rose protocol transcatheter pressure...

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Rose Protocol: Transcatheter pressure monitoring to assure hemodynamic effect

and to quantify a hemodynamic endpoint for embolization

Steven C. Rose ∙ Rachel Schrader

1 OVERVIEW

This protocol provides set‐up instructions for

the transcatheter pressure monitoring

configuration shown in Figure 1. Additionally,

this protocol explains how pressure

measurements are taken and interpreted.

With this transcatheter pressure monitoring

method, one can accurately compare systemic

blood pressure (BP) with the pressure at the tip

of the microcatheter with balloon occlusion to

determine:

1) if the microcatheter is adequately

occlusive

2) if blood flow will be directed into the

downstream vascular compartment from

adjacent vascular compartments to

provide antegrade protection from

nontarget embolization and likely

increase the proportion of embolic

delivery into the tumor

3) a potential hemodynamic endpoint for

embolization

This method uses two transducers to allow for

simultaneous comparison of the systemic

blood pressure with the pressure at the tip of

the microcatheter with balloon occlusion.

Given the patient’s BP will change moment to

moment, simultaneous comparison is

important for accuracy and to mitigate

measurement artifacts.

Keywords Chemoembolization ∙

Radioembolization ∙ Embolization Endpoint ∙

Embolization ∙ Pressure‐directed ∙ Balloon

occlusion

S. C. Rose () ∙ R. Schrader

Department of Radiology 8756, UCSD Medical Center,

University of California, San Diego Health Sciences, 200

West Arbor Drive, San Diego, CA 92103‐8756, USA

e‐mail: [email protected]

©Embolx, Inc. 2019. MK‐0327‐03 Rev. A

Figure 1: Transcatheter pressure monitoring configuration

7 11

11

10

1. Microcatheter balloon

2. Microcatheter

3. Microcatheter hub

4. Base Catheter

5. Introducer sheath

6. Rotating Hemostasis Valve

7. Saline lines packaged with transducer

8. 20 ml syringe, introducer sheath flush

9. 20 ml syringe, microcatheter flush

10. 20 ml syringe, transducer flush

11. 3‐way stopcock, packaged with transducer

12. 3‐way stopcock, stand‐alone

13. Embolic agent injection line

Tran

sducer 2

MICROCATH

Tran

sducer 1

SHEA

TH

8

7

9

11

1

2

5

6

11

3

11

10

4

13

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2 SET‐UP

2.1 ITEMS NEEDED FOR SET‐UP QUANTY ITEM

1 Embolx Sniper® Balloon Occlusion Microcatheter

2 Edwards LifeSciences™ TruWave™ Disposable Pressure Transducer (PX272)

2 Reusable Edwards LifeSciences Transducer to bedside monitor cable (PX1800). Contact Edwards Lifesciences for the specific cable version to connect a TruWave transducer to your bedside monitor model

1 Reusable IV pole mount for Edwards LifeSciences TruWave Disposable Pressure Transducer (TCLIP05)

1 3‐way stopcock

4 20 ml syringe filled with saline

1 Laser level

2.2 SET‐UP PROCEDURE 1. Set‐up two (2) Edwards LifeSciences TruWave Disposable Pressure Transducers (Figure 2):

a. Open on the sterile field two (2) TruWave Pressure Transducers.

b. Disconnect tubing lines from transducers. Each transducer is packaged with two (2) lines connected: one line

has a vent spike; the other line has a 3‐way stopcock.

c. Discard two (2) spike vent lines.

d. Save two (2) transducers for later use.

e. Save two (2) saline lines with 3‐way stopcocks for later use.

Figure 2: Pressure Transducer Set‐up

Tran

sducer 1

Save

Tran

sducer 2

Transducers from packages

Discard

Lines connected Lines disconnected

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2. Set‐up two (2) 20 ml syringes (Figure 3):

a. Open on the sterile field two (2) 20 ml syringes.

b. Fill both syringes with saline, label one SHEATH and the other MICROCATH.

c. Attach the first 20 ml syringe filled with saline to a 3‐way stopcock on a saline line from step 1e.

d. Attach the second 20 ml syringe filled with saline to the remaining 3‐way stopcock on the other saline line

from step 1e.

Figure 3: 20 ml flush syringe set‐up

3. Set‐up two (2) transducers (Figure 4):

a. Clip the transducer mount firmly onto IV pole.

IMPORTANT! Use an IV pole originating on the procedure

table because when the patient table moves up or down, it

is important that the transducer location relative to the

patient is maintained.

b. Label one transducer “SHEATH” and other

“MICROCATH”

c. Fill two (2) 20 ml syringes with saline.

d. Attach the first 20 ml syringe filled with saline to a

transducer from step 1d.

e. Attach the second 20 ml syringe filled with saline to the

remaining transducer from step 1d.

f. Mount two (2) transducers with 20 ml syringe filled

with saline to transducer holder on IV pole with the

transducer connection cables hanging down.

g. Connect two (2) sterile saline lines from step 2 to both

transducers.

h. Discard the white caps on both transducer 3‐way

stopcocks.

i. Connect both transducer connection cables to two bedside monitor cables. Connect the bedside monitor

cables to the appropriate bedside monitor ports.

Figure 4: Transducer set‐up

SHEA

TH

MICR

OCAT

H

SHEA

TH

MICR

OCAT

H

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4. Position and level the two transducers to the patient’s mid‐axillary line and 4th intercostal space (Figure 5):

a. Move IV pole forward or backward on the patient’s table until the transducers are positioned at the patient’s

4th intercostal space.

b. Using a laser level, slide the transducers up or down on the IV pole into position so that they are level to the

patient's mid‐axillary line while maintaining position at the patient’s 4th intercostal space.

IMPORTANT! The laser level should be aligned with the top of the 3‐way stopcocks on the transducers.

IMPORTANT! The transducers must be exactly positioned to ensure accurate pressure readings.

Figure 5: Exact positioning of the two transducers*

5. Figure 6):

a. Turn 3‐way

stopcocks on both transducers open to air

(pointed up as shown in Figure 4)

b. Label the transducers on the monitor:

“MICROCATH” and “SHEATH”.

c. ZERO both transducers by pressing the ZERO

on the monitor.

d. Set the scale on the monitor for both the

MICROCATH and the SHEATH pressure

measurements to a 150 scale or slightly

greater than systolic blood pressure as

measured on the noninvasive system.

* Edwards Lifesciences TruWave Transducer Setup. https://www.edwards.com/devices/pressure‐monitoring/transducer

Figure 6: Bedside monitor set‐up

Set‐up bedside monitor (

Raise or lower transducers until level with mid-axillary line

Move the IV pole until transducers are positioned at the patient’s 4th intercostal space

Noninvasive BP measurement

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6. Connect the stand‐alone 3‐way stopcock, V5, to

the end of the microcatheter saline line as

shown in Figure 7.

7. Flush the saline lines from the transducers to a

point just beyond valves V3 and V5 creating an

air and bubble free continuous fluid column

(Figure 7):

a. With valves V3 and V4 in the "syringe

off" position and V5 in the “embolic

agent inject off” position, pull the snap

tab on the transducer while

simultaneously filling the saline lines

using syringes S1 and S2. Tap the lines

while holding them upright to work out

any air bubbles.

b. Move the 3‐way stopcock to the

"transducer off" position on valves V3

and V4 per motion marked A. This action

keeps air from entering the lines

towards the transducers.

c. Use syringes S3 and S4 to flush residual

air out of the open end of the saline

lines. Tap the lines to work out air

bubbles.

d. Move the 3‐way stopcock to the "saline line off" position on valve V5 per in motion marked B. This action

keeps air from entering the microcatheter saline line.

IMPORANT! Check the entire configuration for air bubbles and line kinks which are the most‐common problem

when measuring pressure and can result in inaccurate readings. Pressure measurement requires a continuous

fluid column.

8. Connect the saline lines to both the introducer sheath and the microcatheter (Figure 8).

a. Connect sheath line to the introducer sheath per configuration shown in Figure 8.

b. Connect microcatheter line to the microcatheter 3‐way stopcock per configuration shown in Figure 8.

Figure 7: Initial saline line flush to remove air and bubbles

MICROCATH

SH

EATH

MICR

OCAT

H SH

EATH

Snap Tab Flush

Tap lines while holding upright to work out air bubbles

Tap lines while holding upright to work out air bubbles

Air and bubbles are removed and replaced with saline

S3

S4 S1 S2

V1 V2

V3

V4 V5

Embolic agent inject

Microcatheter connect

Sheath connect

A

A

B

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3 PRESSURE MEASUREMENT AND EMBOLIC AGENT DELIVERY

1. Measure and record pressures from both the introducer sheath and the microcatheter (Figure 8):

a. Flush the sheath and microcatheter lines using syringes S3 and S4.

b. Move the 3‐way stopcock to the "syringe off" position on valves V3 and V4 per motion marked A.

c. Record sheath pressure. Record microcatheter pressure. For each pressure measurement of the sheath and

microcatheter lines, record the systolic, diastolic and mean pressures from the bedside monitor. Once embolic

agent delivery commences, wait until BP pressure readings stabilize before measuring pressures.

2. Inject Embolic agent via the microcatheter with occlusion balloon inflated (Figure 9):

a. Move the 3‐way stopcock to the "transducer off" position on valves V3 and V4.

b. Move the 3‐way stopcock to the "saline line off" position on valve V5 for embolic agent injection.

Figure 8: Pressure measurement configuration Figure 9: Embolic agent injection configuration

A

A

S3

S4

V4 V5

MICROCATH

SHEA

TH

V3

SHEA

TH

MICR

OCAT

H

S3

S4

V4 V5

MICROCATH

SHEA

TH

V3

SHEA

TH

MICR

OCAT

H

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4 PRESSURE MEASUREMENT INTERPRETATION

Studies to date on transcatheter pressure monitoring to assure hemodynamic effect and to quantify a hemodynamic

endpoint for embolization have been focused on the liver. Therefore, the following pressure measurement interpretation

guidance is based on liver experience only. While this protocol could be utilized in organs outside the scope of the liver

(e.g., kidney, prostate, pancreas, uterus), further study is to verify the hemodynamic effects of balloon occlusion in extra‐

hepatic organs, each with its own unique angioarchitecture.

As noted in the protocol, transducers are utilized to measure the systolic, diastolic, and mean systemic arterial blood

pressure (referred to as SHEATH), and the systolic, diastolic, and mean downstream vascular compartment arterial blood

pressure (referred to as MICROCATH). The systemic arterial blood pressure is measured directly through the side arm of

the femoral artery sheath. The sheath should have an inner diameter that is at least one French larger than the outer

diameter of the coaxial base catheter. Flushing the system vigorously with saline prior to each reading will help ensure

fidelity of the measurements.

The blood pressure within the vascular compartment that is downstream from the microcatheter is measured directly

through the lumen of the balloon mounted microcatheter. When the balloon is deflated, the downstream vascular

compartmental blood pressure should closely approximate the systemic arterial blood pressure unless the microcatheter

occupies a large portion of the arterial cross‐sectional area or unrecognized upstream arteriospasm has occurred. When

the balloon has been inflated to the point of arterial occlusion, the blood pressure in the downstream vascular

compartment should be reduced by 20‐50 mmHg relative to the systemic arterial blood pressure (1,2).

The systemic compartmentalized arterial pressure differential (SCAPD) = mean systemic arterial blood pressure (mmHg)

minus the mean downstream vascular compartment arterial blood pressure (mmHg). When calculating the SCAPD, using

the mean systemic and downstream blood pressures appears to be the most reliable pressure measurement. The systolic

blood pressure has excessive statistical noise (variability), and diastolic blood pressure downstream may actually be

higher than the systemic diastolic blood pressure (even before embolization) due to damping of the arterial wave form.

If the SCAPD is less than 20 mmHg, most likely the balloon is not occlusive. Additional inflation is indicated until an

appropriate SCAPD has been achieved. Once a suitable SCAPD has been attained (typically in the order of 40 mmHg),

then blood flow in hepaticoenteric arteries can be confidently assumed to flow hepatopetally, thus providing antegrade

protection from nontarget embolization in addition to the designed retrograde protection.

As a result of the 20‐50 mmHg SCAPD, blood flow enters the downstream vascular compartment not only through

hepaticoenteric arteries, but also through hepatic artery‐to‐hepatic artery connections between neighboring hepatic

segments. This results in reversal of downstream compartmental hepatic arterial blood flow due to collateral

reconstitution. Essentially embolic agent is flushed out of the nontumorous hepatic tissues. Presumably the tumor is a

separate vascular compartment, thus continues to fill with embolic agent. The net result, as supported by a number of

reported investigations (2,3,4) is increased delivery of agent to the tumor and reduced delivery to nontumorous liver. Of

note, if tumors receive competing arterial inflow from outside the downstream vascular compartment (i.e., “Watershed”

tumors), then these results may be less predictable (5).

Use of an occlusion balloon during embolization confounds the visual fluoroscopic clues used to determine the end point

of embolization. Specifically, the occlusion balloon dramatically reduces the forward blood flow velocity. In addition, by

design, the occlusion balloon serves as a back stop to reversal of blood flow. As embolization progresses, particles

occlude portions of the vascular compartment compartmental microvasculature, thus raising the downstream resistance

to blood flow. This increased downstream resistance results in progressive reduction in the SCAPD (6,7). The algorithm

adopted by the UCSD team involves repeated intraprocedural measurement of SCAPD after each delivery of

approximately 10% of the intended chemoembolization or Y90 radioembolization resin microsphere dose. Of note, Y90

glass microsphere doses cannot be partitioned. When relatively large volumes of liver are at risk (e.g., lobar delivery),

data seems to support safety using a 70% relative reduction in SCAPD as an embolization end point (7). In cases with

relatively small volumes of liver at risk (e.g., segmental or subsegmental delivery), then intentional over embolization may

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be an effective means for increasing embolic penetration into tumor and dealing with “watershed” tumors. Detailed

review of hemodynamic principals and preliminary clinical evidence has been presented [8].

As an example, Figure 10 shows the bedside monitor display at the first pressure measurement when the microcatheter’s

balloon was initially inflated, balloon occlusion was achieved (e.g. 38 mmHg pressure difference), and embolic agent (drug

eluting embolic with doxorubicin) injection has not yet commenced. Figure 11 shows the first and sixth pressure

measurement recordings (see section 6 for the measurement spreadsheet) with calculated mean pressures, pressure

difference (SCAPD) and percentage reduction of the SCAPD after delivery of approximately 60% of the intended dose of

embolic dose.

5 REFERENCES

1. Rose SC, Kikolski SG, Chomas JE. Downstream hepatic arterial blood pressure changes caused by deployment of the

surefire antireflux expandable tip. Cardiovasc Intervent Radiol 2013;36:1262‐9.

2. Rose SC, Halstead GD, Narsinh KH. Pressure‐Directed Embolization of Hepatic Arteries in a Porcine Model Using a

Temporary Occlusion Balloon Microcatheter: Proof of Concept. Cardiovasc Intervent Radiol 2017.

3. Irie T, Kuramochi M, Takahashi N. Dense accumulation of lipiodol emulsion in hepatocellular carcinoma nodule during

selective balloon‐occluded transarterial chemoembolization: measurement of balloon‐occluded arterial stump

pressure. Cardiovasc Intervent Radiol 2013;36:706‐13.

4. Pasciak AS, McElmurray JH, Bourgeois AC, Heidel RE, Bradley YC. The impact of an antireflux catheter on target volume

particulate distribution in liver‐directed embolotherapy: a pilot study. J Vasc Interv Radiol 2015;26:660‐9

5. Kothary N, Takehana C, Mueller K, et al. Watershed Hepatocellular Carcinomas: The Risk of Incomplete Response

following Transhepatic Arterial Chemoembolization. J Vasc Interv Radiol 2015; 26: 1122‐1129.

6. Rose SC, Lim GM, Arellano RS, Easter DB, Roberts AC. Temporary splenic artery balloon occlusion for protection of

nonsplenic vascular beds during splenic embolization. AJR 1998;170:1186‐8.

7. Rose SC, Kikolski SG, Morshedi MM, Narsinh KH. Feasibility of Intraprocedural Transluminal Hepatic and Femoral

Artery Blood Pressure Measurements as an Alternative Embolization Safety Endpoint When Antireflux Devices Are

Used During Lobar Chemoembolization. AJR 2015;205:196‐202.

8. Rose SC, Narsinh KH, Isaacson AJ, Fischman AM, Golzarian J. The Beauty and Bane of Pressure‐Directed

Embolotherapy: Hemodynamic Principles and Preliminary Clinical Evidence. AJR 2019 Mar;212(3):686‐695.

Figure 10: Bedside monitor display at baseline measurement Figure 11: Measurement recording example

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6 APPENDIX: PRESSURE MEASUREMENT RECORDING SPREADSHEET

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