Heart Failure in Tetralogy of Fallot due to Associated Hypertrophic Obstructive Cardiomyopathy: A Lesson to Learn.

Tetralogy of Fallot (TOF) is the most common cyanotic congenital heart disease. Heart failure (HF) in a case of uncomplicated TOF is uncommon but can occur under special circumstances. TOF associated with hypertrophic obstructive cardiomyopathy (HOCM) is a very rare combination of anomalies, and very few cases have been reported in the literature. Here, we report the case of a 2-month-old male infant who presented to us with central cyanosis and features of HF. He was worked up and found to have TOF with HOCM and advised surgical correction. Hence, we propose that HOCM is also one factor which can precipitate HF in a patient of TOF along with the classical causes mentioned in the literature. Furthermore, the left ventricular outflow tract obstruction of HOCM in a patient of TOF has an inverse relation with the degree of cyanosis. Copyright:

INTRODUCTION

Tetralogy of Fallot (TOF) is the most common cyanotic congenital heart disease. It is slightly more common among males. Patients of TOF most often present in infancy with cyanosis due to right-to-left shunt at the level of ventricular septal defect (VSD). The degree of right ventricular outflow tract obstruction (RVOTO) often correlates with the degree of cyanosis and timing of presentation. Right ventricular (RV) failure is uncommon in patients with TOF and can occur in special circumstances.[1] Hypertrophic obstructive cardiomyopathy (HOCM) is the most common genetic heart disease, occurring in at least 1:500 of the general population. It has an autosomal dominant inheritance due to mutations in 11 or more genes of the sarcomere or adjacent Z-disc. Genetic testing differentiates HOCM from other diseases mimicking it due to left ventricular (LV) hypertrophy such as protein kinase AMP-activated non-catalytic subunit gamma 2 (PRKAG2), Fabry's disease, and Lysosome-associated membrane protein 2 (LAMP2).[2] The combination of TOF and HOCM is extremely rare, and very few cases have been reported in the literature.[34567] Here, we report the case of a 2-month-old male infant who presented to us with central cyanosis and features of heart failure (HF) who was worked up and found to have TOF with HOCM.

CASE REPORT

We report the case of a 2-month-old male infant who presented to us with complaints of difficulty in feeding, sweating over the forehead during feeding, failure to thrive, and bluish discoloration of the mucous membranes and digits from the age of 20 days of life. He was born out of a nonconsanguineous marriage, first in birth order, by a full-term vaginal delivery, after an uneventful pregnancy from a 24-year-old mother. The child had a birth weight of 2.8 kg, cried immediately after birth, and had no perinatal complications. There was no family history of cardiac disease. Physical examination revealed a weight of 3.1 kg, mild central cyanosis with an oxygen saturation of 81% on room air, tachypnea, subcostal retraction, and hepatomegaly with no dysmorphic features or skeletal deformities. Auscultation revealed an ejection click in the second right intercostal space (ICS), a single S2, an S3 gallop, and a Grade 4/6 ejection systolic murmur at the third left ICS. Phonocardiogram at the third left ICS confirmed these findings [Figure 1a]. Twelve-lead surface electrocardiogram showed right-axis deviation with clockwise depolarization, peaked P waves in leads V1 and II, RV hypertrophy, and rS complexes in precordial leads indicative of reduced pulmonary blood flow and underfilled left ventricle [Figure 1b]. Chest X-ray showed situs solitus, levocardia, RV upturned apex with decreased pulmonary blood flow, left aortic arch, right atrial enlargement, and concave pulmonary bay [Figure 1c]. Echocardiography showed large malaligned perimembranous VSD with outlet extension, overriding of aorta, valvular and infundibular pulmonary stenosis with peak gradient 66 mmHg, RV hypertrophy, and asymmetric septal hypertrophy with interventricular septal thickness 12.6 mm (Z-score: 12.57) with dynamic LV outflow tract obstruction (LVOTO) with peak gradient 40 mmHg [Figure 2a-d and Videos 1-4]. A diagnosis of TOF with HOCM was considered. The infant was started on propranolol 2 mg/kg/day and furosemide 2 mg/kg/day in three divided doses and was advised admission for an emergency modified Blalock–Taussig shunt and further management. The patient relatives refused for admission at the index consultation and requested an admission in the coming week but were then lost to follow-up and could not be traced.

Figure 1

(a) Phonocardiogram at the third left intercostal space showing S1, ejection click (EC), crescendo-decrescendo ejection systolic murmur from S1 to S2, single S2, and the presence of S3. (b) Twelve-lead surface electrocardiogram showing right-axis deviation with clockwise depolarization, peaked P waves in V1 and II, right ventricular hypertrophy, and rS complexes in precordial leads. (c) Chest X-ray anteroposterior view showing situs solitus as indicated by the gastric bubble on the left, levocardia, right atrial and right ventricular enlargement with decreased pulmonary blood flow, concave pulmonary bay (arrow), and left aortic arch

Figure 2

(a) Transthoracic echocardiography in apical five-chamber view with continuous wave Doppler cursor placed in the left ventricular outflow tract in the subaortic area at the level of mitral leaflet tip showing a peak gradient of 40 mmHg. The a is obtained from Video 3 by placing the continuous wave Doppler cursor in the left ventricular outflow tract in the subaortic area at the level of mitral leaflet tip. (b) Transthoracic echocardiography in subcostal coronal sweep anterior view with continuous wave Doppler cursor placed at the level of the right ventricular outflow tract showing a peak gradient of 66 mmHg. The b is obtained from Video 4 by placing the continuous wave Doppler cursor at the right ventricular outflow tract. (c) Transthoracic echocardiography in parasternal long-axis view showing asymmetrical septal hypertrophy with septal thickness in diastole of 1.26 cm. (IVS = Interventricular septum, LA = Left atrium, LV = Left ventricle, RV = Right ventricle, and PW = Posterior wall). (d) Transthoracic echocardiography showing dimensions of the main pulmonary artery, right pulmonary artery, and left pulmonary arteries with Z-scores of the main pulmonary artery = −5.71, right pulmonary artery = −2.14, and left pulmonary artery = −1.55

DISCUSSION

The causes of HF in TOF include TOF with pulmonary atresia with large systemic arterial collaterals, accessory tricuspid valve tissue causing partial obstruction of VSD causing suprasystemic RV pressure, associated absent pulmonary valve, systemic hypertension, aortic stenosis or regurgitation, infective endocarditis of aortic valve, and hyperdynamic circulatory states such as anemia and thyrotoxicosis.[18] Thus, we propose that HOCM in association of TOF can be considered another factor responsible for HF in a patient of TOF by causing RV and LV pressure overload and resulting in early presentation with HF. HF results in S3 gallop which is normally not heard in uncomplicated TOF.[8] The interplay between the severity of RVOTO and LVOTO has an impact on the degree of cyanosis and HF. Increased RVOTO with less LVOTO causes more cyanosis while increased LVOTO and less RVOTO cause less cyanosis but higher likelihood of HF.

Echocardiography plays a pivotal role in the diagnosis. Asymmetric septal hypertrophy in parasternal long-axis view maybe the first clue to the presence of HOCM in a case of TOF. Careful Doppler interrogation of the LV outflow tract in all such cases can pick up the LVOTO, confirming the diagnosis of HOCM with TOF. Beta-blockers remain the first-line treatment in cases of TOF and also in cases of HOCM and hence beneficial in this anomaly of the combination of the two.

No consensus is available for the surgical treatment of this entity. Physiology of both the conditions should be taken into account while planning surgical repair. Increased pulmonary venous return after either aortopulmonary shunt or total correction of TOF in a patient with HOCM where the left ventricle has a small volume and increased LV end-diastolic pressure (LVEDP) may result in pulmonary edema.[3] Other surgical challenges are increase in the LVOTO after closure of VSD, failure to wean off from cardiopulmonary bypass, and increased pulmonary regurgitation and RV failure due to preexistent increased LVEDP after transannular patch repair.[3] Patients may later require myectomy and implantable cardioverter defibrillator. In spite of aggressive treatment, the mortality rate in this condition remains high.[3]

Further investigations to rule out storage or metabolic disorders and surgical outcome following modified Blalock–Tausig shunt and corrective surgery are not available as the patient was lost to follow-up. However, we would like to report this case in view of the rarity of the condition, important learning objectives, and the importance of images.

Declaration of patient consent

The authors certify that they have obtained all appropriate patient consent forms. In the form, the guardian has given consent for images and other clinical information to be reported in the journal. The guardian understands that name and initials will not be published and due efforts will be made to conceal identity, but anonymity cannot be guaranteed.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.