Apico-Aortic Conduit for severe aortic stenosis: Technique, applications, and systematic review

Abstract

Patients referred for aortic valve replacement are often elderly and may have increased surgical risk associated with ascending aortic calcification, left ventricular dysfunction, presence of coronary artery disease, previous surgery, and/or presence of several co-morbidities. Some of these patients may not be considered candidates for conventional surgery because of their high risk profile. While transcatheter aortic valve replacement constitutes a widely accepted alternative, some patients may not be eligible for this modality due to anatomic factors. Apico-Aortic Conduit (AAC) insertion (aortic valve bypass surgery) constitutes a possible option in those patients. Apico-Aortic Conduit is not a new technique, as it has been used for decades in both pediatric and adult populations. However, there is a resurging interest in this technique due to the expanding scope of elderly patients being considered for the treatment of aortic stenosis. Herein, we describe our surgical technique and provide a systematic review of recent publications on AAC insertion, reporting that there is continued use and several modifications of this technique, such as performing it through a small thoracotomy without the use of the cardiopulmonary bypass.

1. Introduction

Before the advent of surgical aortic valve replacement in the early 1960s, symptomatic severe aortic stenosis was uniformly associated with a poor prognosis and average life expectancy of less than three years (Schwarts et al., 1982; Turdma et al., 1987). No medical treatment is available to improve survival or quality of life in afflicted patients (Varadarajan et al., 2006).

Surgical aortic valve replacement has revolutionized the care of those patients and becomes the treatment of choice with expected surgical mortality of 2% or less in ideal candidates (Chiappini et al., 2004; Edwards et al., 2001).

Nevertheless, a substantial number of patients with severe valvular aortic stenosis and co-morbidities do not undergo surgical valve replacement due to high expected surgical mortality and morbidity rates (Branstedt, 2003). The concept of less invasive balloon aortic valvoplasty was developed by Cribreir et al. (1986), but it was associated with a significant periprocedural risk and no proven survival benefit (Klein et al., 2006; Otto et al., 1994).

Transcatheter aortic valve implantation (TAVI) is emerging as an alternative option in those patients. The first human transcatheter valve was implanted in the pulmonary position in 2000 (Bonhoeffer et al., 2000) and subsequently in the aortic position by Cribier et al. (2002). As of this writing, more than 10,000 patients worldwide have undergone TAVI, but the approach is still not available to all high-risk patients in all centres. There are anatomic factors such as peripheral vascular disease, coronary anatomy, severe left ventricular dysfunction, and others which can make TAVI high-risk or contraindicated (Ruel and Labinaz, 2010).

Modifications of median sternotomy approach for aortic valve replacement have been used with variable results but still need full cardiopulmonary bypass and cardiac arrest with their inherent complications (Farahat et al., 2003). However, there is a great promise from new or resurging technology. In this regard, two techniques offer off pump aortic valve replacement: The first is transapical aortic valve replacement (direct access insertion), a form of TAVI (Rosengart et al., 2008). The second is the insertion of an Apico-Aortic Conduit (AAC), also called aortic valve bypass surgery. Both techniques need thoracotomy and are considered less invasive approaches to aortic valve replacement. The second approach is discussed in detail in this article.

2. History of Apico-Aortic Conduit

The idea that another left ventricular outflow tract can be created is an old one: Alex Carrel in 1910 described his experimental work to create a bypass between the left ventricle and the thoracic aorta, by using a vein graft (Carrel, 1910).

Sarnoff et al. (1955), used this approach in animals and they were able to direct all the cardiac output from the left ventricle to the thoracic aorta with a Hufangel valve implanted in a Lucite tube. In dogs so treated, the ascending aorta was totally and permanently occluded without impairment of the circulation. Postoperatively dogs had no physical limitations. In 1963 Templeton implanted Sarnoff’s prosthesis in five patients, and one patient survived more than 10 years (Renzulli et al., 2000).

In the late 70s and early 80s this approach was used in both pediatric and adult population with congenital aortic stenosis or left ventricular outflow tract obstruction, by using the ascending or descending thoracic or abdominal aorta for the distal anastomosis. In these series there was a high incidence of prosthesis dysfunction that required reoperation, so the programs of Apico-Aortic Conduit were mostly discontinued (Renzulli et al., 2000; Ergin et al., 1981; Didonato et al., 1984; Norman et al., 1980; Cooley et al., 1975).

3. Materials and methods

3.1. Literature search

A systematic search of all publications was carried out by searching the Medline and Embase databases from the earliest achievable date to March 2010, by using the following keywords: Apico-Aortic Conduit, aortic valve bypass surgery, aortic valve surgery, redo aortic valve replacement, and porcelain aorta .We did also a search on the cardiac surgery network (CTSNet) web site. All citation was examined according to the title and abstract. The reference lists of the related studies were examined for relevant work. Purely pediatric studies as well as veterinary studies were excluded. For non-English studies we used either the abstract or the translation of the full article if available.

3.2. Data extraction

Study author, year and country, journal of publication, study design, patient selection criteria, surgical technique, procedural outcomes, and the results of the study were extracted.

3.3. Quality assessment

The studies identified were subjectively and qualitatively assessed as to their quality and contributions to the bulk of evidence.

4. Results

Our literature search identified a total of 369 of potential articles. Of those 51 were found relevant to our search. There were no randomized or prospective controlled studies found in the literature. Selected were 11 studies that were observational retrospective series and 21 case reports, all summarized in Table 1.

Table 1.

Reports of Apico-Aortic Conduits.

Study/journal	Patient population	Technique	Main findings
Schreiber et al. (2002)	73-year-old woman, calcified aorta. OPCAB followed 1 month by AAC	Left lateral thoracotomy AAC: LV – descending aorta	AAC indicated in the adult population with multiple previous operations or porcelain aorta
Takemura et al. (2003)	84-year-old woman with end stage aortic stenosis. Small aortic annulus	Left lateral thoracotomy with CPB. Bioprosthetic AAC: LV – descending aorta	Discharged without complications
Vassiliades, 2003	Three patients high risk for AVR. Age: 75, 76, and 83 years. Patent coronary bypass grafts in 2 patients. Porcelain aorta in the third	Left lateral thoracotomy. No CPB. Using core device and AAC: LV – descending aorta	No hospital mortality. Improved functional class and hemodynamics
Skrabal et al. (2004)	One patient with previous AVR 3 times including repair of an annular abscess.	Left lateral thoracotomy. Mechanical AAC: LV – descending aorta	No evidence of paravalvular leak, hemolysis or LVH progression
Chiu et al. (2006)	76-year-old male with a porcelain aorta	Median sternotomy. CPB. Bioprosthetic conduit LV – bilateral subclavian arteries	Uneventful recovery, MRI angio showed patent graft
Miyateke et al. (2006)	69-year-old female, Severe AS, LV dysfunction porcelain aorta	Left thoracotomy, Fem-fem CPB. Bioprosthetic AAC: LV – descending aorta	No anastomosis stenosis was detected 8 months postoperatively
Nishimura et al. (2007)	75-year-old female patient with severe AS, porcelain aorta and previous OPCAB	Left lateral thoracotomy. Fem-fem CPB and electrical fibrillation. Mechanical AAC: LV – descending aorta	Uncomplicated postoperative course. CT showed unobstructed conduit
Strecker et al. (2007)	58-year old male patient with 2 previous AVR-CABG	Median sternotomy, CPB. LVOT closed by a patch. Mechanical AAC: LV – ascending aorta	Well-functioning apico-aortic conduit at 4 months postoperatively by echo and CT scan.
Hirnle et al. (2009)	73-year-old male patient with AS and porcelain aorta	Without CPB. Hegar dilator inserted through the LV apex allowed anastomosis of dacron tube to the apex. AAC: LV – descending aorta	Maximal gradient through the native valve was 95, after operation dropped to 33 mmHg
Hirota et al. (2009)	29-year-old male, hemodialysis calcified aorta and bifemoral aortic bypass surgery.	Left lateral thoracotomy. Bioprosthetic AAC: LV – descending aorta on beating heart	Un complicated postoperative. CT scan showed no compression or stenosis of the AAC
Sadaba et al. (2009)	65-year-old female, previous AVR with size 16 mechanical valve. Presented with severe patient prosthesis mismatch. Had CHF, COPD and PH	Left lateral thoracotomy. Fem-fem CPB. Mechanical AAC: LV – descending aorta	Improved exercise tolerance
Shin et al. (2009)	74-year-old woman suffered Severe AS, with small aortic annulus and severely calcified aorta	Apical connector AAC: LV – descending aorta	The pressure gradient across the native aortic valve fell from 64 mmHg before the operation to 19 mmHg afterward
Dimitrakakis et al. (2009)	49-year-old male pre-op AVR, previous Coarctation repair and CABG (patent)	Left lateral thoracotomy. Fem-fem CPB	Six weeks after the procedure, CT-scan revealed a massive left hemothorax, collapsed left lung, a patent AAC with extensive dehiscence from the LV and a pseudoaneurysm. Underwent a redo AAC procedure. At 3 months follow-up, MRI imaging confirmed that the AAC had remained in situ and was conveying almost 60% of cardiac output
Herrmann et al. (2009)	16-year-old girl with severe AS, calcified aorta	Left thoracotomy. Bioprosthetic AAC: LV – descending aorta. Median sternotomy MVR bioprosthetic	Echocardiography documented well-functioning AAC. No anticoagulation was required
Shimizu et al. (2010)	80-year-old woman with severe AS, porcelain aorta extending to abdominal aorta	Median sternotomy. Bioprosthetic apico-brachiocephalic artery bypass under DHCA	Two months postop, no pressure gradient was observed between the left ventricle and the valved conduit on echocardiography, a slight blood flow was observed through the native aortic valve
Shontz et al. (2010)	76-year-old woman with severe AS, multiple co-morbidities and porcelain aorta	Left Thoracotomy. AAC:LV – descending aorta, stentless valve	Transesophageal echocardiography documented well-functioning valve

4.1. Clinical series

Renzulli et al. (2000) reported the long-term results of Apico-Aortic Conduit in four patients (age range 24–65 years). Two patients were alive 15 and 19 years after initial operation and two patients died one from wound infection another died from unnatural causes 13 years after operation. All the survivors showed bioprosthetic degeneration leading to conduit thrombosis and the need for reoperation. The authors used the ascending aorta for implantation of the conduit in 3 patients and the abdominal aorta in the 4th patient.

Cooley et al. (2000) described a simplified technique using a left thoracotomy for insertion of an Apico-Aortic Conduit in seven patients. Apico-Aortic Conduit was performed under peripheral cardiopulmonary bypass and electrical fibrillation of the heart. A special coring device was used for connection of the apical portion and a conduit with either a bioprosthesis in three patients or a mechanical valve in four patients. The distal anastomosis was done to the descending thoracic aorta.

Crestanello et al. (2004) and Ruzmetov et al. (2006) published their series of 36 patients who underwent Apico-Aortic Conduit (AAC). The left thoracotomy approach was used in 33 patients while Crestanello et al. (2004) used the sternotomy and bilateral thoracotomy in another three. Ruzmetov et al. (2006) used the beating heart without CPB in all the cases (n = 23) while Crestanello et al. (2004) used the CPB in all the cases (n = 13). Crestanello et al. (2004) kept the heart beating (n = 5), fibrillating (n = 7) and arrested (n = 1). Both series used conduit with bioprosthesis (n = 16), homografts (n = 10) and mechanical valve (n = 9). The series from Ruzmetov et al. (2006) included children and adults (range 1 week–36 years) most of them had subaortic stenosis isolated or multileveled (n = 13). They reported late survival with bioprothesis AAC (n = 2) who had to be re-replaced with mechanical valve AAC, 13 and 14 years after the initial AAC insertion. They reported one pseudo left ventricular aneurysm and concluded that AAC is a good palliation. They also demonstrated the ability to proceed without the need of CPB. Crestanello et al. (2004) in their series of adults (mean age 71 years) with calcified ascending aorta and root (n = 6), patent grafts (n = 5), retrosternal colonic interposition (n = 1) and multiple sternotomies (n = 2) had three in-hospital deaths from ventricular failure (n = 1) and two of non-cardiac origin. At a mean follow-up of 2.1 years, there were four late deaths unrelated to the AAC. The authors commented that this approach provides an acceptable alternative to AVR in selected high-risk patients.

Gammie et al. (2006) reported on 14 high-risk patients (mean age 78 years) with aortic stenosis who underwent aortic valve bypass surgery. Twelve of 14 patients had previous cardiac surgery with patent bypass grafts. All operations were performed through a left thoracotomy with beating heart. CPB support was used for six patients. There were two non-cardiac perioperative deaths, both with intact AAC. Nine of 10 surviving patients were in functional class I and are living independently. Early postoperative echocardiography confirmed excellent aortic valve bypass function with good ventricular function and an average gradient across the native aortic valve of 8.8 ± 3.3 mmHg.

Takemura and Tusda (2006) inserted an Apico-Aortic Conduit in seven elderly patients (mean age 81 years) for symptomatic critical aortic stenosis, calcified ascending aorta, and small aortic annulus. In all patients a left thoracotomy approach was used with CPB support in six patients. The distal anastomosis was done at the descending thoracic aorta by using a partial occluding clamp. A composite woven Dacron conduit was used with a stented (n = 2) and stentless bioprosthesis (n = 5). Postoperative echocardiography showed relief of the left ventricle-aortic gradient in all patients. After a mean follow-up period of 22 months, there was no late death, while three patients had been readmitted due to congestive heart failure.

Lockowandt (2006) reported on 13 cases who had severe calcific aortic stenosis, mean age of 75 ± 8.7 years. The AAC insertion was done because of a porcelain aorta (n = 4), previous coronary bypass grafting (n = 6), or both (n = 3). The off-pump technique was used in nine patients, and a heparinized miniextracorporeal circulation system was used in four patients. Mean intensive care and mean hospital length of stay were 2 ± 2.7 days and 12 ± 8 days, respectively. The 30-day mortality was 15% (two patients; postoperative days 3 and 28, both caused by myocardial infarction). Postoperative late mortality was 23% for reasons unrelated to Apico-Aortic Conduit. The remaining eight patients were doing well, and were all in NYHA class I or II at follow-up, with echocardiography showing a low gradient through the valved conduit.

White et al. (2007) studied twelve patients (mean age – 78 years) who underwent evaluation by using retrospective ECG-gated Multidetector CT (MDCT) using a 16-detector-row scanner several days after placement of an AAC. All images were assessed by two radiologists who reviewed the appearance of the Apico-Aortic Conduit. The conduit was visible in all. The valve within the conduit was visible in 91% of the patients who received intravenous contrast material. Common findings were periconduit outpouching, and hypoperfusion of the left ventricle. Complications included pericardial hemorrhage, hemothorax, and ventricular pseudoaneurysm.

Brown and Gammie (2007) and Gammie et al. (2008) published their recent experience in 131 high risk elderly patients (range of age: 62–91 years) who were treated with an AAC. They used the left thoracotomy approach. Between 71% and 82% of the patients had prior cardiac surgery with patent grafts and 12–16% had porcelain aorta. Brown and Gammie (2007) showed an excellent postoperative hemodynamic result in all the patients with improved or unchanged LV function, indicating that the AAC did not impair the LV function. Moreover, the gradient through the AAC was (mean 8.8 ± 3.3 mmHg) similar or lower than the gradient obtained with conventional AVR. Gammie et al. (2008) showed that the postoperative gradient through the native valve was significantly decreased (10.4 ± 5.4 mmHg versus 43.5 ± 5.15 mmHg) and that an average of 72% of the total cardiac output was passing through the AAC.

Balaras et al. (2009) performed computational modeling to determine the effects of aortic valve bypass on aortic and cerebral blood flow, as well as the effect of conduit size on relative blood flow through the conduit and the native valve. The predicted native (stenotic) valve to conduit flow ratios was 45:55, 52:48, and 60:40 for conduits with diameters of 20, 16, and 10 mm, respectively. Mean gradients across the native aortic valve were calculated to be 12.5, 13.8, and 17.6 mm Hg, respectively. Post-aortic valve bypass cerebral blood flow was unchanged from pre-operative aortic valve stenosis configurations and was constant across all conduit sizes. In all cases modeled, cerebral blood flow was completely supplied by blood ejected across the native aortic valve; this configuration may decrease the long-term risk of cerebral thromboembolism.

4.2. Case reports

The case reports found in our literature search fall into one of the three categories:

First: case presentations for unusual clinical situations and Apico-Aortic Conduit insertion that was pre-operatively planned; second, AAC performance in response to a surgical challenge in the operative room; and third, discussing unusual complications after Apico-Aortic Conduit (Table 1).

5. Report of a typical AAC case at the University of Ottawa Heart Institute

A 57-year-old male patient had had CABG performed twice. He presented with increasing symptomatic bicuspid aortic valve stenosis, NYHA functional class III, with a peak gradient of 84 mmHg and AVA 0.74 cm². Third time sternal re-entry was judged at high risk due to a patent LITA (grafted to a diagonal artery) and RITA (grafted to the left anterior descending artery that crossed the midline). For these reasons, an apical to descending aorta-valved conduit operation was chosen. The surgery consisted of placing a 22-mm Medtronic, Hancock® LV connector (Medtronic Inc., Minneapolis, MN, USA) and a 22-mm Medtronic, Hancock® bioprosthetic-valved conduit low-porosity (Medtronic Inc., Minneapolis, MN, USA) between the left ventricular (LV) apex and the descending aorta. The procedure was done through a left thoracotomy, using femoro-femoral cardiopulmonary bypass (see operative technique below). The surgery went well; the postoperative follow-up was uneventful with excellent hemodynamics and a mean gradient of approximately 5 mmHg through the valved conduit. (Figs. 1 and 2).

Figure 1.

Chest X-ray: anteroposterior and lateral views (left and right, respectively). The apico-aortic can readily be visualized in plain chest X-ray.

Figure 2.

CT scan showing the apico-aortic conduit from the left ventricle apex to the descending thoracic aorta.

6. Comment

The idea of creating another left ventricular outflow in order to relieve aortic valve stenosis is not new (Sarnoff et al., 1955; Cooley et al., 1975). Apico-Aortic Conduit or aortic valve bypass surgery is a time-tested option for high-risk patients for aortic valve replacement for aortic stenosis. The procedure is well standardized with reproducible results.

The pre-operative evaluation of the patient consists on the complete evaluation of the thoracic and abdominal aorta with a multi slice-computed tomography (CT) with or without contrast. Also the pre and intraoperative echocardiography is a valuable tool as well (Balaras et al., 2009). Computerized Tomography (CT) angiogram represents a good tool for post operative evaluation of the Apico-Aortic Conduit (Pulitani et al., 2007).

6.1. Operative technique

Our preference is to perform the operation by using beating heart and pump support with femoro-femoral cardiopulmonary bypass (CPB) and mild hypothermia 33 °C. The patient is under general anesthesia, endotracheal intubation using a double lumen endotracheal tube or bronchial blocker is used to isolate the left lung. The anesthetic management consists of placement of a three leads electrocardiogram, Swan-Ganz catheter with continuous cardiac output measurements via the right internal jugular vein, a left radial artery heart line to measure the blood pressure and a Foley catheter to measure the core temperature and urine output. Finally, a transesophageal echocardiogram (TEE) is used perioperatively to monitor the cardiac function, the positioning of the guide wires and cannulae, and also evaluate the heart and valve function in the immediate post bypass care period.

The patient is positioned in right lateral decubitus with hips externally rotated to allow access to the left femoral vessels. Both the left femoral artery and vein are exposed using an oblique incision aligned with the inguinal ligament. We use purse strings with a 4-0 Prolene on the artery and a 5-0 Prolene on the vein to facilitate the future decannulation. Then a left lateral thoracotomy is performed through the 5th intercostal space, the left lung is collapsed and the inferior pulmonary ligament is divided. The lung is retracted cephalad and the diaphragm is displaced caudally to show both the cardiac apex and the descending aorta. The parietal pleura is incised over the distal descending thoracic aorta for its exposure. The pericardium is opened anterior to the phrenic nerve and suspended to expose the cardiac apex. After proceeding to the full heparinization, a partial occlusion clamp is applied onto the distal descending aorta. The distal end of an appropriate size (Medtronic, Hancock® low porosity bioprosthetic-valved conduit 20–22 mm) is anastomosed end-to-side onto the descending aorta with a running 4-0 Prolene reinforced with Teflon strips. Once the anastomosis is completed, the partial occluding clamp is repositioned on the tube graft, checking for anastomotic leak.

The femoral vessels are then cannulated using the Seldinger technique (14F needle, guide wire) under TEE guidance. We use a Bio-Medicus® 19-21F (Biomedicus, Medtronic Inc., Minneapolis, MN, USA) and a Fem Trak Edwards Lifesciences® 21-24F cannula (Edwards Lifesciences, CA, USA) for the artery and vein, respectively. The tip of the venous cannula will be positioned into the right atrium at the base of the superior vena cava to allow maximum decompression of the heart. Vacuum assist is used as needed. While on pump support, with the heart beating and decompressed, we use a Medtronic, Hancock® Trocar Blade coring device (Medtronic Inc., Minneapolis, MN, USA) to create an opening away from the coronary artery and the thinned portion of the left ventricle apex. The opening could be enlarged if needed with a scalpel. The blood from the left ventricle is evacuated using the cardiotomy suction or a vented sump drain. Interrupted pledgeted 2-0 Ethibond mattress sutures (10–12) are placed around the cardiac apex in a circular fashion .These sutures are then sewn to the cuff of the Medtronic, Hancock® Apical left ventricle connector 20–22 mm and attached to the apex of the left ventricle. If in need of additional haemostasis the circumference of the connector can be circled with a running suture of Prolene 3-0. Biological glue (Bio Glue® Cryolife, NW Kennesaw, Georgia USA) may also be used. Finally, the two conduits are anastomosed together end-to-end by using a running 4-0 Prolene. Great care is taken to prevent any kinking of the conduits and careful deairing is achieved. The CPB is weaned with inotropes if needed. A complete echocardiography examination is completed to verify the good function of the conduit. When the hemodynamics are to our satisfaction, protamine is given to reverse the heparin. Two straight chest tubes will be put in the left pleural space. The lung is reinflated and the thoracotomy is closed in the usual fashion while the cannulae are removed and the groin area is closed.

Several techniques of insertion of the AAC has been described in the literature with variable access from median sternotomy and left thoracotomy, with or without cardiopulmonary bypass and with different types of valves:mechanical, bioprosthetic stented or stentless and homografts (Gammie et al., 2006; Takemura and Tusda, 2006; Speziali and Zahr, 2007).

6.2. Advantages of Apico-Aortic Conduit

The AAC procedure eliminates the disruption of the calcified native aortic valve. There is no permanent prosthetic material forced over the calcified valve leaflets (with resultant risk of both perioperative and long-term stroke). Diverting the blood from the native calcified aortic valve may also has a brain protective effect in the long term as this distribution of the blood flow after AAC would protect the brain against thromboembolism because the AAC does not alter the antegrade flow to the brain, minimizing the risk of stroke and no retrograde flow from the conduit was derived to the brain (Gammie et al., 2008; Balaras et al., 2009). The procedure prevents the manipulation of a porcelain ascending aorta; this further minimizes the risk of plaque embolization. With the use of AAC there is no risk of direct coronary artery encroachment, prosthetic valve migration or paravalvular leak. Moreover, there is no risk of heart block caused by overzealous decalcification of the aortic annulus or caused by compression of the conduction bundle by the prosthetic material. Because the valve does not have to be sized within the native annulus a larger valve size can be used reducing the occurrence of prosthesis-patient mismatch. The major advantage of the Apico-Aortic Conduit is the ability to redo the conduit surgery in cases of valve dysfunction in a much simpler way than that of the conventional AVR and possibly without cardiopulmonary bypass (Hainse and Neal, 1989).

6.3. Limitations and contraindications of Apico-Aortic Conduit

One of the main limitations of the Apico-Aortic Conduit is that it is reserved for patients with pure aortic stenosis. Any significant aortic regurgitation precludes the AAC. Presence of severe circumferential atherosclerosis of the descending aorta is another limitation, however this can be overcome by choosing another site for the outflow position e.g. Subclavian or bracheocephalic arteries (Chiu et al., 2006). The presence of significant left pleural adhesions or marked impairment of pulmonary function will contraindicate the left thoracotomy approach for insertion of an Apico-Aortic Conduit. Presence of a left ventricle thrombus should also preclude the use of the AAC.

6.4. Indications

The main indication for AAC is the heavily calcified ascending aorta (porcelain aorta). Other patients can benefit from AAC. Those who have a history of multiple previous cardiac or thoracic operations that complicates safe sternal re-entry, e.g. presence of patent coronary grafts close to the midline or crossing it, adherent structures to the sternum, e.g. dilated right ventricle, interposition of colon, prior sternal wound infection with muscle flap. Patients with failed enlargement of the aortic annulus, and patients with severe or complex LVOT obstruction at the valvular, subvalvular or ventricular level constitute another group of patients who can benefit from AAC (Renzulli et al., 2000; Speziali and Zahr, 2007).

6.5. Potential complications

AAC dehiscence from LV apex and formation of pseudoaneurysm, myocardial infarction, mitral regurgitation, chest infections, pulmonary embolism, thrombus formation in the aorta (due to fractionation of the cardiac output and possible stagnation of the blood), arrhythmias, sepsis, endocarditis and bleeding are the potential complications of Apico-Aortic Conduit. Late complications are related to prosthetic valve structure failure commanding the replacement of the valve component of the graft (Dimitrakakis et al., 2009; Takeda et al., 2006; Parsa et al., 2009; Kotani et al., 2010).

7. Conclusions

Apico-Aortic Conduit has been used safely as a surgical alternative option for patients with left ventricular outflow tract obstruction or severe calcified aortic valve stenosis. It is a valuable technique especially in the subset of high-risk patients with multiple co-morbidities, ineligible for TAVI, and/or at risk of a sternal re-entry for stenotic aortic valve surgery or with a porcelain aorta.

7.1. Future prospective

The new generation of bioprostheses, the use of composite conduit with low profile mechanical valves, and the incorporation of new apical connectors used for left ventricular assist devices may further simplify and reduce the morbidity and mortality associated with the Apico-Aortic Conduit operations. A prospective study is needed for better evaluating the role of the Apico-Aortic Conduit in management of high-risk patients with severe aortic valve stenosis.