The overall goal of this procedure is to accurately and reproducibly predict complete pulmonary vein or PV occlusion and electrical isolation during cryoballoon ablation for atrial fibrillation, while minimizing the use of fluoroscopy and radio iodine contrast. This is accomplished by first connecting the cryoballoon to a continuous pressure monitoring system. Next, using standard fluoroscopic views and intracardiac ultrasound, the deflated balloon is advanced over the G wire or achieve catheter, and is inflated on the left atrium or LA side of the PV antrum.
Then using fluoroscopy or ultrasound guidance, the balloon is advanced and placed in opposition with the PV osteum until complete occlusion is achieved. Finally, the freezing process is initiated. Ultimately, the results show the presence or absence of PV electrical isolation as recorded by the achieve or lasso catheter.
The significant advantage of this technique over existing methods such as de de guided visualization contrast and fluoroscopy, is the significant decrease in the total amount of contrast and fluoroscopy required, as well as the high predictive value of pulmonary vein electrical isolation. When characteristic pressure wave forms are observed upon cryoballoon inflation, Visual demonstration of these techniques is critical because the cryoballoon apparatus is complex in itself and the addition of the pressure monitoring system adds more complexity to it. Also, interpretation of the waveforms can be cumbersome, particularly if the presenting rhythm is atrial fibrillation.
After draping the patient, obtain vascular access in the right and left femoral veins using a pressure transducer via the radial or femoral artery. Continuously monitor systemic arterial pressure. Next, advance the intracardiac echocardiography or ice ultrasound probe to the right atrium intravenously, infuse a heparin bolus and check activated clotting time or a CT every 20 minutes to maintain an A CT over 350 seconds.
For the duration of the procedure with standard fluoroscopic views and ICE guidance, use a preface or SL one sheath to achieve transseptal puncture. Place a J TTI 0.035 inch wire in the left superior PV and exchange the transseptal sheath with the flex calf sheath. To prepare for the ablation procedure, select a balloon size in accordance with the diameter of the patient's pulmonary veins or pvs, previously determined from cardiac MRI or CT measurements.
If any. PVT osteo have a diameter larger than 20 millimeters, a 28 millimeter cryoballoon is used. The balloon has an inner lumen that is typically used for radio iodine contrast injection through the distal tip of the balloon.
A continuous pressure monitoring system is connected to the lumen to allow for pressure waveform analysis through a three-way manifold attached via a TUI to the cryoballoon. Before using the system, thoroughly flush it and remove any air bubbles. The three ports of the manifold are saline, flush, contrast, and pressure monitoring or transducer.
The transducer port is connected to a standard cardiac catheterization laboratory pressure transducer, and the pressure wave forms are displayed on the electrophysiology recording system live. Monitor advance the cryoballoon over a wire or the achieve catheter in the left atrium, and then using ice and fluoroscopic guidance advance it into the antrum of each pv. Set the pressure recordings at a scale of 25 millimeters of mercury and the sweep speed at 50 millimeters per second.
The channels displayed on the page include one or two surface electrocardiogram or ECG derivations, coronary sinus, or CS electrograms and arterial and left arterial or LA pressures prior to ablation. Record electrograms of the PV LA Junctions continuous recording is displayed on a separate page on the EP system. When occlusion is assessed using standard fluoroscopic views and intracardiac ultrasound advance the balloon over the G wire or achieve catheter and inflate it on the LA side of the PV antrum.
The pressure page will be displayed and the pressure line is opened to the transducer such that pressure is recorded from the tip of the balloon catheter when the balloon does not occlude the osteum of the pv. A characteristic LA pressure is recorded during sinus rhythm. Atrial or A and ventricular or V waves are recorded with the wave having a typical isosceles triangle morphology during atrial fibrillation.
However, there is no consistent a wave generated since there is no atrial contraction and only the V wave morphology is seen. Using fluoroscopy or ultrasound guidance advance the balloon and place it in apposition to the PV osteum. When occlusion is achieved, there is an abrupt change in the pressure wave form during sinus rhythm.
There is a loss of the A wave and an increase in amplitude and morphology of the V wave. Since the recording is now that of transcapillary pulmonary arterial pressure, the V wave has the typical characteristic of a more rapid rate of rise and a delayed downstroke in this case, the apex of the Vwa triangle moves to the right when compared to the LA pressure Vwa recording. This is evident in sinus rhythm and atrial fibrillation or af.
Because this characteristic pressure wave form confirms complete occlusion cease any forward pressure or catheter manipulation at this point. If desired, use contrast medium to further confirm PV occlusion. Once occlusion has been verified to promptly detect phrenic nerve injury during the freezing process, perform phrenic nerve pacing from a catheter located in the superior vena cava during the freezing process.
Once the temperature monitor reaches minus 10 degrees Celsius, the inner lumen of the balloon will freeze and pressure can no longer be recorded at this stage, toggle the recording system page to the Intracardiac Electrogram page to demonstrate the time to effect of PV isolation. Continue the cryo application for 240 seconds after the freezing is complete and thawing has occurred. Record the pressure and repeat the process as many times as necessary for permanent PV isolation.
As shown here, we assessed the accuracy of pressure monitoring in predicting complete PV occlusion. In 35, patients with paroxysmal or persistent AF six patients had a prior AF ablation. A total of 128 PVS were assessed with pressure monitoring during balloon inflation.
Occlusive pressure was demonstrated with balloon inflation in 113 pvs, of which 111 were electrically isolated with cryoablation or CB.A lack of occlusive pressure waveform was more frequently noted in the right inferior PV or RIPV two veins with demonstrated occlusive pressure. Waveform were still electrically connected despite concurrent demonstration of PV occlusion. By contrast, venography, the positive predictive value was 99%In the RIPV, we observed a requirement for up to three cryo applications per vein when occlusive pressure was observed in 90%of R IPVs, whereas 10%of veins with occlusive pressure required four cryo applications.
In contrast, when occlusive pressure was not observed in the RIPV four or five cryo applications were performed in 70%of r IPVs. After watching this video, you should be able to use a pressure monitoring methodology to accurately predict pulmonary vein occlusion while using cryoballoon ablation for treatment of paroxysmal atrial fibrillation. You should be able to incorporate this methodology in your daily practice and interpret pulmonary vein pressures for treatment of atrial fibrillation and for accurately predict pulmonary vein occlusion, both in sinus rhythm and atrial fibrillation.
But don't forget that working with the cryoballoon initially can be difficult due to the complexity of the apparatus and that the addition of a pressure manifold system can increase the the need for an additional set of hands. Whether a fellow or a well-trained technician in your lab.
