Vascular steal syndromes Notes

NOTES NOTES VASCULAR STEAL SYNDROMES GENERALLY, WHAT ARE THEY? PATHOLOGY & CAUSES ▪ AKA steal syndrome ▫ Occlusion → blood follows path of least resistance → abnormal blood flow ▪ Hemodynamics ▫ Length, width of vessel ▪ Obstruction/narrowing of vessel → increased resistance → blood follows path of least resistance → area distal to obstruction/narrowing receives less blood, others receive more blood TYPES ▪ Coronary steal syndrome ▫ Coronary arteries ▪ Subclavian steal syndrome ▫ Subclavian artery DIAGNOSIS DIAGNOSTIC IMAGING ▪ Incidental finding CT angiography ▪ Blood flow/occlusion Doppler ultrasound ▪ Retrograde blood flow LAB RESULTS ▪ Atherosclerosis, elevated troponin OTHER DIAGNOSTICS ▪ Nuclear stress test ▪ ECG alterations ▪ Heart catheterization CAUSES ▪ Narrowing/obstruction of vessel ▪ Atherosclerosis/structural abnormalities SIGNS & SYMPTOMS ▪ See individual disorders TREATMENT MEDICATIONS ▪ Pharmacological treatment; see individual disorders SURGERY ▪ Revascularization of ischemic area ▫ Endovascular methods, bypass surgery, percutaneous transluminal angioplasty OSMOSIS.ORG 153

CORONARY STEAL SYNDROME osms.it/coronary-steal-syndrome PATHOLOGY & CAUSES ▪ Narrowed/obstructed coronary vessel + vasodilator alters cardiac circulation → blood shunted away from area distal to narrowing/obstruction exacerbating ischemia ▪ AKA cardiac steal syndrome ▪ Artery narrowing/obstruction → dilation of distal arteries to compensate for decreased blood flow → addition of vasodilator → dilation of resistance vessels → blood supplying ischemic zone shunted away to areas of least resistance → more ischemia ▪ Narrowing of coronary arteries + vasodilator (e.g. dipyridamole, adenosine) → blood flows to non-obstructed vessels → exacerbating ischemia ▫ Dipyridamole: antiplatelet, vasodilator → all coronary vessels dilate when in individual with partial obstruction of coronary artery ▫ Vasodilator may steal blood from deprived region distal to obstruction ▪ Dilation of resistance vessels → blood shunted away from coronary vessels CAUSES ▪ Coronary artery bypass grafting surgery (CABG) ▫ Rare ▫ Due to left internal mammary artery (LIMA) graft ▫ Retrograde flow from LIMA to left subclavian artery 154 OSMOSIS.ORG ▪ Drugs ▫ Dipyridamole, nitroprusside, isoflurane (inhaled anesthetic), vasodilators ▪ Coronary arteriovenous fistula between coronary artery, cardiac chamber COMPLICATIONS ▪ Recurrent myocardial infarction (MI), ischemia SIGNS & SYMPTOMS ▪ Cerebrovascular ▫ Presyncope/syncope, vertigo, vision loss, memory loss, weak pulse ▪ Chest pain ▪ Unequal pulses in upper extremities ▪ Blood pressure differences between arms DIAGNOSIS OTHER DIAGNOSTICS ▪ Cardiac stress test ▫ Vasodilator produces ischemic ECG changes (with/without exercise) ▪ Coronary angiography TREATMENT SURGERY ▪ Balloon angioplasty, stent insertion, coronary bypass

Chapter 23 Vascular Steal Syndromes SUBCLAVIAN STEAL SYNDROME osms.it/subclavian-steal-syndrome PATHOLOGY & CAUSES ▪ Stenosis/occlusion in subclavian artery → reversal of blood flow in vertebral artery ▪ Occlusion/narrowing in subclavian artery → blood drawn away from head, flows retrogradely to supply oxygen to upper extremities (e.g. blood to brain stolen to supply left upper limb) ▫ More often on left than right due to anatomical location of left subclavian artery ▪ Narrowing of subclavian artery → short low resistance pathway becomes high resistance ▪ Blood flows up right brachiocephalic → right subclavian → right vertebral artery → basilar artery, left vertebral joins → blockage of left vertebral upstream → blood from right vertebral artery enters left vertebral → left subclavian → flows back to left arm ▪ Rare condition RISK FACTORS ▪ Smoking, diabetes, obesity, lack of exercise, unhealthy diet, family history ▪ More common in individuals who are biologically male COMPLICATIONS ▪ Upper limb ischemia, neurological problems CAUSES ▪ Atherosclerosis (most common) ▫ Narrowing, hardening of arteries due to plaque buildup ▪ Takayasu disease (least common) ▫ Chronic inflammation of aorta, large vessels ▪ Giant cell arteritis ▪ Blalock Taussig shunt ▫ Surgical procedure to increase blood flow to lungs; tube placed between subclavian, pulmonary arteries ▪ Thoracic aortic dissection ▪ Thoracic outlet compression ▪ Interrupted aortic arch ▪ Congenital aortic coarctation Figure 23.1 An illustration depicting the flow of blood in subclavian steal syndrome. Blood flows around the blockage in the proximal subclavian artery, reversing flow in the internal carotid and “stealing” the blood from the brain. OSMOSIS.ORG 155

SIGNS & SYMPTOMS ▪ Asymptomatic ▪ Numbness of arm, extends to fingertips (most frequent) ▪ Vertebrobasilar artery insufficiency ▫ Presyncope/syncope, neurologic deficits ▪ Upper extremity claudication ▪ Tingling sensation/numbness in face ▪ Decreased blood pressure on affected side ▪ Transient hemiparesis (weakness) of affected side ▪ Blood pressure (BP) in left arm < BP in right arm ▪ Pulse in left arm < pulse in right arm DIAGNOSIS DIAGNOSTIC IMAGING ▪ CT angiography ▪ Doppler ultrasound scan TREATMENT SURGERY ▪ Balloon stenting, angioplasty ▪ Endarterectomy 156 OSMOSIS.ORG