To the best of our knowledge, the present study is the largest series of ruptured PAVMs to date. In recent years, only isolated case reports have described this condition [8; 15–18; 20]. We identified 18 patients who developed pulmonary hemorrhage associated with ruptured PAVMs. The incidence of ruptured PAVMs was 5.49% in our study, which is similar to the incidence observed by Ference et al. (8%) . Significantly more patients in our study than in the study by Ference et al. were diagnosed with hemoptysis as the first symptom. Thus, we consider that ruptured PAVMs are more likely to present with hemoptysis.
According to previous studies, the incidence of PAVMs increased to 0.038% as the use of CT became more widespread, and the use of this imaging modality is more common than previously thought . In addition, CTA can clearly reveal afferent arteries, draining veins, and the sac of PAVMs. Therefore, we recommend the use of CTA to achieve a definitive diagnosis of PAVM before therapy [3; 6; 13].
In the present study, four patients in the hemoptysis group had undergone ineffective BAE, and one patient in the hemothorax group had been initially misdiagnosed with lung cancer. We believe that the cause of the misdiagnosis in these patients was the absence of a pre-procedural plan established by CTA. To our knowledge, no data are currently available to predict which PAVMs are most likely to rupture.
However, we have observed that ruptured PAVMs exhibited a regular pattern on imaging examinations. Most lesions were located at the peripheral area of lower lobes, especially in patients with acute hemothorax. Furthermore, ruptured PAVMs in the hemothorax group manifested as the “anomalous bulge sign” on CTA and “double shadow sign” on angiography, which were helpful for confirming rupture. Therefore, we consider that CTA is conducive to the detection of ruptured PAVMs, contributes to classification of the lesions, and directs the next step of treatment [28; 29]. Even for patients in unstable conditions, we strongly recommend performance of CTA after endotracheal intubation and airway protection prior to therapy.
In addition to the CTA findings, the patients’ clinical histories are also helpful. In our study, 12 of the 18 patients had HHT, and 58.33% of these 12 patients were female. Therefore, we consider that HHT, especially HHT in female patients, is a significant risk factor for the occurrence of PAVM rupture. This is in line with previous studies [3; 6; 30]. Furthermore, we found that one patient with HHT had a history of massive hemoptysis during pregnancy. We believe that pregnancy is also a potential risk factor for spontaneous rupture of PAVMs, as previous studies have described [6; 20]. Although the probability of spontaneous rupture of PAVMs is low, we strongly recommend that PAVM rupture must be considered when managing patients with hemothorax or hemoptysis, especially female patients with a clear family history of HHT [31–33].
Treatment of PAVMs includes surgical resection, endovascular embolization, and conservative medical treatment [21; 23; 28]. Patients with active massive hemorrhage have a high mortality rate during surgical resection because of hemorrhagic anemia, respiratory insufficiency, or unconsciousness. Therefore, we recommend emergency embolotherapy instead of thoracoscopic surgery for patients with ruptured PAVMs [21; 23]. In addition, a longer period of time is usually required to prepare for emergency thoracoscopic surgery, and the PAVM might re-rupture during that time. In contrast, emergency embolotherapy may be more convenient and easily repeatable, and it facilitates immediate and adequate hemostasis. In addition to its safety and effectiveness, embolotherapy involves the use of recent embolic devices and materials that do not significantly influence any special examinations, especially magnetic resonance imaging.
If multiple PAVMs are found during embolotherapy, we recommend embolization of all suitable PAVMs regardless of whether they have ruptured. Embolization of a ruptured PAVM might influence the pulmonary arterial pressure, and whether this can induce rupture of other PAVMs is unknown. In line with previous research, we recommend embolization of all PAVMs with feeding arteries ≥ 3 mm in diameter besides the ruptured PAVM [3; 6; 34; 35].
In the present study, we observed varying degrees of hemorrhagic anemia and respiratory insufficiency in all patients before embolotherapy, and an inflammatory reaction occurred 2 days after embolotherapy. Therefore, our experience indicates that post-procedural antibiotics and oxygen therapy are indispensable. These treatment measures vastly shorten the average duration of hospitalization by timely adequate hemostasis combined with proper supportive treatment, thus assisting in the recovery of patients with ruptured PAVMs.
Our study did have some limitations. Because of the rare nature of ruptured PAVMs, our study was a relatively small, retrospective single-center analysis, although it was the largest to date to our knowledge. A family history of HHT was not confirmed in all 328 patients with PAVMs, and genetic tests for HHT were not available in all 18 patients enrolled in our study. We did not measure the pulmonary artery pressure before and after embolization under the emergency conditions in this study.