The Journal of Thoracic and Cardiovascular Surgery, Vol 106, 739-744, Copyright © 1993 by The American Association for Thoracic Surgery and The Western Thoracic Surgical Association
Pulmonary microthrombi. Caveat for successful modified Fontan operation
TM Olson, DJ Driscoll, WD Edwards, FJ Puga and GK Danielson
Section of Pediatric Cardiology, Mayo Clinic, Rochester, Minn. 55905.
We reviewed medical records from eight patients (4 to 29 years of age) with
a functional single ventricle and pulmonary microthrombosis as observed on
open lung biopsy specimens. Hemodynamic assessment before biopsy revealed
pulmonary hypertension (mean pulmonary artery pressure 19 to 53 mm Hg) in
the seven patients tested and severely increased pulmonary arteriolar
resistance (6 to 13 U.m2) in three of the five patients in whom these
measurements were performed. Pulmonary blood flow varied (< 4 L/min per
square meter in two patients and > 5 L/min per square meter in four
patients), and the pulmonary/systemic blood flow ratio was low or normal
(0.6 to 1.1) in five of six cases. Hemoglobin values were increased (16.4
to 22 gm/dl) in seven of eight patients. Lung biopsy specimens revealed
thrombotic obstructive lesions in 56% (range 28% to 96%) of muscular
pulmonary arteries. Coexistent medial hypertrophy was absent or mild in all
but one specimen, and none had features of plexogenic pulmonary
arteriopathy. Microscopic pulmonary thrombi accounted for unexpected
pulmonary hypertension, precluding the Fontan operation, in five patients
and unsuccessful Fontan operation in two. Clinically significant thrombi
should be considered in patients with severe polycythemia (hemoglobin value
> 20 gm/dl) and unobtainable or unreliable pulmonary blood flow or
pulmonary resistance determinations.
