13. Diseases of the Arteries and Veins (1).ppt

Diseases of the Arteries and Veins Aortic Dissection Dissection begins:  either in the proximal aorta, just above the aortic valve, involving the ascending aorta= type A  or at a site beyond the origin of the left subclavian artery, involving the descending aorta= type B Aortic Dissection C...

Diseases of the Arteries and Veins Aortic Dissection Dissection begins:  either in the proximal aorta, just above the aortic valve, involving the ascending aorta= type A  or at a site beyond the origin of the left subclavian artery, involving the descending aorta= type B Aortic Dissection Clinical Findings A. Symptoms and Signs:  Severe, persistent chest pain of sudden onset, later progressing to the abdominal and hip areas  Partial or complete occlusion of the arteries arising from the aortic arch  Peripheral pulses and blood pressures may be diminished or unequal  An aortic diastolic murmur may develop as a result of dissection close to the aortic valve, resulting in valvular regurgitation, heart failure and cardiac tamponade. Aortic Dissection B. Laboratory Findings:  EKG: LVH from long- standing hypertension C. Imaging:  Chest X-ray: wide superior mediastinum, pleural or pericardial effusion  CT scan with contrast enhancement and MRI: both sensitive studies but too time- consuming  Immediate angiography- needed by surgeons preoperatively.  Transesophageal echo of the aorta= becoming the diagnostic study of choice !!! Differential Diagnosis  Myocardial infarction  Pulmonary embolism  Renal- visceral ischemia Treatment A. Medical Measures:  Aggressive measures to lower the blood pressure to 100 mm Hg by: 1) A rapid – acting i.v. drug (Nitroprusside 0.5 mL/min or Trimetaphan 1-2 mg/mL) 2) Intravenous beta-blockers (Metoprolol or Propranolol 0.15 mg/kg) given over a 5 min period and repeated as necessary to maintain the pulse rate at 60/min. Treatment B. Need for surgery:  if pain is not relieved by or if it reappears on this regimen;  if significant occlusion of a major branch of the aorta develops;  if progressive aortic enlargement, suggesting impending rupture occurs;  in al type A dissections. Surgical Measures  In all type A dissections: the ascending aorta and if necessary, the aortic valve and arch may be replaced with re-attachement of the coronaries and brachiocephalic vessels. Mortality rate: 20% or more  Type B dissections: surgical removal of the origin of the dissection, closure of the false lumen, graft insertion to deliver the blood through the normal lumen. Mortality rate: higher than for type A  For patients with poor surgical risk, permanent medical therapy: beta- blockers, aggressive antihypertensive drugs Prognosis  Without treatment, mortality rate at 3 months > 90%  Surgical mortality is higher in type B patients because of co- morbid illnesses  Medical therapy of type A dissection associated with prohibitively high mortality rate ( at least 30% in 24 h, up to 75% in 1 week).  Survival without treatment, usually due to recanalization, does occasionally occur. Atherosclerotic Occlusive Disease Atherosclerotic Occlusive Disease  Occlusive disease of the aorta and its branches is a common cause of disability  It is also a predictor of morbidity for patients with cardiac disease and those undergoing general surgery  Smoking must be interdicted in all individuals  Serum cholesterol should be determined in all Occlusive Disease of the Aorta and Iliac Arteries  Begins more frequently just proximal to the bifurcation of the common iliac arteries or just distal to the bifurcation of the aorta  Progression involves the complete occlusion of one or both common iliac arteries and then the abdominal aorta up to the segment just below the renal vessels.  Although atherosclerosis is generalized disease, occlusion tends to be segmental in distribution  Abrupt worsening of limb ischemia symptoms may be associated with plaque rupture Clinical Findings  Intermittent claudication is almost always present in         the calf muscles and is usually present in the thighs and buttocks Impotence is a common complaint in men Rest pain : infrequent, but serious symptom Femoral pulses are absent or very weak, distal pulses are often impalpable A bruit may be heard over the aorta or over the iliac and femoral arteries Systolic blood pressure, normally higher in the leg, is greater in the brachial artery than at the ankle Atrophic changes of the skin and muscles in the leg Aortography demonstrates the level and extent of the occlusion and the condition of vessels distal to the block Doppler ultrasonography offer noninvasive evaluation Treatment  Surgical or angioplastic treatment is indicated if claudication interferes with the patient’s essential activities or work  Discontinuation of smoking is essential  Many patients have coexisting ischemic heart disease: their medical management should be maximized Treatment A. Conservative Care       A program of daily walking for fixed periods, stopping for claudication, may improve collateralization and function Cilostazol 2x10 mg/day Pentoxyphylline 400 mg three times daily may reduce the need of surgery Limited use of beta- blockers (except BB with peripheral vasodilating properties: Nebivolol) Antiplatelets: Clopidogrel Statins Treatment B. Arterial Graft (Prosthesis): An arterial prosthesis bypassing the occluded segment is effective for complex aorto-iliac occlusive disease. C. Thrombendarterectomy: generally used when the occlusion is limited to the common iliac arteries and when the external iliac and common femoral arteries are free of significant occlusive disease. D. Percutaneous transluminal angioplasty. Acute Arterial Occlusion  Symptoms and signs depend on the artery occluded, the     organ or region supplied by the artery and the adequacy of the collateral circulation to the area primarily involved Occlusion in an extremity usually results in pain, numbness, tingling, weakness and coldness There is pallor ; motor, reflex and sensory alteration Pulsations are absent in arteries distal to the occlusion. Occlusions in other areas result in such conditions as cerebrovascular accidents, intestinal ischemia and gangrene, and renal and splenic infarcts. Arterial Embolism  Is generally a complication of heart disease  A minority of those with embolism have rheumatic heart disease, but most have ischemic heart disease, with or without myocardial infarction  Atrial fibrillation is often present  Emboli tend to lodge at the bifurcation of major arteries, with over half going to the aortic bifurcation or the vessels in the lower extremities  The carotid system is involved in 20%, the upper extremity and the mesenteric arteries in the remainder Arterial Embolism A. Clinical Findings  In an extremity, the initial symptom are usually pain (sudden or gradual onset), numbness, coldness.  Signs include absence of pulsations in the arteries distal to the block, coldness, pallor, hypoesthesia or anesthesia, weakness or paralysis.  The superficial veins are collapsed  Later skin necrosis may appear, and gangrene can result. Arterial Embolism Treatment Immediate embolectomy is the treatment of choice in almost all early case of emboli in the extremities. It is best done within 4-6 hours after the embolic episode A. Emergency Preoperative Care: 1) Heparin- heparin sodium 5000 U i. v., given as soon as the diagnosis is made, maintaining PTT at twice the normal level. 2) Protect the part- the extremity kept below the horizontal plane, protected 3) Imaging- arteriography, echocardiography Arterial Embolism B. Surgical Measures:  local anesthesia, removal of the embolus by Fogarty catheter;  heparinization for a week or more postop.,  prolonged anticoagulation with warfarin  Delayed embolectomy carried out more than 12 hours following embolism involves a high risk of acute respiratory distress syndrome or acute renal failure Thrombophlebitis Thrombophlebitis Thrombophlebitis is a partial or complete occlusion of a vein by a thrombus with secondary inflammatory reaction in the wall of the vein. Trauma to the endothelium of the vein resulting in exposure of sub endothelial tissues to platelets may initiate thrombosis, especially if a degree of venous stasis also exists. Platelet aggregates form on the vein wall followed by the deposition of fibrin, leukocytes, and finally erythrocytes; a thrombus results that may propagate along the vein as a free-floating clot. Thrombophlebitis Within 7-10 days, this thrombus becomes adherent to the vein wall, and secondary inflammatory changes develop The thrombus is ultimately invaded by fibroblasts, resulting in scarring of the vein wall and destruction of the valves. Central recanalization may occur later, with restoration of the flow through the vein; however, the valves do not recover function, directional flow is not reestablished, leading to secondary functional and anatomic problems Thrombophlebitis of the Deep Veins Pain in the calf or thigh, occasionally associated with swelling; alternatively, there may be no symptoms. History of congestive heart failure, recent surgery, neoplasia, oral contraceptive use, or varicose veins; prolonged inactivity also predisposes Physical signs are unreliable Ultrasound is abnormal; venography is diagnostic. General Considerations The deep veins of the lower extremities and pelvis are most frequently involved. The process begins 80% in the deep veins of the calf, with propagation into the popliteal and femoral veins in approx. 25% of cases. About 3% of patients undergoing major surgery will develop clinical manifestations of thrombophlebitis at up to 2 weeks postop.; certain operations ( total hip replacement) are associated with higher incidence of thromboembolic complications. General Considerations Illnesses that involve a period of bed rest (cardiac failure, stroke), use of oral contraceptive drugs, smoking, adenocarcinomas of pancreas, prostate, breast and ovary are associated with higher risk of thrombophlebitis. Rare conditions: protein C and S deficiencies and antithrombin III deficiency should be considered in young patients with positive family histories and recurrent venous thrombosis. Clinical Findings Approx. half of patients have no symptoms or signs in the early stages. The patient may suffer a pulmonary embolism, presumably from the leg veins, without symptoms or demonstrable abnormalities in the extremities. A. Symptoms: dull ache, a tight feeling, or frank pain in the calf or, the whole leg, especially when walking. B. Signs: - slight swelling in the involved calf, distension of the superficial venous collaterals, slight fever and tachycardia. - when the femoral and iliac veins are involved, there may be tenderness over these veins, swelling of the extremity. - the skin may be cyanotic if venous obstruction is severe, or pale and cool if a reflex arterial spasm is superimposed. Diagnostic Techniques 1. Ascending contrast venography - is the most accurate method of diagnosis, will define location, extent and degree of attachment of the thrombosis. -because of the time, expense and discomfort involved, this test is not used as a screening study and is unsuitable for repeated monitoring. -it may on occasion exacerbate a thrombotic process in 55% of pts. Diagnostic Techniques 2) Doppler ultrasound blood flow detector - make it possible to examine the major veins in an extremity for thrombosis. Doppler ultrasound is of value as a rapid screening procedure for the detection of thrombosis in large veins and may be particularly helpful in detecting an extension of small thrombi in the calf veins into the popliteal and femoral veins. Differential Diagnosis Calf muscle strain or contusion may be difficult to differentiate from thrombophlebitis Cellulitis Obstruction of the lymphatics or the iliac vein in the retroperitoneal area from tumor or irradiation may lead to unilateral swelling, more chronic and painless. Acute arterial occlusion: more painful, absent distal pulses, no swelling Bilateral leg edema due to heart, kidney or liver disease. Complications Pulmonary thrombembolism Chronic venous insufficiency Prevention 1. 2. 3. 4. Nonpharmacological Means: Elevation of the foot of the bed 15-20 degrees with slight flexion of the knees. Leg exercises, immediately following major surgery; intermittent pneumatic compression of the legs Elastic antiphlebitic stockings (especially in patients with varicose veins; Walking for brief but regular periods postoperatively, during long airplane and automobile trips Prevention Anticoagulation 1. Low- dose heparin, 5000 units every 812 h s.c. , 2 h preoperatively and during the postoperative period (adjusted- dose heparin to a PTT in the upper half of the normal range, or warfarin to an INR of 1.5-2.0). LMW heparin used increasingly 2. Aspirin, 80- 325 mg daily. Treatment A. Local Measures: legs elevated 15-20 degrees, slightly flexed; duration of bed rest: 7-10 days, tailored to the individual patient. B. Medical Measures (Anticoagulants)- nonfractionated heparin or LMW heparin. Treatment with heparin does not affect thrombi that have already developed but stops propagation and allows fibrinolysis to occur. Duration of therapy: 7-10 days, oral anticoagulation for at least 12 weeks. Permanent anticoagulation may be considered if the stimulus to thrombosis is chronic (congestive heart failure, recurrent thrombosis, repeated pulmonary embolism). Prognosis With adequate treatment the patient usually returns to normal health and activity within 3-6 weeks. The prognosis in most cases is good once the period of danger of pulmonary embolism has passed. Occasionally, recurrent episodes of phlebitis will occur in spite of good local and anticoagulant management. Such cases may even have recurrent pulmonary emboli as well. Chronic venous insufficiency may result, with its associated complications.