Doppler ultrasonography in suspected subclavian artery obstruction and in patient monitoring after subclavian stenting

Subtypes of the Completely Reversed Flow Waveform in Vertebral Artery Can Help to Differentiate Subclavian Artery Occlusion from Severe Stenosis

OBJECTIVES

To investigate the value of subtypes of completely reversed flow (CRF) waveform in vertebral artery (VA) on Doppler ultrasound in differentiation occlusion from severe stenosis of the ipsilateral proximal subclavian artery (SA).

METHODS

A total of 357 patients with CRF in the VA on Doppler US were reviewed retrospectively. Among them, 49 patients (mean age, 68.2 ± 7.8 years) confirmed by digital subtraction angiography (DSA) were included. According to the status of diastolic flow, the CRF was divided into continuous CRF (CCRF, n = 27) and intermittent CRF (ICRF, n = 22). The correlation of subtypes of CRF waveform and VA parameters with the severity of SA stenosis was evaluated. The severity of SA stenosis was determined by DSA.

RESULTS

Of those 49 patients, SA occlusion was observed in 33 patients (67%, occlusion group) and severe stenosis in 16 patients (33%, stenosis group). The subtypes of CRF waveforms showed a significant between-group difference (p = 0.005). CCRF exhibited an accuracy of 85.2% (23/27) in diagnosing SA occlusion. The diameter of the target VA with ICRF showed a significant between-group difference (p = 0.041). The target VA diameter ≥ 3.8 mm in ICRF achieved an accuracy of 81.8% (18/22), and its combination with CCRF achieved an accuracy of 83.7% (41/49) in the differentiation of SA occlusion from severe stenosis.

CONCLUSIONS

Subtypes of CRF in VA can help to differentiate SA occlusion from severe stenosis. CCRF has higher accuracy in diagnosing SA occlusion. The CCRF waveform plus VA diameter in ICRF is more accurate for differentiating SA occlusion from severe stenosis.

Ultrasound Evaluation of Subclavian Artery and Internal Thoracic Artery Before Coronary Artery Bypass Grafting as Part of Preoperative Vascular Assessment

RATIONALE AND OBJECTIVES

Noninvasive diagnostic imaging of subclavian artery (SCA) and internal thoracic artery (ITA) is crucial to the patients planning to use ITA for coronary artery bypass grafting (CABG). The guidelines have not yet provided guidance on screening high-risk groups. The present study aimed to evaluate the contribution of ultrasonography in the assessment of SCA and ITA, especially for the patients referred for CABG who planned to use ITA graft.

MATERIALS AND METHODS

Patients diagnosed with multivessel coronary heart disease were enrolled and some of them planned CABG. Bilateral SCAs and ITAs were routinely evaluated by color Doppler ultrasound (CDUS) before operation. The luminal diameter and the peak systolic velocity of the proximal and distal parts of SCA and ITA were measured. Depending on the Doppler waveform, the lumen narrowing rate was calculated.

RESULTS

The final analysis was carried out in 572 patients. Thirty-five patients had moderate (50%-69%), severe (70%-99%) stenosis or occlusion in the SCA (left-sided in 21 and right-sided in 14). One patient had severe proximal stenosis in left ITA and one patient had no flow in left ITA due to the occlusion in left SCA. One patient had anatomic variation of isolated right aortic arch with aberrant left SCA. All of those cases were confirmed with multidetector computed tomography angiography.

CONCLUSION

CDUS could be used for the evaluation of SCA and ITA before CABG as part of presurgical vascular assessment and provide an import basis for the imaging diagnosis and surgical plan.

Subclavian Artery Calcification: A Narrative Review

Subclavian artery calcification (SAC) affects 2% of the population and presents a serious risk of developing into subclavian steal syndrome (SSS). Risk factors for plaque formation of the subclavian artery include diabetes, hypertension, and smoking. While SAC generally presents as asymptomatic, symptoms in severe cases may include numbness, pain at rest, and ischemic gangrene. Patients with severe SSS are at high risk of developing neurological symptoms as a result of vertebrobasilar insufficiency affecting posterior cerebral perfusion. On physical examination, SSS is preliminarily diagnosed from bilateral inter-arm systolic blood pressure discrepancy (>10 mmHg), which can be further confirmed with vascular imaging. Duplex ultrasound (DUS) is a cost-effective and non-invasive baseline technique for visualizing luminal stenosis and quantifying peak systolic velocity (PSV). Computed tomography angiography (CTA) provides high-quality, fast, three-dimensional (3D) imaging at the cost of introducing nephrotoxic contrast agents. Magnetic resonance angiography (MRA) is the safest 3D imaging modality, without the use of X-rays and contrast agents, that is useful in assessing plaque characteristics and degree of stenosis. DUS-assisted digital subtraction angiography (DSA) remains the gold standard for grading the degree of stenosis in the subclavian artery and determining the distance between the puncture site and lesion, which can be carried out in a combined procedure with endovascular management strategies. The fundamental treatment options are surgical and endovascular intervention. Endovascular treatment options include percutaneous transluminal angiography (PTA) for recanalization of the stenosed vessel and permanent balloon stenting to prevent collapse after PTA. Overall, the benefits of endovascular management encompass faster recovery, lower stenosis recurrence rate, and lower incidence of complications, making it the treatment of choice in low-risk patients. Surgical interventions, although more complex, are considered gold-standard treatment options.

Resolution of ischemic symptoms after percutaneous angioplasty for a symptomatic subclavian artery stenosis

OBJECTIVE

A minor part of patients with subclavian or innominate artery occlusive disease (subclavian artery stenosis [SAS]) experience symptoms of vertebrobasilar insufficiency, upper extremity exertional ischemia (UEEI), or cardiac ischemia owing to subclavian-coronary steal (SCS) in some instances. The study aimed to assess the impact of percutaneous transluminal angioplasty (PTA) of symptomatic SAS on symptom resolution and to determine factors related with SAS recurrence.

METHODS

Symptom resolution and incidence of restenosis (RS) were evaluated for up to 15 years in patients who had undergone successful PTA of SAS.

RESULTS

The study group comprised 232 consecutive subjects after successful PTA of SAS (61.9 ± 8.4 years old 53.4% men). The mean follow-up time was 101 ± 40 months (range, 5-188 months). One month after PTA, 85.4% of the study participants were free from dizziness, 94.4% from imbalance, 97.1% from visual disturbances, 97.8% from syncope, 98.7% from UEEI, and 100% from SCS. RS was found in 37 patients (15.9%) in long-term observation. UEEI, dizziness, imbalance, and SCS were significantly more frequent in patients with SAS recurrence, as compared with patients with patent artery (65.9% vs 3.1% [P < .001] 63.4% vs 19.4% [P < .001]; 26.8% vs 9.4% [P = .005]; and 100% vs 15.4% [P = .018], respectively). Smaller stent diameter (odds ratio [OR], 0.87; 95% confidence interval [CI], 0.79-0.96; P = .004), implantation of ≥2 stents for a lesion (OR, 1.15; 95% CI, 1.05-1.26; P = .003), concomitant stenosis in the carotid or vertebral artery (OR, 1.10; 95% CI, 1.01-1.21; P = .036), high-sensitivity C-reactive protein level (OR, 1.20; 95% CI, 1.09-1.31; P < .001), and high-density lipoprotein level (OR, 0.91; 95% CI, 0.82-0.98; P = .021) were associated independently with risk of RS, whereas recurrence of UEEI (relative risk, 1.71; 95% CI, 1.55-1.90; P < .001), dizziness (OR, 1.26; 95% CI, 1.14-1.39; P < .001), limb paresthesia (OR, 1.14; 95% CI, 1.04-1.25; P = .005), and angina in subjects after coronary artery bypass grafting (OR, 1.11; 95% CI, 1.01-1.21; P = .024) were associated with RS/SAS progression after PTA.

CONCLUSIONS

Angioplasty of SAS leads to symptom resolution in most patients. UEEI, dizziness, and angina recurrence are predictors of RS or SAS progression; high-sensitivity C-reactive protein, smaller stent diameter, and number of implanted stents predict RS.

Waveform patterns and peak reversed velocity in vertebral arteries predict severe subclavian artery stenosis and occlusion

This study investigated the value of analyzing spectral Doppler waveform patterns and measuring the peak reversed velocity (PRV) of the vertebral artery (VA) in predicting proximal severe subclavian artery (SA) stenosis and occlusion. Fifty-one patients with proximal SA stenosis were studied retrospectively. Based on the depth of the mid-systolic notch, the Doppler waveforms of the ipsilateral VA were divided into five subtypes (type I, n = 8; type II, n = 8; type III, n = 6; type IV, n = 13; and type V, n = 16). PRV was also measured. PRV receiver operating characteristic curves were constructed to obtain the best cutoff value for predicting severe SA stenosis or complete SA occlusion. The results indicated that both VA Doppler waveform and PRV were associated with the degree of SA stenosis (p < 0.05). PRV and the Doppler waveform in the VA had similar accuracy in predicting SA occlusion (84.3%, 43/51). PRV was more accurate than VA waveforms in predicting severe SA stenosis (98%, 50/51 vs. 94.1%, 48/51). However, no significant differences between the two methods in predicting severe SA stenosis were observed (p = 0.84). Thus, with severe obstruction of the SA, typical Doppler waveform patterns of the VA could be observed. PRV is a helpful criterion in predicting severe stenosis and occlusion of the SA.

Iatrogenic subclavian artery and aortic dissection with mesenteric ischemia following subclavian artery angioplasty: Endovascular management

Subclavian stenosis affects up to 5% of patients referred for coronary artery bypass grafting. Albeit usually asymptomatic, this condition can cause myocardial ischemia due to a steal phenomenon from the distal subclavian artery when the left internal mammary artery is used as a coronary bypass. We describe a case of proximal subclavian artery angioplasty complicated with aortic dissection and subsequent life-threatening mesenteric ischemia. For the first time, we illustrate an endovascular approach to both complications consisting in urgent stenting of the celiac trunk and the superior mesenteric artery followed by staged thoracic endovascular aortic repair due to progressive aortic dilatation.

Completely reversed flow in the vertebral artery does not always indicate subclavian steal phenomenon

We evaluated the causes, differential diagnosis and clinical significance of completely reversed flow (CRF) in the vertebral artery (VA). Twenty-three patients diagnosed with CRF in the VA by Doppler ultrasound were studied retrospectively. CRF was divided into intermittent CRF and continuous CRF. The peak reversed velocity (PRV) and ratio of time in intermittent CRF to one cardiac cycle (tICRF/CC) were calculated. Causes of CRF were determined on the basis of previous angiography results. The results indicated that subclavian steal phenomenon (SSP) caused all cases of continuous CRF (n = 8). Intermittent CRF was caused by SSP (n = 6) or proximal VA occlusion (n = 9). PRV and tICRF/CC were increased in SSP as compared with VA occlusion (p < 0.05). Using a cutoff of tICRF/CC = 0.30, we achieved excellent accuracy in predicting the cause of intermittent CRF (100%) and posterior circulatory infarction (91%). Thus, analysis of CRF patterns and measurements of VA parameters can be used in differential diagnosis of the causes of CRF and in prediction of posterior circulatory infarction.

Color Doppler ultrasonography in occlusive diseases of the brachiocephalic and proximal subclavian arteries

OBJECTIVE

The purpose of this study was to investigate the capability of color Doppler ultrasonography (CDU) in showing the brachiocephalic and proximal subclavian arteries and to determine the accuracy of CDU for diagnosis of occlusive diseases of those arteries.

METHODS

Two groups of patients were examined. The first group was examined with CDU to determine whether the brachiocephalic and subclavian artery origins could be seen. The second group, including patients with occlusive arterial disease, was examined with CDU before digital subtraction angiography (DSA). Results of CDU and DSA were compared.

RESULTS

In the first group, the origins of 42 (84%) of 50 brachiocephalic arteries, 48 (96%) of 50 right subclavian arteries, and 25 (50%) of 50 left subclavian arteries could be displayed by CDU. In the second group, 8 (89%) of 9 lesions on the right and 23 (96%) of 24 lesions on the left were diagnosed correctly. Color Doppler ultrasonography had sensitivity, specificity, positive predictive value, negative predictive value, and accuracy values of 88%, 94%, 78%, 97%, and 94%, respectively, for detecting major stenosis and 100%, 98%, 94%, 100%, and 99% for detecting occlusion. Agreement between the CDU and DSA findings was substantial for stenosis (kappa = 0.78) and almost perfect for occlusion (kappa = 0.96).

CONCLUSIONS

The percentage of proximal left subclavian arteries shown on CDU was considerably lower compared with the right subclavian and brachiocephalic arteries. However, there was no significant difference between the two sides in diagnosing occlusive arterial diseases. With CDU, occlusion can be diagnosed more accurately than stenosis.