Obstructive Lesions

Obstructive Lesions

Pulmonic Stenosis

Pulmonary valve stenosis obstructs right ventricu-lar outflow and causes concentric right ventricular hypertrophy. Severe obstruction presents in the neonatal period, whereas lesser degrees of obstruc-tion may go undetected until adulthood. The valve is usually deformed and is either bicuspid or tricus-pid. Valve leaflets are often partially fused and dis-play systolic doming on echocardiography. The right ventricle undergoes hypertrophy, and poststenotic dilatation of the pulmonary artery is often present. Symptoms are those of right ventricular heart fail-ure. Symptomatic patients readily develop fatigue, dyspnea, and peripheral cyanosis with exertion as a result of the limited pulmonary blood flow and increased oxygen extraction by tissues. With severe stenosis, the pulmonic valve gradient exceeds 60–80

Hg, depending on the age of the patient. Right-to-left shunting may also occur in the presence of a patent foramen ovale or atrial septal defect. Cardiac output is very dependent on an elevated heart rate, but excessive increases in the latter can compromise ventricular filling. Percutaneous balloon valvulo-plasty is generally considered the initial treatment of choice in most patients with symptomatic pul-monic stenosis. Anesthetic management for patients undergoing surgery should maintain a normal or slightly high heart rate, augment preload, and avoid factors that increase PVR.