Ch30: Cardiac Surgery & Peripheral Vascular Disease（心脏外科与周围血管疾病）

Preparatory Mindset

This chapter covers cardiac surgery (17 Cardiac part I 18.8KB + 18.1 part II 13.2KB) and peripheral vascular disease (18.2, 22.3KB). The exam tests: coronary artery disease & CABG, valvular heart disease (stenosis vs regurgitation), congenital heart disease basics, and the peripheral arterial disease (claudication, critical limb ischemia, AAA, acute ischemia) + varicose veins (venous disease).

Exam mindset: the coronary anatomy (RCA/LAD/circumflex — see Anatomy Ch14), CABG conduits (LIMA, saphenous vein), valve lesions & murmurs, and the PAD triad (claudication → rest pain → ulceration/gangrene) with the Rutherford/ankle-brachial index (ABI) staging. Varicose veins: the great saphenous vein course (see Anatomy Ch02) and CEAP classification.

Core Concepts

1. Cardiac surgery — overview

• Cardiopulmonary bypass (CPB): the heart-lung machine oxygenates & pumps blood while the heart is arrested (cardioplegia — cold potassium solution arrests the heart in diastole)
• Approaches: median sternotomy (most), thoracotomy, minimally invasive (MICS/robotic), catheter-based (TAVI, PCI)
• Post-cardiac surgery care: ICU, chest drains, pacing wires, inotropic support, anticoagulation (after valve/mechanical)

2. Coronary artery disease & CABG (MUST KNOW)

- RCA: SA node (60-70%), right marginal, posterior interventricular (80-85% — right dominant) → inferior MI - LCA: LAD (anterior interventricular — anterior wall & septum, "widow maker"), circumflex (lateral wall)

- Left main disease (>50%) — CABG preferred - 3-vessel disease with diabetes/impaired LV function — CABG (survival benefit) - Failed PCI, unsuitable anatomy (chronic total occlusion, heavy calcification) - Acute coronary syndromes per guidelines (PCI preferred for STEMI — primary PCI)

• Coronary anatomy (recap — see Anatomy Ch14):
• Indications for CABG (vs PCI):
• Conduits (MUST KNOW): LIMA (left internal mammary artery) → LAD (best long-term patency — the standard); saphenous vein grafts → other vessels (from Anatomy Ch02: great saphenous vein course, anterior to the medial malleolus); RIMA, radial artery
• On-pump vs off-pump (OPCAB); outcomes: 5-yr patency LIMA >90%, vein ~75-80%
• Complications: graft occlusion, MI, bleeding, atrial fibrillation (common post-op), stroke, sternal wound infection, renal failure

3. Valvular heart disease (MUST KNOW)

• Infective endocarditis: fever + new murmur + emboli (Janeway, Osler, splinter hemorrhages); treat antibiotics; surgery for heart failure, uncontrolled infection, emboli, fungal, large vegetations
• Prosthetic valves: mechanical (lifelong warfarin) vs bioprosthetic (tissue — anticoagulation short-term; prefer in elderly/pregnancy)
• Aortic valve replacement (AVR), mitral valve repair (preferred over replacement when feasible — MVP, degenerative)

4. Congenital heart disease (surgical overview)

• Acyanotic (L→R shunt): ASD (ostium secundum most common), VSD (most common congenital defect), PDA — later pulmonary HTN (Eisenmenger) if unrepaired
• Cyanotic (R→L): Tetralogy of Fallot (VSD + overriding aorta + RV outflow obstruction + RV hypertrophy), transposition (TGA), tricuspid atresia
• Treatment: repair (ASD/VSD closure, PDA ligation), palliative shunts (Blalock-Taussig for TOF — subclavian → pulmonary), arterial switch (TGA)
• Marfan syndrome: aortic root dilation → dissection → elective root replacement (Bentall)

5. Peripheral arterial disease (PAD) (MUST KNOW)

1. Asymptomatic (bruits, absent pulses) 2. Intermittent claudication (间歇性跛行) — calf pain on walking, relieved by rest; reproducible at a fixed distance; buttock/thigh (aortoiliac — Leriche syndrome: claudication + impotence + absent femoral pulses) 3. Rest pain (静息痛) — pain in the foot at night, relieved by hanging the leg down — critical limb ischemia (CLI) 4. Ulceration & gangrene (溃疡、坏疽) — tissue loss; critical limb ischemia (Rutherford 4-6)

- Ankle-Brachial Index (ABI) (MUST KNOW): normal 0.9-1.3; <0.9 = PAD; <0.5 = severe (rest pain); >1.3 = calcified (diabetes — falsely high); toe pressures - Duplex US (first-line), CT angiography/MRA (planning), catheter angiography (gold standard, invasive)

- Risk factor modification + exercise (supervised walking) + antiplatelet (aspirin) + statin — for claudication - Endovascular: angioplasty ± stenting (iliac — good results; femoral) - Surgical: bypass grafting (femoro-popliteal, aorto-bifemoral) using vein (saphenous) or prosthetic (PTFE); endarterectomy - Critical limb ischemia: urgent revascularization (endovascular or bypass) to save the limb; amputation if unsalvageable - Wound care, diabetes control, infection management (foot ulcer — osteomyelitis)

- Pain, Pallor, Pulselessness, Paresthesia, Paralysis, Poikilothermia (cold) - Cause: embolism (AF — most common) vs thrombosis (on atheroma) vs trauma/dissection - Treatment: EMERGENCY — heparin + urgent revascularization (embolectomy — Fogarty catheter, or thrombolysis/angioplasty) within 6 h; fasciotomy for compartment syndrome; amputation if irreversible - The "blue leg" with preserved pulses = venous (phlegmasia cerulea dolens)

• Cause: atheroma (most common), embolism, trauma — arterial stenosis/occlusion of the lower limbs
• Risk factors: smoking (most important), diabetes, hypertension, hyperlipidemia, age
• Clinical spectrum (Rutherford classification):
• Signs: cold extremity, decreased/absent pulses, bruits, hair loss, shiny skin, pallor on elevation & rubor on dependency, ulcers (toes/heel), gangrene, decreased sensation/movement (acute ischemia)
• Investigations:
• Treatment (MUST KNOW):
• Acute limb ischemia (acute arterial occlusion) — MUST KNOW (the "6 Ps"):

6. Aortic disease (MUST KNOW)

• Abdominal aortic aneurysm (AAA): infrarenal most common; risk (smoking, male, age, family); asymptomatic pulsatile mass → screening US; repair (open or EVAR — endovascular aneurysm repair) when >5.5 cm or symptomatic/rapid growth; RUPTURE = sudden abdominal/back pain + shock + pulsatile mass → emergency open/EVAR (mortality >50%)
• Aortic dissection: sudden tearing chest/back pain (CM exam tested); risk (HTN, Marfan, bicuspid); Stanford A (ascending — surgical emergency) vs B (descending — medical: β-blockers, BP control); imaging CT angiography; complications (tamponade, aortic regurgitation, malperfusion)

7. Venous disease — varicose veins (MUST KNOW)

- Conservative: compression stockings, elevation, exercise, weight loss — first-line for mild - Interventional: endovenous laser/radiofrequency ablation (EVLA/RFA), foam sclerotherapy, or surgical (high ligation + stripping — for severe/large truncal disease; phlebectomy for tributaries) - Venous ulcer: compression (the cornerstone), wound care, infection control, treat reflux (surgery/ablation) to prevent recurrence

• Anatomy (recap): great saphenous vein (anterior to the medial malleolus → saphenous opening → femoral vein) & small saphenous (posterior to the lateral malleolus → popliteal vein); perforators connect deep & superficial
• Pathophysiology: venous reflux (incompetent valves — primary) or obstruction (DVT — secondary); venous hypertension → dilation, tortuosity
• Risk factors: female, age, pregnancy, prolonged standing, family history, obesity, prior DVT
• Clinical: dilated tortuous veins, leg heaviness/aching (worse at the end of the day), ankle swelling, varicose eczema, lipodermatosclerosis, ulceration (medial malleolus — the classic venous ulcer), thrombophlebitis
• Complications: varicose eczema, superficial thrombophlebitis, bleeding, venous ulceration; deep venous insufficiency
• Investigations: Duplex US (reflux, saphenofemoral/saphenopopliteal junction incompetence, perforators, exclude DVT)
• Treatment (MUST KNOW):
• Chronic venous insufficiency (CVI) vs PAD: venous ulcer = medial malleolus, shallow, painless-ish, good pulses; arterial ulcer = toes/heel, painful, absent pulses — always check ABI before compression!

High-Yield Points

• CABG for left main & 3-vessel disease (esp. diabetic); LIMA→LAD (best patency); saphenous vein grafts
• AS: syncope, angina, HF (triad); systolic murmur → carotids; avoid vasodilators
• MS: rheumatic (Asia); diastolic rumble + opening snap; AF & embolism risk
• MR: holosystolic apex → axilla; MV repair preferred
• PAD: claudication → rest pain → ulcer/gangrene; ABI <0.9 = PAD, <0.5 = severe, >1.3 = calcified (diabetes)
• Acute limb ischemia: 6 Ps — emergency heparin + revascularization (embolectomy) within 6 h
• AAA: >5.5 cm → repair (open/EVAR); rupture = shock + pulsatile mass (mortality >50%)
• Dissection: Stanford A = surgical; B = medical (β-blockers)
• Varicose veins: great/small saphenous; duplex US; compression first; EVLA/RFA/surgery for reflux
• Venous ulcer: medial malleolus (compression); arterial ulcer: toes (revascularize — never compress without ABI)
• Endocarditis: fever + new murmur + emboli → antibiotics ± surgery

Topic Summary

Cardiac surgery: CPB & cardioplegia; CABG for left main/3-vessel disease (LIMA→LAD, vein grafts); valve disease (AS — triad + systolic murmur; MS — rheumatic rumble; MR — holosystolic, repair preferred; AR — diastolic, wide pulse pressure); congenital basics (ASD/VSD/PDA acyanotic; TOF cyanotic). PVD: PAD from atheroma — claudication → rest pain → ulcer/gangrene (Rutherford); ABI; risk modification + antiplatelet + statin, angioplasty/stenting, bypass for CLI; acute limb ischemia 6 Ps — emergency embolectomy; AAA >5.5 cm repair, rupture emergency; dissection Stanford A surgical/B medical. Varicose veins: saphenous reflux; compression, ablation/sclerotherapy/surgery; venous vs arterial ulcer differentiation (ABI before compression).