Patients ranged in age from 20 to 70 years (45 ± 15 years) with a male to female ratio of 1.1:1. The preoperative and postoperative hemodynamic data in the 33 patients are presented in Table 1. Significant declines in pulmonary artery mean pressure and pulmonary vascular resistance, as well as a rise in cardiac output, were noted postoperatively. Buy Advair Diskus Online
All patients underwent a pulmonary thromboendarterectomy. However, in 27 patients, some segmental arteries (4.6 ±2 segments) were not dissected at surgery. Twenty-one (78 percent) of these patients demonstrated steal in one or more (2.5 ±2 segments) of these untouched segments. In six patients, all pulmonary arterial segments were endarterectomized. Two patients in this group demonstrated a steal phenomenon. Thus, steal occurred in 23 (69 percent) of the 33 cases reviewed.
The most common site of steal occurrence was the left upper lobe. In most instances, the perfusion decrements were visually striking (Fig 2). Further analysis of possible predictive factors disclosed a strong association between postoperative steal and a normal preoperative angiogram and perfusion scan in a given segment (Fishers exact test, p<0.0005, odds ratio: 3.14). We also noted an increased incidence of steal in undissected relative to dissected segments (p<0.0001, odds ratio: 3.40). These two factors were synergistic in that a given segment with a normal preoperative arteriogram and scan that was not dissected was ten times more likely to demonstrate steal than a segment with an abnormal preoperative arteriogram and scan that was endarterectomized. Follow-up pulmonary angiograms were available for review in 10 of the 23 patients who demonstrated steal. In nine of them, the arterial segments with steal were normal preoperatively and remained so on the follow-up arteriogram. An example is shown in Figure 2. In one patient, the site of steal was abnormal on the preoperative angiogram and remained so at follow-up. The postoperative arteriograms were also reviewed in five of the ten cases without postoperative perfusion scan steal. We did not detect any new vascular abnormality on the postoperative study in any case.
Figure 2a (upper). 1bp row: Preoperative anterior view perfusion scan (left) and arteriogram (right) of the left lung. The upper lobe pulmonary artery is unobstructed on the arteriogram and perfusion is normal on the scan image. Figure 2b (lower). Bottom row: Postoperative anterior view on predischarge perfusion scan (left) and follow-up arteriogram (right) of the left lung. Please note the decrement in predischarge perfusion of the upper lobe, demonstrating upper lobe vascular steal and the normal follow-up angiographic appearance of the upper lobe pulmonary artery.
Table 1—Preoperative and Postoperative Hemodynamic Data
|PAP, Hg||41.7 ±12||24.2±6||<0.001|
|Cardiac output, L/min||3.85 ± 1.1||5.9±1.0||<0.001|
|PVR, dyne-s/cm||789+420||200 ±100||<0.001|
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