Invasive aortic valve assessment remains an essential cath lab procedure. The most widely used invasive technique for more than a decade has been performed with a Langston^® Dual Lumen Catheter (Teleflex – Morrisville, NC), which has a 6Fr outer catheter and a 4Fr inner lumen enabling simultaneous measurement of left ventricular (LV) and aortic (AO) pressures.¹ The catheter was recalled in March 2020 due to several instances of separation of the inner catheter during power injection.^{2, 3} This leaves cardiologists without a straightforward technique for simultaneously measuring LV and AO pressures in the cath lab. This Tip of the Month focuses on the various techniques available to perform an invasive aortic valve study.^4–6

1. Single Catheter Pullback

A catheter is advanced retrograde across the aortic valve and then pulled back into the aorta. The LV and AO pressures are measured on two sequential beats.

Pros: It is a simple technique.

Cons: It can only assess peak-to-peak gradient, is vulnerable to ectopy and artifact, and is unable to assess simultaneous pressures.

2. Femoral Sheath: Surrogate for Central AO Pressure

A catheter is advanced through the femoral sheath retrograde across the aortic valve. The femoral pressure serves as a surrogate for central AO pressure.

Pros: It is a simple technique.

Cons: It is limited by the need to temporally shift tracings to account for transmission delay (which tends to overestimate severity) and to account for pressure recovery (which tends to underestimate severity).

3. Long Sheath: Measurement of Central AO Pressure

A 90cm sheath is placed via the radial or femoral artery, ideally terminating in the ascending aorta. Examples include Destination^® (Terumo – Somerset, NJ) (radial or femoral) or Arrow-Flex^®-armored (Teleflex – Morrisville, NC) sheaths (femoral). A catheter is then advanced through the sheath retrograde 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 4Fr pigtail. 

Pros: It is a simple technique.

Cons: While it is possible to use the long sheath from a radial approach, it may be difficult to advance a long catheter through brachiocephalic/subclavian tortuosity or reach the ascending aorta in tall patients.

The sheath also requires meticulous flushing to prevent clots.

4. Dual Arterial Punctures

Two arterial access sites are obtained. A catheter is advanced through one sheath into the ascending aorta. A catheter is advanced through the second sheath retrograde across the aortic valve. Simultaneous LV and AO pressures are recorded.

Pros: It provides for simultaneous pressures.

Cons: It involves two arterial punctures.

5. “Mother and Daughter” Technique

This technique uses a 6Fr guide catheter with a 4Fr catheter inside it in a “mother and daughter” configuration (Figure 1). The guide catheter must be 90 cm long to allow a 110 or 120 cm 4Fr pigtail to exit the end. A detachable Check-Flo^® valve (Cook Medical – Bloomington, IN), the end from a Destination^® sheath (Terumo – Somerset, NJ), or a homemade equivalent such as a trimmed 4Fr sheath⁶ is required to transduce pressure (using a Tuohy loses 10cm of length). Lastly, the “loop” of the pigtail loses 10cm, and it may be preferable to use a 125 cm 4F JR4, multipurpose, or glide catheter instead. 

Pros: It is most similar to the dual lumen catheter.

Cons: Not all labs have a full range of 4Fr catheters, 90cm guides, or Destination^® sheaths.

6. Pressure Wire Within Catheter^{8, 9}

A 5Fr AL1 or JR4 catheter is positioned in the aorta (Figure 2). A Tuohy valve is placed on the catheter, and a pressure wire is advanced through this. The pressure is “normalized” in the ascending aorta. The pressure wire is removed from the catheter, and the aortic valve is crossed in a conventional manner with an 0.035” wire introducing the catheter into the ventricle. A J-Tip is formed on the pressure wire, which is then advanced through the catheter into the LV. The catheter is pulled back into the ascending aorta, leaving the pressure wire in the LV. Simultaneous pressures are displayed on the pressure wire console, which enables assessment of peak-to-peak pressure gradient for the Hakki-derived valve area (cardiac output divided by the square root of the peak-to-peak gradient).¹⁰ Some hemodynamic systems can import both pressures, enabling measurement of mean gradient for the Gorlin-derived valve area.

Pros: 5Fr access is least likely to produce a “Carabello” effect, as only a wire and not the catheter is advanced across the stenotic valve.

Cons: Pressure wire consoles may not relay dual pressures to the cath lab hemodynamic system, which restricts valve-area calculation to the peak-to-peak gradient.

7. Transseptal Evaluation

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.

Pros: Transseptal measurement of LV pressure may reduce stroke risk, as no aortic valve crossing is required.

Cons: It involves a transseptal puncture.

Conventionally, all techniques involve heparin administration dosed at 40–50 U/Kg.

Conclusion

The need for invasive aortic valve assessment continues despite the lack of a dual lumen catheter. Several alternative techniques exist, leaving operators options from which to choose depending on individual circumstances. 

References

1. Bradaric C. Simultaneous Measurement of Differential Pressures with a Dual Lumen Catheter. Cardiac Interventions Today. 2019 Mar/Apr;3:25–27.
2. Barlagiannis D (@dbarlag). https://twitter.com/dbarlag/status/1302120019183185922?s=21. 2020 Sep 5.
3. U. S. Food and Drug Administration (April 30, 2020). Vascular Solutions, Inc. Recalls Langston Dual Lumen Catheter Due to Risk of Separation During Use. Retrieved from https://www.fda.gov/medical-devices/medical-device-recalls/vascular-solutions-inc-recalls-langston-dual-lumen-catheter-due-risk-separation-during-use
4. Nishimura RA and Carabello BA. Hemodynamics in the cardiac catheterization laboratory of the 21st century. 2012 May 1;125(17):2138–50.
5. Gjertsson P, Caidahl K, Svensson G, et al. Important pressure recovery in patients with aortic stenosis and high Doppler gradients. Am J Cardiol. 2001 Jul 15;88 (2):139–44.
6. Saikrishnan N, Kumar G, Sawaya FJ, et al. Accurate assessment of aortic stenosis: a review of diagnostic modalities and hemodynamics. 2014 Jan 14;129(2):244–53.
7. Geloo N (@NadimGelooMD). https://twitter.com/nadimgeloomd/status/1306409089422032897?s=21. 2020 Sep 16.
8. Bae JH, Lerman A, Yang E, et al. Feasibility of a pressure wire and single arterial puncture for assessing aortic valve area in patients with aortic stenosis. J Invasive Cardiol. 2006 Aug 1;18(8):359–62.
9. Feldman T. Assessment of the transvalvular pressure gradient in aortic stenosis. J Invasive Cardiol. 2006 Aug;18(8):363–64.
10. Hakki AH, Iskandrian AS, Bemis CE, et al. A simplified valve formula for the calculation of stenotic cardiac valve areas. Circulation. 1981 May 1;63:1050–55.

Figure 1. “Mother and Daughter” Technique Using a 6F Guide and 4F Pigtail

(A) Pigtail exiting through a 90cm guide catheter. (B) Valve from a Destination sheath assembled on the distal end of the guide catheter. (C) Valve from a Destination sheath shown disassembled on the distal end of the guide catheter. (D) 4Fr sheath with its shaft cut to within 2cm of the sheath assembled onto the distal end of the guide catheter (note the loss of usable catheter length relative to B), and pigtail inserted into the 4Fr sheath.

Figure 2. Demonstration of the Pressure Wire Technique

(A) Catheter in the aorta and pressure wire in the LV. (B) Pressure wire console displaying simultaneous peak-to-peak pressures.