Vol.48 - Número 4, Octubre/Diciembre 2019 Imprimir sólo la columna central

Abnormal parahisian accessory pathway radiofrequency ablation in a patient with left ventricular noncompaction


Instituto Cardiovascular de Rosario (ICR).
(2000) Rosario, Santa Fé, Argentina.

Recibido 21-MAR-2019 – ACEPTADO después de revisión el 17-ABRIL-2019.
There are no conflicts of interest to disclose.



Left ventricular noncompaction (LVNC) is a rare primary genetic cardiomyopathy, due to the arrest of normal embryogenesis of the endocardium and myocardium (between the 5th and 8th weeks of gestation), developing multiple prominent hypertrabeculations with deep intertrabecular recesses reported primarily in the left ventricular chamber. The diagnosis is made more frequently between 20-40 years. Patients may remain asymptomatic or present a variable clinical expression. This anomaly is frequently associated with heart failure, arrhythmias and thromboembolic complications. The electrocardiogram does not present a specific diagnostic pattern, and electrocardiographic changes are frequent. Case reports have been reported associated with Wolff-Parkinson-White syndrome (WPW). We report a 27-year-old patient with noncompaction cardiomyopathy associated with WPW syndrome, with symptomatic episodes of regular paroxysmal palpitations, with an accessory pathway located in the parahisian region, successfully ablated with RF energy.
Key words:
Left ventricular noncompaction. Radiofrequency. Wolff-Parkinson-White. Arrhythmias Accessory pathway.


Noncompacted myocardium (NCM) is a rare primary genetic cardiomyopathy, due to arrest of normal embryogenesis of the endocardium and the myocardium, the main characteristic of which is the development of multiple prominent hypertrabeculations with deep intertrabecular recesses, manly communicated with the left ventricular chamber, with no other congenital cardiac malformations, which causes a “sea sponge” appearance [1-2].

Isolated NCM was described first by Engberding and Bender in 1984 due to its typical echocardiographic appearance [3]. Nevertheless, in 2006 this entity was acknowledged and included as primary cardiomyopathy of genetic origin [4]. This disorder was described as “persistence of isolated myocardial sinusoids” due to the absence of their normal regression during embryogenesis [3].

The age of presentation is highly variable, from childhood until adulthood; with diagnosis being more usual between the ages of 20-40 years, with a greater prevalence in men (2:1 ratio). Patients may remain asymptomatic for a long period of time or present early clinical expression. This anomaly is frequently associated with heart failure, arrhythmias and thromboembolic complications [5-7].

Electrocardiograms do not present a specific diagnostic pattern, and ECG alterations are frequent. Conduction disorders have been reported, such as left bundle branch block or complete heart block, as well as repetitive atrial arrhythmias such as paroxysmal supraventricular tachycardia or atrial fibrillation in 4 to 26% of cases. Ventricular arrhythmias present a very variable incidence [8-9].

The basic morphogenetic anomaly of NCM could be due to arrest in the normal process of compaction of myocardial fibers during embryogenesis (between the 5th and 8th weeks of pregnancy), associated to the cessation of the normal development of the valve fibrous ring [10]. Cases of isolated NCM associated to Wolff-Parkinson-White (WPW) syndrome have been reported [11-12]. The electrocardiographic findings in NCM related to WPW syndrome would be due to the valve fibrous ring defects during cardiac embryogenesis and would explain the subendocardial position of atrioventricular accessory pathways located around the tricuspid valve [12].


Male, 27-year-old, sportsman, with no cardiovascular risk factors or history of cardiovascular disease. Dock worker, he drove large cranes in his work environment. The patient had presented at age 8, an episode of regular and rapid paroxysmal palpitations of sudden onset and ending, of approximately one hour of duration, associated to presyncope, not requiring pharmacological treatment or hospitalization. Subsequently, he presented paroxysmal episodes of regular palpitations of less duration, which caused his consultation. In the physical examination, normal-sounding cardiac sounds and mitral systolic murmur with 1-2/6 intensity were auscultated. Electrocardiogram was performed, on which manifest ventricular preexcitation pattern was verified. (Figure 1).

Figure 1. Basal, 12-lead ECG. Sinus rhythm with manifest ventricular preexcitation (anomalous pathway with anteroseptal location).


The patient was assessed by color Doppler echocardiogram, reporting left ventricle of 53/41 mm, septum and posterior wall 13/10 mm, asynchronous septum with hypokinesis in the rest of the segments, LV systolic function with moderate deterioration (EF 43%), increase in LV lateral wall trabeculations; non-myxomatous prolapse of the mitral anterior leaflet with mitral insufficiency in a mild degree. In 24 h Holter (3 channels), there was evidence of sinus rhythm with ventricular preexcitation pattern, manifesting permanently. Ergometer was conducted, which was submaximal and persistent ventricular preexcitation pattern was verified throughout the test (stage V, 14.8 Mets). Also, cardiac magnetic resonance imaging (MRI) was performed with gadolinium, showing left ventricle with preserved size, EF 41%, mild septal asynchrony with hypokinesis in the rest of the myocardial segments. Increase in left ventricular trabeculations is observed, compromising the medial and apical segments of the lateral wall, apex and septo-apical wall, with 2:6 ratio of noncompacted/compacted areas; mild mitral anterior leaflet prolapse with negligible mitral insufficiency, mild left ventricular dilatation and absence of post-gadolinium fibrosis (Figure 2).

Figure 2. Cardiac MRI with gadolinium.


Due to the clinical symptoms of the patient, endocavitary electrophysiology study was made, showing short HV interval (-5 ms), anterograde effective refractory period of accessory pathway (APERP) <250 ms (short), and subsequently, during programmed atrial stimulation, orthodromic atrioventricular reentrant tachycardia was induced, with less VA interval in the right anteroseptal region, interrupted by atrial overdrive. Later, a detailed mapping was made on the accessory pathway on sinus rhythm and during orthodromic AV reentrant tachycardia, verifying more precocity in the parahisian anteroseptal region. Radiofrequency ablation was applied, with temperature control (EPT catheter, 4 mm tip), of the parahisian anomalous pathway during sinus rhythm and atrial overdrive, achieving the abolition of conduction through it, with no modification of atrioventricular conduction through the AV node. Controls were made after the application of radiofrequency energy, verifying bidirectional block of the anomalous pathway with preserved AV conduction and no induction of arrhythmias (Figures 3, 4, 5 and 6).

The patient is asymptomatic after ablation, with no recurrences of the previously described tachycardia.

Figure 3. Electrocardiographic leads DI, DII, DIII, V1 and V6 and endocavitary recordings of the coronary sinus (proximal to distal CS) and ablation catheter (proximal and distal ABL). Induction of orthodromic atrioventricular reentrant tachycardia during programmed atrial stimulation (S1-S1 500 ms; S1-S2 280 ms) (50 mm/sec).

Figure 4. Electrocardiographic leads DI, DII, DIII, V1 and V6, and endocavitary recordings of the coronary sinus (proximal to distal CS) and ablation catheter (proximal and distal ABL). During the application of radiofrequency energy, in the place of most precocity, the disappearance of conduction was verified through the parahisian anomalous pathway with preserved AV conduction (3rd beat). The presence of His bundle potential can be seen (arrow) in the ablation catheter during the application of RF energy when conduction disappears through the accessory pathway (50 mm/sec).

Figure 5. Fluoroscopic image of the site of efficient ablation (right and left anterior oblique projection). It is possible to observe the decapolar catheter in the coronary sinus and EPT quadripolar catheter ablation, of 4 mm tip, on the site of most precocity: parahisian region.

Figure 6. Post-ablation ECG: sinus rhythm with no ventricular preexcitation.



Noncompacted cardiomyopathy is a rare genetic cardiomyopathy, the main characteristic of which is the presence of multiple prominent trabeculations that protrude over the left ventricular endocardium, with deep intertrabecular spaces or recesses, mainly communicated with the left ventricular chamber.

In literature, the most commonly used name is noncompaction of the left ventricle (NCLV), as it mainly affects this chamber; and on the other hand, there is a difficulty to define right ventricular compromise due to its natural trabeculated process. Approximately between the 5th and 8th weeks of pregnancy, the compaction process occurs, in a direction from the epicardium to the endocardium and the base of the cardiac apex [13].

The prevalence of NCLV in the general population is unknown, being a very rare clinical entity, with an incidence of 0.05%/year [14-15]. According to its presentation two groups are differentiated: isolated NCLV, when there is no other relevant structural alteration, and non-isolated NCLV, when associated to other congenital heart diseases. Mortality 6 years after the diagnosis is high; half of cases due to sudden cardiac death [10].

Clinical manifestations are very variable; patients could be asymptomatic or present symptoms of heart failure, arrhythmias or thromboembolic complications [15-16]. Most of the patients present symptoms of heart failure, with the origin of it being microcirculatory dysfunction and consequently, subendocardial hypoperfusion. Abnormal ECG findings are frequent, but no alteration is specific to NCM. The anomalies described are basically branch blocks and arrhythmias, such as atrial fibrillation and paroxysmal supraventricular tachycardia. On the other hand, the association of NCM with WPW syndrome has been reported [11-12].

The diagnosis is frequently made by echocardiography. However, other imaging modalities as for example MRI, computed tomography and left ventriculography may diagnose or confirm the clinical suspicion [4].

The main differential diagnoses of NCM include: dilated cardiomyopathy, hypertensive heart disease, apical hypertrophic cardiomyopathy, infiltrative cardiomyopathy, and endomyocardial fibrosis. The main emphasis in the therapy of patients with NCM should be treatment of heart failure and arrhythmias, as well as prevention of thromboembolic complications, following the recommendations by clinical guidelines for patients with heart failure by other etiologies.

Transcatheter ablation with radiofrequency (RF) energy is the treatment of choice in symptomatic patients carriers of anomalous pathways. Radiofrequency energy is the most commonly used source for the treatment of cardiac arrhythmias with optimal results [17-19]. However, in particular situations, there may be limitations as in the case of antero- and medioseptal accessory pathways ablation, or other septal arrhythmogenic substrates, due to the possibility of causing complete AV block requiring permanent pacemaker implant. Anomalous pathways (AP) with parahisian location are rare, and are located anteriorly and medially, near the His bundle. The most important limitations during the ablation of these pathways is their closeness to the His bundle and catheter stability [20-22].

Although radiofrequency ablation of the antero and medioseptal AP is generally successful and safe [20-22], there may be complications such as normal conduction system impairment [23-25]. A “minimally aggressive” method has been proposed to approach these pathways, based on an accurate mapping, a stable position of the catheter and low power and temperature parameters during radiofrequency energy applications [26]. Although this method is safe, its main disadvantage is the high rate of recurrences in some centers, near 20% [27]. Also, there have been reports on the usefulness of atrial overdrive before the appearance of active rhythm of the union during RF application in patients with parahisian AP as a technique to prevent the appearance of atrioventricular block [28].

Transcatheter cryoablation would offer some comparative advantages in relation to radiofrequency ablation, such as the chance to test each application before the formation of a permanent injury, the chance to interrupt it before the presence of incipient signs of normal conduction system damage. The effect of cryoadhesion allows for the applications to be made before sudden changes in heart rhythm, which also enables pacing during application to test clinical tachycardia inducibility. On the other hand, applications are painless, which is very useful in children [29-31]. A limitation could be a higher rate of recurrence in comparison to RF energy.

On the other hand, other approaches have been reported for the ablation of parahisian anomalous pathways, through the superior vena cava (jugular or subclavian) or transaortic approach through the noncoronary cusp or right coronary cusp [32-34]; however, most of parahisian AP could be ablated safely and efficiently through the inferior vena cava [35].


A clinical case is presented, of a patient carrier of noncompacted myocardium associated to WPW syndrome, symptomatic by regular paroxysmal palpitations associated to presyncope, in whom successful transcatheter ablation procedure of parahisian anomalous pathway was performed, through femoral approach and using radiofrequency energy with temperature control, not observing complications associated to the procedure or recurrences during follow-up.

Currently, the ablation of septal arrhythmogenic substrates could be made with cryoenergy or radiofrequency energy with good results and a low rate of complications in centers with proper complexity and operators with expertise.



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Publication: December 2019


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