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Anesthesia and Transesophageal Echocardiography for WATCHMAN Device Implantation
Author’s Accepted Manuscript Anesthesia and TEE for WATCHMAN TM Device Implantation Ludmil Mitrev, Natalie Trautman, Vadlamudi, Nayan Desai, Sajjad A. Sabir
Ratna
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S1053-0770(16)30184-7 http://dx.doi.org/10.1053/j.jvca.2016.06.012 YJCAN3725
To appear in: Journal of Cardiothoracic and Vascular Anesthesia Received date: 23 September 2015 Cite this article as: Ludmil Mitrev, Natalie Trautman, Ratna Vadlamudi, Nayan Desai and Sajjad A. Sabir, Anesthesia and TEE for WATCHMAN TM Device Implantation, Journal of Cardiothoracic and Vascular Anesthesia, http://dx.doi.org/10.1053/j.jvca.2016.06.012 This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting galley proof before it is published in its final citable form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.
Anesthesia and TEE for WATCHMANTM Device Implantation
Authors:
1
Ludmil Mitrev, M.D. , e-mail: [email protected] 1
Natalie Trautman, M.D. , e-mail: [email protected] 2
Ratna Vadlamudi, M.D. , e-mail: [email protected] 3
Nayan Desai, M.D. , e-mail: [email protected] 3
Sajjad A Sabir, M.D. , e-mail: [email protected]
1
Department of Anesthesiology and Division of Cardiothoracic Anesthesiology, Cooper University
Hospital, One Cooper Plaza, Camden, NJ 08103, U.S.A. 2
Department of Anesthesiology, Emory University, Atlanta, GA 30322, U.S.A.
3
Department of Cardiology, Cooper University Hospital, Camden, NJ 08103, U.S.A.
Corresponding Author: Ludmil Mitrev, M.D., e-mail: [email protected], tel. +1 (856) 968-7334
Conflicts of Interest: None
Acknowledgements The authors wish to thank Kelly Speich, MS for his assistance with gross anatomy images.
Keywords Watchman device; left atrial appendage closure device; atrial fibrillation; ischemic stroke.
1
Anesthesia and TEE for WATCHMANTM Device Implantation
Abstract Only 30% to 50% of patients with non-valvular atrial fibrillation are treated with anticoagulation to reduce the risk of thromboembolic events, due to patient adherence and the side effect profile of such therapy.1 Several left atrial appendage occlusion devices have been proposed as alternative approaches to minimization of the risk of thromboembolic events. The present article reviews the anesthetic and TEE implications of the WATCHMANTM (Boston Scientific, Marlborough, MA, USA) Left Atrial Appendage Closure Device implantation.
Introduction Stroke is a common cardiovascular event with significant morbidity and mortality. A 2015 annual report from the American Heart Association estimated the annual incidence of stoke in the United States to be approximately 795,000 2 cases, of which 77% were new events, and the remainder – recurrent strokes. Eightyseven percent of all strokes are ischemic. The age-adjusted death rate per 100,000 population in 2009-2011 was 38.9, accounting for some 128,932 strokerelated deaths in 2011. When considered separately from other cardiovascular diseases, stroke ranked 4th among all causes of death in the United States, behind diseases of the heart, cancer, and chronic lower respiratory diseases 2. The global prevalence of stroke was 33 million cases in 20103, and stroke was
2
second only to ischemic heart disease in terms of mortality on a global basis, accounting for 11.13% of total deaths worldwide.
Atrial fibrillation (AF) is an independent risk factor for stroke, increasing the risk 5-fold in all age groups. The attributable risk of stroke related to AF increases with age, and may be substantially underestimated, due to the fact that AF can be asymptomatic and can remain undetected4. Atrial fibrillation is said to contribute to greater than 20% of strokes, and many efforts are directed towards stroke prevention in AF sufferers. Historically, warfarin has been used for anticoagulation and has been effective in reducing the risk of stroke by ~60%. 5 Recently, novel oral anticoagulants such as dabigatran, rivaroxaban, apixaban, and edoxaban have shown comparable efficacy to warfarin with potentially better safety profiles.6-9 Although anticoagulation can be effective in prevention of thromboembolic events in patients with atrial fibrillation, only 30% to 50% of patients are treated with it, due to various barriers and contraindications. Chief among those barriers is the elevated risk of bleeding associated with warfarin or the novel oral anticoagulants, which is reported in clinical trials to be in the vicinity of 1.4% to > 3% per year.10 The incidence of major hemorrhage with anticoagulation seems to be higher for patients older than 80 years of age.
In an alternative approach to stroke prevention in patients with non-valvular AF, several implantable, self-expandable left atrial appendage (LAA) occlusion devices have been developed. Those devices are inserted into the LAA through
3
catheter-based delivery systems, via transseptal puncture from the right to left atrium. This group of endocardial closure devices includes the Watchman™ device (Boston Scientific Corp., Marlborough, MA), the Amplatzer™ Cardiac Plug (ACP) and Amplatzer™ Amulet™ devices (St. Jude Medical, St. Paul, MN), and the Coherex WaveCrest® device (Coherex Medical Inc., Salt Lake City, UT).11 A review of the FDA device approval web pages on August 30th, 2015, revealed that only the Watchman device had FDA approval in the United States. All of the aforementioned devices have a CE (Conformité Européenne) mark for use in the European Union.
The Lariat® suture delivery device (SentreHeart Inc., Redwood City, CA) deploys a different strategy for ligation of the LAA that combines a transseptal and an epicardial approach. Applying the Lariat suture, or snare, to the epicardial surface of the LAA ostium requires subxiphoid pericardial access. This may not be achievable in the presence of pericardial adhesions, can provoke pericarditis, and is not suitable for all LAA anatomies. The Lariat device has received 510(k) clearance by the FDA for facilitation of suture placement and knot tying in surgical applications where soft tissues are being approximated, but essentially all of its use has been as an LAA exclusion device.12, 13 Although case series do exist describing results with the device both in Europe12 and the United States14, long-term non-inferiority or superiority randomized controlled trial data vis-à-vis anticoagulation, is lacking. A putative advantage of the Lariat suture application is electromechanical isolation of the left atrial myocardium from the LAA, the
4
latter in itself being a known trigger for AF15, 16. A future randomized controlled trial (AMAZE Trial) will evaluate the use of the Lariat device for the ligation of the LAA as an adjunctive treatment to ablation in patients with persistent or longstanding persistent AF.
Several methods for the ligation of the LAA during concomitant cardiac surgery exist as well. Postoperative TEE data suggests that up to 60% of these closures may be unsuccessful, as judged by the presence of LAA remnants > 1cm, flow in the LAA remnant, or thrombi in the LAA remnant.17 Despite the uncertainty about the efficacy of varying surgical approaches to LAA ligation and its effects on the development of thromboembolic complications such as stroke, the 2014 guideline for the management of patients with AF from the American College of Cardiology/American Heart Association/Heart Rhythm Society made a class IIb recommendation to attempt excision of the LAA in patients undergoing cardiac surgery (level of evidence C).18 In the same guideline, the percutaneous devices such as the Watchman device were briefly described, but the authors did not find sufficient evidence in the literature to make a formal recommendation about their use at the time. Since the publication of that guideline, FDA has approved the WATCHMAN device. The 2012 focused update of the European Society of Cardiology guidelines for the management of atrial fibrillation gave class IIb (LOE B) recommendation for use of Watchman device for patients at high risk for stroke but long-term contra-indication to anticoagulation.19
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In the remainder of this article, we focus on the Watchman device and the anesthetic and TEE implications during its implantation.
Left Atrial Appendage Morphology and Its Implication for Device Implantation and Thromboembolism The left atrial appendage is a remnant of the primary atrium, which forms during the third week of embryonic development. It is distinct from the main left atrial chamber in that it is trabeculated, has increased distensibility, and, on a cellular level, contains a high concentration of atrial natriuretic factor. The left atrium proper forms from the outgrowth of the pulmonary veins after the 4th week of embryonic development.20 Thrombus has a predilection for forming in the LAA both in non-valvular AF, as well as in patients with mitral valve disease who are either in AF or sinus rhythm. The LAA is the site of thrombus formation in more than 90% of patients with non-valvular AF, and in 60% of patients with rheumatic mitral valve disease (predominantly mitral stenosis).20, 21 Figure 1 shows a gross anatomic specimen of the LAA, demonstrating its trabecular structure, in contrast to the smooth-walled body of the left atrium.
The shape of the LAA is highly variable. Several predominant morphologies have recently been described that have gained attention due to their association with varying degrees of thromboembolism, as well as ease of occlusion with devices such as the Watchman. Di Biase et al.22 examined 932 patients who were
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scheduled to undergo AF ablation, with either cardiac CT or MRI, and subclassified the LAA morphology into 4 types, which they termed “cactus” (30%), “chicken wing” (48%), “windsock” (19%), and “cauliflower” (3%). The cactus morphology was described as having a dominant central lobe with secondary lobes extending from it in both superior and inferior directions. The distinguishing feature of the chicken wing variety is a bend in the proximal or middle part of the dominant lobe, or a folding back of the LAA on itself at some distance from the perceived LAA ostium. The authors stated that this type of LAA could have secondary lobes or twigs. The windsock morphology is characterized by a single, elongated lobe of the LAA as the primary structure, although it, too, can have secondary or tertiary lobes. Lastly, the cauliflower variety presented as a LAA with limited overall length, and a variable number of lobes. The feature distinguishing it from the cactus variety is the absence of a dominant lobe. This subtype could also have a complex internal structure, and irregular or ovoid shape of the LAA orifice. Some authors have referred to this anatomical variant as a broccoli subtype.1
Using two separate multivariate logistic regression models and controlling for CHADS2 score, gender, and AF types, Di Biase et al. demonstrated that patients with the chicken wing LAA morphology were significantly less likely to have had a history of stroke or TIA than those with the remaining subtypes. Although the overall size of the LAA has been reported in autopsy studies to correlate with the risk of stroke or TIA, this association was not corroborated in the Di Biase study.
7
Figures 2-5 demonstrate the TEE imaging equivalents of the four LAA morphologies. Proper identification of the type of LAA by the echocardiographer may be valuable during insertion of a transcatheter LAA occlusion device, because the size and depth of the main lobe of the LAA relative to the LAA ostium will determine the size of the device to be used, and the relative ease of successful occlusion. It is worth noting that ideal images that conform to one of the aforementioned shapes can be difficult to obtain via TEE, and may challenge the skills of the echocardiographer.
Characteristics of the WATCHMAN™ Device The WATCHMANTM Left Atrial Appendage Closure Device is composed of a selfexpanding central nitinol (nickel-titanium) compartment surrounded by 10 fixation anchors, along with a fabric cap, or skirt (Figure 6).1 The cap is crafted from polyethylene terephthalate, which at the time of implantation serves as a 160 micron filter designed to block emboli from exiting the LAA. It is available in 21, 24, 27, 30 and 33 mm sizes (device diameter). The approved indication is for LAA occlusion in patients who are at an increased risk for stroke and systemic embolism based on CHADS2 or CHA2DS2-VASc scores, and are recommended for anticoagulation with warfarin, but have an appropriate rationale to seek a nonpharmacologic alternative to warfarin. Table 1 summarizes the CHADS 2 and CHA2DS2-VASc scoring systems for predicting the risk of stroke based on comorbidities, age, and in the latter case also gender.18, 23-25 Intracardiac
8
thrombus, presence of ASD or PFO occlusion device, or inability to tolerate warfarin, aspirin, or clopidogrel, are contraindications to implantation of the device. Table 2 presents a summary of these contraindications. The Watchman device Directions For Use document does not distinguish between absolute and relative contraindications. Therefore, the list of contraindications should be treated as absolute.
The patient is typically maintained on aspirin and warfarin for 45 days post implantation. At that time, if echocardiographic surveillance does not reveal peridevice leak jet ≥ 5mm in diameter, thrombi, dislodgement, or other device complications, the patient is transitioned to aspirin and clopidogrel26. After 6 months, monotherapy with aspirin may be considered. In the PREVAIL trial, warfarin was discontinued after 45 days in 92% of patients, and in > 99% after 12 months.26 Endocarditis prophylaxis should be offered during the initial 6 months after device implantation. Longer prophylaxis is at the discretion of the treating cardiologist.
The safety and long-term efficacy of the Watchman device has been evaluated in a randomized, prospective pivotal study (the PROTECT AF trial)27, as well as a follow-on prospective, randomized trial (the PREVAIL trial)26. The multi-institution PROTECT AF trial in the United States and Europe compared LAA occlusion with the Watchman device versus warfarin anticoagulation. Patients with nonvalvular atrial fibrillation and at least one of the following were included: previous
9
stroke or TIA, congestive heart failure, diabetes, hypertension, or age greater than 75. The primary efficacy endpoint in this study was occurrence of ischemic or hemorrhagic stroke, cardiovascular or unexplained death, or systemic emboli within up to 3 years. The trial showed that at 3.8 years of follow-up, there was a primary event rate of 2.3 events per 100 patient-years for the device group, compared to a primary event rate of 3.8 events per 100 patient-years for the warfarin group, thus meeting the criteria for both non-inferiority and superiority. In the device group, there were lower rates of both cardiovascular mortality and allcause mortality.28 The PREVAIL trial showed that use of the Watchman device was not inferior to warfarin therapy for ischemic stroke prevention, with a significantly lower early safety events rate than the PROTECT AF trial (2.2%). Registry studies seem to confirm non-inferiority to warfarin.
Device Implantation and TEE Understanding the steps required to successfully implant the Watchman device aids the anesthesiologist in providing the best care to the patient, and in communicating with the invasive cardiologist or cardiac surgeon performing the procedure. TEE is essential for identifying the morphology, size and depth of the LAA, number and location of lobes relative to LAA ostium, and for proper positioning of the device.1, 29 Use of fluoroscopic guidance alone may not be sufficient, particularly in cases where the LAA anatomy is complex and involves several lobes. Additionally, demonstrating absence of any absolute or relative contraindication to the procedure such as LAA thrombus, prior interatrial septal
10
device, aneurysmal interatrial septum, PFO, ASD and significant mitral regurgitation, is essential. TEE also allows for rapid recognition of any procedural complications such as development of pericardial effusion. As the procedure becomes more prevalent and is performed in smaller centers, cardiac anesthesiologists may find themselves providing more perioperative TEE services in this type of procedure, similar to the TEE services provided during open heart surgery.
After induction of appropriate anesthesia or sedation, the TEE probe is inserted and the LAA ostium size and usable length are measured in 4 dimensions: a) 0 – 20° in the mid-esophageal (ME) four-chamber view; b) 45–60° corresponding to the ME aortic valve view; c) 90° in the ME two-chamber view; and d) 120 – 135° in the aortic valve long-axis view.1, 29 One can also utilize X-plane at 0° to obtain a simultaneous 90° orthogonal imaging plane and an X-plane from 45° will yield a 135° view. The 0° and 135° views often show the largest ostial diameter. When using 2D multiplane TEE, the ostium diameter should be obtained from the level of the circumflex artery or the superior edge of the mitral valve annulus to a point 2cm from the limbus of the left upper pulmonary vein. Three-dimensional TEE can also be used to assess the size of the LAA ostium (Fig. 7).30-32 The 10 active fixation anchors on the LAA side of the device engage the tissue to offer device stability, but the Watchman device is kept in place largely by radial forces generated from compression of the device. The goal, therefore, is for a 12-20% compression of the device to be achieved once it is implanted, and the device,
11
accordingly, is selected to be some 12-20% wider than the widest measurement of the LAA orifice. For example, for a LAA orifice of 19mm, a 21mm device will typically be selected. The maximum LAA ostium and the LAA depth measurements are used as a basis for selecting the device size. The length of the Watchman device is the same as the device size. Therefore, the dominant lobe of the LAA should ideally be at least as deep as the device size selected in order to accommodate the device. This ‘usable depth’ of the LAA is measured from the ostium line to the apex of the LAA or the deepest portion of its dominant lobe (Fig. 2, 3 and 4). The maximum LAA ostium size should be between 17 to 31 mm to accommodate the currently available device sizes. Other structures to consider during the baseline TEE exam include the pulmonary veins and flow, the mitral valve structural integrity and function, biventricular performance, presence of pericardial effusion, and presence of any significant aortic atheromatous disease.
The absence of clot in the atrium or LAA must be verified. The morphology of the LAA should also be assessed. The windsock type of LAA is easiest to occlude as it consists of one long tube-like space. The cauliflower type LAA may be short relative to the size of its orifice, making it hard to occlude with a Watchman device. Likewise, the chicken wing type may have a short proximal portion, which is less optimal for occlusion. In certain instances, device deployment may be successful even if the protrusion of the shoulder is 40-50% of the device depth.33
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As the Watchman device skirt covers 50% of the device surface, this protruding area will be covered and will endothelialize, leading to successful occlusion.
Next, the echocardiographer should guide the position of the transseptal sheath and needle. The recommended position for transseptal crossing is the inferoposterior part of the septum.1 The catheters are more difficult to manipulate and position if the transseptal puncture is too close to the plane of the mitral valve orifice. In bicaval view the transseptal sheath and catheter are slowly pulled inferiorly from SVC towards the mid portion of the septum. A leftward tenting of the interatrial septum can be seen when the transseptal needle comes into contact with the septum (Figure 8). Next, a modified short axis view at the aortic valve level in the mid esophagus is used to position the transseptal access sheath posteriorly (away from aortic valve) with a clockwise rotation. Another useful ME TEE view for transseptal puncture guidance is the bicaval view with an X-plane through the tented site demonstrating modified short axis view at the aortic valve level at the same time. Live 3D or 3D zoom can also be used to confirm the proper transseptal puncture site, although use of 3D images for this purpose is not necessary. After crossing the interatrial septum, it is important to measure the LA mean pressure to ensure it is ~15 mmHg to avoid underestimation of the LAA ostial size from hypovolemia (since the patients are NPO prior to the procedure).33
13
After the needle and sheath are advanced into the left atrium, the sheath is further advanced into the left upper pulmonary vein (LUPV). After administration of 100 IU/kg heparin, the WATCHMAN access sheath is passed over a guidewire into the LUPV. Activated clotting time is maintained at 200-300 seconds and is checked at 30-minute intervals. A pigtail catheter is inserted through the WATCHMAN access sheath. With the help of TEE, it is then pulled back from the LUPV and inserted into the distal portion of the LAA. The appropriate position is verified both angiographically and echocardiographically. A full sweep from 0 to 135° on multiplane TEE is recommended. Ongoing assessment for any evidence of pericardial effusion is performed. The WATCHMAN access sheath is then advanced in the correct position in the LAA over the pigtail catheter, the pigtail catheter is removed, and, after rechecking the access sheath positioning, the Watchman delivery system is introduced. The delivery catheter tip position in the LAA is reconfirmed on fluoroscopy and TEE. The device is then deployed by retracting the access sheath and delivery catheter assembly. At this point, the device is still attached to the core wire.
A set of device release criteria should then be confirmed using fluoroscopy and TEE. The release criteria are Position, Anchor, Size and Seal (PASS). Position is verified by confirming that the plane of maximum diameter of the device is at or just distal to the ostium, and that it spans the entire LAA ostium. Too distal deployment increases the risk of uncovered LAA lobes, incomplete seal or residual flow in the LAA. Too shallow a placement may lead to low compression
14
or unstable device. In addition, the device may protrude too far into the LA. Three-dimensional TEE can add useful information about the fit and position of the device.29 The invasive cardiologist or surgeon verifies the device anchoring by using a “tug test” that involves retracting and releasing the deployment knob. An anchored device should gently tug on the LAA. Size is verified by measuring the maximum diameter of the Watchman device in the same 4 dimensions used to measure the ostium size on TEE. The “threaded insert” (Fig. 9) must be visible when measuring on echo to ensure the device was measured at its widest crosssection in all angles. The size of the device, once deployed, should be 8 to 20% smaller than its original dimension as this degree of compression yields adequate radial pressure that helps keep the device in place. Finally, seal is verified using color flow Doppler and angiography. All of the lobes of the LAA should be sealed. Small peri-device leaks are permissible (<5mm) and may not require repositioning of the device1. However, if gaps or leaks greater than 5mm exist, the device should be recaptured and repositioned, or completely removed. Recapture of the device can be achieved by advancing the delivery assembly over the shoulders of the device until it is fully collapsed.
The procedure ends when the delivery system is removed and local hemostasis is achieved. Once the patient is awake, a neurologic exam should be performed. Figure 9 shows a successfully deployed Watchman device. The same device is shown in 3D zoom in Figure 10.
15
Throughout deployment and before case completion, the echocardiographer should also monitor for hemopericardium, device migration or dislodgement, interference with the function of the mitral valve or pulmonary vein flow, or thrombus formation. Typically at the end of the procedure, a small ASD can be seen at the site of transseptal puncture, normally with left to right shunt which can easily be identified using color flow Doppler.
Data from the PROTECT AF trial showed that the most common peri-procedural complications were pericardial effusions and air embolism causing stroke.1 The effusions seemed to be associated with manipulation of the device or the delivery sheath within the LAA, the transseptal puncture, or the tug test. The air embolism could have arisen from the large 12F transseptal access sheath. Low LAA pressures related to dehydration from pre-procedural fasting should be avoided in order to minimize the chances of left-sided air emboli.
General Anesthesia Vs. Monitored Anesthesia Care For Device Implantation Due to the importance of continuous TEE monitoring, in the United States implantation of the Watchman device is most frequently performed under general anesthesia. Standard ASA monitors with arterial blood pressure recording are utilized. We suggest techniques that will ensure rapid emergence and extubation at the end of the procedure. Blood gas analysis and activated clotting time assessment should be available. The ability to rapidly resuscitate the patient in the event of a hemodynamic catastrophe should be present.
16
After device deployment, the ACT is allowed to drift back to the patient’s baseline, and the patient is extubated. The patient will recover in the postanesthesia care unit and is then transferred to a cardiology floor bed until he or she is ready for discharge. Select patients are transferred to the cardiology care unit if closer monitoring is warranted. Institutional practices will often determine the exact post-operative care arrangements.
The Watchman device can also be implanted under conscious sedation or monitored anesthesia care. Mobius-Winkler et al.1 recommend conscious sedation with midazolam and propofol. Chan et al.34 demonstrated eleven successful LAA occlusion device implantations, both Watchman and ACP, performed under conscious sedation utilizing midazolam and fentanyl, with no complications arising from conscious sedation. If conscious sedation is chosen as the type of anesthesia for this procedure, emergency airway devices should be readily available.1
Conclusions In an aging population, atrial fibrillation is a growing problem. A large percentage of thromboembolic strokes are the result of thrombi arising in the LAA in patients with non-valvular atrial fibrillation. Anticoagulation has been the mainstay of therapy for those patients, but is not suitable for all due to the risk of hemorrhagic
17
complications. The WATCHMANTM Left Atrial Appendage Closure Device (Boston Scientific, Marlborough, MA, USA) has proven to be a suitable nonpharmacologic alternative for thromboembolism prevention in patients who are at an increased risk for stroke and systemic embolism based on CHADS2 or CHA2DS2-VASc scores.
Both general anesthesia and monitored anesthesia care have been used successfully for procedural sedation. TEE is essential in guiding implantation of the device, together with angiography. The ability to develop multiplanar images of the LAA and an understanding of the predominant LAA morphologies, as well as the procedural steps, aids the echocardiographer in providing the required information to the cardiologist performing the implantation of the device.
Experience with the Watchman device and the availability of future device alternatives will likely make percutaneous LAA occlusion more common. Use of alternatives to TEE such as intracardiac echo to image the LAA have been described.35 Until further experience with such methods demonstrates sufficient and universal reliability as a peri-procedural guidance tool, TEE will likely remain essential during Watchman device implantation.
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Figure Legends
Figure 1. LAA - gross anatomy specimen Figure 2. Chicken wing LAA morphology Figure 3. Cauliflower (broccoli) LAA morphology Figure 4. Windsock LAA morphology Figure 5. Cactus LAA morphology Figure 6. Watchman device Figure 7. 3D TEE full volume multiplane reconstruction of the LAA, with diameter measurements at the ostium Figure 8. Transseptal needle tenting the interatrial septum before puncture Figure 9. Watchman device post deployment Figure 10. 3D zoom image of a successfully deployed Watchman device.
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Holmes DR, Reddy VY, Turi ZG, et al.: Percutaneous closure of the left atrial appendage versus warfarin therapy for prevention of stroke in patients with atrial fibrillation: a randomised non-inferiority trial. Lancet. 374:534-542, 2009.
29.
Chue CD, de Giovanni J, Steeds RP: The role of echocardiography in percutaneous left atrial appendage occlusion. Eur J Echocardiogr. 12:i310, 2011.
23
30.
Shah SJ, Bardo DM, Sugeng L, et al.: Real-time three-dimensional transesophageal echocardiography of the left atrial appendage: initial experience in the clinical setting. J Am Soc Echocardiogr. 21:1362-1368, 2008.
31.
Brinkman V, Kalbfleisch S, Auseon A, et al.: Real time three-dimensional transesophageal echocardiography-guided placement of left atrial appendage occlusion device. Echocardiography. 26:855-858, 2009.
32.
Nakajima H, Seo Y, Ishizu T, et al.: Analysis of the left atrial appendage by three-dimensional transesophageal echocardiography. Am J Cardiol. 106:885-892, 2010.
33.
Saw J, Lempereur M: Percutaneous left atrial appendage closure: procedural techniques and outcomes. JACC Cardiovasc Interv. 7:12051220, 2014.
34.
Chan NY, Lau CL, Tsui PT, et al.: Experience of left atrial appendage closure performed under conscious sedation. Asian Cardiovasc Thorac Ann. 23:394-398, 2015.
35.
MacDonald ST, Newton JD, Ormerod OJ: Intracardiac echocardiography off piste? Closure of the left atrial appendage using ICE and local anesthesia. Catheter Cardiovasc Interv. 77:124-127, 2011.
24
Table 1. CHADS2 and CHA2DS2-VASc scoring systems CHADS2 Points 1
Score
CHA2DS2VASc Points 1
C
Congestive Heart Failure
1
H
Hypertension
1
1
A
Age ≥75 years
2
1
D
Diabetes Mellitus
1
2
S2
Stroke or Transient ischemic attack
2
V
1
A
Vascular Disease (e.g. peripheral artery disease, myocardial infarction, aortic plaque rupture) Age 65-74 years
Sc
Sex category (female gender)
1
1
Score
Stroke Risk
Recommended Anticoagulation
0
Low
No antithrombotic therapy (or Aspirin)
1
Moderate
Oral anticoagulatant (or Aspirin)
2
High
Oral anticoagulant
25
Table 2. Contraindications to Watchman device implantation Intracardiac thrombus visualized by echocardiographic imaging An atrial septal defect repair or closure device, or a patent foramen ovale repair or closure device The LAA anatomy will not accommodate a device Any of the customary contraindications for other percutaneous catheterization procedures (e.g. patient size too small to accommodate TEE probe or required catheters) or conditions (e.g. active infection, bleeding disorder) Contraindications to the use of warfarin, aspirin, or clopidogrel Known hypersensitivity to any portion of the device material or the individual components
®
Based on WATCHMAN Directions For Use, https://www.bostonscientific.com/content/dam/Manuals/us/current-rev-en/9074622101C_Watchman%20Device_DFU_en-US_s.pdf th Last accessed November 28 , 2015.
26
27
28
29
30
31
32
33
34
Ratna
www.elsevier.com/locate/buildenv
PII: DOI: Reference:
S1053-0770(16)30184-7 http://dx.doi.org/10.1053/j.jvca.2016.06.012 YJCAN3725
To appear in: Journal of Cardiothoracic and Vascular Anesthesia Received date: 23 September 2015 Cite this article as: Ludmil Mitrev, Natalie Trautman, Ratna Vadlamudi, Nayan Desai and Sajjad A. Sabir, Anesthesia and TEE for WATCHMAN TM Device Implantation, Journal of Cardiothoracic and Vascular Anesthesia, http://dx.doi.org/10.1053/j.jvca.2016.06.012 This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting galley proof before it is published in its final citable form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.
Anesthesia and TEE for WATCHMANTM Device Implantation
Authors:
1
Ludmil Mitrev, M.D. , e-mail: [email protected] 1
Natalie Trautman, M.D. , e-mail: [email protected] 2
Ratna Vadlamudi, M.D. , e-mail: [email protected] 3
Nayan Desai, M.D. , e-mail: [email protected] 3
Sajjad A Sabir, M.D. , e-mail: [email protected]
1
Department of Anesthesiology and Division of Cardiothoracic Anesthesiology, Cooper University
Hospital, One Cooper Plaza, Camden, NJ 08103, U.S.A. 2
Department of Anesthesiology, Emory University, Atlanta, GA 30322, U.S.A.
3
Department of Cardiology, Cooper University Hospital, Camden, NJ 08103, U.S.A.
Corresponding Author: Ludmil Mitrev, M.D., e-mail: [email protected], tel. +1 (856) 968-7334
Conflicts of Interest: None
Acknowledgements The authors wish to thank Kelly Speich, MS for his assistance with gross anatomy images.
Keywords Watchman device; left atrial appendage closure device; atrial fibrillation; ischemic stroke.
1
Anesthesia and TEE for WATCHMANTM Device Implantation
Abstract Only 30% to 50% of patients with non-valvular atrial fibrillation are treated with anticoagulation to reduce the risk of thromboembolic events, due to patient adherence and the side effect profile of such therapy.1 Several left atrial appendage occlusion devices have been proposed as alternative approaches to minimization of the risk of thromboembolic events. The present article reviews the anesthetic and TEE implications of the WATCHMANTM (Boston Scientific, Marlborough, MA, USA) Left Atrial Appendage Closure Device implantation.
Introduction Stroke is a common cardiovascular event with significant morbidity and mortality. A 2015 annual report from the American Heart Association estimated the annual incidence of stoke in the United States to be approximately 795,000 2 cases, of which 77% were new events, and the remainder – recurrent strokes. Eightyseven percent of all strokes are ischemic. The age-adjusted death rate per 100,000 population in 2009-2011 was 38.9, accounting for some 128,932 strokerelated deaths in 2011. When considered separately from other cardiovascular diseases, stroke ranked 4th among all causes of death in the United States, behind diseases of the heart, cancer, and chronic lower respiratory diseases 2. The global prevalence of stroke was 33 million cases in 20103, and stroke was
2
second only to ischemic heart disease in terms of mortality on a global basis, accounting for 11.13% of total deaths worldwide.
Atrial fibrillation (AF) is an independent risk factor for stroke, increasing the risk 5-fold in all age groups. The attributable risk of stroke related to AF increases with age, and may be substantially underestimated, due to the fact that AF can be asymptomatic and can remain undetected4. Atrial fibrillation is said to contribute to greater than 20% of strokes, and many efforts are directed towards stroke prevention in AF sufferers. Historically, warfarin has been used for anticoagulation and has been effective in reducing the risk of stroke by ~60%. 5 Recently, novel oral anticoagulants such as dabigatran, rivaroxaban, apixaban, and edoxaban have shown comparable efficacy to warfarin with potentially better safety profiles.6-9 Although anticoagulation can be effective in prevention of thromboembolic events in patients with atrial fibrillation, only 30% to 50% of patients are treated with it, due to various barriers and contraindications. Chief among those barriers is the elevated risk of bleeding associated with warfarin or the novel oral anticoagulants, which is reported in clinical trials to be in the vicinity of 1.4% to > 3% per year.10 The incidence of major hemorrhage with anticoagulation seems to be higher for patients older than 80 years of age.
In an alternative approach to stroke prevention in patients with non-valvular AF, several implantable, self-expandable left atrial appendage (LAA) occlusion devices have been developed. Those devices are inserted into the LAA through
3
catheter-based delivery systems, via transseptal puncture from the right to left atrium. This group of endocardial closure devices includes the Watchman™ device (Boston Scientific Corp., Marlborough, MA), the Amplatzer™ Cardiac Plug (ACP) and Amplatzer™ Amulet™ devices (St. Jude Medical, St. Paul, MN), and the Coherex WaveCrest® device (Coherex Medical Inc., Salt Lake City, UT).11 A review of the FDA device approval web pages on August 30th, 2015, revealed that only the Watchman device had FDA approval in the United States. All of the aforementioned devices have a CE (Conformité Européenne) mark for use in the European Union.
The Lariat® suture delivery device (SentreHeart Inc., Redwood City, CA) deploys a different strategy for ligation of the LAA that combines a transseptal and an epicardial approach. Applying the Lariat suture, or snare, to the epicardial surface of the LAA ostium requires subxiphoid pericardial access. This may not be achievable in the presence of pericardial adhesions, can provoke pericarditis, and is not suitable for all LAA anatomies. The Lariat device has received 510(k) clearance by the FDA for facilitation of suture placement and knot tying in surgical applications where soft tissues are being approximated, but essentially all of its use has been as an LAA exclusion device.12, 13 Although case series do exist describing results with the device both in Europe12 and the United States14, long-term non-inferiority or superiority randomized controlled trial data vis-à-vis anticoagulation, is lacking. A putative advantage of the Lariat suture application is electromechanical isolation of the left atrial myocardium from the LAA, the
4
latter in itself being a known trigger for AF15, 16. A future randomized controlled trial (AMAZE Trial) will evaluate the use of the Lariat device for the ligation of the LAA as an adjunctive treatment to ablation in patients with persistent or longstanding persistent AF.
Several methods for the ligation of the LAA during concomitant cardiac surgery exist as well. Postoperative TEE data suggests that up to 60% of these closures may be unsuccessful, as judged by the presence of LAA remnants > 1cm, flow in the LAA remnant, or thrombi in the LAA remnant.17 Despite the uncertainty about the efficacy of varying surgical approaches to LAA ligation and its effects on the development of thromboembolic complications such as stroke, the 2014 guideline for the management of patients with AF from the American College of Cardiology/American Heart Association/Heart Rhythm Society made a class IIb recommendation to attempt excision of the LAA in patients undergoing cardiac surgery (level of evidence C).18 In the same guideline, the percutaneous devices such as the Watchman device were briefly described, but the authors did not find sufficient evidence in the literature to make a formal recommendation about their use at the time. Since the publication of that guideline, FDA has approved the WATCHMAN device. The 2012 focused update of the European Society of Cardiology guidelines for the management of atrial fibrillation gave class IIb (LOE B) recommendation for use of Watchman device for patients at high risk for stroke but long-term contra-indication to anticoagulation.19
5
In the remainder of this article, we focus on the Watchman device and the anesthetic and TEE implications during its implantation.
Left Atrial Appendage Morphology and Its Implication for Device Implantation and Thromboembolism The left atrial appendage is a remnant of the primary atrium, which forms during the third week of embryonic development. It is distinct from the main left atrial chamber in that it is trabeculated, has increased distensibility, and, on a cellular level, contains a high concentration of atrial natriuretic factor. The left atrium proper forms from the outgrowth of the pulmonary veins after the 4th week of embryonic development.20 Thrombus has a predilection for forming in the LAA both in non-valvular AF, as well as in patients with mitral valve disease who are either in AF or sinus rhythm. The LAA is the site of thrombus formation in more than 90% of patients with non-valvular AF, and in 60% of patients with rheumatic mitral valve disease (predominantly mitral stenosis).20, 21 Figure 1 shows a gross anatomic specimen of the LAA, demonstrating its trabecular structure, in contrast to the smooth-walled body of the left atrium.
The shape of the LAA is highly variable. Several predominant morphologies have recently been described that have gained attention due to their association with varying degrees of thromboembolism, as well as ease of occlusion with devices such as the Watchman. Di Biase et al.22 examined 932 patients who were
6
scheduled to undergo AF ablation, with either cardiac CT or MRI, and subclassified the LAA morphology into 4 types, which they termed “cactus” (30%), “chicken wing” (48%), “windsock” (19%), and “cauliflower” (3%). The cactus morphology was described as having a dominant central lobe with secondary lobes extending from it in both superior and inferior directions. The distinguishing feature of the chicken wing variety is a bend in the proximal or middle part of the dominant lobe, or a folding back of the LAA on itself at some distance from the perceived LAA ostium. The authors stated that this type of LAA could have secondary lobes or twigs. The windsock morphology is characterized by a single, elongated lobe of the LAA as the primary structure, although it, too, can have secondary or tertiary lobes. Lastly, the cauliflower variety presented as a LAA with limited overall length, and a variable number of lobes. The feature distinguishing it from the cactus variety is the absence of a dominant lobe. This subtype could also have a complex internal structure, and irregular or ovoid shape of the LAA orifice. Some authors have referred to this anatomical variant as a broccoli subtype.1
Using two separate multivariate logistic regression models and controlling for CHADS2 score, gender, and AF types, Di Biase et al. demonstrated that patients with the chicken wing LAA morphology were significantly less likely to have had a history of stroke or TIA than those with the remaining subtypes. Although the overall size of the LAA has been reported in autopsy studies to correlate with the risk of stroke or TIA, this association was not corroborated in the Di Biase study.
7
Figures 2-5 demonstrate the TEE imaging equivalents of the four LAA morphologies. Proper identification of the type of LAA by the echocardiographer may be valuable during insertion of a transcatheter LAA occlusion device, because the size and depth of the main lobe of the LAA relative to the LAA ostium will determine the size of the device to be used, and the relative ease of successful occlusion. It is worth noting that ideal images that conform to one of the aforementioned shapes can be difficult to obtain via TEE, and may challenge the skills of the echocardiographer.
Characteristics of the WATCHMAN™ Device The WATCHMANTM Left Atrial Appendage Closure Device is composed of a selfexpanding central nitinol (nickel-titanium) compartment surrounded by 10 fixation anchors, along with a fabric cap, or skirt (Figure 6).1 The cap is crafted from polyethylene terephthalate, which at the time of implantation serves as a 160 micron filter designed to block emboli from exiting the LAA. It is available in 21, 24, 27, 30 and 33 mm sizes (device diameter). The approved indication is for LAA occlusion in patients who are at an increased risk for stroke and systemic embolism based on CHADS2 or CHA2DS2-VASc scores, and are recommended for anticoagulation with warfarin, but have an appropriate rationale to seek a nonpharmacologic alternative to warfarin. Table 1 summarizes the CHADS 2 and CHA2DS2-VASc scoring systems for predicting the risk of stroke based on comorbidities, age, and in the latter case also gender.18, 23-25 Intracardiac
8
thrombus, presence of ASD or PFO occlusion device, or inability to tolerate warfarin, aspirin, or clopidogrel, are contraindications to implantation of the device. Table 2 presents a summary of these contraindications. The Watchman device Directions For Use document does not distinguish between absolute and relative contraindications. Therefore, the list of contraindications should be treated as absolute.
The patient is typically maintained on aspirin and warfarin for 45 days post implantation. At that time, if echocardiographic surveillance does not reveal peridevice leak jet ≥ 5mm in diameter, thrombi, dislodgement, or other device complications, the patient is transitioned to aspirin and clopidogrel26. After 6 months, monotherapy with aspirin may be considered. In the PREVAIL trial, warfarin was discontinued after 45 days in 92% of patients, and in > 99% after 12 months.26 Endocarditis prophylaxis should be offered during the initial 6 months after device implantation. Longer prophylaxis is at the discretion of the treating cardiologist.
The safety and long-term efficacy of the Watchman device has been evaluated in a randomized, prospective pivotal study (the PROTECT AF trial)27, as well as a follow-on prospective, randomized trial (the PREVAIL trial)26. The multi-institution PROTECT AF trial in the United States and Europe compared LAA occlusion with the Watchman device versus warfarin anticoagulation. Patients with nonvalvular atrial fibrillation and at least one of the following were included: previous
9
stroke or TIA, congestive heart failure, diabetes, hypertension, or age greater than 75. The primary efficacy endpoint in this study was occurrence of ischemic or hemorrhagic stroke, cardiovascular or unexplained death, or systemic emboli within up to 3 years. The trial showed that at 3.8 years of follow-up, there was a primary event rate of 2.3 events per 100 patient-years for the device group, compared to a primary event rate of 3.8 events per 100 patient-years for the warfarin group, thus meeting the criteria for both non-inferiority and superiority. In the device group, there were lower rates of both cardiovascular mortality and allcause mortality.28 The PREVAIL trial showed that use of the Watchman device was not inferior to warfarin therapy for ischemic stroke prevention, with a significantly lower early safety events rate than the PROTECT AF trial (2.2%). Registry studies seem to confirm non-inferiority to warfarin.
Device Implantation and TEE Understanding the steps required to successfully implant the Watchman device aids the anesthesiologist in providing the best care to the patient, and in communicating with the invasive cardiologist or cardiac surgeon performing the procedure. TEE is essential for identifying the morphology, size and depth of the LAA, number and location of lobes relative to LAA ostium, and for proper positioning of the device.1, 29 Use of fluoroscopic guidance alone may not be sufficient, particularly in cases where the LAA anatomy is complex and involves several lobes. Additionally, demonstrating absence of any absolute or relative contraindication to the procedure such as LAA thrombus, prior interatrial septal
10
device, aneurysmal interatrial septum, PFO, ASD and significant mitral regurgitation, is essential. TEE also allows for rapid recognition of any procedural complications such as development of pericardial effusion. As the procedure becomes more prevalent and is performed in smaller centers, cardiac anesthesiologists may find themselves providing more perioperative TEE services in this type of procedure, similar to the TEE services provided during open heart surgery.
After induction of appropriate anesthesia or sedation, the TEE probe is inserted and the LAA ostium size and usable length are measured in 4 dimensions: a) 0 – 20° in the mid-esophageal (ME) four-chamber view; b) 45–60° corresponding to the ME aortic valve view; c) 90° in the ME two-chamber view; and d) 120 – 135° in the aortic valve long-axis view.1, 29 One can also utilize X-plane at 0° to obtain a simultaneous 90° orthogonal imaging plane and an X-plane from 45° will yield a 135° view. The 0° and 135° views often show the largest ostial diameter. When using 2D multiplane TEE, the ostium diameter should be obtained from the level of the circumflex artery or the superior edge of the mitral valve annulus to a point 2cm from the limbus of the left upper pulmonary vein. Three-dimensional TEE can also be used to assess the size of the LAA ostium (Fig. 7).30-32 The 10 active fixation anchors on the LAA side of the device engage the tissue to offer device stability, but the Watchman device is kept in place largely by radial forces generated from compression of the device. The goal, therefore, is for a 12-20% compression of the device to be achieved once it is implanted, and the device,
11
accordingly, is selected to be some 12-20% wider than the widest measurement of the LAA orifice. For example, for a LAA orifice of 19mm, a 21mm device will typically be selected. The maximum LAA ostium and the LAA depth measurements are used as a basis for selecting the device size. The length of the Watchman device is the same as the device size. Therefore, the dominant lobe of the LAA should ideally be at least as deep as the device size selected in order to accommodate the device. This ‘usable depth’ of the LAA is measured from the ostium line to the apex of the LAA or the deepest portion of its dominant lobe (Fig. 2, 3 and 4). The maximum LAA ostium size should be between 17 to 31 mm to accommodate the currently available device sizes. Other structures to consider during the baseline TEE exam include the pulmonary veins and flow, the mitral valve structural integrity and function, biventricular performance, presence of pericardial effusion, and presence of any significant aortic atheromatous disease.
The absence of clot in the atrium or LAA must be verified. The morphology of the LAA should also be assessed. The windsock type of LAA is easiest to occlude as it consists of one long tube-like space. The cauliflower type LAA may be short relative to the size of its orifice, making it hard to occlude with a Watchman device. Likewise, the chicken wing type may have a short proximal portion, which is less optimal for occlusion. In certain instances, device deployment may be successful even if the protrusion of the shoulder is 40-50% of the device depth.33
12
As the Watchman device skirt covers 50% of the device surface, this protruding area will be covered and will endothelialize, leading to successful occlusion.
Next, the echocardiographer should guide the position of the transseptal sheath and needle. The recommended position for transseptal crossing is the inferoposterior part of the septum.1 The catheters are more difficult to manipulate and position if the transseptal puncture is too close to the plane of the mitral valve orifice. In bicaval view the transseptal sheath and catheter are slowly pulled inferiorly from SVC towards the mid portion of the septum. A leftward tenting of the interatrial septum can be seen when the transseptal needle comes into contact with the septum (Figure 8). Next, a modified short axis view at the aortic valve level in the mid esophagus is used to position the transseptal access sheath posteriorly (away from aortic valve) with a clockwise rotation. Another useful ME TEE view for transseptal puncture guidance is the bicaval view with an X-plane through the tented site demonstrating modified short axis view at the aortic valve level at the same time. Live 3D or 3D zoom can also be used to confirm the proper transseptal puncture site, although use of 3D images for this purpose is not necessary. After crossing the interatrial septum, it is important to measure the LA mean pressure to ensure it is ~15 mmHg to avoid underestimation of the LAA ostial size from hypovolemia (since the patients are NPO prior to the procedure).33
13
After the needle and sheath are advanced into the left atrium, the sheath is further advanced into the left upper pulmonary vein (LUPV). After administration of 100 IU/kg heparin, the WATCHMAN access sheath is passed over a guidewire into the LUPV. Activated clotting time is maintained at 200-300 seconds and is checked at 30-minute intervals. A pigtail catheter is inserted through the WATCHMAN access sheath. With the help of TEE, it is then pulled back from the LUPV and inserted into the distal portion of the LAA. The appropriate position is verified both angiographically and echocardiographically. A full sweep from 0 to 135° on multiplane TEE is recommended. Ongoing assessment for any evidence of pericardial effusion is performed. The WATCHMAN access sheath is then advanced in the correct position in the LAA over the pigtail catheter, the pigtail catheter is removed, and, after rechecking the access sheath positioning, the Watchman delivery system is introduced. The delivery catheter tip position in the LAA is reconfirmed on fluoroscopy and TEE. The device is then deployed by retracting the access sheath and delivery catheter assembly. At this point, the device is still attached to the core wire.
A set of device release criteria should then be confirmed using fluoroscopy and TEE. The release criteria are Position, Anchor, Size and Seal (PASS). Position is verified by confirming that the plane of maximum diameter of the device is at or just distal to the ostium, and that it spans the entire LAA ostium. Too distal deployment increases the risk of uncovered LAA lobes, incomplete seal or residual flow in the LAA. Too shallow a placement may lead to low compression
14
or unstable device. In addition, the device may protrude too far into the LA. Three-dimensional TEE can add useful information about the fit and position of the device.29 The invasive cardiologist or surgeon verifies the device anchoring by using a “tug test” that involves retracting and releasing the deployment knob. An anchored device should gently tug on the LAA. Size is verified by measuring the maximum diameter of the Watchman device in the same 4 dimensions used to measure the ostium size on TEE. The “threaded insert” (Fig. 9) must be visible when measuring on echo to ensure the device was measured at its widest crosssection in all angles. The size of the device, once deployed, should be 8 to 20% smaller than its original dimension as this degree of compression yields adequate radial pressure that helps keep the device in place. Finally, seal is verified using color flow Doppler and angiography. All of the lobes of the LAA should be sealed. Small peri-device leaks are permissible (<5mm) and may not require repositioning of the device1. However, if gaps or leaks greater than 5mm exist, the device should be recaptured and repositioned, or completely removed. Recapture of the device can be achieved by advancing the delivery assembly over the shoulders of the device until it is fully collapsed.
The procedure ends when the delivery system is removed and local hemostasis is achieved. Once the patient is awake, a neurologic exam should be performed. Figure 9 shows a successfully deployed Watchman device. The same device is shown in 3D zoom in Figure 10.
15
Throughout deployment and before case completion, the echocardiographer should also monitor for hemopericardium, device migration or dislodgement, interference with the function of the mitral valve or pulmonary vein flow, or thrombus formation. Typically at the end of the procedure, a small ASD can be seen at the site of transseptal puncture, normally with left to right shunt which can easily be identified using color flow Doppler.
Data from the PROTECT AF trial showed that the most common peri-procedural complications were pericardial effusions and air embolism causing stroke.1 The effusions seemed to be associated with manipulation of the device or the delivery sheath within the LAA, the transseptal puncture, or the tug test. The air embolism could have arisen from the large 12F transseptal access sheath. Low LAA pressures related to dehydration from pre-procedural fasting should be avoided in order to minimize the chances of left-sided air emboli.
General Anesthesia Vs. Monitored Anesthesia Care For Device Implantation Due to the importance of continuous TEE monitoring, in the United States implantation of the Watchman device is most frequently performed under general anesthesia. Standard ASA monitors with arterial blood pressure recording are utilized. We suggest techniques that will ensure rapid emergence and extubation at the end of the procedure. Blood gas analysis and activated clotting time assessment should be available. The ability to rapidly resuscitate the patient in the event of a hemodynamic catastrophe should be present.
16
After device deployment, the ACT is allowed to drift back to the patient’s baseline, and the patient is extubated. The patient will recover in the postanesthesia care unit and is then transferred to a cardiology floor bed until he or she is ready for discharge. Select patients are transferred to the cardiology care unit if closer monitoring is warranted. Institutional practices will often determine the exact post-operative care arrangements.
The Watchman device can also be implanted under conscious sedation or monitored anesthesia care. Mobius-Winkler et al.1 recommend conscious sedation with midazolam and propofol. Chan et al.34 demonstrated eleven successful LAA occlusion device implantations, both Watchman and ACP, performed under conscious sedation utilizing midazolam and fentanyl, with no complications arising from conscious sedation. If conscious sedation is chosen as the type of anesthesia for this procedure, emergency airway devices should be readily available.1
Conclusions In an aging population, atrial fibrillation is a growing problem. A large percentage of thromboembolic strokes are the result of thrombi arising in the LAA in patients with non-valvular atrial fibrillation. Anticoagulation has been the mainstay of therapy for those patients, but is not suitable for all due to the risk of hemorrhagic
17
complications. The WATCHMANTM Left Atrial Appendage Closure Device (Boston Scientific, Marlborough, MA, USA) has proven to be a suitable nonpharmacologic alternative for thromboembolism prevention in patients who are at an increased risk for stroke and systemic embolism based on CHADS2 or CHA2DS2-VASc scores.
Both general anesthesia and monitored anesthesia care have been used successfully for procedural sedation. TEE is essential in guiding implantation of the device, together with angiography. The ability to develop multiplanar images of the LAA and an understanding of the predominant LAA morphologies, as well as the procedural steps, aids the echocardiographer in providing the required information to the cardiologist performing the implantation of the device.
Experience with the Watchman device and the availability of future device alternatives will likely make percutaneous LAA occlusion more common. Use of alternatives to TEE such as intracardiac echo to image the LAA have been described.35 Until further experience with such methods demonstrates sufficient and universal reliability as a peri-procedural guidance tool, TEE will likely remain essential during Watchman device implantation.
18
Figure Legends
Figure 1. LAA - gross anatomy specimen Figure 2. Chicken wing LAA morphology Figure 3. Cauliflower (broccoli) LAA morphology Figure 4. Windsock LAA morphology Figure 5. Cactus LAA morphology Figure 6. Watchman device Figure 7. 3D TEE full volume multiplane reconstruction of the LAA, with diameter measurements at the ostium Figure 8. Transseptal needle tenting the interatrial septum before puncture Figure 9. Watchman device post deployment Figure 10. 3D zoom image of a successfully deployed Watchman device.
19
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Bartus K, Han FT, Bednarek J, et al.: Percutaneous left atrial appendage suture ligation using the LARIAT device in patients with atrial fibrillation: initial clinical experience. J Am Coll Cardiol. 62:108-118, 2013.
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Pillarisetti J, Reddy YM, Gunda S, et al.: Endocardial (Watchman) vs epicardial (Lariat) left atrial appendage exclusion devices: Understanding the differences in the location and type of leaks and their clinical implications. Heart Rhythm. 12:1501-1507, 2015.
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Massumi A, Chelu MG, Nazeri A, et al.: Initial experience with a novel percutaneous left atrial appendage exclusion device in patients with atrial fibrillation, increased stroke risk, and contraindications to anticoagulation. Am J Cardiol. 111:869-873, 2013.
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Table 1. CHADS2 and CHA2DS2-VASc scoring systems CHADS2 Points 1
Score
CHA2DS2VASc Points 1
C
Congestive Heart Failure
1
H
Hypertension
1
1
A
Age ≥75 years
2
1
D
Diabetes Mellitus
1
2
S2
Stroke or Transient ischemic attack
2
V
1
A
Vascular Disease (e.g. peripheral artery disease, myocardial infarction, aortic plaque rupture) Age 65-74 years
Sc
Sex category (female gender)
1
1
Score
Stroke Risk
Recommended Anticoagulation
0
Low
No antithrombotic therapy (or Aspirin)
1
Moderate
Oral anticoagulatant (or Aspirin)
2
High
Oral anticoagulant
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Table 2. Contraindications to Watchman device implantation Intracardiac thrombus visualized by echocardiographic imaging An atrial septal defect repair or closure device, or a patent foramen ovale repair or closure device The LAA anatomy will not accommodate a device Any of the customary contraindications for other percutaneous catheterization procedures (e.g. patient size too small to accommodate TEE probe or required catheters) or conditions (e.g. active infection, bleeding disorder) Contraindications to the use of warfarin, aspirin, or clopidogrel Known hypersensitivity to any portion of the device material or the individual components
®
Based on WATCHMAN Directions For Use, https://www.bostonscientific.com/content/dam/Manuals/us/current-rev-en/9074622101C_Watchman%20Device_DFU_en-US_s.pdf th Last accessed November 28 , 2015.
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29
30
31
32
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