Persistent postsurgical pain is a well-established entity in the adult pain literature, but in children, it has only recently been recognized as an important consequence of surgery. We know from adult studies that the prevalence of persistent pain after sternotomy ranges from 20 to 50 % (Eisenberg et al. 2001; Meyerson et al. 2001; Bruce et al. 2003; Lahtinen et al. 2006; van Gulik et al. 2011; Rodriguez-Aldrete et al. 2015). In adults, chronic pain after sternotomy most closely presents like neuropathic pain, although in some cases, it is mixed with inflammatory or nociceptive pain. This observation is consistent with what we know about chronic postsurgical pain, which is that it is more common after surgeries where surgical nerve injury is most likely to occur (Kehlet et al. 2006).

Children commonly undergo cardiac surgery that requires sternotomy for repair of lesions that include, but are not limited to, Tetralogy of Fallot, transposition of the great arteries, and hypoplastic left heart syndrome. Most recently, Lauridsen and colleagues (2014) studied 121 children ages 0–12 that required median sternotomy. They found that 4 years after cardiac surgery, roughly 20 % of these children had recent or persistent pain. In 24 out of the 26 children with pain reports, pain could be provoked by physical activity, and 12 out of the 26 children reported a pain intensity ≥4 on a numerical rating scale (Lauridsen et al. 2014). Based on these children’s reported pain characteristics, post-sternotomy pain appears to have a neuropathic component. Redo sternotomy, a known risk factor in adults for persistent postsurgical pain, did not prove in this study to be a risk factor for the development of persistent post-sternotomy pain, though there was a trend toward a higher pain prevalence in children with more than one sternotomy (van Gulik et al. 2011). Thus far, surgical technique (mini-sternotomy versus full-sternotomy) for atrial septal defect repair has failed to show a significant difference in immediate postoperative pain scores and development of chronic pain (Laussen et al. 2000).

Thoracotomies are one of the most painful surgical procedures in children, having a higher analgesic requirement than other incisions (Shima et al. 1996; Gerner 2008). Chronic post-thoracotomy pain (CPTP), defined as persistent or recurring incisional pain for at least 2 months after thoracotomy, is rarely studied in children (Merskey 1999). Chou and colleagues (2014) recently reported a prevalence of chronic pain in a predominantly male population of 51 subjects who had their first thoracotomy at a median 5.7 years of age to be 1.96 % (0.00–10.4 % CI) (Chou et al. 2014). The results from this retrospective cross-sectional study, which mostly looked at children with a single nonelective thoracotomy, stand in contrast to CPTP prevalence data in adults, which has been quoted to be as high as 50 %. These results are also different from previous pediatric studies that estimate CPTP in adults who were 20 years status post-thoracotomy for coarctation repair between age of zero and 25 years old as 16 % (Matsunaga et al. 1990; Pluijms et al. 2006; Kristensen et al. 2010). It is possible that in children increased CNS plasticity accompanies the synaptic abundance and may allow for a reduced period of recovery, but prospective studies are needed (Johnston 2009).

In the immediate postoperative period, pain after thoracotomy can hinder respiratory dynamics by promoting splinting and delay mobilization. The postoperative course can be particularly rocky after posterolateral thoracotomies that do not employ a muscle-sparing technique, as the serratus anterior and latissimus dorsi muscles are compromised resulting in more postoperative nerve impairment0 (Ponn et al. 1992; Benedetti et al. 1998). Pediatric or adult data do not strongly support a surgical technique as being advantageous in preventing CPTP, but it is understood that minimizing muscle injury and rib retraction is likely to preserve intercostal nerves. It is generally desirable to minimize opioids in most cases since opioids can further compromise the patient’s respiratory function and trigger opioid-related side effects like nausea and constipation. Institutions today typically treat the immediate postoperative pain from thoracotomy with thoracic epidural analgesia (TEA), patient-controlled analgesia (PCA), paravertebral catheters, intercostal nerve catheters, or a combination of these (TEA plus PCA). Due to evidence of equivalent analgesia with a more favorable side-effect profile, ultrasound-guided thoracic paravertebral blocks are increasingly challenging the long-held gold standard TEA. Several small pediatric retrospective studies exist comparing different analgesic modalities in the immediate postoperative period, but these studies are often too small and with too brief follow-up periods to definitively show superiority of one analgesic technique over another, particularly as it pertains to the development of chronic postsurgical pain (Gonzalez et al. 2015). This is a controversy that extends into adult literature. In a Cochrane Database Systematic Review from 2012 where 250 adults were included as participants, regional anesthesia for thoracotomy to prevent chronic pain at 6 months had an odds ratio of 0.33 (95 % CI 0.20 to 0.56), and paravertebral block for breast cancer surgery to prevent chronic postsurgical pain at 5–6 months had an odds ratio of 0.37 (95 % CI 0.14 to 0.94) (Andreae and Andreae 2012). Another important controversy that adult studies have tackled has been the question of preoperative versus postoperative TEA for thoracotomies. While there seems to be no difference in their incidence of CPTP, preoperative TEA seems to perform as a better analgesic for acute postoperative pain (Andreae and Andreae 2012). The methodology of many of the included studies was intermediate, and the inclusion of children in further studies is needed to generalize this data to the pediatric population. There are currently no pediatric studies supporting the use of gabapentinoids, antidepressants, ketamine, local anesthetic infiltration, or cryoanalgesia to prevent CPTP.

For post-sternotomy and post-thoracotomy pain, ruling out secondary pain due to wound dehiscence, broken sternal wires causing tissue injury, or a localized infection precedes the diagnosis of a primary pain syndrome. The etiology of CPTP is both neuropathic, from iatrogenic intercostal nerve injury, and myofascial in origin (Gerner 2008; Steegers et al. 2008; Wildgaard et al. 2009). In adult patients, there seems to be some association between poorly controlled pain and the appearance of neuropathic features in the acute postoperative period with the eventual development of CPTP, but this has not been fully studied in the pediatric population (Searle et al. 2009). Sensory deficits and paresthesias, particularly allodynia, defined as pain elicited by a non-painful stimulus such as clothes or light touch, are frequently encountered along the thoracotomy scar and along the territory of intercostal nerves (Merskey and Bogduk 1994). Patients with a greater component of neuropathic pain can suffer with severe pain that can be continuous or paroxysmal and that interferes with sleep, school, sports, and activities of daily living. To make the diagnosis of neuropathic pain, there must be pain in a dermatomal distribution, partial or complete sensory loss in all or part of the painful area, and the presence of disease or injury preceding pain (Kehlet et al. 2006). Initial management of CPTP is usually conservative and starts with an anti-neuropathic agent such as gabapentinoids (gabapentin or pregabalin), serotonin-norepinephrine reuptake inhibitors, or a tricyclic antidepressant like amitriptyline dosed based on the child’s weight. If pain persists and medical therapy fails to relieve the neuropathic symptoms, an intercostal nerve injection, a paravertebral single injection or catheter, pulsed radiofrequency of the dorsal root ganglion, or intercostal radiofrequency ablation can be considered, but pediatric data is lacking (Fishman et al. 2010). One could consider trigger point injections or botox injections into the intercostal muscles to address the myofascial component of the pain (Fishman et al. 2010). There is currently no supportive evidence in children for minimally invasive pain therapies, such as nerve blocks, and the evaluation of a child with CPTP should include a referral to an interdisciplinary pediatric pain clinic to investigate the physiologic and psychosocial contributors of pain chronicity (Cohen et al. 2008).

The concepts in management for post-sternotomy pain are similar to those of CPTP. Given that much of post-sternotomy pain has a neuropathic quality, anti-neuropathic agents (gabapentinoids, serotonin-norepinephrine reuptake inhibitors, tricyclic antidepressant) are potential therapies once secondary pain has been ruled out. Referral to an interdisciplinary pediatric pain clinic should also be considered for assessment and management of chronic post-sternotomy pain.

For children with congenital heart disease undergoing noncardiac surgery, regional anesthesia may provide the benefit of analgesia while minimizing the respiratory depressant effects of opiate analgesics (Harnik et al. 1986). The following are neuraxial and regional techniques that may be useful alone or in combination with general anesthesia for the care of patients with congenital heart disease.

Spinal and epidural blocks have been used for adults and children undergoing cardiac surgery, and it has been a standard in at least one center (Hammer et al. 2000; Peterson et al. 2000; Steven and McGowan 2000; Weiner et al. 2012). And although the risk of epidural hematoma seems exceptionally low, the potentially devastating neurologic injury that may occur in patients undergoing systemic anticoagulation dissuades practitioners from utilizing neuraxial techniques (Chaney 2009; Weiner et al. 2012). This may be of greater concern for cyanotic patients with increased risk for epidural collateral vessels, increased central venous pressures, and coagulopathy (Steven and McGowan 2000).

Nonetheless, neuraxial blocks have benefits for children with congenital heart disease undergoing noncardiac surgery, including thoracolumbar and lower extremity procedures (Hardacker and Tolley 2004). Intrathecal blocks, as well as caudal, thoracic, or lumbar epidural blocks, are useful in a variety of thoracolumbar procedures, and placement of an epidural catheter allows for continuous postoperative pain control (Hardacker and Tolley 2004; Ivani and Mosseti 2009).

Both spinal and epidural anesthesia in combination with general anesthesia have been shown to mitigate the stress response to cardiothoracic surgery better than systemic opiates, which may improve patient outcomes (Anand et al. 1990; Anand and Hickey 1992; Wolf et al. 1998). This includes attenuating hemodynamic changes, mitigating immunologic and metabolic derangements, and moderating platelet activation. The improved respiratory mechanics seen after thoracotomy, along with the decreased need for narcotics, can also facilitate extubation (Slinger et al. 1995). Reports of successful and safe use of these techniques for women with congenital heart disease in the peripartum period seem to indicate their safety in high-risk patients with single-ventricle physiology and pulmonary hypertension (Fong et al. 1990; Peng et al. 1997; Lockhart et al. 1999; Maxwell et al. 2013).

Only minor, if any, self-resolving hemodynamic changes have been seen with neuraxial techniques, including high spinal anesthesia, in children with congenital heart disease, and they are typically not observed in those less than 8 years old (Murat et al. 1987; Hammer et al. 2000; Finkel et al. 2003; Kachko et al. 2012; Shenkman et al. 2012). Neuraxial anesthesia can therefore likely be performed with less of a concern for hemodynamic changes in these younger children.

While neurologic injury has been reported even after uneventful epidural block placement, neurologic injury is rare, with only 9 transient neurologic injuries in 37,543 epidural blocks, including caudal epidural blocks, reviewed in French, British, and American pediatric databases (Meyer et al. 2012).

Given the concern for devastating neurologic injuries, even after uneventful placement of thoracic epidural catheters, safety has driven use of regional anesthetic techniques with a lower risk profile. Additionally, in patients in whom neuraxial anesthesia is contraindicated, or those undergoing unilateral or ambulatory procedures, alternative truncal blocks from which patients may recover more quickly may be preferred (Oliver and Oliver 2013). The following are chest and abdominal blocks that avoid the neuraxial space.