2024, Number 1
Complete heart block in an adult patient with isolated congenitally corrected transposition of the great arteries and situs inversus
Full text
10.35366/115000
Language: English
References: 11
Page: 16-21
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ABSTRACT
Congenitally corrected transposition of the great arteries (ccTGA) is a rare congenital heart disease. Many patients remain asymptomatic when no cardiac lesions are present (isolated ccTGA). In ccTGA, the atrioventricular conduction system may be abnormal, resulting in progressive dysfunction and, eventually, a Complete Heart Block (CHB). In ccTGA with situs inversus, the conduction pathway resembles a normal tract, but the atrioventricular node is located posteriorly. Compared with situs solitus, spontaneous CHB is uncommon in ccTGA patients with situs inversus. We report the case of a 40-year-old female without previous medical conditions or having a family or personal history of heart disease presented with loss of consciousness. At admission, electrocardiography revealed bradycardia, CHB, and hypertrophy of the right ventricle. Cardiovascular imaging tests detected an isolated ccTGA with situs inversus and levocardia. The Holter monitor revealed intermittent CHB. Exercise testing demonstrated chronotropic incompetence. An epicardial pacemaker was implanted, and the patient was discharged symptom-free. At a two-years follow-up remains asymptomatic. This case illustrates the importance of cardiovascular imaging in defining cardiac anatomy, ruling out other congenital heart defects, and facilitating pacing therapy in complex congenital heart disease. Congenital heart disease patients should be treated by a multidisciplinary team with expertise in permanent pacing.INTRODUCTION
A congenitally corrected transposition of the great arteries (ccTGA) is a rare congenital heart disease characterized by discordant atrioventricular and ventriculo-arterial connections.1,2 The right atrium (RA) enters the morphological left ventricle (LV), which rises to the pulmonary artery, and the left atrium (LA) communicates with the morphological right ventricle (RV), which gives rise to the aorta.2 Among the associated lesions are ventricular septal defects (70%), pulmonary stenosis (40%), and dysplastic systemic tricuspid valves.1 The clinical course of adults with ccTGA is relatively unknown, with cases of isolated ccTGA rarely developing complications before adulthood.1,3,4 In most cases, the position of the atrioventricular node and the bundle of his is abnormal, resulting in abnormal atrioventricular conduction.1 In patients with ccTGA and situs inversus, complications are lower than in patients with situs solis, including Complete Heart Block (CHB).4 Visceroatrial situs inversus with ccTGA is a rare congenital condition.5,6 Given the rarity of this condition, there are limited reports of CHB in adult patients with isolated ccTGA and situs inversus. Therefore, we report a case of symptomatic intermittent CHB in an adult patient with ccTGA, situs inversus, and levocardia who required pacing therapy.
CASE PRESENTATION
A 40-year-old female was admitted to the emergency department after briefly losing consciousness at work in the last 12 hours. The patient felt well before and immediately following the episode, and there was no apparent trauma or confusion. As part of her initial evaluation at another center, an electrocardiogram revealed a CHB (Figure 1), which led to her referral to this facility. The patient denied having any previous medical conditions or having a family or personal history of heart disease and also denied taking any medications.
On examination at admission, she was afebrile, with a blood pressure of 125/67 mmHg and a heart rate of 40 beats/min. The cardiovascular examination revealed a high-pitched and loud grade 4/6 pansystolic murmur in the tricuspid valve area, which increased upon inspiration.
On admission, electrocardiography revealed a CHB with right ventricular hypertrophy B. In addition, the blood tests were relevant for high cholesterol and triglyceride levels, with the rest of the studies in the normal range (Table 1).
Transesogapheal echocardiography revealed a mirror-image atrial arrangement, with right-sided LA connected to a morphological RV with an emerging aorta, a left-sided RA connected to a morphologic LV with an arising pulmonary artery, a right ventricular ejection fraction (RVEF) of 38%, an estimated pulmonary artery systolic pressure of 106 mmHg, mild pulmonary regurgitation, intact interatrial and interventricular septums, moderate tricuspid regurgitation, and no intracavitary thrombus. Cardiac computed tomography revealed an isolated ccTGA with visceroatrial situs inversus and levocardia (Figures 3 and 4).
The Holter monitor showed intermittent CHB alternated with sinus rhythm and premature ventricular contractions (Figure 5). In the exercise testing, the patient achieved 4.6 METS, showed chronotropic incompetence, and was suspended by fatigue (Figure 6).
Based on the results of these studies, a permanent epicardial pacemaker was implanted; the patient was discharged symptom-free and with a functioning pacemaker. At a two-year follow-up, the patient remained asymptomatic, and a TTE showed RVEF 38% with moderate tricuspid regurgitation with a functional pacemaker.
DISCUSSION
Described by Von Rokitansky in 1875, ccTGA accounts for approximately 0.5% of all congenital heart defects, with limited information on adult patients.7
Concerning the conduction system, the atrioventricular node and His bundle follow an unusual path, and many patients have dual AV nodes. Second anomalous AV nodes and bundles are usually anterior, and the long, penetrating bundle is prone to fibrosis with increasing age. As a result, the conduction system is somewhat tenuous, with the incidence of complete AV block rising at 2% per year.2,8,9
In 10% of ccTGA cases, situs inversus is present; in this condition, the conduction pathway resembles a normal tract with an atrioventricular node located posteriorly.4,10 Levocardia usually exists with situs solitus, but dextrocardia can complicate the anatomical presentation in approximately 25% of the cases.10
In the literature, no significant differences in ventricular septal defect, pulmonary tract stenosis, and long-term mortality were found between ccTGA with situs inversus or situs solitus. There was, however, a lower incidence of nonsurgically related CHB (0 vs 42%, p = 0.032), development of CHB in 7.4 years (12.5 vs 57%, p = 0.045), tricuspid valve anomalies (0.0 vs 50%, p = 0.01), overall complications (25 vs 73%, p = 0.034) and heart failure (p = 0.038).4
The radiographic and electrocardiographic findings often lead to the diagnosis of ccTGA when symptoms are absent and physical findings are subtle.1,8,10 Electrocardiograms frequently reveal ventricular hypertrophy and atrial enlargement, even in the absence of other cardiac lesions.1,10 To confirm the diagnosis of ccTGA, cardiac imaging is essential, which aids in defining cardiac anatomy despite clinical suspicion.1
Pacemaker implantation may be justified in patients who suffer from symptomatic chronotropic incompetence. Current recommendations for cardiac pacing in patients with congenital heart disease and high-degree atrioventricular block are as follows: a) symptoms, b) pauses > 3 times the cycle length of the ventricular escape rhythm, c) broad QRS escape rhythms, d) prolonged QT interval, e) complex ventricular ectopy, and f) the mean daytime heart rate < 50 beats/min.11
The patients have a reduced life expectancy; 50% would still be alive at 60 years of age if they did not have associated lesions. Additionally, no evidence exists that medical treatment is associated with preventing heart failure or improving outcomes.1
Surgery is generally reserved for symptomatic and asymptomatic patients with evidence of deteriorating RV function and worsening tricuspid regurgitation. Intervention in asymptomatic patients with preserved RV and tricuspid valve functions without any other septal defects is controversial.10
CONCLUSIONS
Isolated ccTGA usually does not manifest symptoms until adulthood; CHB results from abnormalities in the atrioventricular conduction system associated with discordant atrioventricular and ventriculoarterial connections. Patients with situs inversus and ccTGA have a lower incidence of CHB than those with situs solitus. In this group of patients, cardiovascular imaging studies are essential for defining cardiac anatomy and facilitating pacing therapy.
REFERENCES
AFFILIATIONS
1 Hospital Regional 1o de Octubre, ISSSTE, Mexico City, Mexico.
2 Internist, Cardiology Resident. ORCID: 0000-0001-6631-7228
3 Cardiologist, Cardiovascular Imaging Specialist.
4 Cardiologist, Cardiac Electrophysiologist.
Declaration of patient consent: the authors declare they have followed their workplace protocols for using patient data. Also, they certify that the patient has received sufficient information and has given written informed consent for her images and other clinical information to be reported in the journal, without names or initials, to protect the right to privacy.
Funding: no financial support was received for this study.
Conflict of interest: the authors declare no conflict of interest.
CORRESPONDENCE
Virginia Campos-Garcilazo. E-mail: vickycampos2000@yahoo.comReceived: 11/21/2023. Accepted: 02/21/2024