Aortic aneurysms-anaesthesia PowerPoint Presentation

Slide 1 -

Aortic aneurysms and anesthesia Moderator: Dr. Renu Presenters: Dr. Dipal Dr. Mridu www.anaesthesia.co.in anaesthesia.co.in@gmail.com

Slide 2 -

Sub acute aortic dissection Expanding aortic aneurysm Stable aortic aneurysm Coarctation of aorta Atherosclerotic disease Bioprosthetic valve Graft failure Progression Pseudo aneurysm

Slide 3 -

Anatomy of aorta:

Slide 4 -

ppt slide no 4 content not found

Slide 5 -

ppt slide no 5 content not found

Slide 6 -

ppt slide no 6 content not found

Slide 7 -

ppt slide no 7 content not found

Slide 8 -

Aortic Aneurysm: Definition: Dilatation of aorta containing all the 3 layers of the vessel wall that has diameter of at least 1.5 times that of the expected normal diameter of that given aortic segment. I = 5.9/100000 Age: 65 yrs n above M > F

Slide 9 -

Pseudo aneurysms: Localized dilatation Wall : not all 3 layers, clots, connective tissue, surrounding tissue Cause: contained rupture of aorta intimal disruptions penetrating atheromas partial dehiscence of suture line

Slide 10 -

Risk factors: Hypertension Hypercholesterolemia Prior tobacco use Collagen vascular disease Family history Smoking Diabetes mellitus Male Obesity

Slide 11 -

Classification: Etiology: Atherosclerosis: most common cystic medial necrosis descending: distal to L Subclavian A, large and medium size vessels Theories: Inflammation, CRP, IL-6, Aspirin, Statins, cholesterol, estrogen, antioxidants,

Slide 12 -

Classification contd.. Annuloaortic ectasia: AR, younger age Syndromes: Marfans, Ehler-Danlos, Turner Familial: 19%, younger Inflammatory: giant cell arteritis, mycotic, takayasu, syphilis Aortic dissection Trauma: deceleration, partial/ complete transection at isthmus, saccular, discrete

Slide 13 -

Classification contd.. Location: Aortic root and Ascending aorta: 60% AR, bicuspid aortic valve Descending aorta :40 % endovascular Arch of aorta: 10% cerebral protection Thoracoabdominal: 10%, paraplegia, multiple segments

Slide 14 -

Classification contd.. Shape: Fusiform: common atherosclerosis/ CVD longer segment dilation of entire segment Saccular: localized isolated segment localized out pouching Size: physiologic effect, consequences

Slide 15 -

Clinical manifestations: Most asymptomatic Incidental : x-ray, ct scan, echo AR CHF Mass effect: trachea/ main stem bronchus, pulmonary veins, esophagus, rln, bone Pain due to dissection/rupture Pulsatile mass in epigastrium

Slide 16 -

Diagnosis: X-ray chest: mediastinal widening, tracheal deviation CECT: confirm, size, suprarenal CT angiography: MR angiography: aortic root Transthoracic ECHO: aortic root, not mid/ distal ascending aorta, marfan Transesophageal ECHO USG: screening AAA

Slide 17 -

Screening: Recommended : all men 60-85 yrs all women 60-85 yrs with CVS risk factors both with family history and age >50yrs

Slide 18 -

Medical management: Inform and warn Discontinue smoking Avoid heavy lifting/straining ß blockers Statins ACE inhibitors Antihypertensives: 105-120 mmHg Familial: screening Serial imaging: 6mths, 1yr.

Slide 19 -

Indications for repair: Symptoms refractory to medical treatment Evidence of rupture Increase in diameter ≥ 1cm/yr Diameter: ascending aorta≥5.5cm (5cm) descending aorta≥6.5cm (6cm) Severe aortic regurgitation

Slide 20 -

Indications for repair contd.. Aortoannular ectasia with dilated aortic root Congenital bicuspid aortic valve:≥4cm Contained or impending rupture Earlier: marfans, family history of dissection/ aortic disease

Slide 21 -

Pre existing medical illness Aortic valve disease Cardiac tamponade PVD: embolus, ischemia, stroke CVD: failure, ischemia, infarction, arrthymias, pulmonary edema Cardiomyopathy/ valvular disease Cerebrovascular disease

Slide 22 -

Pre existing medical illness contd.. Pulmonary disease: postop failure, pneumonia Renal insufficiency: fluid, drugs Esophageal disease: TEE Coagulopathy: ↑ bleeding, transfusion, h’ggic cx, epidural, CSF drainage Prior aortic operations

Slide 23 -

Airway assessment: Cervical spine: TEE Large airways mass effect: difficult intubation, OLV, airway compromise

Slide 24 -

Perioperative morbidity Non fatal and fatal MI: 4.9% and 2.3% Long term MI: 8.9% and 9.1% Coronary artery revascularization and prophylaxis trial ACC/AHA guidelines

Slide 25 -

Assessment of cardiovascular risk: ECG: Baseline Prior MI: risk stratification Dysrhythmias: other than sinus: risk Lacks sensitivity

Slide 26 -

Assessment of cardiovascular risk: Exercise ECG: 30-70% cannot reach target HR Poor functional capacity, ß blocker etc If 85% of predicted maximal HR achieved: low risk Arm exercise: fatigue precedes increase

Slide 27 -

Assessment of cardiovascular risk: Myocardial perfusion imaging: DTI: most common, non invasive, RR 4.6 2 images, steal phenomenon 3 outcomes: normal, myocardium at risk, fixed perfusion defect Eagle et al and L’italien et al: no additional stratification for pts classified as low or high risk. Classified 80% of intermediate risk into low or high risk.

Slide 28 -

Assessment of cardiovascular risk: Ambulatory ECG monitoring: RR 2.7 Detect dysrythmias Sensitivity: in pts with high pretest probability 80-90% MI silent: periop morbidity Low cost Not in LBBB, pacemaker dependency, LVH, significant strain or digitalis

Slide 29 -

Assessment of cardiovascular risk: Echocardiography: With 5 or > abnormal segments: 4-6 fold ↑ risk of cardiac Cx Stress echocardiography: TEE superior to transthoracic DSE: sensitivity: and specificity 80-90% Stratifies pts only with risk factors Pericardiac events unlikely if result –ve Best predictor: RR 6.2

Slide 30 -

Assessment of cardiovascular risk: Radionuclide ventriculography: LVF at rest or exercise RR 3.7 Independent predictor of periop cardiac morbidity EF < 35% : 75-85% MI risk >35% : 19-20% However limited use

Slide 31 -

Assessment of cardiovascular risk: Summary: DTI, AECG, DSE: high negative predictive value Low risk not = 0 risk Negative result does not guarantee pt has no CAD None has high positive predictive value

Slide 32 -

Assessment of pulmonary risk: COPD, smoking, chronic bronchitis ABG: baseline PACO2 > 45 = higher risk PFT: FEV1<1lit/ MBC<50% Steroids short course: helpful in copd/ asthma May benefit from epidural analgesia and anesthesia

Slide 33 -

Assessment of renal function: HTN, atherosclerosis, diabetic nephropathy, renal artery stenosis Pre and intraop dye loads: nephrotoxic Aortic cross clamping:↓ bld flow Embolic plaque Fluctuations in CO and intravascular vol ARF: abt 7%

Slide 34 -

Assessment of renal function: Preop ARF most imp predictor of postop ARF Pathogenesis: ATN Clamp distal to Subclavian A: 85-94%↓ in bld flow Infrarenal: >30%↓ S. Creat > 2 mg% : high risk

Slide 35 -

Pre-anesthetic assessment: Urgency of operation Pathology and extent of disease Median sternotomy/ thoracotomy/ endovascular approach Mediastinal mass effect Airway compromise/ deviation

Slide 36 -

Preoperative medications: All cardiac, antihypertensive, pulmonary, antiseizure to continue OHA: discont, metformin(48hrs prior) Insulin: 1/3rd – ½ usual dose Warfarin: 3-7 days prior, INR Heparin infusion Aspirin, clopidogrel; Ticlopidine Anxiolytics: BDZ/opioids

Slide 37 -

General Anesthetic management: Haemodynamic monitoring: Neurophysiologic monitoring OLV for thoracotomy Bleeding potential Antibiotic prophylaxis Temperature monitoring Blood sugar monitoring

Slide 38 -

Haemodynamic monitoring: ECG IBP: proximal aortic pressure: R radial- Innominate A, BP: repair of arch/ prox L radial A: ACP, B/L Femoral: distal aortic pressure, avoided in PVD CVP: RAP, vasoactive drugs PAC: PAP, CO, mixed Svo2, (CPB, DHCA, partial LSHB, aortic-cross clamping) TEE: ventricular ft

Slide 39 -

Neurophysiologic monitoring: To monitor for intraop spinal ischemia: SSEP MEP EEG Jugular venous oxygen saturation Lumbar CSF pressure Body temperature

Slide 40 -

SSEP: Electrical stimuli to peripheral nerves and record evoked potential at peripheral nerves, spinal cord, brainstem, thalamus, cerebral cortex ↓/ disappearance of amplitude in LL v/s UL Balanced anesthesia technique, MAC <0.5 Monitors only posterior column not motor

Slide 41 -

MEP: Paired stimuli to scalp and record evoked potential in anterior tibialis muscle ↓/ disappearance of amplitude in LL v/s UL TIVA without N-M blockade

Slide 42 -

ppt slide no 42 content not found

Slide 43 -

Temperature monitoring: Core: Urinary catheter with temp probe PAC probe Nasopharyngeal probe Rectal probe

Slide 44 -

OLV L thoracotomy or L thoracoabdominal approach of TAAA Adv: improves surgical exposure ↓lung contusion or torsion protects R lung in bleeding DLT/ BB Advantages and disadvantages of each If DLT- exchange at the end of Sx

Slide 45 -

Bleeding potential Increased risk: Intrinsic disease Vascular anastomosis Extracorporeal circulation Hypothermia

Slide 46 -

Bleeding potential contd.. Strategies: Discontinue anticoagulants/antiplatelets Large bore i.v. access Immediate availability of blood products Fluid warming unit Urine output monitoring Precise control of BP Cell salvage Bio glue Antifibrinolytics: ε-aca, traxenamic acid Factor VII A

Slide 47 -

Drugs: Vasopressors and vasodilators Etomidate: haemodynamic stability Narcotics, NMDR, inhalational Doses ↓ 30°C, stopped:18°C, resumed at rewarming EEG/ SSEP: barbiturates/ propofol avoided, inhalational = 0.5 MAC MEP: TIVA

Slide 48 -

Ascending TAA: Mortality: 3-5% Median sternotomy TEE: valve sparing Sx, diameter, AR post repair CPB Wheat procedure: AVR + tube graft Bentall procedure: AVR Ross procedure: PV-> AV Carbol technique: coronary reimplantation

Slide 49 -

Arch aneurysms: Cerebral protection: embolus, ischemia DHCA Trifurcated tube grafts Elephant trunk procedure

Slide 50 -

ppt slide no 50 content not found

Slide 51 -

Descending TAA: Mortality: 4% Lateral thoracotomy/ thoracoabdominal incision Cross clamping/ partial L heart bypass/ DHCA Spinal cord, mesenteric, LL protection Endovascular stent grafts

Slide 52 -

Staged repair: Multiple segments Greater risk of rupture Placing of clamps Elephant trunk procedure

Slide 53 -

Abdominal AA Mortality: 4-6% (elective), 2% in low risk Elderly Atherosclerosis, coexisting illness Risk of rupture: 3 times > F, smokers, HTN, rapid rate of expansion Classification: with and without dissection

Slide 54 -

Crawford classification of TAAA

Slide 55 -

Abdominal AA contd.. Renal, Mesenteric, LL, Spinal Cord ischemia Monitoring Fluid management Epidural analgesia Cross clamping/ Gott shunt/ DHCA Endovascular stent grafts Infrarenal good survival

Slide 56 -

Aortic clamping Mortality and paraplegia related to : position and length of resected aorta condition of pt duration≥ 30 min

Slide 57 -

AoX Passive recoil distal to clamp ­Catecholamines (and other vasoconstrictors) ­ Impedance to Ao flow Active vasoconstriction proximal and distal to clamp ­R art If coronary flow and contractility do not increase ­Preload ­Coronary flow ­Afterload ­Contractility ­CO ¯ If coronary flow and contractility increase

Slide 58 -

ppt slide no 58 content not found

Slide 59 -

Haemodynamic changes: ↑BP ↑ Segmental wall motion abnormalities ↑ Left ventricular wall tension ↓ Ejection fraction ↓ Cardiac output ↓ Renal blood flow ↑ Pulmonary occlusion pressure ↑ CVP ↑ Coronary blood flow

Slide 60 -

Metabolic changes: ↓ Total body oxygen consumption ↓ Total body CO2 production ↑Mixed venous O2 saturation ↓ Total body oxygen extraction ↑ Epinephrine , nor epinephrine Respiratory alkalosis Metabolic acidosis

Slide 61 -

% change in CVS variables

Slide 62 -

Therapeutic interventions: Afterload reduction: SNP Inhaled anesthetics Amrinone Shunts and aorto-femoral bypass Preload reduction: NTG Controlled phlebotomy Atrial to femoral bypass

Slide 63 -

Therapeutic intervention: Renal protection: Fluid administration Distal aortic perfusion techniques Mannitol Drugs to augment renal perfusion Other changes: Hypothermia ↓ Minute ventilation Sodium bicarbonate

Slide 64 -

Aortic unclamping:

Slide 65 -

ppt slide no 65 content not found

Slide 66 -

Haemodynamic changes: ↓Myocardial contractility ↓ BP ↑PAP ↓ CVP ↓ Venous return ↓ CO

Slide 67 -

Metabolic changes: ↑Total body oxygen consumption ↓ Lactate ↓ Mixed venous O2 saturation ↓ Prostaglandins ↓ Activated complement ↓ Myocardial depressant factors ↓ Temperature Metabolic acidosis

Slide 68 -

Therapeutic interventions: ↓ Inhaled anesthetics ↓ Vasodilators ↑Fluid administration ↑ Vasoconstrictor drugs Reapply cross clamp for severe hypotension Consider mannitol Consider sodium bicarbonate

Slide 69 -

Endovascular stent graft repair: Fabric/ synthetic tube grafts reinforced by a wire frame Requires 1 cm long non-tapered region of aorta on either end of aneurysm for landing

Slide 70 -

ppt slide no 70 content not found

Slide 71 -

Endovascular stent graft repair: Intraop angiography/ TEE Long term benefits to be determined Problems: vessel injury intravascular migration strut # postop paraplegia intravascular leaks

Slide 72 -

ppt slide no 72 content not found

Slide 73 -

Hypertension: Moderate: not independent risk factor Continue them: prevent rebound increase in HR, BP, avoid withdrawal Clonidine: ↓ anesthetic req, catecholamine levels, BP lability CCB: MI not affected ACE inhibitors: intraop hypotension, avoided Shorter acting drugs

Slide 74 -

ß- blockers: ↓ mortality and morbidity with silent MI, acute MI, CHF Prevention of catecholamine induced arrhythmia, plaque disruption Blunting neurohumoral and haemodynamic effects of sympathetic stimulation ACC/ AHA: level I recommendation

Slide 75 -

Pre-op CVS assessment… ACC/AHA Guidelines for periop CVS evaluation for noncardiac surgery Functional activity Clinical predictors of risk Deg of surg. stress

Slide 76 -

ACC-AHA Guidelines. Functional capacity Metabolic equivalent (MET) 1 MET- 02 (Vo2) consumption of a 70kg man in a resting state (3.5 ml/kg/min) MET- daily activities Excellent (>10 METS) Good (7-10 METS) Moderate (4-7 METS) Poor (<4 METS)

Slide 77 -

Estimated Energy Requirements for Various Activities

Slide 78 -

Major Unstable Coronary Syndromes Recent myocardial infarction* with evidence of important ischemic risk by clinical symptoms or non-invasive study Unstable or severe† angina (Canadian class III or IV)‡ Decompensated congestive heart failure Significant dysrhythmias High-grade atrioventricular block Symptomatic ventricular dysrhythmias in the presence of underlying heart disease Supraventricular dysrhythmias with uncontrolled ventricular rate Severe valvular disease Clinical Predictors of Increased Perioperative Cardiovascular Risk

Slide 79 -

Intermediate Mild angina pectoris (Canadian Class I or II) Prior myocardial infarction by history or pathologic Q waves Compensated or prior congestive heart failure Diabetes mellitus Renal insufficiency Minor Advanced age Abnormal ECG (left ventricular hypertrophy, left bundle-branch block, ST-T abnormalities) Rhythm other than sinus (e.g. atrial fibrillation) Low functional capacity (e.g., inability to climb one flight of stairs with a bag of groceries) History of stroke Uncontrolled systemic hypertension Clinical Predictors of Increased Perioperative Cardiovascular Risk (Contd.)

Slide 80 -

ppt slide no 80 content not found

Slide 81 -

ppt slide no 81 content not found

Slide 82 -

ppt slide no 82 content not found

Slide 83 -

ppt slide no 83 content not found

Slide 84 -

CNS: h/o TIA or stroke: Duplex imaging of Carotid A and angiography of Brachiocephalic and Intracranial A: if >80-90%stenosis of one or both: Consider Carotid Endarterectomy before elective operation.

Slide 85 -

BP: Proximal: maintain 100mmHg Can upto 180-200 if no CI(intracranial h’gge) and if acceptable operating conditions. Relative hypotension(<20% of resting pressure) should be avoided unless shunts used to perfuse lower parts of body. Distal pressure maintain at 50mmHg