Residual Pulmonary Hypertension Research Articles

Hemodynamic abnormalities in response to mild and intense upright exercise following operative correction of an atrial septal defect or tetralogy of Fallot.

Patients are often asymptomatic after operative correction of an atrial septal defect (ASD) or tetralogy of Fallot (TF). However, the maximal functional capacity of their hearts relative to that of normal subjects has not been defined. Twelve asymptomatic patients who had ASDs closed and 10 asymptomatic patients who had total correction of tetralogy of Fallot were evaluated by catheterization studies at rest and during mild and intense treadmill exercise. Except for small right ventricular outflow gradients in the tetralogy of Fallot group (2-21 mm Hg), data recorded at rest were normal or nearly so in each subject. However, at a level of upright exercise sufficiently intense to lower pulmonary arterial oxygen saturation to 30%, cardiac output was below that attained by normal subjects (mean, 8.9 ± 0.3 liters/min/m 2 ) in seven of 12 ASD patients (mean, 6.6 ± 0.6 liters/min/m 2 ) and in eight of 10 tetralogy of Fallot patients (mean, 6.1 ± 0.3 liters/min/m 2 ). Right ventricular (RV) outflow gradients, measured during upright exercise in six TF patients, increased in each; RV systolic pressures reached levels of 75-106 mm Hg in four of the six patients studied. No outflow gradients were observed in the ASD group. Thus, patients with operative closure of an ASD and normal hemodynamic findings at rest may have impairment of their cardiac output response to intense upright exercise in the absence of residual shunts, arrhythmias, or pulmonary arterial hypertension. Although the cardiac output response in patients with corrected tetralogy of Fallot is consistently reduced, it is remarkably good considering the complicated nature of their defect and operative repair; however, the RV outflow gradient and RV systolic pressure may increase markedly with exercise. The longterm significance of these findings remains to be determined.

Clinical and hemodynamic observations after surgical closure of large atrial septal defect complicated by heart failure

Hemodynamic and clinical re-evaluation was carried out in 13 adults with a large atrial septal defect and preoperative evidence of left ventricular failure who underwent successful surgical closure of their lesion. The interval separating surgical correction and the postoperative study ranged from 5 months to 10 years (average 4.25 years). Subjective improvement, variable in extent, occurred in all patients, but a return to completely normal hemodynamics both at rest and during exercise occurred in only 1 patient. Eight patients had residual pulmonary hypertension at rest, and in 4 others this developed during exercise. Three patients had elevated pulmonary arterial wedge pressure at rest, and in 5 others it developed during exercise. Right atrial pressure was elevated in 2 at rest, and in 1 during exercise. Six of the 12 patients with postoperative flow data had an abnormally low resting cardiac index at rest, and 4 others had an inappropriately low flow response during exercise. There was no apparent correlation between the age at which the operation was performed and the degree of hemodynamic improvement. These data suggest that heart failure occurring in the patient with a large atrial septal defect does not preclude clinical improvement after surgical repair. There is, however, a high incidence of residual hemodynamic abnormalities.

Some physiologic features of atrial septal defect: Observations in 38 adult patients

1. (1) Thirty-eight adult patients with atrial septal defect have been studied before operation, and 20 have been restudied postoperatively. 2. (2) Of the group, two had significant mitral valve disease and two were of the ostium primum type although they could not be separated from the secundum defects by their hemodynamic findings. 3. (3) The major physiologic findings before operation were: (a) marked increase in pulmonary blood flow; (b) normal systemic blood flow; (c) mild elevation of pulmonary artery pressure; (d) lower than normal total pulmonary vascular resistance; (e) increased right ventricular pressure work; (f) normal systemic arterial blood oxygen saturation. 4. (4) Surgical correction of the atrial septal defect resulted in a reversion of the physiologic abnormalities towards or to normal. 5. (5) “Relative” pulmonary stenosis may be present in the face of marked increases in the pulmonary blood flow. 6. (6) The genesis of pulmonary hypertension in certain cases is not totally understood but may be related to: (a) pulmonary arteriolar sclerosis; (b) residual fetal pulmonary hypertension; (c) associated mitral valve disease; (d) “spasm” of the pulmonary arterioles.