Winning Abstracts from the 2009 Medical Student Abstract Competition: Incidental Diagnosis of Patent Ductus Arteriosus in an Adult
Authors: First Author: Jay Parikh, MS III Second Author: Nripesh Pradhan, MD Third Author: Shobhana Chaudhari MD
Patent Ductus Arteriosus (PDA) is a congenital abnormality rarely seen in adults in the developed world. Normally, spontaneous closure of a PDA is achieved at birth, but in a smaller subset of patients closure may be delayed or absent. For such patients, the PDA is either symptomatic or asymptomatic. In patients who begin to develop left-sided congestive heart failure, correction of the shunt is of great urgency to prevent the development of irreversible pulmonary hypertension.
A 39 year-old migrant Mexican man with a history of diabetes mellitus was hospitalized for decreased urine output since eight days prior to admission. Examination revealed a Blood Pressure of 150/78 mmHg with a heart rate of 92 beats per minute, elevated jugular venous pressure, normal first heart sound with loud P2 component of second heart sound, grade 4/6 machinery murmur best heard in the left second intercostal space and mild pedal edema. Electrocardiogram showed right axis deviation and left ventricular hypertrophy. Chest X-Ray displayed cardiomegaly and features of pulmonary hypertension. Transthoracic echocardiogram (TTE) revealed a PDA between the descending aorta and main pulmonic artery, moderately decreased ejection fraction (35-45%), dilated left atrium and ventricle, moderate mitral and tricuspid regurgitation, small pericardial effusion, and moderate global hypokinesis of the left ventricle. The calculated Qp:Qs ratio from TTE was 2.2:1; his right ventricular systolic pressure of more than 60mmHg was suggestive of severe pulmonary hypertension. The patient also had mild renal dysfunction as a result of long standing, uncontrolled diabetes. His creatinine was 2.4 mg% and was considered to be a high risk candidate for contrast study. Nevertheless, considering the patient's Qp:Qs ratio and diabetic history, he was referred for cardiac catheterization before surgical closure of his PDA.
Studies have shown that in adult PDA, assessing the progression of pulmonary vascular resistance values, which most accurately reflect the progress of pulmonary hypertension, assume greater priority over direct measurement of pulmonary artery pressure. Generally, in patients with advanced pulmonary hypertension, reflected by a wood unit value greater than 6, surgical or interventional correction of a PDA could be performed but would not result in a desired reversal in pulmonary hypertension and may in fact, quicken its progression.
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