay and overshoot (resonant amplification), requiring shifting of the aortic tracing to match the LV tracing in order to compute the aortic (Ao)-LV gradient (Figure 1). The shifting of the aortic pressure to match the upstroke of the LV tracings resulted in an underestimation of the transvalvular gradient and hence, the aortic valve area. The development of alternative methods to improve upon the hemodynamics included use of a long (45 or 90 cm, e.g., those used for cardiac biopsies) arterial sheath or a second arterial access. The development of a dual lumen pigtail (Figure 2) solved the problems of femoral arterial pressure and need for two arterial punctures, and produced good tracings without the timing delay or systemic pressure overshoot. While the small aortic lumen of the Langston pigtail catheter was, at times, damped, the catheter worked well for valve gradient determinations. However, the 6 Fr dual lumen pigtail (Langston) catheter was recalled last year because of reports of tip fracture and release during LV angiography. From the company’s posting online,1
“Vascular Solutions, Inc. is recalling the Langston Dual Lumen Catheter because there is a potential the inner catheter may separate during use. If the inner catheter separates, it could cause serious health conditions including additional surgical procedures to remove the separated section, damage to the blood vessel or death. If the inner catheter separates outside of the patient’s body, the dye could spray the doctor and lead to an infection that may require the doctor to receive treatment. The FDA has identified this as a Class I recall, the most serious type of recall. Use of these devices may cause serious injuries or death. There have been 8 complaints and no reports of injury or death. This recall involved Lots distributed between July 12, 2019 and March 10, 2020; Model Number: Model 6F 5540.” Full details can be found elsewhere.1
Alternative Methods for Hemodynamic Aortic Valve Assessment
As our old stock of Langstons is gone, I compiled a list of what I believe to be all the methods for aortic stenosis (AS) gradient assessment that involve only one arterial access. Table 1 lists the methods from least to most accurate. Davies et al2 also provide a current review of the techniques to obtain transvalvular hemodynamics and useful methods to replace the Langston catheter. Let’s look at these techniques and methods, and then hear from my colleagues regarding what they use.
Single Catheter Pullback
A catheter is advanced retrograde across the aortic valve and then pulled back into the aorta (Figure 3). The LV and Ao pressures are measured on sequential beats. While this is the most basic and simplest technique, it is the least accurate and is subject to pressure recovery after premature ventricular contractions (PVCs) and artifacts of breathing, and does not provide simultaneous aortic and LV pressure.
Short Femoral Sheath With Pigtail Catheter to the LV
A catheter smaller than the sheath is advanced through the femoral sheath across the aortic valve. The femoral pressure serves as a surrogate for central Ao pressure. This technique was used for many years, also because of its simplicity, but as noted, it requires post-procedure manipulation of the tracings to account for the temporal delay. Unshifted tracings add some gradient because of the transmission delay, which tends to overestimate the gradient and thus the stenosis severity. Shifting the aortic pressure to match the LV upstroke underestimates the gradient because of the overshoot of aortic pressure (Figure 1).
Long Arterial Sheath With Pigtail to the LV
A 90 cm sheath is placed via the radial or femoral artery, ideally terminating in the ascending aorta. Examples include Destination (Terumo) (radial or femoral) or Arrow-Flex (Teleflex) armored sheaths (femoral). A catheter is then advanced through the sheath across the aortic valve. Central Ao pressure is measured from the sheath. Achieving high-quality pressure signals necessitates the use of a sheath that is two French sizes larger than a 4 Fr pigtail. This technique is also simple, but more challenging from the radial approach, due to tortuosity of the brachiocephalic/subclavian arteries. From the leg, it may still be in the descending aorta. All mother-and-child type of sheath and catheter arrangements require careful attention to flushing and bubbles, and systemic heparinization (40-70 u/kg IV).
Dual Arterial Punctures With Two Catheters
While nearly always available, two arterial access sites can be used. If possible, I think we should avoid this approach for obvious reasons. One catheter is advanced to the LV and one catheter is advanced to the central aortic position. Simultaneous LV and Ao pressures are then recorded. The additional arterial access carries additional access site risks.
Guide Catheter and Smaller Pigtail to LV (Mother-and-Child Technique)
This technique uses a 6 Fr guide catheter with a 4 Fr catheter inside it in a “mother-and-child” configuration. The guide catheter is usually long enough to accommodate a 110 or 120 cm 4 Fr pigtail to cross into the LV. A detachable Check-Flo valve (Cook Medical), the end from a Destination sheath (Terumo), or a homemade equivalent such as a trimmed 4 Fr sheath is required to transduce pressure (using a Tuohy loses 10 cm of length) (Figure 4). Lastly, the “loop” of the pigtail loses 10 cm, and it may be preferable to use a 125 cm 4 Fr Judkins right (JR)4, multipurpose, or Glide catheter (Terumo) instead. This technique closely approximates a dual lumen catheter, but equipment may not be available in all labs. Figure 5 shows pressures obtained with a dual lumen pigtail catheter.
Guide or Diagnostic Catheter With .014-Inch Pressure Wire or Micropressure Catheter to LV
A 5 Fr or 6 Fr multipurpose (MP), Amplatz left (AL)1 or JR4 catheter is positioned in the LV using standard guidewire technique to cross an aortic valve. As used for angioplasty, a Y-valved connector is attached to the LV catheter, and an .014-inch pressure wire is advanced through the catheter and situated in the LV (Figure 6). The guidewire pressure is ‘normalized’ or matched with the LV pressure (previously zeroed). The guide catheter is then withdrawn from the LV to the ascending aorta just above the valve, leaving the pressure wire in the LV. It is often helpful to have a gentle curve on the pressure wire so as not to stimulate PVCs in the LV. While the LV pressure wire signal is high fidelity, there can be problems in getting the pressure wire signal into the main hemodynamic recording system, since it comes through a fractional flow reserve (FFR) proprietary system (see comment from Nils Johnson, MD, below). We have taken the tracings from the FFR system and computed the peak-peak Ao-LV pressures as an estimate of the Hakki aortic valve area.
Transeptal Puncture (Venous Access) to LV With Central Aortic Pressure (Arterial Access)
A transseptal puncture is performed with placement of a pigtail or balloon wedge catheter in the LV. Arterial access is obtained and a pigtail catheter is advanced into the ascending aorta. Simultaneous pressures are measured. Transseptal measurement of LV pressure may reduce stroke risk, as no aortic valve crossing is required, but the downside is the transseptal puncture.
Multi-Transducer Micromanometer Catheters
Millar dual transducer catheters are available, but because of price and need to reuse these catheters, their incorporation into clinical practice is currently rare. This catheter offers high-fidelity recordings (Figure 7), although no direct comparison exists to modern .014-inch pressure sensors, and the 3.5 Fr tip and 2.3 Fr body create more iatrogenic gradient than a pressure wire.
What Do Our Expert Colleagues Say is Their Alternative to the Dual Lumen Pigtail?
Mike Ragosta, University of Virginia, Charlottesville, Virginia: Mort, it’s funny you brought this up; I did two cases recently. For one, I used a 90 cm long 6 Fr Flex sheath (Teleflex) that got me above the aortic valve for aortic pressure from the side are of the sheath. For the LV, I used a 120 cm long 4 Fr JB 1 catheter. For the second case, I used a short (90 cm) left internal mammary artery (LIMA) guide catheter for the aortic pressure, with a Tuohy Borst adapter to measure aortic pressure and the same 4 Fr JB 1 catheter. I got better tracings with the 90 cm long sheath and the 4 Fr JB 1 catheter.
Ted Feldman, Irvine, California: The pressure wire retrograde through a 4 or 5 Fr diagnostic (AL1 or 2) is great.3 But don’t forget about transseptal as an option.
Mike Ragosta, University of Virginia, Charlottesville, Virginia: I agree with using the pressure wire. It gives nice high-fidelity waves and no added obstruction across the valve. But the problem with the pressure wire is that some cath systems can’t easily input the waveforms into the cath lab hemodynamic system, so you can’t determine mean gradient and calculate valve area.
Dave Moliterno, University of Kentucky, Lexington, Kentucky: I have always liked the pressure wire approach that Ted mentions. The idea of putting a Swan-Ganz catheter is possible (exchanging over a wire in LV, and transduce off proximal and distal ports), but it may not be so stable and has not been tested (fidelity-wise) versus pressure wire, dual-lumen catheter, or two-catheter systems.
Steve Ramee, Ochsner Clinic, New Orleans, Louisiana: I use a long 6 Fr sheath (of your choice) with a 4 Fr pigtail across the aortic valve. [It’s] cheap and easy.
Mort Kern, Long Beach, California: We connect the pressure wire(s) to the Mac-Lab (GE Healthcare) as any pressure input to do aortic stenosis calculations (Figure 8). Opsens and ACIST pressure wires have compatible outputs into the Mac-Lab. Philips and Abbott Vascular pressure wires do not. I don’t know about the Boston Scientific system (Nils?). When we used the Philips pressure wire in the LV, the FFR screens report the peak systolic pressures as Pd (LV) and Pa (aorta). We get accurate peak-to-peak pressure differences permitting quick use of the Hakki formula for estimates of valve area. If we wanted a gradient, we would need to do a hand planimeter to get the Gorlin area.4
Nils Johnson, University of Texas, Houston, Texas: We use the pressure wires all the time. You can connect Abbott Vascular and Boston Scientific pressure wires into Mac-Lab. Boston provides a “Pd Out” connection from its “FFR Link” box that can be connected to the PDM (patient data module), although you need to ask your representative for the appropriate cable. The Abbott Vascular system has become more complex recently. If you have a newer PDM from GE, SJM wireless receivers must draw their power from the PDM. Due to GE’s redesign, their new PDM can no longer power the SJM pressure wire receiver (or so-called Wi-Box to broadcast the manifold aortic pressure). If your goal is to connect the pressure wire to the Mac-Lab, you need to ask your Abbott representative for a “GE Mac-Lab PDM Adapter Cable (C12988)”. Then you can connect the pressure wire into port P1 of the PDM via the C12988. (Note that if you want to use the Wi-Box, you will need to purchase a PSU [power supply unit] cable from Abbott). I regularly use both Comet (Boston Scientific) and other pressure wire products for Ao/LV measurements of valve severity (in addition to standard coronary work).
John Hirshfeld, University of Pennsylvania, Philadelphia, Pennsylvania: One added benefit of using the pressure wire in a training environment is that it enables trainees to see the pressure wave form undistorted: no damping, no oscillation artifact, no phase shift. This training is helpful to teach fellows to recognize faulty recordings. It also teaches the importance of transducer adjustment for gravitational effects.
George Vetrovec, VCU Pauley Heart Center, Richmond, Virginia: I have always used the long sheath and pigtail technique, varying in catheter size over the years as smaller sizes evolved. I think it is more consistent than the dual lumen single catheter.
The Bottom Line
For the hemodynamic assessment of aortic stenosis, most agree that a single arterial access with a mother-and-child 6/4 Fr combination system or a 6 Fr/.014-inch pressure wire combo work very well. Catheters are cheaper than pressure wires, but signal fidelity is better with a pressure wire. To our industry colleagues, we are looking forward to a new version of a dual lumen pigtail catheter or perhaps a dual transducer high-fidelity pressure wire to improve our hemodynamic data.
Disclosures: Dr. Morton Kern reports he is a consultant for Abiomed, Abbott Vascular, Philips Volcano, ACIST Medical, and Opsens Inc.
Dr. Kern can be contacted at firstname.lastname@example.org
On Twitter @drmortkern
Note: Please read the letter to the editor regarding this month's Clinical Editor's Corner.
- U. S. Food and Drug Administration (April 30, 2020). Vascular Solutions, Inc. Recalls Langston Dual Lumen Catheter Due to Risk of Separation During Use. Accessed March 15, 2021. Available online at https://www.fda.gov/medical-devices/medical-device-recalls/vascular-solutions-inc-recalls-langston-dual-lumen-catheter-due-risk-separation-during-use
- Davies C, Atkinson T, Bagai J. Tips and tricks for invasive assessment of aortic stenosis. Society for Cardiovascular Angiography and Interventions (SCAI). January 19, 2021. Accessed March 16, 2021. Available online at https://scai.org/tips-and-tricks-invasive-assessment-aortic-stenosis
- Fusman B, Faxon D, Feldman T. Hemodynamic rounds: Transvalvular pressure gradient measurement. Catheter Cardiovasc Interv. 2001 Aug; 53(4): 553-561. doi: 10.1002/ccd.1222
- Kern MJ. Aortic valve areas: Gorlin or Hakki? Cath Lab Digest. 2020 Oct; 28(10): 6-12. Accessed March 16, 2021. Available online at https://www.cathlabdigest.com/content/aortic-valve-areas-gorlin-or-hakki