Table 2 reports the procedural characteristics. A single interventionalist conducted all procedures. A median of four device passes was performed, with a median thrombectomy time of 30 min. No adjunctive thrombolytics were used, and no patient required a blood transfusion. The median blood loss per procedure was 50 ml. Venoplasty was performed in all procedures, and four patients (36.4%) received stents. In the four cases that involved stenting following PMT and venoplasty, intravascular ultrasound was used to evaluate the extent of underlying compression or residual stenosis warranting a stent and to guide its placement.

All 11 thrombectomy procedures were completed without intraprocedural adverse events. No malfunctions or complications related to the use of the device were recorded.

Figure 1 shows the estimated reduction in total thrombus occlusion across iliofemoral venous segments (CIV, EIV, CFV, and FV) pre- and post-thrombectomy based on the venogram review. Procedural success was achieved in 10 cases (90.9%). For Patient 8, the PMT procedure was completed as intended with satisfactory results; however, the resulting occlusion reduction (59.6%) did not meet the definition of procedural success. This patient had preprocedural chronic DVT changes with multiple channels reaching the FV and had residual femoral stenosis following the procedure.

All patients had DVT affecting at least two segments, and five (45.5%) had DVT affecting all four segments. A total of 35 iliofemoral venous segments were treated, and complete resolution of occlusion was achieved in 31 (88.6%). Using the segment type, the median preprocedural vessel occlusion ranged from 90% to 100%, with 100% occlusion of the CFV (n = 9) and CIV (n = 7). Following the procedure, the median occlusion rate across the four iliofemoral segment types was 0%.

Chart notes regarding visual inspection of the extracted thrombus following the thrombectomy were available in all cases. The interventionalist documented that the extracted thrombus contained a chronic component for 10 cases (90.9%) (Table 2): four with acute-on-chronic and six with chronic thrombus. The patient-reported symptom duration at baseline was compared with the recorded chronicity. Chronicity was determined by the observed thrombus consistency after extraction and the presence of collaterals on the venogram. Among the five patients with a baseline symptom duration ≤2 weeks, one patient had an acute thrombus, and four patients (80%) had an extracted thrombus with observed chronic components (two with acute-on-chronic and two with chronic). The cases for the four patients with symptoms persisting for ≤2 weeks and chronic thrombus components (Patients 4, 5, 6, and 7) were presented in greater detail in the following section.

All procedures were completed in a single session (Table 2). The median hospital length of postprocedural stay was 1 day, which corresponded to a mean of 1.73 days [standard deviation (SD): ±1.49]. No patients were admitted to the ICU following the procedure. Ten patients were discharged on apixaban, and one was discharged on rivaroxaban. For iliofemoral DVT patients, anticoagulation is typically prescribed for 12 months, and follow-up appointments are scheduled at 1 month and 6–12 months.

Access site complications were assessed at discharge, and there were no complications among the 10 patients with chart notes specific to access site evaluation. At discharge, no adverse events among the 11 patients included in this study were noted.

Three patients did not complete a follow-up office visit, so their outcomes were limited to those at discharge. Among the eight patients who attended their follow-up visits, there was one adverse event, a recurrent DVT that occurred 13 days postprocedure in a patient with advanced-stage cancer and medication failure. The medication of the patient was changed from apixaban to therapeutic enoxaparin, and additional interventional treatment was not provided. This event was not considered related to the device or procedure. No incidence of vessel damage, valve damage, or acute kidney injury was reported.

The following physical examination findings recorded at baseline, discharge, and follow-up visits were assessed: pain, redness, hyperpigmentation, edema, and ulcers. At baseline, all patients had edema on physical examination, 10 (90.9%) patients reported pain, and 1 patient had an ulcer. Other frequent findings at the baseline examination included redness (n = 5) and hyperpigmentation (n = 4). The proportion of patients reporting pain decreased from baseline to discharge (Figure 2) and baseline to the 30-day follow-up visit (Figure 3). All hyperpigmentation had resolved in the three patients with this symptom at baseline, and three patients reported the resolution of their edema prior to the follow-up visit.

The cases for Patients 4, 5, 6, and 7 were selected for summary description because these patients reported symptoms lasting ≤2 weeks, while chart notes regarding visual inspection of the extracted thrombus following thrombectomy indicated a chronic composition.

Patient 4 was referred from the emergency department, reported acute left lower extremity pain and edema persisting for 1 week, and had not received prior DVT treatment. DVT diagnosis was confirmed via duplex ultrasound and computed tomography scanning. A minor PE was incidentally identified via a computed tomography scan prior to the procedure, and the patient was on a heparin drip at baseline. Six passes with the BOLD catheter were performed during the 65-min procedure, of which the thrombectomy time comprised 35 min. Patient 4 had a 100% reduction of the occlusion across three iliofemoral segments, and the extracted thrombus appeared chronic. Figure 4 shows the intraprocedural images from this case, including the preprocedural venogram (Figure 4A), device image during use (Figure 4B), and postprocedural venogram (Figure 4C). The patient reported a resolution of pain and was discharged on apixaban 1 day postprocedure. This patient missed the scheduled follow-up visit, and no further record was available.

Patient 5 was a hospital inpatient with concomitant PE who experienced right lower extremity edema, pain, heaviness, discoloration, and difficulty ambulating for 2 weeks. This patient had previously received DVT treatment with oral anticoagulation and was on a heparin drip at baseline. Patient 5 had a fully occluded CFV and had 100% occlusion reduction across four iliofemoral segments with a chronic extracted thrombus following the procedure. Except for edema, other symptoms resolved at discharge, which occurred 2 days postprocedure, with apixaban prescription. This patient missed the scheduled follow-up visit, and no further record was available.

Patient 6 presented to the emergency department reporting acute pain, edema, and redness of the left lower extremity persisting for 1 week and had received anticoagulation treatment for their DVT. The patient was on a heparin drip at baseline. Following the procedure, patient 6 had 82.1% occlusion reduction across three iliofemoral segments, and an acute-on-chronic thrombus was extracted. The patient was discharged on apixaban 1 day postprocedure and completed the initial follow-up visit. The last follow-up for this patient was completed 131 days postprocedure, and a duplex ultrasound scan conducted at this visit confirmed vessel patency. No adverse events were recorded during the follow-up.

Patient 7 was referred from the emergency department; reported 1 week of acute left lower extremity pain, edema, and difficulty walking; had received DVT treatment with anticoagulation; and was on a heparin drip at baseline. Patient 7 had full occlusion of the FV, CFV, and CIV. Following thrombectomy, 100% occlusion reduction was achieved across the four treated iliofemoral segments. The patient was discharged on apixaban 1 day postprocedure and did not complete the follow-up visit. The patient was readmitted to the hospital 100 days postprocedure for recurrent DVT and reported compliance with the anticoagulation regimen. Upon case review, the probability of the patient having a hypercoagulable condition or May–Thurner syndrome not identified during the index procedure was considered.

Coincidently, three of the four patients whose cases were described above were the patients who missed the follow-up visit (Patients 4, 5, and 7). Patient 7 missed the follow-up visit and was readmitted for recurrent DVT 4 months later. Patients 4 and 5 had no further chart record of related complications or readmission. Subsequently, the follow-up duration was examined for the eight patients who completed their initial follow-up visit (Patients 1, 2, 3, 6, 8, 9, 10, and 11). The median patient follow-up (n = 8) was 137 days (IQR: 65.8–247.8), which corresponded to a mean of 156 days (SD: ±113.2). During the available follow-up (n = 8), no longer-term treatment-related complications were identified via a chart review. Three patients had readmissions during this period: Patient 1 for an elective procedure at 151 days post-thrombectomy, Patient 10 for an unrelated wound infection at 123 days post-thrombectomy, and Patient 11 for a medical surgery at 143 days post-thrombectomy.