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CARDIOVASCULAR JOURNAL OF AFRICA • Volume 29, No 4, July/August 2018
AFRICA
e5
Transthoracic echocardiography (2D-TTE): this remains the
gold standard during the initial diagnostic evaluation of any
patients suspected of CHD. Classical 2D-TTE findings will
include thickened and shortened tricuspid valve (TV) leaflets.
Similar to our two cases, the TV leaflets may become severely
retracted, with reduced leaflet mobility. In most instances, the
septal and anterior TV leaflets are predominantly affected (Figs
1, 2). In advanced stages of TV disease, the leaflets may become
fixed in the semi-open position (Figs 1, 2).
Similar to the tricuspid valve, pulmonary valvular cusps
usually appear thickened, with retraction and reduced leaflet
mobility, and it may be difficult to visualise them during routine
echocardiographic evaluation. Doppler echocardiographic
assessment of the pulmonary valve may be helpful as there are
challenges related to difficulties in demonstrating anatomical
changes. The right atrium and ventricle may become increasingly
dilated over time (Figs 1, 2). A dagger-shaped profile with an
early peak velocity and a rapid decline, which indicates rapid
pressure equalisation between the right atrium and ventricle,
is a common finding during continuous-wave Doppler tracing
in CHD patients presenting with severe tricuspid regurgitation
(Fig. 4).
Management strategies for CHD
The principal management strategies in CHD patients should
strictly focus on primary treatment of right heart failure, therapy
to reduce secretion of tumour product, and valve surgery.
Medical management: medical treatment modalities for right
heart failure in patients with CHD include standard heart-failure
therapy. However these strategic approaches have not been
proven effective in most patients with CHD.
Somatostatin analogue, particularly octreotide, has a direct
effect on reducing the vasoactive peptides and has demonstrated
direct clinical benefit and biochemical improvement.
Alternatively, lanreotide, which has the advantage of less frequent
administration compared with octreotide, may be a good
option. Reports have indicated that somatostatin analogue has
demonstrated symptomatic relief and a decrease in measurable
urinary 5-HIAA excretion and serum serotonin concentration.
10
Newer treatment options include the leukocyte interferon-
alpha, which may be used in conjunction with somatostatin
antagonist. However data on this treatment option are limited.
Cardiac surgery: asymptomatic patients or those who
exhibit minimal symptoms usually need closer follow up with
regular transthoracic echocardiography and exercise testing
to assess their functional status. Patients who develop severe
cardiovascular symptoms related to CHD should be evaluated
for valve-replacement surgery. For suitable candidates, valve
surgery is the only definitive curative treatment modality for
severe heart failure. Although reports have implicated balloon
valvoplasty as an alternative and it has produced symptomatic
improvement in some patients with stenotic valve lesions related
to CHD, data on its application in CHD patients are limited.
17
Indications for surgery: right heart-failure symptoms,
severely impaired exercise capacity, progressive right ventricular
enlargement or decline in right ventricular systolic function
are some of the indications for surgical intervention in CHD
patients. However, some patients with severe CHD may require
cardiac valve surgery despite minimal cardiac symptoms.
Although tricuspid mechanical valve prostheses may be
considered adequately durable and relatively unaffected by
vasoactive substances, bioprosthetic valves may be preferable
since anticoagulants can be avoided.
17-39
Due to high bleeding
tendencies in patients with hepatic metastases, bioprosthetic
valves would be the best option for this group of patients.
However, the life expectancy of bioprosthetic tricuspid valves is
likely to be shorter than that of mechanical valves, particularly in
CHD. Tricuspid valve repair could be an option and important
area of future research, however currently, tricuspid valve repair
does not seem feasible in CHD.
Pulmonary valvectomy or valve replacement is preferred
for those with pulmonary valve disease secondary to carcinoid
disease. Although pulmonary valve replacement may reduce the
risk of right heart dilatation postoperatively, larger studies with
more convincing results are warranted.
Successful surgical intervention has been associated with an
improvement in survival rate and quality of life in those patients
who were successfully treated surgically. Despite this premise,
older patients (over the age of 60 years) remain a high surgical
risk group, with an associated high death rate, which is even
higher in those with significant co-morbidities.
Peri-operative management: the surgical approach for CHD
patients requires a highly skilled multidisciplinary team with
broad experience, as anaesthesia can trigger carcinoid crisis and
subsequent death in patients going for surgery.
26,40-57
The most
crucial pre-operative anaesthetic management should encompass
optimum control of carcinoid symptoms, and intensified and
close monitoring of intra-operative blockade of serotonin
receptors. Drugs that may stimulate the release of vasoactive
substances from tumour cells should be avoided.
26,40-57
The
most important drugs to be avoided during the peri-operative
period include histamine-releasing neuromuscular relaxants
and opioids, as they are associated with detrimental outcomes
in CHD patients. The introduction of somatostatin analogues
remains a key component to prevent peri-operative carcinoid
crisis, and the administration of larger doses of somatostatin
analogue is highly recommended in CHD patients.
Prognosis of CHD
Previous studies have reported outcome differences between
carcinoid syndrome patients with versus those without CHD,
and demonstrated markedly shortened life expectancy in patients
with underlying cardiac involvement.
8,9
Patients with right heart
failure and those with advanced signs of right-sided heart failure
represent a subgroup of patients at high risk. Progression of
CHD contributes to poor survival; as a result, early detection
and regular follow up are mandatory in the management
algorithm of patients with CHD.
8,9
Levels of 5-HIAA should be closely monitored, as this is an
independent predictor for the development or progression of
CHD while on or even after medical management. Although,
it was believed that optimal control of serotonin release may
prevent or delay development of early cardiac lesions, reports
have indicated that somatostatin analogues, chemotherapy and
hepatic de-arterialisation may not sufficiently counteract the
pathophysiological mechanisms involved in the causation and
progression of valvular heart lesions.
8,9
Surgical valve replacement reduces heart-failure symptoms