Bonus online case: Partial anomalous pulmonary venous return

A patient with worsening exertional dyspnea, lower extremity edema, and orthopnea.


The patient

A 58-year-old woman with a history of hypertension, diabetes, smoking, and asthma presented with exertional dyspnea, lower extremity edema, decreased exercise tolerance, and three-pillow orthopnea. These symptoms had been progressively worsening for the past three years. Vital signs included a blood pressure of 164/67 mm Hg, a heart rate of 100 beats/min, a respiratory rate of 24 breaths/min, an oxygen saturation on room air of 98%, and no rales. The examination was remarkable for jugular venous distention and mild bilateral pitting edema of the lower extremities; there was no precordial heave, a normal S2 was present, and there was no S3 gallop.

Figure 1 Cardiac catheterization image showing left pulmonary vein long arrow draining into coronary sinus short arrow
Figure 1. Cardiac catheterization image showing left pulmonary vein (long arrow) draining into coronary sinus (short arrow).

Transthoracic echocardiogram showed a mildly dilated right ventricle with pulmonary hypertension. Complete pulmonary function testing, a chest X-ray, and electrocardiogram were all normal. A chest CT showed an anomalous left pulmonary vein draining into the right-sided circulation (e.g., a left-to-right shunt) with right atrial dilatation. Stress echocardiography was negative for ischemia. Left- and right-heart cardiac catheterization showed the left upper pulmonary vein draining into the underside of the innominate vein with coronary sinus dilatation (Figure) and a pulmonary artery shunt fraction (Qp:Qs) of 2:1. Surgical repair of the abnormal vein was successful, after which shortness of breath improved and exertional dyspnea resolved.

The diagnosis

Partial anomalous pulmonary venous return (PAPVR) is a congenital condition in which some of the pulmonary veins drain into the right atrium or one of its venous tributaries, rather than the left atrium. In adults, rates of PAPVR are estimated at 0.1% to 0.2%, and most cases are found on autopsy. Most anomalous pulmonary veins arise from the right lung, with only 3% to 8% reported to originate from the left lung. PAPVR is often associated with other cardiac defects, including atrial septal defects, and has been reported in certain congenital syndromes, such as Turner's syndrome (monosomy X). The left-to-right shunting of blood that results from the anomalous venous return leads over time to remodeling of pulmonary vasculature, and ultimately pulmonary hypertension and right-sided heart failure. Depending on the size of the shunt, patients can remain asymptomatic or can present at any point from infancy to adulthood.

A cardiac MRI can identify defects and better define structural abnormalities. The gold standard for quantifying shunt volume is cardiac catheterization. This allows for the calculation of “shunt fraction,” or Qp:Qs, which estimates the ratio of blood flow to the pulmonary and systemic circulations. In adult patients, presence of symptoms, clinical evidence of right-sided volume overload, and measured Qp:Qs of 1.5:1 or more are all indications to consider surgical repair. In pediatric patients, PAPVR is usually corrected surgically when the defect is large enough to create a significant shunt. Surgery is generally effective for correction of shunting; complications include arrhythmia and residual shunt. In patients with severe pulmonary hypertension at the time of presentation, repair is unlikely to change disease course, and heart-lung transplantation is the only curative option.

Pearls

  • PAPVR is a rare cause of pulmonary hypertension.
  • In adult patients, symptoms, clinical evidence of right-sided volume overload, and measured shunt fraction of 1.5:1 or more are all indications to consider surgical repair.

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