6.2. Surgical Management
Valve replacement surgery is the most effective treatment for managing
symptomatic CaHD, significantly improving patient outcomes. The criteria
and optimal timing for such surgery, however, remain subjects of debate.
Consensus says that the indications for valve replacement surgery are
symptomatic right heart failure, in conjunction with either progressive
right ventricular enlargement or a decline in right ventricular systolic
function, irrespective of the presence of symptoms.26The decision-making process for valve replacement should be predicated
upon a thorough evaluation by a multidisciplinary team, taking into
account comprehensive operability, the oncological status, and cardiac
functionality. Surgical interventions have shown not only to alleviate
symptoms of RHF but also to reverse right ventricular remodelling.
Studies highlight the postoperative symptomatic improvement and survival
benefits. For instance, a study by Mokhles et al. involving 19 patients
showed a significant improvement in functional capacity one year
post-valve replacement, with survival rates at 1- and 5-year follow-ups
standing at 71% and 43%, respectively.39
Predominant surgical interventions include tricuspid valve replacement
(TVR) and, less frequently, pulmonary valve replacement (PVR). Survival
outcomes post-combined TVR and PVR surpass those of surgeries excluding
PVR, thus advocating for the former as the preferred surgical
intervention for the majority of patients (unless there is significant
pulmonary valve involvement).40 In cases requiring
intervention on both the tricuspid and pulmonary valves, combined valve
replacement has been successfully performed, with reported median
survival times extending from six to eleven years
post-operation.1 Additionally, although balloon
valvuloplasty has been attempted in patients deemed unsuitable for
surgery, its utility is limited due to the high recurrence rate of
valvular disease and the potential for concurrent TV and PV
regurgitation.15
The selection of the valve prosthesis type remains a subject of debate,
with no large comparative studies available. Initial preferences leaned
towards mechanical prostheses to avoid the presumed risk of damage to
bioprosthetic valves from vasoactive substances.1However, the protective potential of somatostatin analogs and other
antitumor therapies against carcinoid plaque deposition on tissue valves
has been recognized, shifting some opinion in favour of bioprosthetic
valves. While bioprosthetic valves are susceptible to early degeneration
from carcinoid-related fibrosis, this risk can be mitigated with
effective postoperative control of neuroendocrine activity. Therefore,
despite the potential for thrombosis, bioprosthetic valves generally do
not require lifelong anticoagulation—typically, a three to six-month
course suffices.26 Conversely, mechanical valves offer
durability but necessitate lifelong anticoagulation, increasing the risk
of bleeding and potentially complicating future interventions. In
instances of bioprosthetic valve deterioration, Transcatheter Valve
Implantation emerges as a logical subsequent treatment
step.15
As often is the case with most surgical interventions, they are not
devoid of risks. In the perioperative phase, the anaesthetist confronts
challenges specific to CaHD, including the risk of carcinoid crisis,
bleeding, and the potential onset of low cardiac output syndrome
attributed to right ventricular (RV) failure.41 To
mitigate these potential complications, an infusion of short-acting
octreotide is initiated 12-24 hours prior to surgery and maintained
throughout the perioperative period for three days, supplemented, if
necessary, by the administration of catecholamines and
histamine-releasing drugs.41 The paramount importance
of bleeding management mandates that surgeons and anesthesiologists
meticulously assess and refine surgical techniques, implement autologous
blood recovery systems, and focus on the optimization of postoperative
coagulation.40 Notably, the operative risk has
decreased from 20% in the 1980s to 10% in more recent years, marking a
significant advancement.15
Furthermore, partial hepatic resection and tumour debulking are
generally reserved for patients with metastatic disease localised to a
specific hepatic lobe.42 Indeed, liver resection is
correlated with a diminished risk of CaHD cardiac progression,
underscoring its critical role in the surgical management of
CaHD.43 In select scenarios of metastatic carcinoid
disease confined to the liver, patients might also be eligible for liver
transplantation and the excision of the primary tumour.
Future Prospects/Recommendations:
As the healthcare field advances its understanding of CaHD, the
trajectory for future management and research is set towards improving
patient outcomes with a focus on innovation and personalised care.
Advances in diagnostic modalities promise a new era where early
detection and precise characterization of CaHD become the norm. The
development of advanced imaging techniques such as 3D echocardiography
and cardiac MRI, alongside specific biomarkers for early disease
detection, are anticipated to revolutionise the diagnostic landscape of
CaHD, enabling earlier and more targeted
interventions.24,31
The exploration into the genetic and molecular bases of CaHD holds the
potential to identify novel therapeutic targets. Uncovering the
mechanisms behind serotonin-mediated valvular disease could pave the way
for therapies that prevent or significantly reduce valvular fibrosis,
moving beyond the current pharmacological approaches that primarily
manage symptoms.1 In tandem with molecular research,
the quest for innovative therapeutic agents that specifically address
the pathophysiological processes of CaHD is critical. This includes not
only drugs that effectively manage serotonin levels but also those that
can inhibit fibrosis or offer cardioprotective effects without the
drawbacks of existing treatments.
Surgical treatment of CaHD is also poised for advancement, with a focus
on developing new valve prostheses and exploring minimally invasive and
transcatheter interventions. The design of valve prostheses that are
resistant to serotonin-induced fibrosis or mechanical valves that
minimise thrombosis risk could significantly improve patient
prognosis.7 Additionally, minimally invasive
techniques could offer viable alternatives for high-risk patients,
reducing perioperative complications and broadening treatment
options.45 Furthermore, personalised treatment
strategies are imperative for the future of CaHD management, advocating
for treatments tailored to individual genetic profiles, disease
severity, and therapeutic responses. This approach necessitates the
creation of comprehensive databases and the application of advanced
analytics, ensuring treatments are both effective and minimised for side
effects. Integral to this personalised approach is the reinforcement of
multidisciplinary care models, emphasising coordinated, patient-centred
management across specialties to optimise treatment timing and patient
care.
In addition, the establishment of patient registries and the commitment
to long-term follow-up will provide critical insights into disease
progression, treatment efficacy, and quality of life. These registries
are essential for facilitating large-scale studies and validating new
management strategies. International collaboration and the development
of consensus guidelines based on the latest evidence will also play a
pivotal role in advancing global standards of care for CaHD, ensuring
patients everywhere have access to the best possible
outcomes.45 Although the ideal scenario would involve
a multicenter, randomised survival study, the rarity of CaHD and
logistical challenges render this prospect unlikely.
Conclusion:
CaHD presents significant challenges in cardiac pathology associated
with neuroendocrine tumours, characterised by valvular dysfunction due
to serotonin-induced fibrosis. Central to its management are
advancements in diagnostic modalities such as echocardiography and
cardiac MRI, which have significantly enhanced the ability to diagnose
the disease early and accurately. The management strategy for CaHD has
evolved into a comprehensive approach, incorporating both medical and
surgical treatments. Medical therapies, including somatostatin analogues
and newer pharmacological options, aim to control symptoms and slow
disease progression. However, surgical valve replacement remains a
well-researched option for those with advanced symptomatic disease,
offering symptomatic relief and improved survival. Ultimately, the goal
in managing CaHD is to improve both survival and the quality of life of
affected patients through early decision, tailored treatment strategies
and ongoing research to refine and discover new therapeutic options.