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Basic Sciences: Answers
139
The coronary sinus is a large vein on the heart which drains into the right atrium. The
coronary sulcus is a groove on the heart which separates the atria from the ventricles. The
costomediastinal recess is an area in the pleural sac where the costal pleura changes to the
mediastinal pleura.
References
Chapter 3. The Thorax: Part II-The Thoracic Cavity. Snell RS, ed. Clinical Anatomy By
Regions. 9
th
edition. Baltimore, USA. Lippincott William & Wilkins. 2012: 58-112.
1.85 Answer: D
The first rib articulates with the sternum directly below the sternoclavicular joint. The
nipple is found in the fourth intercostal space, between the 4th and 5th ribs. The sternal angle
is connected to the costal cartilage of rib 2. Finally, the xiphoid process is located just below
the point where the costal cartilage of rib 7 articulates with the sternum. The root of the lung
consists of the main bronchus, pulmonary and bronchial vessels, lymphatic vessels, and
nerves entering and leaving the lung.
References
Chapter 2. The Thorax: Part I-The Thoracic Wall. Snell RS, ed. Clinical Anatomy By
Regions. 9
th
edition. Baltimore, USA. Lippincott William & Wilkins. 2012: 34-57.
1.86 Answer: D
The oblique pericardial sinus is an area of the pericardial cavity located behind the left
atrium of heart where the serous pericardium reflects onto the inferior vena cava and
pulmonary veins. If you slide your fingers under the heart, they will be in this space. The
other pericardial sinus that you should be familiar with is the transverse sinus. The transverse
sinus is an area of the pericardial cavity located behind the aorta and pulmonary trunk and
anterior to the superior vena cava. It separates the outflow vessels from inflow vessels.
The cardiac notch is an indentation in the superior lobe of the left lung which creates the
lingula. The costomediastinal recess is an area in the pleural sac where the costal pleura
changes to the mediastinal pleura. Finally, the hilar reflection is the reflection of pleura on the
root of the lung, where visceral pleura on the lung becomes continuous with the mediastinal
pleura.
References
Chapter 3. The Thorax: Part II-The Thoracic Cavity. Snell RS, ed. Clinical Anatomy By
Regions. 9
th
edition. Baltimore, USA. Lippincott William & Wilkins. 2012: 58-112.
1.87 Answer: D
The cupola is the cervical parietal pleura, which extends slightly above the level of the
1st rib into the root of the neck. The costodiaphragmatic recess is the part of the pleural sac
where the costal pleura changes into the diaphragmatic pleura. It is the lowest extent of the
pleural sac. The costomediastinal recess is found where the costal pleura becomes the
mediastinal pleura. Endothoracic fascia is connective tissue between the inner chest wall and
costal parietal pleura. The costocervical recess is a made up term.
Shahzad G. Raja
140
References
Chapter 3. The Thorax: Part II-The Thoracic Cavity. Snell RS, ed. Clinical Anatomy By
Regions. 9
th
edition. Baltimore, USA. Lippincott William & Wilkins. 2012: 58-112.
1.88 Answer: C
The left vagus nerve lies against the lateral surface of the arch of the aorta. The left
recurrent laryngeal nerve is an especially important nerve from the vagus which loops around
the aortic arch. This nerve innervates the muscles of the left larynx. If it is damaged, a patient
may experience hoarseness after surgery. Care must be taken to preserve this nerve,
especially during thyroid surgery.
The left and right phrenic nerves, which innervate the diaphragm, are lateral to the vagus
nerves and are not looping near the aortic arch. The left and right sympathetic trunks lie on
the posterior chest wall and are not involved with the aortic arch.
References
Chapter 3. The Thorax: Part II-The Thoracic Cavity. Snell RS, ed. Clinical Anatomy By
Regions. 9
th
edition. Baltimore, USA. Lippincott William & Wilkins. 2012: 58-112.
1.89 Answer: E
The transverse pericardial sinus is an area of the pericardial cavity located behind the
aorta and pulmonary trunk and anterior to the superior vena cava. When entering the
transverse pericardial sinus, a surgeon will insert an index finger between the aorta and
pulmonary trunk on the ventral side and the superior vena cava on the dorsal side. The
oblique pericardial sinus is an area of the pericardial cavity located behind the left atrium of
the heart. If a surgeon places fingers under the apex of the heart, then moves the fingers until
they are stopped by a pericardial reflection, then the fingers are in the oblique sinus.
The cardiac notch is a structure on the left lung which separates the lingula below from
the upper portion of the superior lobe of left lung. The coronary sinus is a venous sinus on the
posterior surface of the heart which receives blood from the smaller veins which drain the
heart. The coronary sulcus is a groove on the heart, between the atria and ventricles. The
coronary sinus, circumflex artery, and right coronary artery lie in the coronary sulcus.
References
Chapter 3. The Thorax: Part II-The Thoracic Cavity. Snell RS, ed. Clinical Anatomy By
Regions. 9
th
edition. Baltimore, USA. Lippincott William & Wilkins. 2012: 58-112.
1.90 Answer: B
The transverse pericardial sinus is an area of the pericardial cavity located behind the
aorta and pulmonary trunk and anterior to the superior vena cava. So, the two large vessels
lying ventral to his finger are the pulmonary trunk and aorta; the large vessel lying dorsal to
his finger is the superior vena cava.
References
Chapter 3. The Thorax: Part II-The Thoracic Cavity. Snell RS, ed. Clinical Anatomy By
Regions. 9
th
edition. Baltimore, USA. Lippincott William & Wilkins. 2012: 58-112.
Basic Sciences: Answers
141
1.91 Answer: B
The costodiaphragmatic recess is the lowest extent of the pleural cavity or sac. It is the
part of the pleural sac where the costal pleura changes into the diaphragmatic pleura. It is also
the area into which a needle is inserted for thoracocentesis, and it is found at different levels
at different areas of the thorax. At the mid clavicular line, the costodiaphragmatic recess is
between ribs 6 and 8; at the midaxillary line it is between 8 and 10; and at the paravertebral
line it is between 10 and 12. So, inserting the needle just above the 9th rib at the midaxillary
line should put you in the costodiaphragmatic recess.
The cardiac notch is a structure on the left lung which separates the lingula below from
the upper portion of the superior lobe of left lung. The costomediastinal recess is found where
the costal pleura becomes the mediastinal pleura. The cupola is the part of the pleural cavity
which extends above the level of the 1st rib into the root of the neck. The oblique pericardial
sinus is an area of the pericardial cavity located behind the left atrium of the heart.
References
Chapter 3. The Thorax: Part II-The Thoracic Cavity. Snell RS, ed. Clinical Anatomy By
Regions. 9
th
edition. Baltimore, USA. Lippincott William & Wilkins. 2012: 58-112.
1.92 Answer: B
The costomediastinal recess is an area right next to the cardiac notch, which is an
indentation in the superior lobe of the left lung. If you take a very deep breath, the lingula of
the left lung, which is formed by the cardiac notch, will tend to expand into the
costomediastinal recess.
The costodiaphragmatic recess is the lowest extent of the pleural cavity or sac. It is the
part of the pleural sac where the costal pleura changes into the diaphragmatic pleura. The
cupola is the part of the pleural cavity which extends above the level of the 1st rib into the
root of the neck. The hilum is found on the medial surface of the lung-it is the point at which
the structures forming the root enter and leave the lung. The pulmonary ligament is a fold of
pleura located below the root of the lung, where the visceral pleura and the mediastinal
parietal pleura are continuous with each other.
References
Chapter 3. The Thorax: Part II-The Thoracic Cavity. Snell RS, ed. Clinical Anatomy By
Regions. 9
th
edition. Baltimore, USA. Lippincott William & Wilkins. 2012: 58-112.
1.93 Answer: E
The tubercle of a rib is a projection located posteroinferior and lateral to the neck of the
rib. It articulates with the transverse process of the vertebra of the same number. So, the
tubercle of rib 7 should articulate with the transverse process of the T7 vertebra. The head of
the rib is the part of the rib that articulates with the demifacets of two adjacent vertebral
bodies. So, the head of rib 7 should articulate with the 6th vertebra superiorly and the 7th
vertebra inferiorly.
References
Chapter 2. The Thorax: Part I-The Thoracic Wall. Snell RS, ed. Clinical Anatomy By
Regions. 9
th
edition. Baltimore, USA. Lippincott William & Wilkins. 2012: 34-57.
Shahzad G. Raja
142
1.94 Answer: B
The cupola is the part of the pleural cavity which extends above the level of the 1st rib
into the root of the neck. So, if a patient was stabbed above the clavicle, it would be very
likely that the cupola was damaged. The costal pleura is the layer of parietal pleura that
covers the costal surface. The hilar reflection is the point where the visceral pleura of the lung
reflects to become continuous with the parietal pleura. The mediastinal pleura is the parietal
pleura on the mediastinal surface, found medial to the lung. Finally, the pulmonary ligament
is a double layer of pleura extending from the inferior end of the hilar reflection downward to
the diaphragm below.
References
Chapter 3. The Thorax: Part II-The Thoracic Cavity. Snell RS, ed. Clinical Anatomy By
Regions. 9
th
edition. Baltimore, USA. Lippincott William & Wilkins. 2012: 58-112.
1.95 Answer: D
The left recurrent laryngeal nerve is a branch of the vagus that wraps around the aorta,
posterior to the ductus arteriosus or ligamentum arteriosum. It then travels superiorly to
innervate muscles of the larynx. It's important to protect this nerve during surgery! If the left
recurrent laryngeal nerve becomes paralyzed, a patient might experience a hoarse voice or
even have difficulty breathing due to a laryngeal spasm. You should make sure that you
understand what this nerve does, what types of procedures might injure this nerve, and the
effects of a damaged left recurrent laryngeal!
The accessory hemiazygos vein is a vein on the left side of the body. It drains the
posterolateral chest wall and empties blood into the azygos vein. The left internal thoracic
artery is a branch of the left subclavian artery that supplies blood to the anterior thoracic wall.
The left phrenic nerve runs lateral to the vagus nerve and its branches in the thorax; it is not
close enough to be damaged by the surgery. The thoracic duct is deep in the chest - it travels
between the azygos vein and the aorta, posterior to the oesophagus.
References
Chapter 3. The Thorax: Part II-The Thoracic Cavity. Snell RS, ed. Clinical Anatomy By
Regions. 9
th
edition. Baltimore, USA. Lippincott William & Wilkins. 2012: 58-112.
1.96 Answer: E
The pulmonary ligament is a double layer of pleura extending from the inferior end of the
hilar reflection downward to the diaphragm. So, it is a structure that would block you from
moving your finger posteriorly at the root of a lung. The costodiaphragmatic recess is the
space at the inferior border of the lung where the costal pleura touches the diaphragmatic
pleura. The cupola is the part of the pleura that extends superiorly above the first rib--it's not
associated with the root of the lung in any way. The inferior vena cava is found in the
mediastinum and would not be near the root of the lung. The left pulmonary veins are part of
the root of the lung and would not block someone from reaching behind the lung.
References
Chapter 3. The Thorax: Part II-The Thoracic Cavity. Snell RS, ed. Clinical Anatomy By
Regions. 9
th
edition. Baltimore, USA. Lippincott William & Wilkins. 2012: 58-112.
Basic Sciences: Answers
143
1.97 Answer: B
The endothoracic fascia is the connective tissue between the inner aspect of chest wall
and the costal parietal pleura. By clearing the endothoracic fascia, it is easy to separate the
costal pleura from the thoracic wall. Deep fascia is a fascial layer that invests a muscle or
muscle group - it is not present around the lungs. The parietal pleura is made up of the cupola
or cervical pleura, costal pleura, diaphragmatic pleura, and mediastinal pleura. It lines the
inner surfaces of the walls of the pleural cavity. The visceral pleura is the serous membrane
that covers the lungs. Finally, the transversus thoracis muscle fascia is only associated with
the transversus thoracis - it would not provide a natural cleavage plane for separating the
costal pleura from the thoracic wall.
References
Chapter 2. The Thorax: Part I-The Thoracic Wall. Snell RS, ed. Clinical Anatomy By
Regions. 9
th
edition. Baltimore, USA. Lippincott William & Wilkins. 2012: 34-57.
1.98 Answer: A
The costodiaphragmatic recess is the area inferior to the lung where the costal and
diaphragmatic pleura are continuous. This is the lowest extent of the pleural cavity. The
costomediastinal recess is a small anterior recess where the costal and mediastinal pleura are
continuous. The cupola is the pleural space that extends above the first rib. The inferior
mediastinum is a term sometimes used to refer to the anterior, middle, and posterior
subdivisons of the mediastinum all together. The pulmonary ligament is a fold of pleura
located beneath the root of the lung.
References
Chapter 3. The Thorax: Part II-The Thoracic Cavity. Snell RS, ed. Clinical Anatomy By
Regions. 9
th
edition. Baltimore, USA. Lippincott William & Wilkins. 2012: 58-112.
1.99 Answer: C
The sternal angle is a very important anatomical landmark which is used when placing
the stethoscope and listening for heart sounds. The sternal angle is the location of the
attachment of the costal cartilage of the second rib to the sternum. So, once you locate the
sternal angle on a patient, you know the location of the second rib, and you can use that
landmark to find the right spots to auscultate each valve of the heart. Also remember that a
horizontal plane through the sternal angle passes through the T4/T5 intervertebral disc and
marks the inferior boundary of the superior mediastinum.
References
Chapter 2. The Thorax: Part I-The Thoracic Wall. Snell RS, ed. Clinical Anatomy By
Regions. 9
th
edition. Baltimore, USA. Lippincott William & Wilkins. 2012: 34-57.
1.100 Answer: C
The costomediastinal recess is an area right next to the cardiac notch, which is an
indentation in the superior lobe of the left lung. This is where the medial area of the superior
lobe of the left lung would tend to expand if it became very inflated. The lung would not enter
the anterior mediastinum, which is an area between the two pleural sacs, bounded anteriorly
Shahzad G. Raja
144
by the sternum and posteriorly by the pericardium. The anterior mediastinum contains areolar
tissue, sternopericardial ligaments, lymph vessels and nodes, but no lung tissue. The
costodiaphragmatic recess is the recess at the inferior border of a lung. This is the space into
which the inferior lobe of the lung would expand following deep inhalation. The cupola is the
serous membrane lining the pleural cavity which extends above the level of the 1st rib into the
root of the neck. The most superior portion of the superior lobe might expand into this space.
The pulmonary ligament is the fold of pleura located below the root of the lung where the
visceral pleura and the mediastinal parietal pleura are continuous with each other.
References
Chapter 3. The Thorax: Part II-The Thoracic Cavity. Snell RS, ed. Clinical Anatomy By
Regions. 9
th
edition. Baltimore, USA. Lippincott William & Wilkins. 2012: 58-112.
Chapter II
Cardiac Surgery
2.1 Answer: C
Heparin-induced thrombocytopenia (HIT), or "white clot syndrome," is
an immune-
mediated, potentially life-threatening thrombotic
complication of heparin therapy that occurs
in 3 to 5% of individuals
approximately 5 to 14 days after heparin exposure. HIT
should be
suspected in any patient who experiences a 50% or
greater decrease in platelet count from
baseline or 30% or greater
decrease in platelet count and associated thrombotic complication
while
on unfractionated heparin for at least 5 days. HIT can occur earlier
in patients who are
within 3 months of previous exposure to heparin.
When testing for platelet factor 4
(PF4)/heparin antibodies in
a patient with suspected HIT, it is recommended that the test
be
repeated on several successive days. Thrombocytopenia usually
resolves within 1 week of
heparin discontinuation, but thrombotic
tendency can persist for up to 1 month. Although HIT
can occur
with the use of low-molecular-weight heparin (LMWH), the incidence
and
development of thrombosis are much less frequent. One study
demonstrated a higher
incidence of saphenous vein graft occlusion among
post-CABG patients with HIT compared
with non-HIT patients within 2
weeks of surgery (68% versus 20%, p < .001). However, the
incidence of internal mammary artery graft occlusion was not
significantly different between
the two groups [HIT patients
= 6% (1 patient) and non-HIT patients = 11% (2 patients)].
Antibodies to heparin/PF4 cause platelet activation and aggregation, as
well as thrombin
formation, resulting most commonly in deep
venous thrombosis, pulmonary embolism, or
cerebral sinus thrombosis.
Following CABG, HIT may present as graft occlusion, left atrial
thrombus, valvular thrombosis, or pulmonary embolism. On average,
25 to 50% of
cardiopulmonary bypass patients who receive heparin
acquire HIT immunoglobulin G (IgG),
but only approximately 7%
develop HIT.
References
Levy JH, Tanaka KA, Hursting MJ. Reducing thrombotic complications in the perioperative
setting: an update on heparin-induced thrombocytopenia. Anesth Analg. 2007;105:570-
82.
Liu JC, Lewis BE, Steen LH, et al. Patency of coronary artery bypass grafts in patients with
heparin-induced thrombocytopenia. Am J Cardiol. 2002; 89:979-981.
Shahzad G. Raja
146
2.2 Answer: E
Antiplatelet agents such as aspirin have been used for many
years for the treatment of
ischaemic heart disease. More recently,
newer drugs such as clopidogrel have been used as
single antiplatelet
treatment or in conjunction with other antiplatelet drugs to
reduce platelet
aggregation and therefore lessen the risk of
myocardial infarction before and after the
insertion of coronary
artery stents. Clopidogrel is a thienopyridine derivative
with a structure
and mechanism of action that is distinct from
other clinically available antiplatelet agents. Its
primary
effect appears to be inhibition of ADP induced platelet aggregation
without directly
affecting arachidonic acid metabolism.
Intermittently patients present for coronary angiography but
after imaging it is apparent
that operative intervention is
required instead of angioplasty despite the continuing use of
clopidogrel. These patients may be at increased risk of complications
from haemorrhage. In
addition, patients with peripheral vascular
disease who are being treated with clopidogrel and
are potentially
at high risk of postoperative adverse events may be referred
for cardiac
surgery.
Intuitive complications of such potent antiplatelets, such as
postoperative haemorrhage,
have potentially serious side effects,
especially in patients undergoing coronary surgery.
Multiple
transfusions after cardiac surgery are associated with significant
morbidity,
mortality, and transmission of viral diseases.
Several studies have investigated the effect of
clopidogrel
and postoperative bleeding in patients undergoing cardiac surgery
and report
varying results.
A meta-analysis of 11 cohort studies published in 2006 combined papers providing data
on patients who either did or did not receive clopidogrel. There was a mean increase in blood
loss of 323 ml, a six-fold increase in the odds of re-exploration, an increase in adverse events
and ventilation time, but no difference in hospital length of stay or mortality.
Several other studies have also reported outcomes for patients who either did or did not
receive clopidogrel. Kapetanakis et al. compared 281 patients having clopidogrel before off-
pump surgery to 1291 patients who did not have clopidogrel. There were no differences in
mean blood loss or mortality, but there was a 2–3 times increase in the odds of transfusion
and a five-fold increase in the odds of re-exploration. Other studies on clopidogrel before
coronary artery bypass grafting (CABG) have shown an increase in re-exploration rate, a 50%
increase in chest drainage, an increase in red cell usage and blood transfusion as well as a
doubling in chest drain output. Ascione in a 1-year cohort study of in-patient referrals found
that there was a three-fold increase in the re-exploration rate, a significantly increased
mortality and more chest drainage. In contrast to these studies, Karabulut et al. found no
increase in chest drainage, re-exploration or red cell transfusion, although the study included
1628 patients of whom only 48 were on clopidogrel. Thus, clopidogrel is associated with
more blood product usage, a 2–5-fold increase in the risk of re-exploration and 30–100%
increase in the chest drain blood loss.
References
Dunning J, Versteegh M, Fabbri A, et al. Guideline on antiplatelet and anticoagulation
management in cardiac surgery. Eur J Cardiothorac Surg. 2008;34:73-92.
Purkayastha S, et al. Does clopidogrel affect outcome after coronary artery bypass grafting?
A meta-analysis. Heart 2006;92:531-532.
Cardiac Surgery: Answers
147
Kapetanakis EI, Medlam DA, Petro KR, et al. Effect of clopidogrel premedication in off-
pump cardiac surgery: are we forfeiting the benefits of reduced hemorrhagic sequelae?
Circulation. 2006;113:1667-74.
Kapetanakis EI, Medlam DA, Boyce SW, et al. Clopidogrel administration prior to coronary
artery bypass grafting surgery: the cardiologist's panacea or the surgeon's headache? Eur
Heart J. 2005;26:576-83.
Yende S, Wunderink R. Effect of clopidogrel on bleeding after coronary artery bypass
surgery. Crit Care Med. 2001;29:2271-5.
Ascione R, Ghosh A, Rogers CA, et al. In-hospital patients exposed to clopidogrel before
coronary artery bypass graft surgery: a word of caution. Ann Thorac Surg. 2005;
79:1210-6.
Karabulut H, Toraman F, Evrenkaya S, et al. Clopidogrel does not increase bleeding and
allogeneic blood transfusion in coronary artery surgery. Eur J Cardiothorac Surg.
2004;25:419-23.
2.3 Answer: C
The CURE study in 2004 was a double-blind RCT of 12,562 patients who had suffered a
non-ST elevation myocardial infarction (NSTEMI). It showed that death, myocardial
infarction (MI) or stroke occurred in 9.3% of patients randomised to clopidogrel and aspirin,
compared to 11.4% in the aspirin alone group. In the subgroup of 2072 patients who
subsequently underwent CABG, the overall benefits of clopidogrel were maintained by the
end of the study. In addition, there was a trend to fewer complications prior to surgery whilst
awaiting the intervention (5.6% vs 6.7%; number needed to treat (NNT) 90). For patients
continuing clopidogrel to within 5 days, preoperatively, there was a non-significant excess in
re-exploration and 9.6% of clopidogrel patients vs 6.3% of placebo patients had a major
bleeding event. The CURE authors recommend that it is safe for all NSTEMI patients to be
started on clopidogrel and aspirin on admission, but that clopidogrel should be stopped 5 days
before surgery.
The CREDO trial showed benefits for clopidogrel loading 6 h before percutaneous
intervention (PCI) and continuing for up to 1 year in a RCT of 2116 patients with no
significant difference in bleeding complications, although there was a high incidence of major
bleeding in the subset of patients proceeding to CABG.
The CLARITY-TIMI-28 trial randomised 3491 patients who had suffered MI within 12 h
to clopidogrel or placebo. This showed a 7% absolute risk reduction for death, MI or stroke
with clopidogrel. A small group of 136 patients who proceeded to CABG did not have an
excess risk of bleeding although neither blood loss nor blood product usage were reported in
detail. The ACC/AHA guidelines of 2002 on the management of NSTEMI and unstable
angina recommend immediate administration of clopidogrel if PCI is planned. They
furthermore recommend cessation of clopidogrel for 5–7 days prior to surgery, giving this a
grade B level of evidence.
The PCI-CURE study provides important data when considering withholding clopidogrel
for patients before CABG: 1313 patients received clopidogrel prior to PCI with 1345 placebo
controls in this double-blind RCT. The mean wait for PCI was 6 days and the incidence of MI
while awaiting intervention was 5.1% in the placebo group but only 3.6% in the clopidogrel
group (p = 0.04, NNT 66 to prevent an MI pre PCI).
Shahzad G. Raja
148
Thus there is a clear benefit in commencing clopidogrel for patients suffering an MI,
NSTEMI or shortly to require PCI, and this therapy should not be withheld even if a possible
future CABG is possible. However, once it is decided that CABG is required, the ACC/AHA
guidelines, the STS guidelines, the meta-analysis and multiple cohort studies would
recommend cessation of clopidogrel for 5–7 days. The CURE study and its sub-analyses
show that cessation of clopidogrel in these patients for this time period is associated with a
1% increase in the risk of MI.
References
Dunning J, Versteegh M, Fabbri A, et al. Guideline on antiplatelet and anticoagulation
management in cardiac surgery. Eur J Cardiothorac Surg. 2008;34:73-92.
Fox KA, Mehta SR, Peters R, et al. Benefits and risks of the combination of clopidogrel and
aspirin in patients undergoing surgical revascularization for non-ST-elevation acute
coronary syndrome: the Clopidogrel in Unstable angina to prevent Recurrent ischemic
Events (CURE) Trial. Circulation. 2004;110:1202-8.
Steinhubl SR, Berger PB, Mann JT 3rd, et al. Early and sustained dual oral antiplatelet
therapy following percutaneous coronary intervention: a randomized controlled trial.
JAMA. 2002;288:2411-20.
Sabatine MS, Cannon CP, Gibson CM, et al: CLARITY-TIMI 28 Investigators. Addition of
clopidogrel to aspirin and fibrinolytic therapy for myocardial infarction with ST-segment
elevation. N Engl J Med. 2005;352:1179-89.
Mehta SR, Yusuf S, Peters RJ, et al. Effects of pretreatment with clopidogrel and aspirin
followed by long-term therapy in patients undergoing percutaneous coronary
intervention: the PCI-CURE study. Lancet. 2001;358:527-33.
2.4 Answer: E
Desmopressin (1-deamino-8-D-arginine vasopressin or dDAVP) is
a synthetic analogue
of vasopressin that was initially devoted
to the treatment of central diabetes insipidus.
Intravenous
administration of desmopressin raises factor VIII and von Willebrand
factor
plasma concentrations in healthy volunteers. The increase
is related to a release from
endothelial intracellular storage
pools and not to de novo synthesis. Therefore, this effect is
rapid, transient, and diminishes with repeated injections at
short intervals. This agent also
transiently increases tissue
plasminogen activator (t-PA) and prostacyclin plasma levels.
Desmopressin has been used successfully in the prevention or
treatment of bleeding due
to minor surgical procedures in mild
hemophilia A and type I von Willebrand‘s disease.
Desmopressin
is also efficacious for indications not involving FVIII and
von Willebrand
factor. Notably, it shortens the bleeding time
in patients with certain acquired platelet function
disorders
(chronic renal failure, acetyl-salicylic acid intake). The usual
dose is 0.3 µg·kg
–1
iv,
and the infusion
should continued for at least 20 min.
Cardiopulmonary bypass leads to alterations in platelet function.
The hypothesis that
desmopressin may be helpful has been supported
by results of initial trials. However, later
studies challenged
this view. A meta-analysis performed by the International Study group of
Peri-Operative
Transfusion (ISPOT), concluded that desmopressin had no significant
influence on the proportion of transfused patients. Another Dutch meta-analysis concluded
that desmopressin did not influence mortality, the
rate of re-operation for hemostasis and the