Aim: To report a case of acyanotic Taussig-Bing heart, anatomically consistent with L-transposition and rheumatic Left AV valve regurgitation associated with complete AV block in an adolescent male. Introduction: Taussig-Bing heart is one of the conotruncal malformation, characterized by double-outlet right ventricle (DORV) and a subpulmonary VSD. Embryologically, abnormal cardiac looping with malalignment of conotruncal septum result its complexity and great artery relationships. Case Report: A 14-year old acyanotic boy presented with severe left-sided AV valve regurgitation and bradycardia. ECG revealed left sided morphologic right ventricular hypertrophy (RVH) as evidenced by a loss of septal Q waves in left precordial leads suggesting ventricular inversion. X-ray chest revealed a straight upper right cardiac border due to loss of normal relationship of great vessels and cardiomegaly due to both left atrial and morphologic right ventricular enlargements suggesting a left-sided regurgitant lesion. Echocardiography revealed the ventricular inversion, primary origin of both L-transposed great arteries from the left-sided morphologic right ventricle suggesting a “double-outlet morphologic right ventricle” with “double discordance” and a subpulmonary VSD of Taussig-Bing type. The left-sided morphologic tricuspid valve is severely regurgitant due to rheumatic process resulting in heart failure which was improved with anti-failure measures and penicillin prophylaxis. Conclusion: The presence of left-sided regurgitation associated with bradycardia is a suspicion of “double discordance” and “double switch” procedure remains the mainstay of its surgical correction. Left AV valve replacement with intraventricular repair is preferred in this child since the malformation is consistent with Taussing-Bing type of DORV with L-transposition.
“Taussig-Bing heart” is a morphological subtype of double-outlet right ventricle (DORV) with subpulmonary VSD (ventricular septal defect) [
A 14-year old boy was admitted with features of heart failure in the intensive care unit. His pulse rate was 50 bpm and blood pressure 110/70 mmHg. He had a history of rheumatic fever during childhood and blood chemistry revealed a positive ASO (anti-streptolysin O) titer. Auscultation revealed a grade 4/6 pansystolic murmur over the cardiac apex with a shift of apical impulse to left 6th space towards axilla. ECG revealed high-grade AV block with features of ventricular inversion and strain pattern due to morphologic RVH as shown in
The child was treated with anti-failure medications such as diuretics, angiotensin-converting enzyme inhibitors (enalapril) with penicillin prophylaxis for a period of one and a half months and the regurgitant lesion became decreased as shown in
Since the great arteries are primarily originating from morphologic RV as in
medical treatment along with lifelong penicillin prophylaxis. Palliative procedures are not indicated in this boy since there is no aortic arch obstruction and outflow tract lesions as shown in
Taussig-Bing suspected a totally different malformation at autopsy in a five and a half year old girl who had cyanosis since birth and died during angiocardiography after a third intravenous injection of contrast material, the diodrast, the child sat bolt upright and the heart stopped. The malformation consists of a transposed aorta, a large pulmonary artery which arises primarily from the right
ventricle and partially overrides the ventricular septum, a high ventricular septal defect, and right ventricular hypertrophy. Maurice Lev was one of the first to call this anomaly as “Taussig-Bing syndrome” [
This anomaly was initially described in 1949 by Taussig and Bing as transposition of the great arteries. The important difference between Taussig-Bing anomaly and transposition of the great arteries were described by Richard Van Praagh in his editorial review and stressed that the absence of pulmonary-mitral continuity is the characteristic feature of this anomaly. Taussig and Bing emphasized that the overriding of pulmonary artery was an integral part of this malformation. This anomaly was eventually named as “Taussig-Bing heart” in 1950 by Lev and associates [
The Taussig-Bing anomaly is relatively rare and it accounted for approximately 8% of cases in Sridaromont series [
valve because of interposed subpulmonary conal free wall musculature as in
During the development of the heart, the outflow regions initially remain exclusively with the primitive right ventricle and undergo extensive remodeling to ventricle appears to represent a primitive embryologic condition as failure to achieve conotruncal inversion and leftward shift of conus results in persistence divide into aorta and pulmonary artery with connection to left and right ventricles respectively. Goor and Edwards [
heart and it normally “loops” to the right (D-loop) resulting in normal morphological position of right ventricle to the right side. The abnormal cardiac looping to the left side (L-loop) brings the morphologic right ventricle to the left and the ventricles are reversed (ventricular inversion), the atrioventricular valves “follow” the ventricles and the two great arteries are transposed or exit from the “wrong” ventricle, but the systemic venous blood flows from the morphologic left ventricle to the pulmonary artery and the systemic arterial blood flows from the morphologic right ventricle to the aorta and so the circulation is corrected. Thus, during embryologic development, left-handed looping of the heart tube
results in AV (atrioventricular) discordance and the aorto-pulmonary septum fails to rotate 180˚, resulting in ventriculo-arterial discordance. This heart defect
is called as “corrected transposition” by Baron Rokitansky in 1875 and described as “Rokitansky’s malformation” [
corrected transposition” (ccTGV) by Schiebler since the correction was a gift of God, rather than the gift of the surgeon [
The tricuspid valve tends to remain competent during the first decade of life, but progressively become incompetent during the 2nd to 5th decade in 20% to 50% of patients and it has been implicated as a cause of ventricular dysfunction due to volume overload. Since the morphologic right ventricle is in the systemic position, it is unable to generate the necessary forces to sustain the increasing work demand, such as exercise, similar to normal systemic left ventricle [
The VSD is neither membranous nor conal septal defect and it is due to its malalignment of well developed parietal conal free walls, the parietal and septal bands, which may separate or dissociate widely in Taussig-Bing malformation. In L-TGA, the VSDs occur in 60% - 80% of cases, usually perimembranous, located below the pulmonary valve, extends posteriorly and inferiorly towards the crux of the heart and opening into the inlet of the morphologic left ventricle as in
The molecular and biological forces that dictate the abnormal cardiac looping in humans are not clear. Cytogenetic analysis identified the discrete chromosomal lesions in the morphogenesis of the heart and appears to be associated with subtypes of DORV. Type 1 DORV (with subaortic VSD) is associated with chromosome 22q11 deletion, the type II (with subpulmonary VSD (supracristal) -Taussig Bing type) with trisomy 13 or 18. The transcription factors are postulated to influence the development of right ventricle and great arteries [
Animal studies also implicate diverse teratogens, the commonly used drugs (ephedrine, theophylline, sodium valproate, retinoic acid/vitamin A, tedral (combination of theophylline, ephedrine, phenobarbitone), other agents including bis-diamine, bromodeoxyuridine), copper citrate, environmental factors such as hair dye, air pollutants [
Transthoracic echocardiography is the first line modality to assess the specific relations of the different segments of the heart and to determine the presence of any associated malformations. The anatomical designation is first assigned by demonstrating atrial position, ventricular and arterial loopings. The morphology of right ventricle is determined by the presence of coarse trabeculations, moderator band and the level of tricuspid valve, which is inferior (apical) to mitral valve, also give a clue to ventricular inversion as shown in
The anatomic objective such as “double discordance”, i.e., discordant connection at both atrioventricular and ventriculo-arterial junctions can be defined by echocardiography. The discordance between the atrium and ventricle as left atrium is connected to the morphologic Right ventricle (mRV) and the right atrium is connected to the morphologic left ventricle (mLV) was shown in
The origin of great arteries in relation to the septum and its spatial relationships are best visualized in subcostal coronal views.
Systemic AV valve regurgitation is a potential risk factor for the development of dysfunction of the morphologic RV and early heart failure [
In patients with widened QRS complex (QRS duration > 120 - 140 ms, sometimes > 200 ms) due to bundle branch blocks, the electromechanical dyssynchrony create insufficiency in ventricular ejection and restoration of electrical synchrony with transvenous permanent para-Hisian pacing (cardiac resynchronization therapy) reduces the QRS duration and improves the hemodynamics of the failing systemic right ventricle [
Complete heart block is also a common cause of death [
The evolution of surgical repair for the Taussig-Bing anomaly has progressed from atrial baffle procedures to arterial switch with VSD closure and intraventricular repair. The need for surgical interventions vary according to the associated defects and several options are available as:
1) Physiologic or conventional repair-which emphasizes the correcting of associated defects without addressing the discordant connections and leaves the morphologic RV to propel the systemic circulation. The tricuspid valve and morphologic RV function is the Achilles heel of the physiology of ccTGV [
2) Anatomical repair―In physiological correction, the morphological RV will likely to fail over long-term, there is an increasing trend towards anatomical correction by “switch procedures” introduced in 1987 by Ilbawi and colleagues with an aim to utilize the morphologic LV as a systemic pumping chamber and the mitral valve as the systemic valve [
It represents a group of procedures in which AV discordance is corrected by an inflow, baffling procedure at atrial level, called as atrial or venous switch (Mustard or Senning) and the ventriculo-arterial discordance is corrected by either an outflow procedure called as arterial or ventricular switch or by translocation of the aortic root (Jatane procedure) and collectively termed as “double-switch”. The choice of procedures depending on the underlying anatomy of LVOT/or morphology of VSD [
The indication for anatomic repair for those with a “balanced” systemic and pulmonary blood flow without clinically significant cyanosis is still unclear. Current indication for “double switch” operation include patients who have developed symptoms attributed to tricuspid regurgitation or RV dysfunction or both [
For patients with Taussig-Bing type of DORV, the “arterial switch” operation still appears to be the procedure of choice and can be performed in the neonatal period [
3) Single-ventricle palliation-such as “Fontain circulation” (redirection of systemic (deoxygenated) blood into the pulmonary artery without traversing a ventricle) should be considered in more complex and unfavourable anatomy due to small RV, chordae straddling and remote VSD, however, it may affects the organs outside the heart leading to cirrhosis, protein loosing enteropathy and plastic bronchitis [
In patients without tricuspid valve regurgitation, the survival rate at 20 years is > 90% and it is < 50% in regurgitant lesions. Unfortunately, the patients are often referred late for surgery when a progressive RV dysfunction is already initiated, however, if the surgery is performed when the RV ejection fraction is > 40%, the patients do reasonably well. In addition, a number of reports of ccTGA in adults come to medical attention for either cardiac or non cardiac reasons in 6th to 8th decade, indeed, the right ventricle can function as a systemic ventricle for many years [
The 14-year old boy was presented with features of “double discordance” (
The septal malalignment in situ solitus alters the cardiac hemodynamics and conduction pathways, leading to increased risk of complications. The atrial and ventricular septa are malaligned and the AV node cannot penetrate the ventricular mass, indeed, a secondary node penetrates the anterior septum, predisposing to high grade atrioventricular block [
On aggressive medical management with antifailure measures and penicillin prophylaxis, the severe tricuspid regurgitation decreases as shown in Figures 19 and
The boy remains acyanotic with an improvement in hemodynamic status, the medical measures are continued with lifelong penicillin prophylaxis and advised periodic echocardiographic evaluation to assess the ventricular function. Since the left-sided morphologic RV is a systemic pumping chamber, it is hypertrophied (
Taussig-Bing heart is one of the variants of double-outlet right ventricle (DORV) [
Muthiah, R. (2018) Rheumatic “Taussig-Bing Heart”: A Case Report. Case Reports in Clinical Medicine, 7, 7-36. https://doi.org/10.4236/crcm.2018.71002