Page 772 - Cardiac Nursing

748 P AR T IV / Pathophysiology and Management of Heart Disease

Blood returning to the heart from the systemic circulation is Management
ejected from the right ventricle into the aorta, sending unoxy- All patients who have had surgical repair for TGA should be fol-
genated blood back into the systemic circulation. Complete TGA, lowed at a regional adult congenital heart disease center at 6 to
26
also referred to as d-transposition of great arteries, occurs in 5% to 12 months intervals. In addition to an echocardiogram, a cardiac
8% of all congenital heart diseases. There is a male preponderance MRI for more detailed assessment of right ventricular function is
in patients with transposition of the great arteries, with a sex ratio recommended at least every 3 years.
of 1.5. 53 Natural survival is extremely rare, and survival into Medical management is directed to maintain right ventricle
adulthood is dependent on the early use of palliative shunting function or to support a failing systemic right ventricle as well as
procedures (atrioseptectomy, atrioseptostomy), pulmonary artery control and/or treat development of complications. Arrhythmias
banding to regulate pulmonary flow, and, later, the atrial switch are mainly treated using antiarrhythmic drugs or by catheter ra-
procedures known as the Mustard or Senning operation. Both of diofrequency ablation. In patients who develop poor chronotropic
these procedures divert caval blood to the mitral valve and pul- response to exercise, permanent pacing is indicated.
monary venous blood to the tricuspid valve. In the Mustard pro- Data on surgical reintervention are rather limited. 56 In Mus-
cedure, venous blood is diverted to the mitral valve by means of tard and Senning patients, it is most frequently performed in the
an intra-atrial baffle. In the Senning procedure, a tunnel is created setting of baffle obstruction or leaks that result in shunting. The
within the right atrium that carries caval blood to the mitral valve. latter is more often observed in patients after the Mustard opera-
While mid-term survival rates associated with the atrial switch tion than after the Senning operation. 54 Following the arterial
procedures have been reasonably good, the commonly occurring switch operation, patients are monitored for right and left ventri-
complications of arrhythmias, baffle obstruction, and progressive cle outflow tract obstruction in the supravalvular areas, due to su-
failure of the systemic right ventricle have lead surgeons to replace ture line stenosis. If an outflow tract obstruction occurs, balloon
the Mustard and Senning procedures with an arterial switch oper- angioplasty or surgical intervention with patch augmentation is
ation. 52–57 Carried out in an infant’s first few weeks of life, the ar- the treatment of choice. Patients with transposition of the great
terial switch procedure involves surgically detaching the coronary arteries often have residual defects, therefore endocarditis prophy-
arteries from the aorta, then separating the aorta and pulmonary laxis is recommended. 20
arteries above the semilunar valves. The aorta is then reimplanted
to the stump of the pulmonary trunk, and the pulmonary artery
is reimplanted to the stump of the aortic root. The coronary ar-
teries are then anastomosed to the new aorta. While long-term CYANOTIC HEART DEFECTS WITH
survival data are limited, results appear to be very good. COMMON MIXING

Pathophysiology In certain heart defects there is common mixing of pulmonary and
For survivors of TGA who have undergone the Mustard or Sen- systemic venous blood within the heart or great vessels, resulting in
ning operation, the preservation and integrity of the systemic desaturation of arterial blood. 17 Heart defects with common mix-
right ventricle is the main concern. The long-term outlook for ing are associated with or without obstruction of pulmonary blood
these patients is related to the demand placed on the right ventri- flow. Patients with ventricular outflow obstruction have a dimin-
cle to support the systemic circulation. Additional long-term ished pulmonary blood flow, whereas those without ventricular
complications that may increase demand placed on the right ven- outflow obstruction have an increased pulmonary blood flow. 17
tricle include tricuspid regurgitation, sinus node dysfunction,
atrial re-entrant tachycardia, and baffle obstruction or leaks. In a Truncus Arteriosus
20-year postoperative course, about 40% of the patients experi-
ence at least one form of arrhythmias, of which sinus node dys- Description
function and atrial flutter are most prevalent. 54 After arterial In this lesion, which occurs in .1% of all congenital heart dis-
switch operation, the majority of patients are asymptomatic, ven- eases, the primitive trunk fails to divide into two great arteries
tricular function is good, and rhythm disturbances are uncommon. (Fig. 31-14). Thus, a single great vessel emerges from the base of
The major concern in the long-term survival of these patients is the the heart through a single semilunar valve, straddling both ventri-
status of coronary arteries. Earlier studies reported kinking and ob- cles over a large VSD. The truncus, which is the aorta, receives
struction of the reimplanted arteries resulting in myocardial is- blood from both ventricles and gives rise to both pulmonary and
chemia and infarction; however, as the operative techniques have systemic circulations, as well as coronary arteries. The second
improved, the incidence of coronary insufficiency has decreased. 21 semilunar valve is absent but a short pulmonary trunk without a
Survival rates without coronary events were 92.7%, 91%, and valve may emerge from the side of the truncus and give rise to the
88.2% at 1, 10, and 15 years, respectively. 55 right and left pulmonary arteries (Type I), or both pulmonary ar-
teries may arise directly from the posterior or lateral walls of the
Clinical Manifestations truncus (Type II). Pulmonary blood flow then arises entirely by
Following an atrial switch operation, the second heart sound is way of collaterals from bronchial arteries or a PDA. In more than
usually single, due to the anterior position of the aortic valve. In 80% of patients, a large VSD is also present. 58
the absence of an associated defect, there should be no murmurs. Survival rate of patients with truncus arteriosus is variable. 59
In the presence of tricuspid insufficiency, a systolic murmur is au- About 56% of the patients die in infancy or childhood before op-
60
dible, and if due to the presence of a VSD, a pansystolic murmur eration or during the immediate postoperative period. Late mor-
is audible along the left sternal border. A harsh systolic ejection tality of hospital survivors, up to 20 years after the operation, is
murmur along the left midsternal border will be heard in the set- about 15%. 60,61 As a result, it is estimated that only 30% of the pa-
ting of valvar or subvalvar pulmonary stenosis. tients with truncus arteriosus will reach adulthood. Only patients