Transposition of the Great Arteries



Fig. 8.1
d-Transposition of the great arteries with intact ventricular septum (Copyright © 2014 New Media Center, University of Basel. All Rights Reserved)




8.1.1.1 Surgical Repair Techniques


Before surgical repair became available, d-TGA was a lethal condition with an average life expectancy at birth of 0.65 years [2]. When open-heart surgery became feasible in the mid-1950s, survival changed dramatically. In the contemporary era, d-TGA has become a well-treatable condition and survival to adulthood is the rule [3, 4].

The first widely used repair technique was the atrial switch operation (Senning or Mustard procedure) with redirection of the venous blood flow at the atrial level [5, 6]. By the late 1980s, the arterial switch operation (Jatene operation) with redirection of blood flow at the level of the great arteries superseded the atrial switch procedure [7]. For the small subset of patients with d-TGA, concomitant ventricular septal defect and pulmonary stenosis, the Rastelli operation was and is an important surgical option [8]. Although the atrial switch operation is no longer performed today, the majority of patients who underwent this operation are still alive and there remains a substantial cohort of women in the childbearing age. As a consequence, all three repair techniques may be encountered in women of childbearing age. Relevant aspects of physiology, long-term complications and pregnancy-specific problems regarding these three types of repair will be discussed below.


  1. (i)


    The atrial switch operation (the Senning and Mustard procedure): The principle of the atrial switch operation is illustrated in Fig. 8.2. Although technically slightly different procedures, the physiological result after the Senning and the Mustard operation is the same: redirection of systemic venous blood at the atrial level by surgically created baffles. The atrial switch operation leaves the morphological right ventricle as the systemic (subaortic) ventricle and the tricuspid valve as the systemic atrioventricular valve.

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    Fig. 8.2
    Atrial switch operation (Copyright © 2014 New Media Center, University of Basel. All Rights Reserved)

     

  2. (ii)


    The arterial switch operation (the Jatene procedure): The principle of the arterial switch operation is illustrated in Fig. 8.3. The operation anatomically corrects the transposed arteries by transection of the aorta and the pulmonary artery above the valve level, reimplantation of the coronary arteries into the neo-aortic root and forward translocation of the pulmonary artery into its new position anterior to the aorta. The benefit of the Jatene technique is that the anatomic left ventricle is located in the systemic (subaortic) position and surgical manipulation of the atria is avoided. With refinement of the surgical technique, the arterial switch operation has become the standard procedure for patients with d-TGA since the late 1980s/early 1990s. Therefore, the cohort of women after the ASO of childbearing age is younger than the atrial switch cohort, and data regarding pregnancy issues and outcomes in this novel adult patient cohort are less robust.

    A338684_1_En_8_Fig3_HTML.gif


    Fig. 8.3
    Arterial switch operation (Copyright © 2014 New Media Center, University of Basel. All Rights Reserved)

     

  3. (iii)


    The Rastelli operation: The Rastelli operation was introduced in 1969 to repair patients with d-TGA with concomitant ventricular septal defect and obstruction to pulmonary outflow. The principle of the Rastelli operation is illustrated in Fig. 8.4. After the Rastelli repair, the morphological left ventricle is established in subaortic position, and the continuity between the subpulmonic right ventricle and the pulmonary artery is created by implantation of a bioprosthetic valved conduit.

    A338684_1_En_8_Fig4_HTML.gif


    Fig. 8.4
    Rastelli operation (Copyright © 2014 New Media Center, University of Basel. All Rights Reserved)

     

Long-term outcomes of patients with repaired d-TGA are largely determined by the type of repair and type and severity of residual haemodynamic lesions. The most common long-term complications in patients after atrial switch repair are arrhythmias (particularly atypical atrial flutter and sinus node dysfunction) and progressive dysfunction of the subaortic right ventricle with or without progressive systemic tricuspid valve regurgitation. Furthermore, baffle obstruction and baffle leaks as well as pulmonary hypertension can occur. On average, this patient group has substantially reduced exercise capacity compared to the general population [9]. Cardiac complications become more common as patients age. These patients have a reduced life expectancy, which is important for pre-pregnancy counselling. There is however a wide range in individual variation of disease courses. Long-term follow-up data beyond the fifth decade of life is not yet available.

The majority of adult survivors after the arterial switch operation are still young, and their outcome beyond the third decade of life is not yet known. To date, it seems that subaortic ventricular dysfunction and arrhythmias are less common compared to patients after the atrial switch operation [1012]. The main reason for re-intervention is obstruction of the branch pulmonary arteries. Potential long-term complications include neo-aortic root dilatation, neo-aortic valve regurgitation or obstruction of the reimplanted coronary arteries [13, 14]. Survival to adulthood is the rule but lifelong specialised follow-up remains mandatory.

In patients after the Rastelli repair, re-intervention due to deterioration of the right ventricular-pulmonary artery conduit is inevitable. Subaortic left ventricular dysfunction and arrhythmias are relatively common. In the largest published series on long-term outcomes after Rastelli repair, overall freedom from death and transplantation was 52 % at 20 years [15]. In contrast, in the Canadian cohort, the estimated survival at 17 years of follow-up was 89 % [16].




8.2 Pregnancy Outcome


Data regarding pregnancy outcomes in women with the atrial switch operation are limited to several medium-sized and smaller retrospective case series [1723]. Reports of pregnancy outcomes in women after the arterial switch operation and Rastelli repair are sparse [24, 25]. Reported pregnancy outcomes of series of patients with repaired d-TGA are summarised in Table 8.1 [26].


Table 8.1
Summary of pregnancy outcomes of women with repaired d-TGA




































































































































































 
Atrial switch

Arterial switch

Rastelli

Study

Clarkson et al.

Genoni et al.

Drenthen et al.

Canobbio et al.

Metz et al.

Trigas et al.

Cataldo et al.

Tobler et al.

Radford, Stafford

Publication year

1994

1999

2005

2006

2011

2014

2015

2010

2005

Number of women

9

11

28

40

10

34

21

9

6a

Number of pregnancies

15

13

69

70

21

60

34

17

12

Cardiac outcomes

Women with cardiac complications (%)

0

9

61

45

14 (baffle obstruction in 36 %)

NR

62

22

50 (LVOTO 100 % in d-TGA)

Arrhythmia (%)

0

0

16

36 (no further specification)

7

5

14

6

0

Heart failure (%)

0

9

3

7

6

0

0

0

Deteriorating NYHA class (%)

0

23

25

NR

12

14

0

NR

Obstetric and fetal outcomes

Hypertension-associated complications (%)

20

NR

13

17

7

2

NR

NR

NR

Miscarriages in first trimester (%)

13

15

25

14

29

18

NRb

23

41

Live births (%)

80

77

71

77

67

73

NRb

76

50 (25 % in d-TGA)

Live births at <35 weeks of gestation (%)

0

0

33

39

50

25

38 (<37 weeks)

0

16 (50 % in d-TGA)

Number of infants with CHD

0

0

0

0

0

0

0

1

0


Modified from Roche [26]

CHD congenital heart disease, LVOTO left ventricular outflow tract obstruction, NYHA New York Heart Association, NR not reported, TGA transposition of the great arteries

aThree women with d-TGA, three women with other types of CHD

bReport on completed pregnancies only


8.2.1 Cardiac Risks


Cardiac events during pregnancy and peripartum in women after the Mustard or Senning operation include arrhythmias, heart failure and thromboembolic or cerebrovascular events. In a meta-analysis of peer-reviewed literature, Drenthen et al. reported pregnancy outcomes of 170 pregnancies in women after the atrial switch operations. The most frequently encountered cardiac complication was arrhythmia (15.6 %) followed by heart failure (10.8 %) [27].

The major concern of pregnancy in women after the atrial switch operation is the fact that in two reported series, the risk of worsening subaortic ventricular function during pregnancy was reported to be as high as 25 % of pregnancies, with no recovery in the majority of cases [22, 28]. Although the mortality risk is small, pregnancy-related deaths have been reported [18, 29]. In a recent report from three tertiary care centres, five life-threatening events occurred in 60 pregnancies (8 %), two of which were cardiac arrest complicating delivery, with successful resuscitation [22]. In a North American cohort of 14 pregnancies that resulted in live births, symptomatic baffle obstruction was observed in five (36 %) pregnancies [21]. In three of these five women, baffle obstruction became symptomatic in their second pregnancy. In all instances, the superior limb of the systemic venous atrial baffle was affected.

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Aug 12, 2017 | Posted by in CARDIOLOGY | Comments Off on Transposition of the Great Arteries
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