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Ann Thorac Surg 2010;90:957-964. doi:10.1016/j.athoracsur.2010.05.008
© 2010 The Society of Thoracic Surgeons
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Original Articles: General Thoracic

Angiographic Predictors of Hemodynamic Improvement After Pulmonary Endarterectomy

Takashi Kunihara, MD, PhDa, Monika Möllera, Frank Langer, MDa, Fumihiro Sata, MD, PhDb, Dietmar Tscholl, MDa, Diana Aicher, MDa, Hans-Joachim Schäfers, MD, PhDa,*

a Department of Thoracic and Cardiovascular Surgery, University Hospital of Saarland, Homburg, Germany
b Department of Epidemiology, National Institute of Public Health, Wako, Japan

Accepted for publication May 3, 2010.

* Address correspondence to Dr Schäfers, Department of Thoracic and Cardiovascular Surgery, University Hospital of Saarland, Kirrbergerstr. 1, 66421 Homburg, Germany (Email: h-j.schaefers{at}uniklinikum-saarland.de).

Presented at the Forty-sixth Annual Meeting of The Society of Thoracic Surgeons, Fort Lauderdale, FL, Jan 25–27, 2010.


   Abstract
Top
 Abstract
Introduction
 Material and Methods
 Results
 Comment
 Discussion
 References
 
Background: Postoperative outcome after pulmonary endarterectomy (PEA) for CTEPH (chronic thromboembolic pulmonary hypertension) is difficult to predict. We analyzed specific angiographic findings to predict the success of PEA.

Methods: Pulmonary angiograms were reviewed retrospectively in 90 patients with CTEPH who underwent PEA. The proximal 2 cm of a segmental artery were classified into the following: A, occlusion; B, pouch or membrane; or C, delayed perfusion. The number of involved segments was recorded. Logistic regression analysis was used to predict mortality and hemodynamic improvement after PEA.

Results: An average of 15.7 ± 2.9 segments were involved angiographically per patient (A, 7.6 ± 2.9; B, 4.6 ± 3.1; C, 3.5 ± 2.7). No variable was significant in multivariate analysis to predict early mortality (n = 6, 6.7%). More than 50% reduction in postoperative pulmonary vascular resistance (PVR) at 24 hours (n = 71) could be predicted by higher PVR, more involved segments, male gender, and higher diastolic pulmonary arterial pressure with an area under the curve in the receiver operating characteristics curve of 0.9021. The PVR less than 400 dynes · sec · cm–5 at 48 hours after PEA (n = 81) could be predicted by type B lesions, duration of symptoms, more involved segments, and serum creatinine level with area under the curve in the receiver operating characteristics curve of 0.9160. The PVR at 48 hours after PEA could be predicted by serum creatinine level, involved segments, PVR, and gender (P < 0.001, R = 0.551, R2 = 0.304).

Conclusions: Angiographic criteria can predict the success of PEA. Segments with obstruction but preserved peripheral perfusion seem to have more impact than occluded segments on hemodynamic improvement.


   Introduction
Top
 Abstract
 Introduction
Material and Methods
 Results
 Comment
 Discussion
 References
 
Even with recent technical advances, pulmonary endarterectomy (PEA) for chronic thromboembolic pulmonary hypertension (CTEPH) is still associated with relevant mortality and morbidity, and its postoperative outcome is difficult to predict. Operative mortality after PEA has been reported to be as high as 24% in the last decades [1, 2]. Based on multidisciplinary teamwork the largest experience exists at the University of California, San Diego, where operative mortality has reached 4.4% in the latest 500 cases [3]. While this has been an improvement, the risk is still relevant and higher than normally seen after routine cardiac surgery.

A key issue has been the indication for PEA, and decision-making for or against surgical intervention remains subjective. Possible predictors for success of PEA are considered to be preoperative hemodynamics, preoperative radiologic findings, and comorbidities of patients [1, 2]. It is well known that higher preoperative pulmonary vascular resistance (PVR) is associated with higher postoperative mortality [3–7]. However, patients with PVR in the range of 700 to 1,100 dynes · sec · cm–5 are typically referred to surgical centers and many of these individuals will still benefit from surgical disobliteration [1]. Thus there is still the need to identify predictors that will help in this decision making process for these patients.

Jamieson and colleagues [3] and Thistlethwaite and colleagues [8] have advocated classification of CTEPH into four groups according to location and property of thrombus and vessel wall pathology, and showed that this classification correlates well with postoperative outcome. They classified the anatomic findings into proximal and peripheral lesions and demonstrated that peripheral disease is associated with worse results. However, this classification is based on intraoperative findings and thus not useful to facilitate a decision before PEA. A quantitative analysis of the pulmonary angiography should theoretically allow a similar classification preoperatively. The purpose of this study is to analyze specific angiographic findings in conjunction with hemodynamic data to predict mortality and hemodynamic improvement after PEA.


   Material and Methods
Top
 Abstract
 Introduction
 Material and Methods
Results
 Comment
 Discussion
 References
 
Patients
Between December 1995 and December 2006, 219 patients with CTEPH underwent PEA, of whom 90 patients were retrospectively reviewed with their pulmonary angiograms having been performed with consistent angiographic technique. Identical technical prerequisites (Integris Allura; Philips Medical Systems, Best, The Netherlands, films stored digitally) and consistent angiographic technique were employed. The local ethics committee approved this retrospective investigation and waived the need for patient consent for the anonymous use of their data. Their mean age was 55 ± 14 years old and 57% of them were male. Their mean height was 171 ± 13 cm and body weight was 79 ± 16 kg. Mean New York Heart Association class was 2.9 ± 0.6, and mean duration of symptom was 44.1 ± 46.6 months. A history of symptomatic deep vein thrombosis of the lower extremities was present in 25 patients (27.8%). Placement of an inferior vena cava filter prior to the operation was not performed. Preoperative serum creatinine level was 1.1 ± 0.4 mg/dL and only two patients had preoperative serum creatinine level of 2.0 mg/dL or more without need of hemodialysis. Preoperative arterial blood gas analysis revealed a mean partial pressure of oxygen of 62.5 ± 15.4 mm Hg and partial pressure of carbon dioxide of 29.4 ± 6.0 mm Hg. Preoperative mean forced expiratory volume in one second was 2.5 ± 0.7 L (83% ± 16% of expected value) and volume capacity was 3.3 ± 0.9 L (89% ± 15% of expected value). Tricuspid valve regurgitation was seen in almost all patients; the mean grade was 2.2 ± 0.5.

Angiographic Findings
All analyzed angiograms were performed in our institution. Pulmonary angiograms were performed through a right femoral vein approach with a standard technique in all study patients. Two projections were obtained for each pulmonary artery. Contrast material (30 mL per injection) was given at 18 mL/second. The right side was studied by frontal and lateral position, the left by 20 degree left anterior oblique and lateral projections. If the lower lobe vessels were not well visualized, the lower lung fields were studied in an additional angiogram with the same projections and constant application.

The proximal 2 cm of each segmental artery were classified into three categories: A, occlusion; B, pouch or membrane; and C, delayed perfusion (Fig 1). Segments with type B showed anatomic obstruction but preserved antegrade peripheral perfusion. Figure 1D shows the delayed perfusion of the pulmonary vascular tree in type C disease. Higher contrast is seen in proximal vessels. Prior to angiography a complete hemodynamic assessment was performed. Mean preoperative systolic, diastolic, and mean pulmonary arterial pressure (PAP) were 81 ± 18 mm Hg, 26 ± 9 mm Hg, and 45 ± 10 mm Hg, respectively. Mean PVR was 827 ± 416 dynes · sec · cm–5 and cardiac index (C.I.) was 2.0 ± 0.6 L · min–1 · m–2.


Figure 1
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  		Fig 1. Typical angiographic findings (defined by arrows) according to our classification into three categories. (A) Type A: occlusion segment. (B) Type B: membrane segment. (C) Type B: pouch segment; (D) Type C: delayed perfusion segment.

 
Anesthesia and Operative Technique
All patients received general anesthesia using a standard technique including continuous intravenous administration of propofol and sufentanyl. Neither steroids nor mannitol were given routinely. Nitric oxide was not given. The Swan-Ganz catheter was placed in the pulmonary artery through a right internal jugular venous approach, and pulmonary hemodynamics were continuously monitored throughout the procedure. Inhalation of nebulized iloprost (Ilomedin; Bayer Vital GmbH, Leverkusen, Germany) was administered with 20 µg/hour throughout the operation. Topical cooling of the head with ice packing was started after initiation of cardiopulmonary bypass (CPB) and continued until the end of systemic circulatory arrest.

The details of our routine technique of PEA have been described before [5]. Briefly, the patients were placed on CPB and cooled. The ascending aorta was clamped and cold blood cardioplegia was given into the aortic root A left atrial vent was used. When the nasopharyngeal temperature reached 18°C, CPB was discontinued and PEA was begun on the left side, followed by the right side after a brief period of systemic reperfusion. Pulmonary endarterectomy was started at the level at which the most proximal extent of thrombus or scar tissue could be identified. In 22 patients (24%) this was at the level of the segmental arteries. The dissection plane was developed with a scalpel and dissection was continued to the level of the subsegmental branches using long forceps and a long suction tip [9]. If the period of circulatory arrest for a single side exceeded 20 minutes, a brief period of systemic reperfusion was allowed. Other concomitant cardiac procedures were performed during the rewarming phase. We did not perform tricuspid valve repair routinely except in one case with preoperative echocardiographic evidence of leaflet retraction. At a core temperature of 34°C, weaning from CPB was initiated using intravenous administration of norepinephrine if necessary to maintain adequate perfusion pressure. Volume was returned carefully to the patient to avoid a mean PAP of more than 30 mm Hg.

Postoperative Care
In the intensive care unit, hyperventilation of the patient was initiated with a tidal volume of 10 mL/kg and a positive end-expiratory pressure of 5 mm Hg in order to achieve a partial pressure of carbon dioxide of less than 30 mm Hg. Intravenous nitroglycerine (2 mg/hour) was administered continuously and inhaled iloprost (20 µg) was given every 2 hours. Care was taken to avoid pulmonary hypertension (mean PAP > 30 mm Hg). Fluids were administered to provide a urine output of at least 1 mL · kg–1 · hour–1. For treatment of systemic hypotension, norepinephrine or vasopressin was given. Intravenous heparin was started 6 hours postoperatively with a partial thromboplastin time greater than 60 seconds. Oral Coumadin (DuPont, Wilmington, DE) therapy was resumed on the first postoperative day with a target prothrombin time-international normalized ratio between 3 and 3.5. The pulmonary artery catheter was removed in most patients on postoperative day 2.

Statistical Analysis
All values are expressed as mean ± standard deviation. Statistical analysis was performed using the StatView 5.0 program (SAS Institute Inc, Cary, NC) or "Statistical Program for Social Sciences" for windows version 17.0 (SPSS, Chicago, IL). A repeated measures analysis of variance with the Scheffé post hoc test was used for comparison of the continuous variables between the groups. Backward stepwise multivariate logistic regression models for likelihood ratio were used to predict postoperative pulmonary hemodynamic improvement. A p value less than 0.20 in the univariate analysis was defined for selecting variables for entry into the multivariate analysis. Spearman's correlation test was performed to examine the correlation of the clinical variables and postoperative pulmonary hemodynamic improvement. A p value of less than 0.05 was considered statistically significant.


   Results
Top
 Abstract
 Introduction
 Material and Methods
 Results
Comment
 Discussion
 References
 
Angiographic Findings
The angiographic analysis showed 15.7 ± 2.9 segments involved per patient. The right lung (8.6 ± 1.8 segments) had more involved segments compared with the left (7.1 ± 1.9 segments). The total number of segments with occlusion was 7.6 ± 2.9, that with pouch or membrane was 4.6 ± 3.1, and that with delayed perfusion was 3.5 ± 2.7. The total number of segments significantly correlated with preoperative systolic PAP (p = 0.0495, R = 0.208, R2 = 0.043), diastolic PAP (P = 0.0400, R = 0.217, R2 = 0.047, and PVR (P = 0.0225, R = 0.240, R2 = 0.058).

Operative Data and Outcome
Concomitant operations were performed in 13 patients. Coronary artery bypass grafting was performed in 8 patients, closure of patent foramen ovale in 4 patients, and aortic valve replacement in 1 patient. Mean operating, CPB, aortic cross-clamp, and circulatory arrest times were 216 ± 39 minutes, 135 ± 27 minutes, 69 ± 18 minutes, and 34 ± 18 minutes, respectively. The number of surgically disobliterated segments was 12.5 ± 3.1 per patient. Similar to the angiographic findings, more segments were extracted from the right lobe (7.2 ± 2.2 segments) compared with the left lung (5.3 ± 2.2 segments).

Six patients died within 30 days after the surgery for an early mortality of 6.7%. In all patients in our institution, early mortality was 11.0% (24 of 219). Two patients (2.2%) underwent reexploration for bleeding. Mean time of mechanical ventilation was 61.6 ± 75.7 hours (median 33 hours), and mean intensive care unit stay was 5.7 ± 7.3 days (median 4 days). Higher PVR, lower body weight, higher diastolic PAP, less cardiac comorbidity, and lower vital capacity were significant predictors for early mortality in univariate analysis (Table 1). However, no parameter was significant in multivariate analysis.


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  		Table 1 Predictors for Early Mortality in Univariate Analysis
 
Pulmonary Hemodynamics
Compared with preoperative levels PAP significantly decreased at 6 hours postoperatively and remained low up to 48 hours postoperatively (Fig 2). The PVR was also significantly decreased at 6 hours postoperatively and further decreased 24 hours and 48 hours after the operation (Fig 3). Cardiac index significantly increased 6 hours postoperatively and remained so up to 48 hours after surgery (Fig 3).


Figure 2
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  		Fig 2. Postoperative time course of pulmonary arterial pressure (PAP). (bullet = systolic; {blacksquare} = mean; {diamondsuit} = diastolic.)

 

Figure 3
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  		Fig 3. Postoperative time course of pulmonary vascular resistance (PVR) and cardiac index (C.I.). ({square} = PVR; bullet = C.I.)

 
A more than 50% reduction in 24-hour postoperative PVR was achieved in 71 patients (78.9%). These patients were defined as good hemodynamic responders. Backward stepwise multivariate logistic regression models for likelihood ratio identified higher preoperative PVR, more angiographic involved segments, male gender, and higher diastolic PAP as predictors for good hemodynamic response with sensitivity of 92.6% and specificity of 66.7% (Table 2). In the subanalysis of angiographic findings, the number of segments involved with pouch or membrane was the only significant predictor for good hemodynamic response (p = 0.035; occlusion, p = 0.374; delayed perfusion, p = 0.789). Using the following equation we could predict good hemodynamic responders preoperatively:


Formula

When the predictive score is lower than 0.5, PEA may not reduce PVR by 50% of preoperative value. When this score is greater than 0.5, PVR can be reduced more than 50% by PEA. The receiver operating characteristic curve of this prediction (Fig 4) resulted in an area under the curve of 0.9021 (p < 0.0001).


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  		Table 2 Predictors for Good Hemodynamic Response Such as More Than a 50% Reduction of Pulmonary Vascular Resistance at 24 Hours After Pulmonary Endarterectomy
 

Figure 4
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  		Fig 4. The receiver operating characteristic curve to predict more than a 50% reduction in 24-hour postoperative pulmonary vascular resistance. (AUC = area under the curve; CI = confidence interval.)

 
In 81 patients (90.0%) postoperative PVR was reduced to lower than 400 dynes · sec · cm–5 at 48 hours after PEA. Backward stepwise multivariate logistic regression models for likelihood ratio identified a higher number of segments involved with pouch or membrane, shorter duration of symptoms, more involved segments, and lower serum creatinine level as predictors for good hemodynamic response with sensitivity of 100% and specificity of 37.5% (Table 3). Using the following equation we could predict good hemodynamic responders preoperatively:


Formula

When predictive score is lower than 0.5, PEA may not reduce PVR to less than 400 dynes · sec · cm–5. When this score is greater than 0.5, PVR will be reduced to less than 400 dynes · sec · cm–5. The receiver operating characteristic analysis of this prediction (Fig 5) resulted in a high probability with an AUC of 0.9160 (p = 0.00013).


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  		Table 3 Predictors for Good Hemodynamic Response Such as Pulmonary Vascular Resistance at 48 Hours After Pulmonary Endarterectomy Less Than 400 dynes · sec · cm–5
 

Figure 5
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  		Fig 5. The receiver operating characteristic curve to predict postoperative pulmonary vascular resistance lower than 400 dynes · sec · cm–5 at 48 hours after pulmonary endarterectomy. (AUC = area under the curve; CI = confidence interval.)

 
Using Spearman's correlation test, PVR at 48 hours after PEA could be estimated as the following equation:


Formula

The correlation between predicted value and actual value revealed a high reliability (p < 0.001, R = 0.551, R2 = 0.304) as shown in Figure 6.


Figure 6
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  		Fig 6. Spearman correlation coefficient to estimate pulmonary vascular resistance (PVR) at 48 hours after pulmonary endarterectomy.

 

   Comment
Top
 Abstract
 Introduction
 Material and Methods
 Results
 Comment
Discussion
 References
 
In the current study, good hemodynamic responders after PEA could be predicted by preoperative variables. The extent of angiographic involved segments played an important role in conjunction with preoperative hemodynamic severity of the disease in estimating postoperative outcome. These findings confirmed our clinical impression. Above all, segments with obstruction but preserved peripheral perfusion (type B lesion) seemed to have more impact than occluded segments.

In 1980 Daily and colleagues [10] introduced a modern form of bilateral PEA using CPB and hypothermic circulatory arrest. The initial results were encouraging; with increasing experience mortality has improved to 4.4% in the latest 500 cases [3]. This has generated increasing interest in this causative therapy of CTEPH, and approximately 3,500 cases of PEA have been performed worldwide [11]. Not all centers, however, have ideal outcome of PEA [12]. Thus, better identification of surgical candidates who will benefit from PEA should be essential.

Possible predictors for operative outcome of PEA might be preoperative hemodynamics, radiologic findings, and comorbidities of patients [1]. We have previously shown that a PVR greater than 1,136 dynes · sec · cm–5 adversely affected operative mortality [5]. In the same way, several studies have identified PVR greater than 900 to 1,000 dynes · sec · cm–5 as a risk factor for mortality after PEA [3, 4, 7]. Also in the current study, a high PVR was associated with increased mortality in the univariate analysis, which is consistent with previous reports. Interestingly, PVR was no significant predictor for PVR lower than 400 dynes · sec · cm–5 at 48 hours after PEA (p = 0.14 in univariate analysis). This indicates that high preoperative PVR should not lead to exclusion of the patient from surgery, but rather evaluate the angiographic findings carefully before making a decision. Thus, patients with PVR greater than 1,000 dynes · sec · cm–5 have an elevated risk of postoperative mortality but many of them still benefit from PEA. We also tested another criterion of hemodynamic response; more than 50% reduction in PVR at 24 hours after PEA. This assumes that patients with markedly reduced PVR will have a prognostic benefit, even if the reduction is not ideal. This assumption is currently not yet substantiated by long-term data but appears physiologically plausible to us. Decision making for or against PEA for the patients with higher preoperative PVR at the current time should be made carefully and reassessed when more data are available.

Similarly, the level of PAP (systolic > 100 mm Hg, mean > 50 mm Hg) has been defined as a prognostic risk factor [4, 13]. Interestingly, we identified diastolic PAP as a stronger predictor for both mortality and hemodynamic improvement than systolic or mean PAP in this study. We speculate that patients with higher diastolic PAP exhibit a higher degree of irreversible vascular remodeling, a key physiologic phenomenon of CTEPH. These findings advocate either earlier surgery or potential beneficial cotreatment with prostanoids, endothelin-receptor antagonists, or phosphodiesterase-5 inhibitors to achieve better postoperative outcome [14]. Nagaya and colleagues [6] reported that preoperative intravenous administration of prostacyclin had decreased PVR in 28%. Indeed, we have found a positive effect of inhalation of nebulized iloprost in patients with pulmonary hypertension [15].

Pulmonary angiography is still the gold standard in the definitive diagnosis of CTEPH and an essential tool in decision-making for or against PEA. The most crucial prerequisite for success in PTE is surgical accessibility to thromboembolic material. It has repeatedly been reported that extensive central disease is associated with better hemodynamic improvement after PEA than peripheral disease [8, 16, 17]. On the other hand, presence or absence of central thromboembolic change does not predict success or failure of PEA [16, 17]. Therefore, interest should be focused on which patients with peripheral disease may still benefit from surgical intervention. Thus, the need for more detailed interpretation of angiographic findings of peripheral pulmonary vascular tree appears evident [17]. The typical angiographic findings of CTEPH have been characterized as irregular intimal surface, vascular webs or bandlike narrowings, pouch-like termination of segmental branches, abrupt and angular narrowing of the central vessels, and obstruction of pulmonary vessels [18, 19]. We modified and summarized these findings into three categories: type A, occlusion; type B, pouch or membrane; and type C, delayed perfusion. The type B lesion reflects obstructed but preserved distal perfusion. These lesions are generally surgically accessible. By contrast, type C disease does not seem accessible because it represents physiologically impaired pulmonary perfusion without visible anatomic vessel narrowing, which suggests arteriolar-capillary vasculopathy. The type A lesion is unquestionably accessible; however, more peripheral disease or secondary arteriopathy may coexist. In our patients, type B lesions had a higher impact on postoperative hemodynamic improvement after PEA than other lesions. One may speculate that type C lesion with higher PVR is associated with the worst outcome after PEA. In our study, however, patients with early death had fewer type C lesions (2.3 ± 2.5) than survivors (3.6 ± 2.7) (p = 0.278). Type C disease was found in a minority of pulmonary branches in our patients, which may be one of reasons why it did not affect postoperative outcome.

Comorbidities of patients seem to be a matter of debate in selecting suitable candidates for PEA. The San Diego group reported that the need for concomitant cardiac operation was not associated with increased risk with regard to mortality [20], whereas the same group demonstrated contradictory outcome later [21]. Compared with 4.3% mortality after isolated PEA, concomitant coronary artery bypass operation resulted in 10.0% mortality and concomitant valve operation had the highest mortality with up to 16.7% [21]. As shown in Table 1, our patients with cardiac comorbidity were less likely to die in hospital by univariate analysis, which may be due to the limited number of cases. The only unequivocal risk factor for PEA seems to be severe parenchymal lung disease with obstructive or restrictive dysfunction [1, 2, 22, 23]. In the current study, patients with restrictive lung disease were associated with a higher risk of mortality in univariate analysis. In line with our previous analysis [5], female gender was identified as a risk factor for inferior hemodynamic improvement in the current analysis. Interestingly, idiopathic pulmonary arterial hypertension has female predominance, whereas CTEPH does not [24]. Therefore, one could speculate that some female patients with idiopathic pulmonary arterial hypertension may have been included in our patients who underwent PEA. Female gender was associated with higher mortality (10.3% vs 3.9%, p = 0.2325) and significantly lower body weight (73 ± 19 kg vs 84 ± 12 kg, p = 0.0031) compared with male gender. This might contribute to our result that lower body weight was a risk factor for mortality. Longer duration of symptoms and higher level of serum creatinine were negative predictive factors for hemodynamic improvement in our analysis. Reduced cardiac output will lead to renal failure, making renal function an indicator of long-standing severe heart failure. Interestingly, the San Diego group [13, 20] demonstrated that PAP greater than 100 mm Hg or PEA with concomitant cardiac surgery resulted in a higher risk of postoperative acute renal failure. To achieve sustained and favorable outcome, it may be essential to refer suitable candidates for PEA to an experienced surgeon before the onset of irreversible severe secondary peripheral arteriopathy or right-heart failure [1].

Limitations
The implications of this study should be carefully interpreted. First, this is not a prospective but a retrospective study with selected cohort. The selection process included a bias; approximately 25% of referred patients were not accepted for PEA, mainly if less than 10 segments were angiographically involved and mean PAP exceeded 50 mm Hg. The clinical follow-up of this article was limited to the early phase after PEA. A prospective, larger cohort and long-term follow-up study with decision of indication for PEA using our calculation will be necessary to confirm the essence of this manuscript. Second, the definition of hemodynamic improvement seems still controversial. We defined patients who achieved more than a 50% reduction in 24-hour postoperative PVR or reduction of PVR lower than 400 dynes · sec · cm–5 at 48 hours after PEA as good hemodynamic responders. Fedullo and colleagues [2] summarized the report from worldwide experienced surgical centers between 1997 and 2000 and calculated that the mean reduction in PVR was approximately 65%. This criterion was achieved in only 65.5% of our patients, and we set this criterion milder to 50% reduction that was achieved in 78.9% of our patients, which has also been advocated by Dartevelle and associates [7]. A careful analysis of long-term data will be necessary to define the best threshold for improvement in survival. Third, preoperative management was not uniform in this study. As discussed previously, pretreatment with prostanoids, endothelin-receptor antagonists, or phosphodiesterase-5 inhibitors may modify postoperative outcome favorably [14]. Indeed, some of our recent patients received one of these medications preoperatively, which might have potential effects on the current analysis.

In conclusion, preoperative variables alone can predict good hemodynamic responders after PEA with high sensitivity. Especially, the extent of angiographic involved segments, as well as preoperative hemodynamic severity, plays a key role. Among the former, segments with obstruction but preserved peripheral perfusion have more impact than occluded segments. These novel findings may greatly help identify suitable candidates with CTEPH for PEA and eliminate unnecessary surgical intervention.


   Discussion
Top
 Abstract
 Introduction
 Material and Methods
 Results
 Comment
 Discussion
References
 
DR FRANCIS D. PAGANI (Ann Arbor, MI): What is it about the morphological features of these obstructive lesions that allows you to identify them as having favorable characteristics that permit better extraction of the thrombus at the time of surgery?

DR KUNIHARA: The characteristics of membrane or pouch are limited obstructions that are readily recognized by angiography. Interestingly, the preservation of blood flow peripheral to the lesions may imply better patency of subsegmental vasculature with good physiologic outcome.


   References
Top
 Abstract
 Introduction
 Material and Methods
 Results
 Comment
 Discussion
 References
 

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T. Kunihara, J. Gerdts, H. Groesdonk, F. Sata, F. Langer, D. Tscholl, D. Aicher, and H.-J. Schafers
Predictors of postoperative outcome after pulmonary endarterectomy from a 14-year experience with 279 patients
Eur J Cardiothorac Surg, July 1, 2011; 40(1): 154 - 161.
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