PART III - VENTRICULAR SEPTAL DEFECT CLOSURE
TABLE OF CONTENTS
BOOKSHOP
Updated on November 20, 2020
PART III

Ventricular septal defect closure

Gianfranco Butera1,2 , Mario Giordano3 , Quang N. Nguyen4 , Biagio Castaldi5 , Luciane Piazza6, Massimo Chessa6, Mario Carminati6
1 Department of Congenital Cardiology - Bambin Gesù Children's Hospital - Rome - Italy
2 Department of Congenital Cardiology - Evelina Children's Hospital - London - UK
3 Department of Pediatric Cardiology - Ospedale Monaldi – Università della Campania L. Vanvitelli – Napoli - Italy
4 Department of Cardiology Vietnam National Heart Institute - Hanoi Medical University - Vietnam
5 Department of Pediatric Cardiology - Padova University - Italy
6 Department of Pediatric Cardiology and ACHD - Policlinico San Donato IRCCS - San Donato Milanese - Italy

Summary

Isolated ventricular septal defect (VSD) is the most common congenital heart disease. Surgery has been performed for many years and remains the gold standard for the treatment of VSD.

However, it is associated with morbidity and mortality. Less invasive techniques have been developed in last fifteen years and the currently available data shows that percutaneous closure of muscular and perimembranous VSD even complex VSD is a possible, safe and effective alternative to the standard surgical approach.

While the transcatheter approach can be considered as a first choice treatment in residual post-surgical VSD, significant limitations still exist in patients with acquired VSD such as post-myocardial infarction defects and traumatic VSD.

Introduction

Ventricular septal defects are the commonest congenital cardiac disease, accounting for almost one-fifth of all malformations [1]. The ventricular septum may be divided into the inlet, outlet, trabecular and membranous portions. Of these septal defects, seventy percent are located in the area of the membranous septum, with variable anatomical extension towards the inlet, outlet or apical components of the right ventricle. These perimembranous defects have an opening towards the inlet excavating beneath the septal leaflet of the tricuspid valve. Importantly there is a close relationship with the electrical conduction axis. Defects opening directly beneath both the aortic and pulmonary valves in the outlet septum are described as being doubly committed and juxta-arterial, or supracristal. These defects are quite rare in western countries, albeit more frequent in Asian countries.

Ventricular septal defects can also be located entirely within the muscular portion of the septum: these account for around one-sixth of patients seen in postnatal life. Rarely the defects can be multiple, with the most extreme example of multiple lesions being the so-called “Swiss cheese” septum.

Acquired ventricular septal defects are rare. They can be seen in patients after myocardial infarction, traumatic events, or as residual defects subsequent to attempted surgical closure of an isolated or complex congenital defect.

Surgical closure of a congenital ventricular septal defect was performed for the first time by Lillehei and associates in 1954 [2]. Since that time, surgical closure has come to be regarded as the gold standard for treatment, however, it remains associated with morbidity and mortality [3, 4, 5, 6, 7, 8, 9, 10], postoperative discomfort, the need for sternotomy and a residual scar. Complications due to significant residual leaks are reported in up to 5% of cases [3, 4, 5, 6, 7], while iatrogenic atrioventricular block can occur in around 1% to 8% of cases [3, 4, 5, 6, 7, 8, 9, 10, 11]. Reoperation for indications other than residual leakage are needed in a further 2% of subjects [3, 4, 5, 6, 7]. Occurrence of the postpericardiotomy syndrome, arrhythmias, infections, and respiratory or neurological complications are also reported [3, 4, 5, 6, 7]. Mortality may occur in a proportion of patients [3, 4, 5, 6, 7], although this would be most unexpected in the current era. Nevertheless, the risk for all these events is increased in small infants, patients with multiple defects, apical defects or associated lesions, or even higher when additional surgery is required in patients with residual defects [3, 4, 5]. It should also be remembered that negative long-term effects on developmental and neurocognitive functions have been reported in children who underwent bypass surgery [10]. It is hardly surprising, therefore, that various attempts have been made over the years to develop less invasive techniques so as to reduce the impact of morbidity, mortality and psychological stress.

Historical perspective

In 1988 Lock and colleagues [12] reported the first human experience of transcatheter closure of muscular defects. They closed such defects in 7 patients using the Rashkind double umbrella device. Since then, various devices have been used, such as the Clamshell or CardioSEAL STARflex device [13, 14], the Sideris buttoned device [15], Gianturco coils [16] and Nit-Occlud(®) Lê VSD coil [17, 18]. The rate of success of such procedures was between 77% and 100%, however, residual shunting was reported in between 35% and 100% [12, 13, 14, 15, 16] [19, 20, 21, 22]. Furthermore, the procedure was difficult when using these devices, and complications were encountered with some frequency [12, 13, 14, 15, 16] [19, 20, 21, 22] especially for perimembranous defects due to the proximity of these defects to the aortic and the atrioventricular valves. The introduction of the Amplatzer family of devices has markedly widened the application of transcatheter techniques for closure of these defects [23, 24, 25].

A meta-analysis summarized 37 publications including 4,406 patients with percutaneous VSD closure from 2003 to 2012 showed that the successfully technical rate was 96.6% (95% CI: 95.7-97.5) while the most common complications were residual shunt (25.5%; 95%CI:18.9-32.1%), arrhythmias (10.6%; 95%CI: 8.4-12.7) and valvular defects (4.9%; 95% CI: 3.4-6.4) [26].

The rate of complete atrioventricular block was low but significant (2.4%, 95%CI 1.6-3.2), compared to slightly lower rate after open VSD repair, (< 1%, in 2,079 cases reported by Andersen HØ, et al [27]. VSD is more likely to be associated with heart block than other muscular VSD, as the conduction bundle runs close to the VSD and may be subject to compression by device or surrounding tissue edema or inflammation. It is also expected that closure of perimembranous or subarterial VSD is associated with a higher incidence of aortic valve damage and regurgitation compared to muscular VSD.

Substantially less experience has been reported for percutaneous closure of post-infarction and traumatic ventricular septal defects. It was not until 1998 that successful percutaneous closure of post-infarction VSDs was first reported [28].

Congenital VSD

INDICATIONS AND PATIENT SELECTION

Indications for closure are symptoms of heart failure, and/or signs of left heart volume overload. In patients, particularly in children, with left atrial and ventricular overload, closure may be needed in order to prevent pulmonary arterial hypertension, ventricular dilation, arrhythmias, aortic regurgitation, and development of double-chambered right ventricle. Even asymptomatic patients with small defects, may need closure if they experience endocarditis. A recent paper by Soufflet et al [29] showed that the mid-term outcome of small and unclosed perimembranous VSD in young adults is not uneventful. In fact, during a median follow-up of 6 years (range 4-38 years), 8 out of 220 subjects (4%) experienced endocarditis, 9% pulmonary hypertension, and 1% died suddenly.

Large defects give signs and symptoms of cardiac failure in early infancy, and they have to be treated surgically in the first months of life. Defects of moderate size may also be responsible for failure to thrive, respiratory infections, and diastolic left heart overload. These defects may be suitable for percutaneous closure if they are located within the muscular septum (Muscular Ventricular Septal Defects) or if they are perimembranous (Perimembranous Ventricular Septal Defects). Surgical repair is currently the only option for doubly committed or supracristal defects, for perimembranous defects associated with aortic valve prolapse and aortic regurgitation, and for any defect associated with malalignment of the muscular outlet septum, or straddling and overriding atrioventricular valves.

The 2020 ESC Guidelines for the management of adult congenital heart disease [30] identified a VSD management algorithm. The closure is indicated when a left ventricle volume overload is associated with normal pulmonary vascular resistances (<3 WU) (class I) or mild increase of pulmonary vascular resistances (3-5 WU) with Qp:Qs ≥ 1.50 (class IIa) or significant increase of pulmonary vascular resistances (≥5 WU) with Qp:Qs ≥ 1.50 (class IIb). However, in the latter case, the closure should be evaluated by an expert centre. VSD closure is contraindicated in the cases with high pulmonary vascular resistances (≥5 WU) Qp:Qs < 1.50 (class III). In the absence of a left ventricle volume overload, a VSD-associated prolapse of an aortic valve cusp causing progressive aortic regurgitation (class IIa) or a history of repeated events of infective endocarditis (class IIa) are indication to closure.

MUSCULAR VSD

Echocardiographic pre-catheterisation evaluation

Transthoracic echocardiography is mandatory to assess the size, number and location of VSDs. The parasternal long axis view shows the anterior defects. In the short axis view, near the tip of the mitral valve it is possible to locate muscular VSD (anterior defects between 12 and 1 o’clock; mid-muscular defects between 9 and 12 o’clock; inlet defects between 7 and 9 o’clock). The four-chamber view at the level of the atrioventricular valves shows apical, mid-muscular and inlet defects. Subaortic and anterior defects are best evaluated in the five-chamber view.

Technical and equipment issues
Device

The Amplatzer muscular ventricular septal defect occluder ( Figure 1) is a self-expandable device made of Nitinol wires (thickness 0.004-0.005 inches), consisting of two flat discs having a diameter 8 millimetres larger than a central connecting waist (7 mm long). The diameter of the waist determines the size of the device, and is available in sizes from 4 to 18 millimetres. Three Dacron polyester patches are sewn with polyester thread into both discs and the connecting waist. The device is secured to a delivery cable, and is inserted into a delivery sheath ranging from 6 to 9 Fr in size [31, 32, 33, 34, 35, 36].

Cocoon muscular type VSD Occluder (Vascular Innovations Co., Thailand) and Cera muscular VSD Occluder (Lifetech, China) are other available devices to deal the muscular ventricular septal defects.

Procedure and technique of device implantation ( Moving image 1)

All procedures are performed under general anaesthesia or local anaesthesia (if transoesophageal echocardiographic is not used). Routine right and left catheterisation are performed. Antibiotic prophylaxis and full heparinisation (100 IU/kg) are given routinely. An activated clotting time >200 sec is usually warranted. In addition to echocardiographic views, one or more left ventricular angiographic acquisitions are obtained in left anterior oblique projections for the best evaluation of VSD size and position. Left ventriculography in the hepatoclavicular projection (35° left anterior oblique/35° cranial) is performed to analyse mid-muscular, apical posterior defects. Anterior defects are better seen in 60° left anterior oblique/20° cranial.

  • Technique of device implantation

The basic steps of muscular device implantation have been described in the literature [31, 32, 33, 34, 35, 36] and consist of the following: the VSD is crossed from the left side, by using a Judkins right, AL1 or Cobra catheter and a soft Glidewire (0.035”, J tip; Terumo Corp., Tokyo, Japan); the wire is advanced to pulmonary artery, where it is snared with a Gooseneck snare (Microvena Corporation, St Paul, MN, USA; 20-25 mm in adults, 10-15 mm in children) ( Figure 2), and exteriorised out of the right internal jugular vein or femoral vein establishing an arteriovenous circuit. In order to obtain the straightest course of the delivery system, the right internal jugular vein is chosen for mid-muscular or apical defects, and the femoral vein for muscular defects located more anteriorly. Over the circuit, an appropriate size of delivery sheath is advanced from the vein all the way until the tip of the sheath is in the ascending aorta. The dilator is withdrawn and the sheath is pulled back in the left ventricle.

When the tip of the sheath is placed in the mid cavity of the left ventricle, the dilator and the wire are gently removed. A left ventriculogram is usually repeated to confirm the position of the long sheath and also to obtain additional information about the position and the size of the VSD. Using both angiographic and echocardiographic data a muscular VSD occluder 1 to 2 mm larger than the maximum size of the defect is chosen; the device is attached to the delivery cable, loaded into the plastic loader, introduced and advanced into the sheath. The left disc is deployed in the left ventricular cavity, making sure it does not impinge on the mitral valve apparatus. The entire system is then withdrawn towards the septum, and the central waist and the proximal disc are deployed. A test angiogram is done to verify the correct position of the device: an echocardiographic view is also very important to confirm the position of the two discs on the left and right sides of the septum respectively, and of the central waist within the muscular septum. The device is then released ( Figure 3). A final angiogram is performed approximately 15-20 minutes afterwards to assess the position of the device and possible residual shunt. Patients receive aspirin (2-5 mg/kg/daily maximum 300 mg/daily) for 6 months and are asked to follow a strict regime of endocarditis prophylaxis.

A similar approach may be used to close multiple muscular VSDs ( Figure 4).

Alternative techniques

  • Retrograde approach [37, 38]

This approach can be used in adults and older children where a 7-8 Fr arterial introducer can be used safely. The VSD is crossed from the left ventricle with the help of a soft 0.035” J-tipped Terumo 260 cm exchange wire introduced through a 5 Fr Judkins right coronary artery catheter. The wire is then advanced in the pulmonary artery. The catheter is exchanged with an 80 cm delivery sheath (AGA Medical Corporation, Minneapolis, MN, USA) over the wire to the right ventricle apex. Wire and dilator are removed slowly in order to avoid entraining air. The chosen device is prepared and advanced into the long sheath. The distal disc is opened in the RV apex paying attention to the ventricular wall and tricuspid wall. The whole system is then pulled back to approximately the interventricular septum. The sheath is withdrawn further to open the proximal disc onto the left ventricular surface of the interventricular septum ( Figure 5). Left ventricular angiography and echocardiographic evaluation are performed to confirm the position of the device and the absence of complications. Finally, the device is unscrewed from the delivery cable and angiography performed in the ascending aorta and left ventricle to confirm the final position of the device, to search for residual shunt and to check aortic valve function.

  • Hybrid approach [39, 40] ( Moving image 2)

In infants whose weight is < 5 kg percutaneous closure may be hazardous due to vascular access and haemodynamic intolerance of the procedure.

On the other hand, the surgical approach needs extracorporeal circulation and may be associated with significant morbidity and mortality, particularly in subjects with apical defects. A hybrid approach has been developed to overcome the risks of the two procedures in smaller infants.

After the chest and the pericardium are opened, under TOE control, an 18-gauge needle is used to puncture the right ventricle free wall. A 5-0 polypropylene purse-string suture is placed around the puncture site. The needle is introduced into the right ventricular cavity pointing toward the VSD. A 0.025” short guidewire is passed trough the needle and the VSD in the left ventricle. A short sheath is advanced over the wire to the left ventricle cavity. Finally, the right size of Amplatzer muscular VSD device is delivered in the usual way under TOE monitoring.

Acute and long-term outcomes

Pooling data from the literature [31, 32, 33, 34, 35, 36], the mean success rate is 95% (95% confidence intervals from 88% to 100%)

( Table 1). Complications with closure are reported in 5% of cases (95% confidence interval from 0 to10%). Holzer and co-workers [34] reported the results of a multicentre trial involving 14 tertiary referral centres in the United States of America. In all, 75 patients were treated, with a total of 59 (45%) adverse events, 8 out of 75 (10.7%) major procedure-related complications, including embolisation of the device, cardiac perforation and stroke, and 2 deaths (2.7%). Many of these problems are likely to be related to the learning curve or lack of experience of the operator. Diab et al [41] reported a series of 20 muscular VSD closure in infants aged less than one year with success rate was 95% and major complication rate was 20% such as one patient with haemopericardium, one transient electromechanical dissociation, one device embolisation and one patient with mediastinitis: many of these problems are likely to be related younger subjects with severe clinical status.

In other studies from the literature in older patients, the rate of complications is very low ( Table 1). In a single centre series [36] of 30 patients with muscular defects, the procedure was successfully performed in all, confirming the encouraging results cited in the literature [31, 32, 33, 34, 35, 36].

In the literature there are small series reporting a hybrid approach performed in the operating theatre. Amin et al [39] and Bacha et al [40] have proposed the so-called perventricular approach. Bacha et al [40] have reported a series of 12 infants in whom this approach has been used successfully. Diab et al [41] published on 8 cases of hybrid VSD closure with satisfactory results.

There are some limitations to this approach: ideally, operating rooms with catheterisation laboratory facilities have to be implemented, and materials and devices have to be modified in a proper way in order to deal with this technique.

Place in clinical management

Concerning the limits in terms of weight at which percutaneous closure is possible, muscular defects can ideally be treated in patients weighing more than 5 kilograms. However, closure can be achieved even at weights of less than 3 kilograms, in particular when a hybrid approach is used. The decision to perform percutaneous closure in these latter cases must be carefully weighed, given the challenging nature of the technique as well as the chance of spontaneous VSD closure. The incidence of spontaneous (VSD) closure varies greatly, depending on the age and gender of subjects, the size and site of the defect as well as the types of defect [42].

Spontaneous VSD closure occurs most commonly during the first 6 months and first year of life, less commonly after age of 10 (nearly 60% before age of 3; 90% before age of 8), predominant in female. Spontaneous VSD closure occurs more frequently in small defects (<4-6 mm), in muscular VSD (70-75% compared to 20-30% for perimembranous VSD) and some site (>80% in the anterior, apical and mid-ventricular septum) [43].

FOCUS BOX 1Congenital muscular VSD
Muscular VSD closure can be performed in children weighing more than 5 kg. In smaller children a hybrid approach is a safer alternative

PERIMEMBRANOUS VSD

Echocardiographic pre-catheterisation evaluation

Transthoracic echocardiography is mandatory to assess the size, number and location of VSDs. The presence of a 2 mm or more rim of tissue between the aortic valve and the defect is considered a prerequisite for device closure. The left parasternal long axis view shows the perimembranous defects. In short axis view, at the level of the aortic valve, it is possible to locate exactly the perimembranous VSD (supracristal defects between 12 and 1 o’clock; membranous defects between 9 and 12 o’clock; perimembranous defects between 7 and 9 o’clock). Four-chamber and five-chamber views reveal the perimembranous defects and their extension.


Technical and equipment issues
Device

The Amplatzer membranous ventricular septal defect occluder has two discs of unequal size ( Figure 6). The aortic rim of the asymmetric left ventricular disc exceeds the dimensions of the connecting waist by only 0.5 millimetres so as to avoid impingement on the aortic valve, whereas the apical end is 5.5 millimetres larger than the waist. This apical end of the left ventricular disc contains a platinum marker to facilitate correct orientation during implantation. The right ventricular disc is symmetrical and it exceeds the diameter of the connecting waist by 2 millimetres throughout its circumference. The device is available in sizes from 4 to 18 millimetres, and requires delivery sheaths from 7 to 9 Fr. The delivery system consists of a delivery cable and a pusher catheter having a sharp curvature of 180 degrees inferiorly. This allows correct orientation of the left ventricular disc during implantation. It has a flattened part of the socket that matches the flat portion of the microscrew in order to force the larger part of the left ventricular disc to be oriented downwards so that it points to the left ventricular apex [26], [43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53]. However, the device is currently no longer commercially available.

Recently, a novel device has been introduced to close perimembranous VSD. The Konar-MF (multifunctional) VSD device (Lifetech, China) is a self-expandable, double disc device characterized by a Nitinol wire mesh ( Figure 7). A cone-shaped central waist links the two retention discs. A PTFE membrane is placed within the central waist of the four largest models (9-7; 10-8; 12-10; 14-12) to increase its occlusion ability and to reduce the rate of intra-device shunts. This device may be placed with both a retrograde and an antegrade approach by means of a double-sided screw. A delivery sheath from 4 to 7 French is required to perform the procedure. The device can be used for both perimembranous or muscular VSD closure. Schubert et al. described the first first European experience of percutaneous VSD closure using the Konar-MF VSD device (Lifetech, China) [53].

Other used devices are: Cocoon Membranous type VSD occluder and Cocoon aneurysmal type VSD occluder (Vascular Innovations Co., Thailand), Cera Membranous VSD Occluder (symmetrical, asymmetrical and eccentric) (Lifetech, China). The Cocoon Membranous type VSD occluder (Vascular Innovations Co., Thailand) is a self-expandable, double disc device made from Nitinol wire mesh coated with platinum. A central “thin” waist links the two retention discs. A PTFE membrane fills both the discs and the central waist to achieve a rapid closure of the defect. The Cocoon aneurysmal type VSD occluder (Vascular Innovations Co., Thailand) is an evolution of the previous device. It is characterized by a taller cone-shaped centrale waist and is designed to improve the closure of aneurismatic perimembranous VSD [55] ( Figure 8). Cera Membranous VSD Occluder (Lifetech, China) is a self-expandable, double disc device containing a nitinol frame covered by ceramic coating. The two discs are linked together a central waist (height: 3 mm). The Symmetric type device is characterized by two retention discs with the same diameter; whereas, the Asymmetric type device shows a left-sided disc larger than the right-sided one. Reversely, the Eccentric type device is structurally similar the Amplatzer membranous VSD occlude, characterized by two discs of unequal size [56] ( Figure 9).

Procedure and technique of device implantation ( Moving image 3)

All procedures are performed under general anaesthesia or local anaesthesia (if transoesophageal echocardiographic guidance is not required). Full heparinisation, using 100 international units per kilogram, is given routinely. Patients receive a dose of cephalosporin during catheterisation, and two further doses at 8-hour intervals.

Vascular access is via the right femoral artery and vein. Angiography is performed using a 60 degree left atrial oblique plus 20 degree cranial view. An angiogram of the ascending aorta is also performed in a 50 degree left anterior oblique view to check for aortic regurgitation. The size of the defect and its relationship to the aorta are confirmed. The defect is crossed from the left ventricle by using a Judkins right, an Amplatz right or IM (the best) catheter and a Terumo wire. The catheter is advanced to the pulmonary arteries or the superior or inferior caval vein. The Terumo wire is then exchanged for a soft noodle wire (AGA Medical Corporation, Golden Valley, MN, USA). The noodle wire is snared with a gooseneck snare, exteriorised from the femoral vein, and an arteriovenous circuit is created ( Figure 10). The AGA braided sheath is advanced over the wire up to the ascending aorta. Sometimes this manoeuvre is technically challenging. A “kissing” technique may be needed, using the tip of the sheath and the arterial catheter over the wire. Another technique consists in holding the guidewire circuit taut and pushing the sheath and the dilator over this rigid system. The dilator is then withdrawn approximately 10 centimetres, the sheath is slowly withdrawn, and the arterial catheter advanced, making a loop of the wire which is then pushed into the left ventricular apex. The sheath is advanced over the wire until it reaches the apex of the left ventricle and the wire is gently removed. The device, having been sized at equal to or 1 millimetre larger than the size of the defect, is secured on the delivery cable and the flat part of the microscrew is aligned with the flat part of the capsule of the pusher catheter. The device is advanced up to the tip of the sheath and the entire system is withdrawn to the left ventricular outflow tract. The left disc deployed, echocardiographic monitoring is of paramount importance at this stage to confirm normal function of both mitral and aortic valves. The platinum marker of the distal disc should point downwards. The proximal disc is then deployed on the right side of the septum and angiographic testing is done before releasing the device ( Figure 11 and Figure 12).

When it is difficult to direct the braided sheath towards the left ventricular apex, the sheath can be placed in the ascending aorta and the left ventricular disc opened under the aortic valve. Next, the right ventricular disc is opened by advancing the delivery cable. After 10 to 15 minutes, a left ventricular angiogram and aortogram are repeated to assess possible residual shunting or aortic regurgitation. Throughout the procedure, the electrocardiogram is carefully monitored in order to assess for abnormalities of atrioventricular conduction or tachyarrhythmias.

Acute and long-term outcomes ( Table 2 )

It is only quite recently that closure of perimembranous defects has become commonplace. At the beginning of one pioneering centre’s experience, Carminati and colleagues used the muscular occluder in 10 selected patients having at least 5 millimetres distance between the superior rim of the defect and the aortic valve. The device was successfully deployed by using a retrograde or an anterograde ( Figure 13) approach in all cases. Similar good results with the use of a muscular device for properly selected patients with perimembranous defects were reported by Arora and colleagues [35] and by Szkutnik and colleagues [38].

When the membranous occluder became available, indications were also expanded to patients having a distance of only 1 to 2 millimetres between the defect and the aortic valve [25, 43].

Pooling data from the contemporary literature, the mean rate of successful closure is 98.5% (95% confidence interval from 95 to 100%). In one series [50], among the 104 patients who had the device successfully implanted, complete closure remained in 97% at 6 months, as in previous reports [50].

The most common morphological variation is the presence of an aneurysm of the ventricular septum ( Figure 13). This feature is present in one third of patients. Under these circumstances closure of the true anatomical defect with the most appropriate device (varies from membranous occluder, muscular occluder or even duct occluder or VSD coil), must be judged on a case by case basis. Sometimes, when the redundant tissue of the aneurysm is relatively small, a device can cover the defect along with the aneurysm. In cases with very large aneurysms, the device can be implanted within the aneurysm itself, aiming to close the true anatomical defect, and not placing the device at the “entrance” on the left ventricular side, in order to avoid the insertion of a dangerously oversized device, which might increase the possibility of complete AV block. Studies reported in the literature show that major acute complications occur in 1.3% of cases (95% confidence interval from 0 to 3%).

The most important complications are embolization of the device, haemolysis, aortic regurgitation, and conduction disturbances. In one series, embolization occurred in 2 cases, however, retrieval of the device was performed and a second device was successfully implanted in both. Transient haemolysis occurred in 2 out of 35 cases in a Phase 1 trial carried out in the United States of America [47], and in 2 out of 104 of a previously mentioned series of patients from Butera G et al [50]. In the latter, trivial aortic and tricuspid regurgitation related to insertion of the device occurred in only 3 cases (2.9%). Complete heart block was the most important complication to be encountered. This manifested over a broad time-frame ranging from the acute procedure itself to more than 6 months post procedure. Implantation of a permanent pacemaker was required in 6 of 104 patients (5.7%). By contrast, no instances of complete heart block were reported by Thanoupoulos and colleagues [44] in 10 children, or by Bass et al [43] in 25 cases and by Bentham in 23 cases [58]. Complete atrioventricular block, however, was reported in 2 out of 35 patients (5.7%) by Fu and associates [47], in 2 out of 100 subjects by Holzer et al [49]. Also transient complete atrioventricular block during catheter maneuvers can result in a procedure being abandoned. Complete atrioventricular block mostly occurred within 30 days after VSD closure (partly can recover after administration of corticosteroid and application of a temporary pacemaker) but can occurred late after 1 year (nearly impossible to restore nomal conduction). The longest follow-up by Bai Y et al [59] on 1,045 perimembraneous VSD closure in 13 years showed that complete atrioventricular block occurred in 1.63%, from which 0.8% needed permanent pacemaker. In comparison of patients aged ≤18 years, patients aged >18 years were more prone to complete AV block (p=0.025). More importantly, no significant parameter can predict later requirement for permanent pacemaker [59]. From data published in the literature, the incidence of complete atrioventricular block needing implantation of a permanent pacemaker is 2.4% (95%CI: 1.6-3.2%) [26].

The occurrence of complete heart block has to be regarded as the major issue in percutaneous closure of perimembranous defects. The proximity of the conduction tissues to the rims of the perimembranous defect explains how, sometimes, a simple catheter or wire manipulation across the defect may cause heart block. If heart block occurs after placement of the device, it is likely that expansion of the device against the conducting tissue plays a major role. The use of oversized devices, therefore, should be avoided. Complete heart block may also occur, however, when the discs appear nicely flat on both sides. Other mechanisms can be considered. The device may give rise to an inflammatory reaction or formation of scarring in the conduction tissue, therefore steroid therapy in high dose associated with aspirin may be useful. The device and/or material might have continuous expansion force on the conduction tissue, therefore some modified design and/or material with less expansion force in long term such as duct occluder or VSD coil might reduce the complete AV block, especially the unpredictable late one.

Perimembranous VSD closure using Nit-Occlud(®) Lê VSD ( Figure 18 and Video 6) showed no case of complete AV block but 1 of transient block in 116 patients by Chungsomprasong P, et al [18] as well as no case of complete block in 20 patients by Odemis E, et al [17]. However, residual shunt after coil deployment (even resulted in surgical removal due to persistent haemolysis) and not suitable for big size VSD were major disadvantages of this kind of coil. ( Figure 15)

Large studies are needed to clarify the real impact of arrhythmic problems in these patients and the mechanism of these events.

Place in clinical management

Those with perimembranous defects can ideally be considered as suitable candidates for closure once their weight is more than 8-10 kilograms. However, in order to reduce the risk of complete AVB, patients should be aged more than 6 years before intervention.

FOCUS BOX 2Complete heart block and perimembranous VSD closure
Risk of complete atrioventricular block in perimembranous VSD device closure is higher in children aged <6 years

Acquired VSD

Acquired VSD may occur as a recurrent VSD after surgical patch closure (post-surgical residual VSD) or as a ventricular septal rupture following myocardial infarction (post-myocardial infarction VSD) or trauma.

POST-SURGICAL RESIDUAL VSD

Present status and clinical indications

Dehiscence of a patch placed for surgical closure of a congenital defect is reported in 1% to 6% of cases [3, 4, 5, 6, 7], result from dehiscence of an existing patch, suture disruption, incomplete closure of the defect or bacterial endocarditis. If the residual defect is haemodynamically significant or endocarditis involved, further surgery could be necessary. In these cases, the risk of mortality or morbidity is significantly increased [3, 7], due to the potential risk of cardiopulmonary by-pass, sternotomy, bleeding and infection as well as the the residual VSD position might not be ideal for surgical closure.

Technical and equipment issues
All patients have chest x-ray, 12-lead electrocardiogram (ECG), TTE prior to the procedure. General anaesthesia and transoesophageal echocardiogram (TOE) are used in all cases during the procedure. All patients receive heparin (100 IU/kg) and antibiotics. Access is obtained via the femoral artery (5–6 Fr) and vein (6–8 Fr). Standard right and left heart catheterisation is performed and the residual shunt is profiled angiographically using the left anterior oblique view with cranial angulation. TOE is performed to assess the shunt size and the valvular function. Device selection is 1–2 mm greater than the VSD size. The residual VSD is usually crossed retrogradely from the left ventricle using a Cobra® type 1 (Cordis Corporation, Miami, FL, USA) or 4–5 Fr Judkins right coronary catheter with the aid of a Terumo guidewire. After crossing the defect, a soft J-tip 0.035” 300 cm Rope wire (AGA Medical Corporation, Plymouth, MN, USA) is exchanged for the guidewire and advanced either to the pulmonary artery (PA) or superior vena cava (SVC). This wire is snared and exteriorised via the venous route to form an arteriovenous circuit. A sizing balloon is frequently used to: i) assess the size of the VSD by stop-flow method; and ii) delineate and profile the VSD more accurately. Procedures are performed in different ways according to “defect-anatomy”:

Perimembranous and high muscular VSDs ( Moving image 4)
Two different approaches are used:
a) anterograde and b) retrograde.

Anterograde approach

The long sheath (TorqVue® delivery system; AGA Medical Corporation, Plymouth, MN, USA) and dilator are advanced from the femoral vein across the VSD and into the ascending aorta. The sheath tip is withdrawn to the left ventricular outflow tract and the guidewire is advanced to the left ventricular apex using the arterial catheter. The sheath and the catheter are advanced to the left ventricular apex. The exchange wire is then withdrawn from either the artery or the vein and the sheath flushed. The device is then loaded and advanced through the sheath until it reaches the tip. The left ventricular disc is deployed in the mid left ventricular cavity under fluoroscopic control. Under echocardiographic guidance, the left ventricular disc is brought into contact with the septum. The waist, followed by the right ventricular disc, is then deployed by retracting the sheath over the “pusher catheter’’. The device is released once the final position is assessed using angiography and echocardiography ( Figure 14).

Finally, in some cases it is impossible to direct the sheath towards the apex of the left ventricle. Therefore, the sheath is placed in the ascending aorta and the left ventricular disc opened coming back from the ascending aorta and through the aortic valve, paying close attention to avoid any interference with the valve.

Retrograde approach

The creation of an arteriovenous circuit is not needed in cases where this approach is used. A Mullins or Flexor® (Cook Medical Inc., Bloomington, IN, USA) sheath was used. The sheath is advanced down the ascending aorta into the RV through the VSD. The distal disc (which is actually the LV disc) is deployed in the RV, followed by the waist. The proximal disc can then be deployed under good control in the left ventricle ( Figure 2).

Mid-muscular and apical VSDs
An anterograde approach is used from the right internal jugular vein (RIJV). The VSD is crossed in the usual manner from the LV side, the wire snared in the PA or the SVC and an arteriovenous circuit completed. The sheath is placed through the RIJV across the VSD into the cavity of the LV. The LV disc is then deployed in the mid LV cavity under fluoroscopic control. Using echocardiographic guidance, the LV disc is brought into contact with the septum. The waist, followed by the RV disc, is then deployed by retracting the sheath. The device is released once the final position is assessed using angiography and echocardiography.

Specific technical aspects

  • Balloon sizing of the defect

Due to the varied anatomy of the substrate it may be difficult to assess accurately the exact size and site of the shunt on TOE and angiography. The presence of patches and patch leaks are other confounding factors. We have found that balloon occlusion of the shunt and assessment with TOE and angiography provide significantly better understanding of the shunt size and site.

  • TOE and angiography

It is essential to have expert TOE guidance in addition to fluoroscopy and angiography throughout the procedure. These modalities complement each other.

  • Aortic retrograde approach

As a majority of these VSDs are located in the muscular septum, there is a potential risk of the sheath passing through or under a trabeculation of the RV. Crossing the VSD from the LV side may prove easier in these cases. In addition, using the standard anterograde approach, it can be difficult to advance the sheath tip to the LV apex. This is probably related to the presence of the surgical patch. Also, there is less space in the subaortic region to deploy the LV disc and an increased risk of complications. To overcome this, if the LV disc is deployed in the ascending aorta, it is more difficult to retrieve it back into the sheath if required, with an increased risk of damaging the aortic valve. Hence, a retrograde approach should be employed to overcome these issues. If the disc/device needs retrieval back into the sheath, it is relatively straightforward and less risky.

Acute and long-term outcomes

Transcatheter closure is an appealing option in these subjects. In our study [57] we reported a series of 22 subjects in whom a successful and complete closure was obtained. Mean hospital stay was 2.5 days. At a mean follow-up of 2.7 years, all subjects but one had a stable result. In one subject, the patch dehisced again, and the patient was finally sent for repeat surgical closure. Finally, one subject experienced sudden arrhythmic death 5 years after the procedure.

The results are few for transcatheter closure of post-surgical residual VSD. Pedra et al [60] reported a series of 3 transcatheter closures of VSD patients: 2 residual post-surgical VSDs, 1 post-infarct VSD, with a 100% success rate. The data from Walsh et al [61] consisted of 9 patients with a residual post-surgical VSD. They used Amplatzer VSD devices. The procedural success rate was 100%: 6 patients had complete closure, and 3 had mild residual shunts.

Zhang B et al [62] reported a series of 21 transcatheter closure of post-surgical residual VSD using perimembranous VSD occluders: 0 deaths and 1 haemolysis (4.8%, lasted for 7 days, and recovered with therapy), 2 trivial intraprosthetic residual shunt (9.5% drop to 4.8% after 6 months). After long term follow-up, no atrioventricular block or new-onset aortic regurgitation occurred. Bigger series of 170 patients were reported by Dua JS et al [57]: all procedures were successful; no additional procedures were required and no late events but trivial residual shunts were seen in 3 patients at follow-up.

These findings suggest that transcatheter closure of postsurgical residual VSD is safe and efficacious option regardless the location or size of postsurgical residual VSD.

Place in clinical management
Closing these residual shunts surgically is usually not an attractive option because it involves further open-heart surgery with another run of cardiopulmonary bypass, sternotomy, bleeding and infection. Also, the residual VSD position may not be optimum for surgical closure, or the myocardium may not be completely healthy. Hence percutaneous device closure offers another option for these residual VSDs. The percutaneous approach is appealing to both patients and their parents alike because it has less psychological impact (given the absence of a skin scar), the time spent in hospital is shorter, the procedure causes less pain and discomfort, and there is no need for admission to an intensive care unit. It is certainly less risky from the point of view of another run of cardiopulmonary bypass, infection, bleeding, atriotomy and a possible ventriculotomy.

FOCUS BOX 3Transcatheter residual VSD closure
    Transcatheter closure of residual VSD should be considered as a first choice treatment. Because of anatomical variations many tips and tricks (defect sizing, retrograde transaortic approach, opening of the left device disc in the ascending aorta) may be needed in order to succeed

POST-MYOCARDIAL INFARCTION VSD

State-of-the-art and clinical indications

Post-myocardial infarction VSDs are not discrete holes but ruptures within necrotic tissue. The defect is more akin to a tear and multiple defects may develop. Rupture of the ventricular septum may occur in a small proportion of myocardial infarctions (0.2%) [62], and remains associated with very high morbidity and mortality [63, 64, 65, 66, 67, 68]. Such defects are usually observed within one week of the initial myocardial infarction [69]. Medical therapy alone yields a survival rate of less than 3% at 1 year [70]. Surgical procedures have a mortality of 30%-60% depending on severity in the individual patient [71, 72, 73, 74].

The clinical course is characterised by sudden hemodynamic deterioration, even in patients who appear clinically stable. Ideally, better results for closure are obtained in subjects more than 3-4 weeks after the initial infarction. An attempt can be made earlier in the face of clinical deterioration. However, early surgical repair is challenging due to the soft and friable injured tissue surrounding the area of VSD and the possibility of VSD enlargement. Even with surgical approach, a residual post-surgical shunt still persisted in 10-37%, in which more than 10% required further surgical procedures [75, 76].

Transcatheter closure of a post-MI VSD might enable closure the defect and immediately stabilize the hemodynamic status as a bridge approach (to future surgery) as well as be suited for treating residual shunts after surgical closure [77, 78, 79, 80].

Technical and equipment issues
Device and procedure and technique of device implantation ( Moving image 5 )

In most instances, the Amplatzer muscular device has been used for closing post-infarction defects. More recently, a new device specifically designed for closure of post-infarction defects has become available [81, 82, 83]. This is the Amplatzer post-infarct muscular ventricular septal defect device ( Figure 15). It is similar to the muscular device, albeit with two important differences. The length of the waist is larger, at 10 millimetres, and the discs are 10 millimetres larger than the connecting waist. The device is available in sizes from 16 to 24 millimetres in 2 millimetre increments and can be delivered through 9 to 10 Fr long sheaths.

The principal steps of the procedure are similar to those used for closure of muscular defects ( Figure 16). However, there are two major differences. First, patients are usually in critical clinical conditions, often requiring inotropic support and intra-aortic balloon pumping. Second, when possible, it is advisable to perform percutaneous coronary arterial revascularisation before attempting closure of the ventricular septal defect. Vascular access is usually obtained from the jugular vein, but maybe from the femoral vein for anterior defects. The defect is usually crossed from the left ventricle by using a right coronary artery catheter and an exchange angled torque wire (0.035” Terumo wire). The wire is often directed towards the pulmonary artery where it is snared and pulled out from the venous access in order to create an arteriovenous circuit ( Figure 16 and Figure 17).

The Terumo wire can be exchanged for an AGA exchange Rope® wire. The defect can be balloon sized to ensure that the guidewire is not trapped around a cord, or that the wire is not crossing the largest hole. Finally, balloon sizing may be useful in order to rule out multiple defects.

Sometimes, in particular in the presence of apical defects, it may be easier to enter the defect from the right ventricle directing the guidewire in the left ventricle and the aorta where it is snared.

Echocardiography (usually transoesophageal) is very useful in order to visualise the maximum left ventricular, septal and right ventricular orifices of the defect and to see the guidewire crossing these orifices. Sometimes, in order to see apical defects better, transthoracic imaging may be more useful. The steps following this are the same as for insertion of the muscular device.

Acute and long-term outcomes

A few studies have reported experiences using Amplatzer devices in these subjects ( Table 3) [84].

These papers from the literature [33] show that, in the acute phase, morbidity and mortality are quite high, i.e., up to 70%, and the rate of successful closure is reduced. In fact, pooling all data from the literature, the mean success rate is 90% (95% confidence intervals from 60% to 100%, with a mortality of 40%, and 95% confidence intervals from 0 to 55%).

By contrast, in the chronic phase, i.e., 14 days after myocardial infarction, results are very encouraging, with low morbidity, mortality and a high rate of complete closure. There are several limitations to the currently available options. Devices should be available in larger sizes, should be softer and should clot quickly. Furthermore, improvements in imaging should help in selecting subjects who could benefit from a percutaneous treatment.

Adjunctive percutaneous mechanical support (such as IABP an axial-flow pump, or a TandemHeart) might stabilize cardiogenic shock patients during the post-MI VSD closure and improve the immediate and long-term outcome post VSD closure procedure. In additional, these devices can be used for concurrent high-risk percutaneous coronary artery intervention or surgical repair [85, 86].

Place in clinical management

Treatment of a post-myocardial infarction VSD remains a major challenge, particularly in the acute phase. In several centres, only subjects surviving more than 3-4 weeks are considered for closure (either surgical or percutaneous). This improves the procedural results; however, an earlier aggressive approach may salvage more subjects. Recurrent post-infarction VSD following surgical patch repair may benefit from transcatheter closure as the treatment of choice.

FOCUS BOX 4Post-myocardial infarction VSD

  • Post-myocardial infarction VSDs are associated with a 97%-99% one-year mortality rate. Surgical procedures have a one-month mortality of 50%-60%

  • Transcatheter device closure has a similar mortality rate in the early phase. Two to four weeks after myocardial infarction or in the case of residual defects after surgical patch repair, the transcatheter approach can be considered the first-choice treatment

Conclusions

In summary, the currently available data show that, following the introduction of the Amplatzer VSD devices, percutaneous closure has become a safe and effective procedure in highly specialised centres. Appropriate patient selection is of paramount importance to the success of the procedure. Device closure of muscular and perimembranous VSD can be considered a true alternative to the standard surgical approach in the paediatric and adult populations. Recently, a novel Lifetech device looks like be promising for VSD closure.

It can be regarded as the first-choice treatment for residual post-surgical defects. In patients with post-myocardial infarction VSD, many problems do still exist. Further improvements in technology are needed in order to overcome present limitations and the risk of complications.

Personal perspective

Efforts have to be made to reduce the dimensions of devices in order to apply this technology to even smaller babies and to reduce the size of introducers used. Furthermore, “softer” or “drug-eluting” devices with anti-inflammatory drugs could be advantageous in reducing traumatic injury to the conduction tissue. Post-infarction VSD may need larger and less traumatic devices. A hybrid approach will need materials and devices specially designed for this purpose. Finally, resorbable devices could be developed in order to minimise the presence of foreign materials within the body.

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