*Exploring Standard and Alternative Sites for Left Ventricular Assist Device Inflow Cannula… DOI: http://dx.doi.org/10.5772/intechopen.114053*

and possible hemolysis or thromboembolic complications [3, 6–9]. The standard IC placement technique - ensuring that the IC's orientation aligns with the direction of physiological blood flow towards the apex, facilitating direct flow from the mitral valve to the IC -should therefore reduce the risk of inflow obstruction, suction events, and thrombosis that can lead to ventricular arrhythmias or device alarms and stroke [7, 9]. Numerical (in silico) and clinical data support the adverse effects of off-axis angulation of the IC [7, 9, 11–13]. The attachment of the IC to the myocardium is facilitated by a sewing ring that is attached to the epicardial surface near the LV's true apex, usually at its anterior wall, about 2 cm lateral to the left anterior descending coronary artery [1, 5, 10]. A circular knife creates a myocardial core directed towards the mitral valve and parallel to the interventricular septum [14]. Different IC surgical fixation techniques exist [15]. In this regard, in in-vitro studies, the sew-then-core technique using epicardial stitching, in which partial-thickness suture bites do not penetrate the endocardium, appears to be associated with the lowest risk of suction events or thrombosis formation [15]. Although lacking robustness, available clinical data has indeed shown a trend towards a higher risk of stroke when the cut-then-sew" technique is utilized compared to the "cut-then-sew" approach [16]. Future studies should also confirm whether surgical access techniques (lateral thoracotomy versus conventional full sternotomy) play a role in optimal IC positioning [12].

The choice of the apical site for IC has been supported by decades of clinical experience. However, it is crucial to consider the individual patient's anatomy, comorbidities, and potential for complications when opting for the standard site [1, 10]. In this regard, several clinical scenarios, such as previous cardiac surgery, severe apical calcifications, aneurismal dilation or thinning of the apical wall, apical hypertrophy, or unique anatomical variations may make apical IC placement unpractical, risky, or undesirable [1, 5, 10, 17] (**Table 2**). These special situations might require exploring


#### **Table 2.**

*Left ventricular assist device implantation with alternative inflow cannula placement.*

unconventional IC placement sites with a certain degree of surgical flexibility and innovation [10], tailored to serve patient's needs best [1, 5, 10]. A recent extensive myocardial necrosis involving the apex may also preclude safe anchoring of the IC's sewing ring. In this case, the IC's sewing ring may be attached to a Dacron patch used to reconstruct the excised necrotic apex [18]. That can also be applied in the cases of concomitant left ventricular reconstruction for (severely calcified) ventricular aneurism or a previous Dor procedure [10, 19–22]. Cannulation of the left ventricular diaphragmatic wall may be a viable alternative to this [1, 10]. Attachment of the IC to the diaphragmatic wall may also be useful in cases of a markedly enlarged LV with altered geometry, the presence of post-myocardial infarction apical aneurysm, and patients with constricted thoracic anatomy [1, 5, 10]. Next, with a significant representation of about 2% among LVAD recipients, patients with restrictive or hypertrophic cardiomyopathy are more prone to right ventricular failure, suction events, and death during LVAD support [23, 24]. The adverse outcomes observed in this specific fraction of LVAD patients are likely due to their distinctive anatomy – having small left ventricular cavities [23, 24] and making them ineligible or challenging for standard apical cannulation [23, 25, 26]. In these cases, a myectomy may be necessary so that enough space is created for the IC [25]. Alternatively, atrial cannulation can be performed, especially considering considerable left atrial enlargement in this patient population [23]. A novel transseptal technique has been described, in which the IC is connected to the left atrium through a Gore-Tex® tube placed into the right atrium and sewn to the surgically created interatrial septum defect [23, 27]. In this case, the sewing ring is attached to the right atrium and the interposition graft [23, 28].

Ultimately, a novel technique intending to overcome the risks associated with the development of intracavitary clot formation and its sequelae has been proposed, in which the IC is attached to a cone-shaped prosthesis connecting the left ventricular apex with the mitral valve [29].

Conclusively, while the true apex of the LV remains the standard and most widely used site for IC placement, the vast array of individual patient anatomies, previous medical interventions, and unique conditions dictate the necessity for adaptable and innovative approaches, guided by the overriding principles of ensuring the best possible outcomes for the patient.
