A Case of Extrinsic Compression of the Left Main Coronary Artery Secondary to Pulmonary Artery Dilatation
A 53-yr-old woman was admitted because of aggravated dyspnea over the previous month on December 13, 2011. The patient had a history of pulmonary tuberculosis and four years before admission, was diagnosed with asthma and pulmonary hypertension, and subsequently was managed for asthma and aggravated right heart failure. However, despite treatment, she complained of markedly limited exercise tolerance (New York Heart Association functional class III), paroxysmal nocturnal dyspnea, orthopnea, and occasional angina-like chest pain.\nOn admission, she was afebrile, with a blood pressure 100/70 mmHg, a pulse rate of 62 beats per minutes, and a respiratory rate of 20 breaths per minutes. Physical examination revealed a cachectic status (body weight 38 kg). In addition, neck veins were engorged, and soft abdominal distension, and bibasilar fine crackles on both lungs were appreciated. There were no signs of cyanosis or clubbing. Resting ECG showed a normal sinus rhythm, P pulmonale, and a right ventricular strain pattern with large biphasic QRS complexes in V2-V6. Chest radiography revealed an enlarged cardiac silhouette involving right chambers, and dilatation of the main pulmonary trunk, and right main pulmonary artery (). Computed tomography of the thorax confirmed these findings and demonstrated LMCA narrowing due to the compressive effect of the dilated pulmonary artery (). In addition, chronic thromboembolism was found in the right lower pulmonary artery. Transthoracic echocardiography (TTE) demonstrated a preserved left ventricular ejection fraction (LVEF) of 52%, an enlarged right atrium and right ventricle, a D-shaped left ventricle, and moderate pulmonary and tricuspid regurgitation, which corresponded to a right ventricular systolic pressure of 70 mmHg. TTE also shows a markedly dilated pulmonary artery trunk immediately adjacent to the take-off the LMCA (). A myocardial perfusion scan with Technetium-99m sestamibi revealed reversible perfusion defects in the apex, anterior wall, and septum. Coronary angiography of the right coronary artery showed minimal stenosis with grade 2 collaterals to the left circumflex artery and an arteriovenous fistula connecting with the pulmonary artery (). Left coronary angiography demonstrated hypoplasia of the left coronary artery; only the diagonal branch was observed and not the left anterior descending (LAD) or left circumflex coronary artery (LCX). This study also revealed narrowing of the LMCA at its take-off from the aorta (). The patient underwent ECG-gated, 128-slice multidetector computed tomography (MDCT) coronary angiography for further evaluation of stenosis of the LMCA, and extrinsic compression of the LMCA by the dilated pulmonary arterial trunk was documented (). Stenosis of the LMCA was treated by dilation and stenting with the intention of providing a metallic scaffold to resist the extrinsic compression. Briefly, a 0.014-inch guidewire (Run-through, Terumo, Japan) was passed through a 7Fr JL 4 guiding catheter with side hole and positioned in the ostial LMCA. Predilatation was performed using a 2.5 × 15 mm sized balloon (Ryujin plus, Terumo, Japan) in LMCA. After ballooning, the LAD and LCX were observed with LMCA dissection (). The LMCA was then stented with a 32 mm long stent to a diameter of 2.75 mm (Promus Element, Boston Scientific, USA). Post-percutaneous coronary intervention showed no residual stenosis of the LMCA (). Dual antiplatelet therapy, anticoagulation for chronic thromboembolism, and decongestive therapy for heart failure and optimal control of asthma were continued. At her 1-yr follow-up visit, coronary angiography and computed tomography with contrast showed a widely patent stent in the LMCA in the proximity of the dilated main pulmonary artery (). Even though there were no observable interval change of LVEF, chamber size and right ventricular systolic function by TTE, she reported improvement for in her functional capacity, chest pain and quality of life.