Effective alcohol septal ablation for left ventricular outflow tract obstruction in a patient with isolated dextrocardia

Abstract

Isolated dextrocardia is a congenital anomaly characterised by the normal position of the thoracic and abdominal viscera with a right cardiac apex. Left ventricular outflow tract obstruction (LVOTO) is a common structural manifestation of hypertrophic cardiomyopathy (HCM). A 65-year-old woman had worsening chest discomfort and dyspnoea on exertion. Chest CT angiography identified the isolated dextrocardia and HCM. Colour Doppler echocardiography showed mosaic flow in the LV outflow, indicating LVOTO. We performed alcohol septal ablation (ASA) under intracardiac echocardiography (ICE)-guided selective myocardial contrasting. This procedure improved provoked intra-LV pressure gradient by Valsalva manoeuvre and nitroglycerin injection from 136 to 50 mm Hg and her symptoms. The unique combination of isolated dextrocardia and left ventricular hypertrophy could have been involved in the formation of latent LVOTO. Even with the anomaly, contrast ICE made it possible to clarify the target septal left ventricular wall of ASA, and we could perform ASA safely.

Background

Isolated dextrocardia of the heart is an uncommon congenital anomaly characterised by normal position of the thoracic and abdominal viscera with a right cardiac apex. Isolated dextrocardia is sometimes associated with additional cardiac malformations.^{1 2}

Hypertrophic cardiomyopathy (HCM) is mainly characterised by asymmetric left ventricular (LV) hypertrophy in the absence of other cardiac or systemic diseases that may cause cardiac hypertrophy. Symptoms and clinical courses of HCM vary, regardless of type and severity. Although many patients stay asymptomatic and experience no serious cardiac events during their lives, some suddenly die, or experience refractory heart failure, repetitive syncope and/or severe angina.^3–5 These various clinical presentations are closely associated with narrowing LV capacity, intra-LV obstruction, severe tissue degradation, extensive myocardial fibrosis and diastolic dysfunction. Alcohol septal ablation (ASA) has been performed to treat hypertrophic obstructive cardiomyopathy (HOCM) when symptoms cannot be treated effectively even after optimisation of medical treatment.^6–8

Since childhood, the patient reported here had isolated dextrocardia. She presented with dyspnoea on exertion with a new murmur that proved to be due to the unique combination of isolated dextrocardia and LV hypertrophy, indicating latent left ventricular outflow tract obstruction (LVOTO).

We performed ASA under intracardiac echocardiography (ICE)-guided selective myocardial contrasting. This procedure improved provoked intra-LV pressure gradient by Valsalva manoeuvre and nitroglycerin injection from 136 to 50 mm Hg and her symptoms. The unique combination of isolated dextrocardia and LV hypertrophy could have been involved in the formation of latent LVOTO. Even with the anomaly, contrast ICE made it possible to clarify the target vessels and septal LV wall of ASA, and we could perform ASA safely.

Case presentation

A 65-year-old woman was admitted because of chest pain 20 years prior. She had been diagnosed with solitary dextrocardia without additional cardiac malformations and HOCM by cardiac echocardiography and catheterisation. She had no history of sudden death in her family, and her genetic background of HCM was unclear; however, it was a familiar form of HOCM such as asymmetrical septal hypertrophy. She had heart failure of New York Heart Association (NYHA) functional classification II and an intra-LV pressure gradient of 80 mm Hg. Administration of a β-blocker (bisoprolol, 5 mg) and a class Ia drug (disopyramide, 150 mg) improved her symptoms. Disopyramide induced liver dysfunction; therefore, cibenzoline (100 mg) was substituted.

She experienced syncope due to sick sinus syndrome, and a dual chamber pacemaker was implanted 5 years prior to admission. However, she again experienced syncope due to ventricular tachycardia. An implantable cardioverter–defibrillator (ICD) was implanted 3 years prior to admission (figure 1). Her pacemaker and ICD did not reduce her LVOTO; however, her symptoms were well controlled by medication. Her chest discomfort and dyspnoea on exertion gradually worsened with NYHA functional class II with moderate limitation (class IIm). Her echocardiography showed that her ejection fraction was 58% using the Simpson method and left ventricular posterior wall thickness and interventricular septum thickness were 9 mm and 24 mm, respectively. Her Doppler echocardiography showed mosaic blood flow in the left ventricular outflow tract (LVOT) and her intra-LV pressure gradient (LVPG) was 18 mm Hg at rest and was 60 mm Hg using the Valsalva manoeuvre (figure 2). We determined that her LVOTO was formed by the hypertrophy of the basal anteroseptal wall.

Figure 1.

(A) Chest X-ray images demonstrating cardiomegaly (CTR: Cardio-Thoracic Ratio 68.7%), postimplantable cardioverter–defibrillator implanted state and dextrocardia. (B) ECG demonstrating negative P in II, III aVF, negative QRS in I aVL and poor R progression in V1–V6.

Figure 2.

(A) Transthoracic echocardiography demonstrating an extremely hypertrophied anteroseptal wall (↑) with mosaic colour Doppler flow in the LVOT. Each size is represented as follows: left ventricular internal dimension in diastole: 45 mm, left ventricular internal dimension in systole: 35 mm, left ventricular posterior wall thickness: 9 mm, interventricular septum thickness: 24 mm, left atrial dimension: 34 mm. (B) The colour Doppler of transthoracic echocardiography demonstrating moderate mitral valve regurgitation. (C) The Doppler of transthoracic echocardiography demonstrating the patient’s intra-LV pressure gradient was 18 mm Hg at rest and 60 mm Hg using the Valsalva manoeuvre. LVOT, left ventricular outflow tract.

Cardiac CT showed that the orifices of the coronary arteries were anatomically normal; however, the LV cavity was rotated clockwise, and the apex was located on the right anterior side of the chest (figure 3). Coronary angiography, left ventriculography, right-sided catheterisation and pressure studies were performed. Pressure gradient (PG) was calculated as the peak-to-peak difference of pressures between the ascending aorta and LV apex using a retrograde approach. Her intra-LVPG at rest was 10 mm Hg; however, a provocation test revealed that PG was 54 mm Hg using the Valsalva manoeuvre, 64 mm Hg using intravenous nitroglycerin (IV-NTG) and 136 mm Hg using both Valsalva manoeuvre and IV-NTG.⁸ We determined that her current drug-refractory symptoms were closely associated with LVOTO, an indication of septal reduction therapy.

Figure 3.

(A) Enhanced CT demonstrating the right heart in red and the left heart in blue. The heart showed clockwise rotation, and the apex was located on the right anterior side of the chest. (B) Three-dimensional fusion image of coronary CT angiography and 99mTc single-photon emission CT demonstrating that the orifices of the coronary arteries were anatomically normal. LV, left ventricle; RV, right ventricle.

She rejected myectomy as septal reduction therapy; therefore, we performed ASA by the transfemoral approach using a 7-Fr percutaneous transluminal coronary angioplasty (PTCA) guiding catheter and a small over-the-wire PTCA balloon. Selective coronary angiography and myocardial contrast echocardiography were performed to identify target septal arteries. Because of the anomaly of solitary dextrocardia, satisfactory images for selective myocardial contrast could not be obtained using transthoracic echocardiography (TTE). ICE provided a good long-axis LV view, identifying the appropriate enhancement of the anterobasal hypertrophic septal segment constituting LVOTO by contrasting from the first major septal branch (figure 4A). Two millilitres of alcohol were slowly injected (0.3 mL/min) through the lumen of the over-the-wire PTCA balloon to this first septal branch. Simultaneous coronary angiography and left ventriculography of pre-ASA and coronary angiography of post-ASA showed her first septal branch was completely ablated (figure 4B,C). LVPG at rest was improved from 10 mm Hg to 4 mm Hg; with the provocation by Valsalva manoeuvre, it improved from 54 mm Hg to 6 mm Hg; using IV-NTG, it improved from 64 mm Hg to 28 mm Hg; and using both Valsalva manoeuvre and IV-NTG, it improved from 136 mm Hg to 50 mm Hg (figure 5A).

Figure 4.

(A) Intracardiac contrast echocardiography demonstrating the anterobasal hypertrophic septal wall was well dyed, and the first septal branch was the best target branch. (B) Simultaneous coronary angiography and left ventriculography of pre-ASA demonstrating the target septal branch (yellow arrow). (C) Angiography demonstrating alcohol was injected to the first septal branch, and the first septal branch was completely ablated. ASA, alcohol septal ablation; LV, left ventricle; RV, right ventricle; Ao, Aorta.

Figure 5.

(A) Cardiac catheterisation demonstrating that the intra-LV pressure gradient at rest of pre and post ASA was improved from 10 mm Hg to 4 mm Hg, from 54 mm Hg to 6 mm Hg in the provocation by the Valsalva manoeuvre, from 64 mm Hg to 28 mm Hg by the IV-NTG and from 136 mm Hg to 50 mm Hg by both the Valsalva manoeuvre and IV-NTG. (B) Transthoracic echocardiography demonstrating that decreased from 60 mm Hg to 18 mm Hg using Valsalva manoeuvre before and 1 year after ASA. ASA, alcohol septal ablation; IV-NTG, intravenous nitroglycerin.

Her brain natriuretic peptide level decreased from 356.1 pg/mL to 253.4 pg/mL. Her symptoms were improved, and NYHA IIm of heart failure got NYHA I. Her LVPG by Doppler of transthoracic echocardiography decreased from 18 mm Hg to 9 mm Hg at rest and from 60 mm Hg to 18 mm Hg using Valsalva manoeuvre 1 year after ASA (figure 5B).

Outcome and follow-up

Age: Event

45 years old: Diagnosed with isolated dextrocardia and HOCM. Medication therapy was started.

60 years old: She developed syncope due to sick sinus syndrome and a dual-chamber pacemaker was implanted.

62 years old: She developed syncope again due to ventricular tachycardia and an implantable cardioverter–defibrillator (ICD) was implanted.

64 years old: Her chest discomfort and dyspnoea on exertion gradually worsened with NYHA functional class II with moderate limitation (class IIm) and her colour Doppler echocardiography showed mosaic blood flow in the LVOT.

Procedure (day 0): Alcohol septal ablation guided by contrast ICE was performed.

Day 7: She had a good clinical course and was discharged.

One year after the procedure (follow-up in cardiologist office): the patient felt well and had good clinical course.

Discussion

LVOTO due to congenital heart disease is often accompanied by large vascular abnormalities and is prone to occur in patients with situs solitus.^{9 10}

In the present case, the patient had no vascular abnormalities or cardiac abnormalities other than HCM. Although it is possible that sustained pressure overload in the squeezing LV cavity may cause LV hypertrophy, we believe that this patient had primary HCM independent of dextrocardia because (1) unlike the pressure overload-induced hypertrophy that is usually concentric, this patient’s myocardial hypertrophy was particularly prominent in the basal anteroseptal wall perceived as ASH, and (2) the incidence of coexistence of dextrocardia and LV hypertrophy has been reported to be rare.1 2 11 12 Of course, the sustained pressure overload might have played some role in the exacerbating HOCM. The unique combination of isolated dextrocardia and LV hypertrophy could have been involved in the formation of her latent LVOTO provoked by Valsalva manoeuvre and/or IV-NTG.

Contrast injection is performed (1) to ensure that the balloon is correctly positioned in the selected septal branch; (2) to rule out the presence of collateral flow from the septal branch towards another branch of the left or right coronary system via numerous septal connections and (3) to confirm that the selected septal branch supplies the septal area obstructing the LVOT.

The previous study reported that ICE could not visualise myocardial contrast well and therefore could not be used to guide ASA in the normal anatomy.¹³ In this case, the anomaly of isolated dextrocardia made it difficult to evaluate target septal branches using contrast TTE. Contrast ICE made it possible to clarify the target septal LV wall and vessels of ASA; therefore, we could perform ASA safely. ASA guided by contrast ICE was efficient and relieved LVOTO and her symptoms.

Learning points.

• We should consider the unique combination of isolated dextrocardia and left ventricular hypertrophy might cause left ventricular outflow tract obstruction (LVOTO).

• Alcohol septal ablation was efficient for treating LVOTO caused by the combination of hypertrophy of the basal anteroseptal wall and the anomalous position of the apex.

• Contrast intracardia echocardiography was useful in a patient in whom it was difficult to perform transthoracic echocardiography because of isolated dextrocardia.