CARDIOVASCULAR JOURNAL OF AFRICA • Vol 23, No 8, September 2012
e12
AFRICA
(1 000
ml). Effusions were also noted within the left thoracic
cavity (200 ml), pericardium (350 ml) and peritoneum (500 ml).
The other major finding at post mortem was the presence of
a small fatty liver. Histology revealed the presence of cirrhosis,
with prominent fibrotic bands. After extensive special stains, the
diagnosis was cryptogenic cirrhosis.
The lungs appeared to be within normal limits at post mortem,
but histology revealed prominent dilatation of the vasculature of
both lungs, consistent with the hepatopulmonary syndrome.
Examination of the brain and endocrine systems confirmed the
clinical findings.
Discussion
Platypnoea (dyspnoea induced by the upright position and
relieved by recumbency) and orthodeoxia (arterial deoxygenation
accentuated by the upright position and improved during
recumbency) is a rare and poorly understood syndrome of
orthostatic accentuation of a right-to-left shunt, usually across
a patent foramen ovale.
1
Another unusual condition involving
right-to-left shunting, while usually chronic, can present in a
very similar fashion to right-to-left interatrial shunt, i.e. with
hypoxaemia, platypnoea, orthodeoxia and a positive bubble
contrast echocardiograph; hepatopulmonary syndrome (HPS).
2
HPS is defined as the triad of liver disease, pulmonary gas
exchange abnormalities leading to arterial deoxygenation, and
widespread pulmonary vascular dilatation.
3
The hallmark of
pulmonary vascular changes in HPS are dilated vessels at the
pre-capillary and direct arterio-venous communications.
3
This
causes right-to-left shunting of blood flow, mismatch between
ventilation and perfusion, and diffusion limitations. Pulmonary
features include digital clubbing, cyanosis, dyspnoea, platypnoea
and orthodeoxia.
3
Impaired arterial oxygenation is a hallmark of HPS. Mild
hypoxaemia is a frequent feature of chronic liver disease; it occurs
in approximately one-third of all patients. By contrast, severe
hypoxaemia (PaO
2
<
60
mmHg) is less common with cirrhosis
alone and is usually without associated cardiopulmonary disease.
In the absence of independent lung disease, severe hypoxaemia
in the setting of liver disease suggests the possibility of HPS.
4
From a physiological viewpoint, HPS provides an excellent
model for clinical research in the pathophysiology of pulmonary
gas exchange. So far it has been possible to show that arterial
hypoxaemia in this condition is (1) partitioned into components
resulting from ventilation–perfusion (VA/Q) mismatching,
intrapulmonary shunt and limitations of oxygen diffusion; (2)
modulated by the interplay between the intrapulmonary and
the extrapulmonary determinants of PaO
2
,
such as cardiac
output and minute ventilation; (3) vulnerable to the influence of
inadequate pulmonary vascular tone, and (4) resolved when the
injured liver is replaced and hepatic function is restored to within
normal limits.
4
Contrast-enhanced echocardiography is considered to be
standard in the diagnosis of HPS. In subjects with normal
pulmonary vasculature, microtubules become lodged in the
pulmonary circulation and are absorbed. The appearance of
microtubules in the left side of the heart indicates right–left
shunts, while bubbles that appear in the left heart immediately
after they have appeared in the right atrium are suggestive of an
intracardiac shunt.
5,6
Conclusion
A high clinical suspicion of right-to-left interatrial shunts and
HPS should be considered in the setting of unexplained hypoxia,
especially with associated platypnoea and or orthodeoxia.
References
1.
Seward JB, Hayes DL, Smith HC,
et al
.
Platypnea–orthodeoxia: clini-
cal profile, diagnostic workup, management and report of seven cases.
Mayo Clin Proc
1984;
59
: 221–231.
2.
Isaac J. Hypoxemia, platypnoea, orthodeoxia and right to left shunt.
Br
J Anaesth
2001;
86
(4): 594–602.
3.
Yilmaz S, Dursum M, Canoruc F,
et al
.
A severe (type II) hepatopul-
monary syndrome in a patient with idiopathic portal hypertension and
treatment with paroxetine.
J Med
2005;
63
(11): 448–452.
4.
Mohammed Alizadeh AH, Fatemi SR, Mirzaee V,
et al
.
Clinical
features of HPS in cirrhotic patients.
Wld J Gastroenterol
2006;
12
(12):
1954–1956.
5.
Leung AN. Case 63: Hepatopulmonary syndrome.
Radiology
2003;
229
(1): 64–67.
6.
Krowka MJ, Wiseman GA, Burnett OL,
et al
.
Hepatopulmonary
syndrome.
Chest
2000;
118
: 615–624.
