Background

Pulmonary atresia with intact ventricular septum is a rare form of CHD with an incidence classically reported of less than 1 in 10,000 live births, recently reported with an incidence of 4.1–4.6 in 100,000 in a 2021 study in Sweden.^{1,Reference Manhem, Hanséus, Berggren and Ekman-Joelsson2}

It was first described by Hunter in 1783 and then revisited by Peacock in 1869. The right ventricular outflow tract is imperforated, which can be either membranous or represented by a longer segment of muscular atresia, characterised by heterogeneity in the right ventricle morphology, its inlet portion, its functional size, and its coronary anatomy. ^{Reference Underleider, Meliones, McMillan, Cooper and Jacobs3} Many of these patients, approximately 31–68% ^{Reference Giglia, Mandell, Connor, Mayer and Lock4} of the cases, have connections between the right ventricle and subepicardial coronary arteries; in some of these patients, this could be of vital importance and may be necessary to sustain adequate myocardial perfusion (right ventricular-dependent coronary circulation or RVDCC). This situation has been described in anywhere from 3 to 34% of patients presenting ventriculocoronary connections. ^{Reference Underleider, Meliones, McMillan, Cooper and Jacobs3}

In 1992, Giglia et al ^{Reference Giglia, Mandell, Connor, Mayer and Lock4} conducted a retrospective study in which they mentioned the hypothesis that the survival of these patients could also depend on the RVDCC; since at first, the surgical management for this cardiopathy had focused primarily on the size of the right ventricle and on the number of right ventricular parts. In their study, 26 of 82 patients with PA-IVS had ventriculocoronary connections. Three groups were made: Group 1: ventriculocoronary connections without stenosis. Group 2: ventriculocoronary connections with stenosis of one coronary artery and Group 3: ventriculocoronary connections with stenosis of two coronary arteries, all groups with different outcomes. This demonstrated that it is very important to correctly evaluate the anatomy and perfusion of the coronary arteries.

The traditional and only way at the moment to evaluate this is by angiography (right ventriculography and coronarography); however, we consider that this method is very subjective because it depends on the interpretation of each evaluator, sometimes incorrectly evaluated as described by Guleserian et al ^{Reference Guleserian, Armsby, Thiagarajan, del Nido and Mayer5} , who had two cases in which the angiography was misinterpreted preoperatively, leading to ischaemia and death.

In addition, there are different criteria taken by the different groups for the definition of RVDCC; one is the Boston group definition, and the other is the definition by the Houston group, who mention the definition as the presence of any coronary-cameral fistula with coronary obstruction, defined as severe stenosis, interruption, or atresia, proximal to the fistula and angiographic evidence of right ventricle perfusion of the myocardium through fistulous communication. ^{Reference Spigel, Qureshi and Morris6} These are some of the most accepted definitions; however, we found that each centre has some variations in their criteria and definitions, and some even take to notice the size of the fistula, considering the ones that are too large as RVDCC, overall, as mentioned by Wright et al: ^{Reference Wright, Knight, Thomas, Oster, St Louis and Kochilas7} difficult to evaluate and to some degree subjective.

There have been efforts to address this situation, as reported by Loomba et al, ^{Reference Loomba and Pelech8} who described an anterograde coronary perfusion scoring system that is predictive of the need for transplantation and mortality.

The most objective report is the temporary decompression reported by Iwai et al. in Japan; ^{Reference Iwai, Kishimoto and Kawata9} nevertheless, it implies a surgical procedure and cardiopulmonary bypass.

For these reasons, in the interventional cardiology department of the National Institute of Paediatrics of México, a percutaneous and transitory technique was designed with the purpose of evaluating coronary circulation in patients with pulmonary atresia with intact ventricular septum with ventriculocoronary connections in whom angiography could not determine if there was right ventricular-dependent coronary circulation.

Case presentation

A 25-day-old female was referred for cyanosis. At the physical examination, we found a continuous infraclavicular heart murmur and oxygen saturation of 70%. The chest X-ray showed a cardiothoracic ratio of 0.67 with decreased pulmonary vascularity (Fig. 1a). Electrocardiogram showed no sign of injury or ischaemia (Fig. 1b). Echocardiography: pulmonary atresia with intact ventricular septum with confluent pulmonary branches, a patent ductus arteriosus, and evidence of ventriculocoronary connections reported as probable right ventricular-dependent coronary circulation. Tricuspid valve annulus 9 mm (Z Score: –2.04). (Fig. 1c).

Figure 1. A: Chest X-ray: CTR of 0.67, decreased pulmonary vascularity. B: Electrocardiogram: no sign of injury or ischaemia. C: Echocardiogram: Apical-4-Chamber: Important RV hypertrophy with small cavity.

Cardiac catheterisation: RV pressure was 170/7-15 mmHg, left ventricle 118/0-12. Right ventriculography showed a small cavity, tripartite, with a small inlet tract but with a normal tricuspid valve annulus. The infundibulum was patent and narrow, the pulmonary valve had membranous atresia, and the pulmonary annulus was 4.5 mm (Z score: –3.08). The ventricular cavity was very hypertrophic with a moderate-sized ventriculocoronary connections with significant systolic retrograde flow in the anterior descendant, even so that we could see the sinus of Valsalva (Fig. 2). There was also a ductus and confluent normal-sized pulmonary branches.

Figure 2. Right ventriculography A: Postero-anterior projection. B: Left lateral (LL) projection. C: Right anterior oblique (RAO) projection. We can see; RV tripartite, small trabecular portion, tricuspid valve annulus, VCCs and pulmonary atresia.

The selective coronarography was not totally conclusive; the anterior descendant had light to moderate stenosis in its middle third and appeared to be thinner from this point (Fig. 3). In addition, there was an absence of contrast in systole, which indicated to-fro flow, and the circumflex artery (CX) showed no alterations (Fig. 4). The right coronary artery and posterior descendant showed anterograde flow.

Figure 3. Left coronarography in telediastole. The AD with stenosis in its middle third, from this point we see a caliber decrease which is more evident in A. CX without alterations. A): 4-chamber (4-C) projection, B): LL projection, C): RAO projection.

Figure 4. Same left coronarography in telesystole: We can see; absence of contrast in the AD which indicates a to-fro flow. CX without alterations. A): 4-C projection. B): LL projection, C): RAO projection.

To evaluate coronary dependency, we decided to perform transtricuspid flow occlusion with a 13.5 mm Z-5 atrial septostomy balloon catheter (Numed® 45 s Street West Cornwall, Ontario K6J1G3 Canada.) placing it in the inlet tract of the right ventricle, and we re-evaluated the coronary flow. The AD flow normalised, and there was no retrograde systolic flow (Figs. 5 and 6). The occlusion was maintained for 10 minutes, and there was no evidence of changes in the electrocardiogram or haemodynamic decompensation. This was considered confirmation of a non-RVDCC, so we decided, in spite of the size of the cavity, to try to decompress the right ventricle and open the pulmonary valve by radiofrequency, but the efforts were unsuccessful; therefore, we performed an atrioseptostomy, and a non-medicated coronary stent was placed in the ductus. Twenty days later, she underwent surgery for right ventricular decompression and outflow tract enlargement with a transannular patch, Blalock–Taussig–Thomas fistula placement with resection of the stent with duct ligation, and closure of the atrial defect with a fenestrated patch.

Figure 5. Left coronarography in telediastole with the transient occlusion of the transtricuspid flow. We can see the AD more clearly, and we can even see its diagonal branches better than before. A): LL projection, B): 4-C projection.

Figure 6. Same left coronarography. A) Protosystole LL Projection. B) Telesystole LL Projection. C) Telesystole 4-C Projection: we can see that the flow is totally anterograde during the occlusion with balloon and there is no evidence of to-fro flow.

After surgery, she stayed in the cardiovascular ICU for 19 days with ventilatory assistance for 16 days. Echocardiogram post-surgery showed adequate flow through the right ventricle outflow tract, no evidence of residual stenosis, free pulmonary insufficiency, and preserved systolic function, without tricuspid regurgitation. After 2 months, the right ventricular cavity showed some enlargement. (Fig. 7)

Figure 7. A. Parasternal short axis view (PSAX): Outflow tract with adequate flow. B: Pulsed Doppler; no stenotic gradient. C: PSAX: systole with anterograde flow. D: PSAX: diastole with free pulmonary insufficiency. E: Apical 4-Chamber: RV cavity larger than the beginning. F: PSAX at ventricular level; larger right ventricular cavity.