Anesthesia for Valvular Heart Surgery * 07/16/96 Anesthesia for Valvular Heart Surgery Charles E. Smith, MD Professor of Anesthesia Director, Cardiothoracic Anesthesia MetroHealth Medical Center Case Western Reserve University *

Objectives Pathophysiology Hemodynamic Goals Anesthetic management * 07/16/96 Objectives Pathophysiology Aortic valve: AS, AI Mitral valve: MS, MR Tricuspid valve: TR Hemodynamic Goals Anesthetic management *

Aortic Stenosis May occur at 3 levels: Valvular Subvalvular * 07/16/96 Aortic Stenosis May occur at 3 levels: Valvular Subvalvular Supravalvular *

Valvular Aortic Stenosis * 07/16/96 Valvular Aortic Stenosis Calcification + fibrosis of normal tricuspid valve- very common Calcification + fibrosis of congenital bicuspid AV Rheumatic- uncommon since antibiotics *

Aortic Stenosis Normal AVA: 2-4 cm2 Severe AS: AVA < 1cm2 * 07/16/96 Aortic Stenosis Normal AVA: 2-4 cm2 Severe AS: AVA < 1cm2 If normal LV- mean PG > 50 mmHg If poor LV function- mean PG may be low! *

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Pathophysiology of Aortic Stenosis * 07/16/96 Pathophysiology of Aortic Stenosis Chronic LV pressure overload Concentric LVH to ↓ wall stress LVH → ↓ diastolic compliance, ↓ coronary blood flow + imbalance of MVO2 supply-demand ↓ diastolic compliance → ↑LVEDP + LVEDV Myocardial ischemia bc LVH, ↑ wall stress, ↓ diastolic coronary perfusion + ↓ coronary flow reserve *

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Hemodynamic Goals: AS SR is crucial. Cardiovert SVTs promptly * 07/16/96 Hemodynamic Goals: AS SR is crucial. Cardiovert SVTs promptly Optimal HR 60-80. Tachycardia → ischemia + ectopy. Bradycardia → low CO due to fixed SV Adequate preload essential but difficult to predict bc diastolic dysfunction [TEE useful] Maintain contractility. Avoid myocardial depressants Treat hypotension promptly- phenylephrine, volume, Trendelenburg *

AS: Considerations Drugs to maintain CPP: Phenylephrine Norepinephrine * 07/16/96 AS: Considerations Drugs to maintain CPP: Phenylephrine Norepinephrine Atrial kick – crucial. HR 60-80 preferred Spinal + epidural anesthesia poorly tolerated if  preload or  HR *

* 07/16/96 AS: Management Premed: young+ anxious get benzos. Frail + elderly  dose (or avoid) Intraop: std monitoring + preinduction art line. Resting HR 60-80. Avoid myocardial depressants CVP, PAC, TEE- routine for optimal management *

AS: Weaning from Bypass * 07/16/96 AS: Weaning from Bypass Thick, hypertrophied heart may be difficult to protect- stone heart still occurs (rare) Noncompliant LV dependent on stable rhythm Inotropes if preop LV dysfunction Dynamic subaortic or cavitary obstruction after AVR if septal LVH Tx w volume, β-blockers. Rarely need myomectomy [inotropes worsen obstruction] *

Septal LVH with SAM. Tx= volume + beta-blockers * 07/16/96 Septal LVH with SAM. Tx= volume + beta-blockers *

Aortic Regurgitation: Etiology Aortic root dilatation- HTN, ascending aorta dissection, cystic medial necrosis, Marfans, syphilitic aortitis, ankylosing spondylitis, osteogenesis imperfecta Deformed + thickened cusps- rheumatic, IE, bicuspid valve Cusp prolapse- dissection

Horse kick to upper chest with severe AI. * 07/16/96 From horse kick to lt upper chest. Tee showed thickening+ prolapse of av leaflets. There was a disruption of the attachment of the RCC to the STJ Horse kick to upper chest with severe AI. The RCC was torn from the STJ *

Pathophysiology: Chronic AR Asymptomatic for many years LV volume + pressure overload occurs LV maintains systolic fct by dilation + ↑ compliance LV decompensates at later stages w ↑ LVEDP + LVEDV→ CHF, arrhythmias, sudden death

Pathophysiology: Acute AR LV unable to dilate acutely LV volume overload occurs ↑ LVEDP + LVEDV→ acute pulmonary edema Emergency surgery often needed

Hemodynamic Goals: AR Optimal HR= 90. Avoid bradycardia- ↑ regurg Avoid high afterload SNP preferred Acute AR- often need inotropes + vasodilator [epi+ SNP/milrinone] IABP- contraindicated

Anesthetic Management: AR Premed w benzos Routine monitoring: art line, CVP, PAC TEE beneficial Narcotic based technique if impaired LV If acute AR: RSI w ketamine-succinylcholine Inotropes if acute AR or preop LV dysfunction

Mitral Stenosis Usually rheumatic- thickening, calcification + fusion of MV leaflets + commissures May be combined w MR + AR Surgery if MVA < 1 cm2 w NYHA class III or IV dyspnea [or embolus- LAA clot]

MS- Pathophysiology Pressure gradient between LA + LV- prevents LV filling Pulmonary HTN w ↑ LAP ↑ LAP → LAE, atrial arrhythmias (Afib) Pulm HTN → RV dysfct, RVE, TR [may need TV repair] LV dysfct uncommon unless CAD

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MS: Hemodynamic Goals Preserve SR, if present * 07/16/96 MS: Hemodynamic Goals Preserve SR, if present Avoid tachycardia which ↓ diastolic filling of LV + worsens MS Avoid factors which worsen pulmonary HTN- hypercarbia, acidosis, hypothermia, sympathetic nervous system activation, hypoxia *

Anesthetic Management: MS * 07/16/96 Anesthetic Management: MS Premed: benzos to avoid tachycardia If pulm HTN- supplemental O2 Control of HR- β blockers, digoxin, CEB, amiodarone *

Intraop Management: MS * 07/16/96 Intraop Management: MS Std monitors + CVP, PAC, TEE PAP underestimates LVEDP + LVEDV Esmolol: single most useful drug with severe MS, even if CHF + pulmonary edema 10-20 mg bolus; 50-100 mcg/kg/min N2O avoided bc effects on pulm HTN Panc avoided bc tachycardia *

Weaning from Bypass: MS * 07/16/96 Weaning from Bypass: MS MV replacement- hemodynamics usually improved bc obstruction to LV filling resolved If preop pulm HTN + RV dysfct- may need milrinone or nitric oxide *

Mitral Regurgitation: Etiology * 07/16/96 Mitral Regurgitation: Etiology Myxomatous degeneration (most common) Ischemic (functional)- papillary muscle dysfunction, annular dilatation, LV dysfct + tethering Infective endocarditis Trauma *

Papillary muscle rupture after blunt trauma * 07/16/96 Papillary muscle rupture after blunt trauma Papillary muscle rupture after blunt trauma *

MR- Pathophysiology Volume overload of LV→ LVE, LAE * 07/16/96 MR- Pathophysiology Volume overload of LV→ LVE, LAE LA can massively dilate Atrial arrhythmias with LAE Dilated LV decompensates at later stages w  LVEDV *

Chronic MR. Dilated LA w normal LAP * 07/16/96 Chronic MR. Dilated LA w normal LAP *

Chronic MR. Dilated LA w normal LAP * 07/16/96 Chronic MR. Dilated LA w normal LAP Acute MR. Small LA with ↑ ↑ LAP+ pulmonary edema *

Severity of MR Pressure gradient between LA + LV Size of regurgitant orifice (ERO) Duration of ventricular systole

Hemodynamic Goals- MR: * 07/16/96 Hemodynamic Goals- MR: Vasodilators: NTG, SNP - ↓ afterload + regurgitant fraction + ↑ forward flow High normal HR to ↑ time of ventricular systole Maintain contractility *

Anesthetic Management MR: * 07/16/96 Anesthetic Management MR: MV repair (v. replacement) preserved papillary muscle + chordae enhanced LV function requires TEE to assess repair LV dysfct unmasked after MV surgery bc LV cannot offload into LA May need inotropes + vasodilators *

Tricuspid Regurgitation Primary: rheumatic, IE, carcinoid, Ebstein’s, trauma Secondary: chronic RV dilatation, often w MV disease

Flail TV after blunt trauma

TR- Pathophysiology RV + RA overloaded + dilated RA v compliant so RAP rises only w end stage disease Pulm HTN due to MV disease- ↑ RV afterload + worsens TR RVE → paradoxical motion LV septum w imapired LV filling + compliance Right heart failure: hepatomegaly, ascites

TR- Hemodynamic Goals If secondary to MV- treat left heart lesion Avoid pulm HTN + high PVR Normal to high preload for RV stroke volume Hypotension treated w inotropes + volume bc vasoconstrictors may worsen pulm HTN

TR- Anesthetic Management Premed- benzos Std monitors + art line, CVP, TEE PAC if pulm HTN + MV pathology; but CO overestimated w severe TR. May be impossible to float Swan Weaning from CPB: if preop RV dysfunction/ dilation- inotropes, inodilators, vasodilators, nitric oxide

Summary- I Knowledge of patient + extent of valvular heart disease * 07/16/96 Summary- I Knowledge of patient + extent of valvular heart disease Functional + hemodynamic status Co-morbidities Planned surgery: cannulation sites, repair vs replacement, minimally invasive vs full bypass. Inotropes, vasodilators, vasopressors, infusion pumps *

* 07/16/96 Summary- II Understand pathophysiology of lesions + hemodynamic goals: AS, AR, MS, MR, TR Monitoring: standard + invasive +TEE Anesthetic technique: most can be used safely. Adjustment of dosages more important than adhering to a rigid anesthetic technique. *