Discussion

This is the first study to characterise the use of transthoracic intracardiac lines and to evaluate factors associated with complications specifically in patients with single ventricle physiology; a population that necessitates meticulous lifelong care. The cohort’s overall complication rate was 6.2% which is similar when compared to other transthoracic intracardiac line studies (0.6–19%)^{Reference Krishnamoorthy, Gadhinglajkar, Palanisamy, Sreedhar, Babu and Dharan3,Reference Flori, Johnson, Hanley and Fineman4,Reference Beham, Dave, Kelly, Frey, Hug and Brotschi6,Reference Gold, Jonas, Lang, Elixson, Mayer and Castaneda8–Reference Garcia, Pye, Tang, Gossett, Prodhan and Bhutta13} and other central venous access (2.2−31.3%).^{Reference Gonzalez and Cassaro14 –Reference de Jonge, Polderman and Gemke18} The most common complication was migration of the line which was 2.4% and similar to other transthoracic line studies (1.2-5.3%).^{Reference Flori, Johnson, Hanley and Fineman4,Reference Gold, Jonas, Lang, Elixson, Mayer and Castaneda8,Reference Kumar, Subramanian and Tansey10,Reference Pratap, Millar, Butt and d’Udekem11}

Surgery involving a shunt placement was associated with higher rates of line complications. Single ventricle patients with shunts typically have tenuous cardiopulmonary haemodynamics resulting in elevated rates of morbidity and mortality.^{Reference Oster, Knight, Suthar, Amin and Kochilas2,Reference Alsoufi, McCracken, Oster, Shashidharan and Kanter19–Reference Sower, Romano, Yu, Lowery, Pasquali and Zampi23} This may have influenced the observed findings. Furthermore, their severity of illness and associated high incidence of complications, such as necrotising enterocolitis,^{Reference Giannone, Luce, Nankervis, Hoffman and Wold24,Reference Kelleher, McMahon and James25} often necessitate long-term vascular access, which may further influence the overall complication rates.

Sustaining peripheral access in any cardiac patient can be challenging, and certain protocols have been formed to help preserve vascular sites.^{Reference Aiyagari, Cooper and Jacobs26} The single ventricle population in particular is medically fragile, often necessitating frequent admissions with the need for long-term vascular access.^{Reference Tabtabai, DeFaria Yeh, Stefanescu, Kennedy, Yeh and Bhatt27} Additionally, any procedure involving peripheral access or administration of anaesthetics poses a risk of cardiopulmonary collapse in this population.^{Reference Brown, DiNardo and Odegard20,Reference Christensen, Gholami, Reynolds and Malviya28–Reference Leyvi and Wasnick30} Thoughtful evaluation of placement and maintenance of vascular access is thus essential to help preserve these sites for future use.^{Reference Aiyagari, Cooper and Jacobs26} Utilising transthoracic lines as the primary access point following cardiac surgery in these patients may contribute significantly to achieving this endeavour.

Generally, there is a preference for patients with single ventricle physiology to sustain lower extremity peripherally inserted central catheters to preserve the upper chest vasculature from thrombosis.^{Reference Kaipa, Mastropietro, Bhai, Lutfi, Friedman and Yabrodi7} This preservation is imperative and life sustaining for future interventions, including superior cavo-pulmonary connections, cardiac catheterizations, and the potential need for heart transplantation.^{Reference Kaipa, Mastropietro, Bhai, Lutfi, Friedman and Yabrodi7} Furthermore, single ventricle patients are at increased risk of lymphatic complications due to factors such as inadvertent thoracic duct injury or obstruction, change in venous flow from palliative surgeries, and increased lymphatic production from elevated venous pressures.^{Reference Dori and Smith31–Reference Chang, Huang and Chen33} While recent literature suggests that upper extremity peripherally inserted central catheters in patients with single ventricle physiology are associated with low rates of catheter-associated thrombosis and venous stenosis,^{Reference Kaipa, Mastropietro, Bhai, Lutfi, Friedman and Yabrodi7} they may exacerbate the potential risk of increased lymphatic pressure and chylothorax.^{Reference Hsu, Chou, Wang and Wu34–Reference Dhande, Kattwinkel and Alford36} The utilisation of transthoracic intracardiac lines can mitigate these risks while preserving vascular access in both the upper and lower extremities.

Our study is subject to several limitations. This cohort was derived from a single-centre and employed a retrospective design. Additionally, we were unable to adjust for severity of illness, which is likely an important confounder in our findings. Institutional practices and experience must also be considered when interpreting the applicability of these results. The specific surgical techniques for transthoracic intracardiac line placement may vary, with certain methods potentially increasing the risk of line complications such as migration and malfunction.^{Reference Kumar, Subramanian and Tansey10} In our cohort, the technique employed a securing cuff positioned beneath the skin, which may have helped mitigate these complications.^{Reference Anton-Martin, Zook, Kochanski, Ray, Nigro and Vellore9} Additionally, it is essential to recognise the learning curve associated with these procedures; therefore, establishment of protocols and techniques for placement, maintenance, and removal of these lines, as well as ongoing education for nursing staff, advanced practice providers, physical and occupational therapists, and physicians is crucial to ensure safe management of these lines and to minimise risk to patients.

Transthoracic intracardiac lines, particularly intra-atrial lines, represent safe alternatives to other central catheters and should be strongly considered as a primary option for long-term access in patients with single ventricle physiology in the postoperative period. Implementing multidisciplinary heart centre protocols for surgical techniques, management, and removal of these lines can contribute to reduced complication rates and, consequently, improved outcomes in this high-risk population.