Mitral regurgitation resident survival guide

Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-in-Chief: Raviteja Guddeti, M.B.B.S. [2]; Mugilan Poongkunran M.B.B.S [3]

Mitral Regurgitation Resident Survival Guide Microchapters
Overview
Causes
FIRE
Complete Diagnostic Approach
Treatment Acute MR Chronic MR
Do's
Don'ts

Overview

Mitral regurgitation (MR), mitral insufficiency or mitral incompetence refers to a disorder of the heart in which the mitral valve fails to close properly during systole. This leads to leakage of blood flow from left ventricle to left atrium during systole and reduction in cardiac output. The symptoms associated with mitral regurgitation are dependent on which phase of the disease process the individual is in. Individuals with acute mitral regurgitation are often gravely ill with significant hemodynamic abnormalities due to decompensated congestive heart failure and low cardiac output that require urgent treatment, whereas individuals with chronic compensated mitral regurgitation may be asymptomatic, with a normal exercise tolerance and no evidence of heart failure. The management of chronic MR depends on whether the condition is chronic primary MR (the mitral valve is usually abnormal) or chronic secondary MR (the mitral valve is usually normal) and the severity of the valve anatomy.

Causes

Life Threatening Causes

Life-threatening causes include conditions which may result in death or permanent disability within 24 hours if left untreated.

• Acute myocardial infarction
• Blunt chest trauma
• Infective endocarditis

Common Causes

Acute Mitral Regurgitation

• Papillary muscle rupture: Acute myocardial infarction, chest trauma, ischemia
• Ruptured mitral chordae tendinae: Acute rheumatic fever, chest trauma, mitral valve prolapse, infective endocarditis, spontaneous rupture

Chronic Primary Mitral Regurgitation

• Marfan's syndrome
• Mitral annular calcification
• Mitral valve prolapse
• Myxomatous degeneration

Chronic Secondary Mitral Regurgitation

• Dilated cardiomyopathy
• Infective endocarditis
• Ischemic heart disease

Click here for the complete list of causes.

FIRE: Focused Initial Rapid Evaluation

A Focused Initial Rapid Evaluation (FIRE) should be performed to identify patients in need of immediate intervention.

Boxes in salmon colour signify that an urgent management is needed.

ARBs: Angiotensin II receptor antagonist; CABG: Coronary artery bypass surgery; HF: Heart failure; IE: Infective endocarditis; LVEF: Left ventricular ejection fraction; LV: Left ventricle; MR: Mitral regurgitation; S1: First heart sound; S2: Second heart sound

Identify cardinal findings that increase the pretest probability of mitral regurgitation: ❑ Murmur: ❑ High pitched and blowing holosystolic murmur (typical) ❑ Best heard over the apex radiating to the axilla and backsoft, low pitched and decrescendo ❑ Other: ❑ Soft, low pitched and decrescendo (in acute MR due to diminished pressure gradient between the left atrium and ventricle) ❑ Silent (in acute ischemic MR) ❑ Heart sounds: ❑ S1 is diminished (typical) ❑ Wide splitting of S2 (low forward flow causing early A2)

Does the patient have any of the following findings of acute mitral regurgitation with instability? ❑ Sudden onset and rapid progression of pulmonary edema: ❑ Shortness of breath ❑ Tachypnea ❑ Crackles or rales ❑ Signs and symptoms of cardiogenic shock ❑ Altered mental status ❑ Oliguria ❑ Cyanosis ❑ Diaphoresis ❑ Tachycardia ❑ Hypotension ❑ History of heart disease: ❑ Congestive heart failure ❑ Coronary heart disease ❑ Rheumatic heart disease and infective endocarditis

Yes

No

Continue with complete diagnostic approach below

Initial resuscitative measures: ❑ Secure airway ❑ O2 ❑ 2 wide bore IV access ❑ Arterial line ❑ ECG monitor ❑ Monitor vitals continuously ❑ ICU admission Order transthoracic echocardiography (TTE) (urgent): ❑ Confirmatory ❑ To determine severity and assess hemodynamic consequences ❑ To establish etiology ❑ To determine prognosis and evaluate for timing of intervention Order other investigations (urgent): ❑ Chest X-ray ❑ CBC ❑ Serum electrolytes ❑ Serum cardiac troponin I and T ❑ Creatine kinase (CK-MB) ❑ Serum urea and creatinine Initiate medical therapy: ❑ Vasodilator therapy: IV nitroprusside AND ❑ Inotropic agents: IV dobutamine Consider the following: ❑ Mechanical ventilation ❑ Pulmonary artery catheterization

Etiology established through clinical, imaging and laboratory findings

'Ischemic mitral regurgitation:' Initiate medical therapy: ❑ In cases of reduced LVEF (ischemic cardiomyopathy) ❑ Medications: ❑ Angiotensin converting enzyme inhibitors ❑ Angiotensin II receptor blockers ❑ Beta blockers Intra-aortic balloon pump: ❑ To improve forward cardiac output ❑ To reduce the impact on regurgitant volume Reperfusion or revascularization: ❑ CABG or coronary angioplasty ❑ Early reperfusion can reduce localized LV remodeling and hence MR Mitral valve surgery: ❑ Papillary muscle rupture ❑ Moderate to severe ischemic MR who are undergoing CABG ❑ Mitral valve repair: ❑ Most preferred ❑ Done in absence of papillary muscle necrosis ❑ Mitral valve replacement: ❑ In complex MR with extensive destruction ❑ Lateral LV wall motion abnormality Cardiac transplantation: ❑ On some occasions with no contraindication for surgery ❑ In patients with severe LV dysfunction

'MR due to acute exacerbation of HF:' Heart failure management: ❑ Click here for acute heart failure resident survival guide ❑ ACE inhibitors or (ARBs) if LVEF is ≤ 40% ❑ Beta blockers ❑ Intravenous inotropic drugs (dobutamine) ❑ Diuretic therapy ❑ IV vasodilators Mitral valve surgery: ❑ When there is no response to medical management ❑ Mitral valve replacement or mitral valve repair

'MR due to infective endocarditis:' Initiate medical therapy: ❑ Click here for infective endocarditis resident survival guide and antimicrobial treatment Mitral valve surgery: ❑ Urgent surgery: ❑ Persistent heart failure ❑ Pulmonary hypertension ❑ Early mitral valve closure ❑ Mitral valve replacement: ❑ Mostly done ❑ Due to extensive tissue destruction ❑ Mitral valve repair: ❑ If less mitral valve destruction

Complete Diagnostic Approach to Mitral Regurgitation

A complete diagnostic approach should be carried out after a focused initial rapid evaluation is conducted and following initiation of any urgent intervention. Shown below is an algorithm summarizing the complete diagnostic approach to mitral regurgitation according to 2014 AHA/ACC guidelines for management of valvular heart disease..
AF: Atrial fibrillation; MR: Mitral regurgitation; EKG: Electrocardiogram; EF: Ejection fraction; S1: First heart sound; S2: Second heart sound; S3: Third heart sound; LV: Left ventricle; MVP: Mitral valve prolapse

Characterize the symptoms: Acute mitral regurgitation: ❑ Symptoms of shock and pulmonary edema: ❑ Shortness of breath ❑ Orthopnea ❑ Paroxysmal nocturnal dyspnea ❑ Cough ❑ Altered mental status ❑ Pedel edema ❑ Oliguria ❑ Cyanosis ❑ Pallor ❑ Diaphoresis ❑ Abdominal pain (may be suggestive of mesenteric ischemia) ❑ Symptoms suggestive of precipitating events: ❑ Chest pain (suggestive of myocardial ischemia) ❑ Fever (suggestive of infective endocarditis) ❑ Petechiae, Osler's nodes, Janeway lesions (suggestive of infective endocarditis) Chronic mitral regurgitation: ❑ Asymptomatic ❑ Typical in isolated mild to moderate MR ❑ Severe MR until there is left ventricular failure, pulmonary hypertension or atrial fibrillation ❑ Symptoms associated with decreased forward flow and increased backflow across mitral valve: ❑ Exertional dyspnea ❑ Orthopnea ❑ Paroxysmal nocturnal dyspnea ❑ Exercise intolerance ❑ Fatigue ❑ Light-headedness ❑ Exertional syncope ❑ Exertional angina ❑ Cough ❑ Symptoms associated with complications: ❑ Palpitations (suggestive of atrial fibrillation) ❑ Hoarseness (recurrent laryngeal nerve compression due to left atrium enlargement) ❑ Fever (suggestive of infective endocarditis) ❑ Stroke (suggestive of thromboembolism) ❑ Hemoptysis (suggestive of thromboembolism) ❑ Flank pain and hematuria (suggestive of septic emboli or glomerulonephritis) ❑ Seizures (suggestive of thromboembolism) ❑ Symptoms of right heart failure: ❑ Ascites ❑ Pedel edema ❑ Abdominal pain (hepatomegaly) ❑Other etiology associated symptoms: ❑ Joint pains (suggestive of rheumatic etiology) ❑ Skin lesions (suggestive of rheumatic etiology)

Obtain a detailed history: ❑ Past medical history: ❑ Congenital heart disease ❑ Rheumatic heart disease ❑ Ischemic heart disease ❑ Valvular heart disease ❑ Cardiomyopathy ❑ Cardiac surgery ❑ Hypertension ❑ Diabetes mellitus ❑ Radiation exposure ❑ Collagen vascular disease ❑ Chest trauma ❑ Family history: ❑ Valvular heart disease ❑ Medications: ❑ Anorectic drug combinations ❑ Ergotamine ❑ Pergolide ❑ Cabergoline

Examine the patient: Vital signs: ❑ Pulse ❑ Rapid and thready (in acute MR) ❑ Low volume with brisk upstroke (in chronic MR) ❑ Irregularly irregular pulse (with onset of AF) ❑ Blood pressure ❑ Hypotension (in acute MR) ❑ Normotensive (in chronic MR with preserved ejection fraction) ❑ Temperature ❑ Fever (suggestive of infective endocarditis) ❑ Respiratory rate ❑ Tachypnea (typical) Skin: ❑ Cool and clammy (in cardiogenic shock) ❑ Cyanosis ❑ Peripheral edema (suggestive of right heart failure) Cardiovascular system: Palpation: ❑ Apical impulse ❑ Leftward displacement (in chronic MR due enlargement of the left ventricle) ❑ Hyperdynamic but in normal location (in acute MR) ❑ Thrill (in acute MR and severe chronic MR) ❑ Elevated jugular venous pulse ❑ Sign of elevated right sided pressure ❑ Seen in acute MR and severe chronic MR Auscultation: ❑ Heart sounds ❑ S1 is diminished (suggestive of MR) ❑ Wide splitting of S2 (low forward flow causing early A2) ❑ Loud and delayed P2 (suggestive of pulmonary hypertension) ❑ New S3 (suggestive of left ventricular dilation) ❑ Murmur ❑ High pitched and blowing holosystolic murmur (typical) ❑ Best heard over the apex radiating to the axilla and back ❑ Starts after S1 and continues up to and sometime beyond and obscuring A2 ❑ Other types of murmur ❑ Silent (in cases of acute MR) ❑ Mid to late systolic murmur (in case of papillary muscle prolapse) ❑ Early diastolic murmur (due to large diastolic flow across severe MR) ❑ Mid systolic click (suggestive of mitral valve prolapse) Respiratory system: ❑ Crackles or rales (suggestive of pulmonary edema) ❑ Tachypnea Abdominal system: ❑ Hepatojugular reflex ❑ Hepatomegaly ❑ Ascites Neurological system: ❑ Stroke (in case of thromboembolism)

Order electrocardiogram (Urgent): ❑ In acute MR ❑ Mostly normal ❑ Findings of myocardial infarction ❑ In chronic MR ❑ Findings of left ventricular hypertrophy with strain ❑ Findings of left atrial enlargement ❑ Findings of pulmonary hypertension ❑ Findings of atrial fibrillation complication Order chest X-ray (urgent): ❑ Acute MR ❑ Normal size cardiac silhouette ❑ Signs of pulmonary edema ❑ Chronic MR ❑ Cardiomegaly ❑ Signs of pulmonary edema if left ventricle fails ❑ Calcification of the mitral valve annulus Order transthoracic echocardiography (TTE) (urgent): ❑ Confirmatory ❑ To determine severity and assess hemodynamic consequences ❑ To establish etiology ❑ To determine prognosis and evaluate for timing of intervention Order lab tests: ❑ CBC ❑ Electrolytes ❑ ESR ❑ Serum cardiac troponin I and T ❑ Creatine kinase (CK-MB) ❑ Serum urea and creatinine Other tests ❑ Transesophageal echocardiography (TEE if TTE is equivocal) ❑ Cardiac catheterization: ❑ In stable acute MR to detect coronary obstruction ❑ To assess hemodynamic status in symptomatic patients when noninvasive tests are inconclusive ❑ To assess the severity when there is discrepancy between noninvasive testing and physical examination ❑ Exercise testing: ❑ Done in asymptomatic severe MR ❑ To confirm the absence of symptoms ❑ To assess the hemodynamic response to exercise ❑ Cardiac MRI ❑ To assess severity when there is a discrepancy between clinical findings and echocardiography

Cardinal findings that are suggestive of acute mitral regurgitation ❑ Sudden onset and rapid progression of pulmonary edema ❑ Signs and symptoms of cardiogenic shock ❑ Silent to holosystolic murmur on auscultation ❑ Normal ECG ❑ Normal size cardiac silhouette on chest X-ray ❑ Echocardiography findings: ❑ Acute severe mitral regurgitation ❑ Normal left ventricular size ❑ Reduced EF ❑ Ruptured mitral chordae tendinae (flail leaflet) ❑ Ruptured papillary muscle

Cardinal findings that are suggestive of chronic mitral regurgitation ❑ Asymptomatic to chronic symptoms ❑ Pre-existing heart disease ❑ Classic holosystolic murmur on auscultation ❑ ECG findings of left ventricular hypertrophy with strain and left atrial enlargement ❑ Cardiomegaly on chest X-ray ❑ Echocardiography findings: ❑ Mitral regurgitation ❑ Left ventricular dilation ❑ Preserved to decreased EF

Mitral valve anatomy

Normal

Abnormal

Chronic primary mitral regurgitation

Chronic secondary mitral regurgitation

Treatment

Treatment of Acute Mitral Regurgitation

Shown below is an algorithm summarizing the approach to the management of acute mitral regurgitation..
LVEF: Left ventricular ejection fraction; MR: Mitral regurgitation; IE: Infective endocarditis

Acute mitral regurgitation

Assess if the patient is hemodynamically stable? ❑ Hemodynamic instability ❑ Hypotension ❑ Cold extremities ❑ Peripheral cyanosis ❑ Altered mental status

Unstable

Stable

Initial resusticative measures: ❑ Secure airway ❑ O2 ❑ 2 wide bore IV access ❑ Arterial line Initiate medical therapy: ❑ Vasodilator therapy ❑ Nitroprusside AND ❑ Inotropic agents ❑ Dobutamine Consider the following: ❑ Mechanical ventilation ❑ Pulmonary artery catheterization

Initial resusticative measures: ❑ O2 ❑ 2 wide bore IV access ❑ Arterial line Initiate medical therapy: ❑ Vasodilator therapy ❑ Nitroprusside

Ischemic mitral regurgitation

Non-ischemic mitral regurgitation

MR due to cardiomyopathy (functional MR)

MR due to IE (organic MR)

Intra-aortic balloon pump Initiate medical therapy: ❑ In cases of reduced LVEF ❑ Medications: ❑ Angiotensin converting enzyme inhibitors ❑ Angiotensin II receptor blockers ❑ Beta blockers Reperfusion or revascularization Mitral valve surgery: ❑ Papillary muscle rupture ❑ Moderate to severe ischemic MR who are undergoing CABG ❑ Mitral valve repair: ❑ Most preferred ❑ Done in absence of papillary muscle necrosis ❑ Mitral valve replacement: ❑ In complex MR with extensive destruction ❑ Lateral LV wall motion abnormality Cardiac transplantation: ❑ On some occasions with no contraindication for surgery ❑ In patients with severe LV dysfunction

Heart failure management: ❑ Click here for acute heart failure resident survival guide ❑ ACE inhibitors or (ARBs) if LVEF is ≤ 40% ❑ Beta blockers ❑ Intravenous inotropic drugs (dobutamine) ❑ Diuretic therapy ❑ IV vasodilators Mitral valve surgery: ❑ When there is no response to medical management ❑ Mitral valve replacement or mitral valve repair

Mitral valve surgery: ❑ Mitral valve replacement: ❑ Mostly done ❑ Due to extensive tissue destruction ❑ Mitral valve repair: ❑ If less mitral valve destrcution Initiate medical therapy: ❑ Infective endocarditis antimicrobial treatment

Treatment of Chronic Mitral Regurgitation

Chronic Primary Mitral Regurgitation

Shown below is an algorithm summarizing the approach to the management of chronic primary mitral regurgitation..
AF: Atrial fibrillation; IE: Infective endocarditis; LVEF: Left ventricular ejection fraction; LVESD: Left ventricular end systolic dimension; MR: Mitral regurgitation; MVP: Mitral valve proplapse; PASP: Pulmonary artery systolic pressure; RHD: Rheumatic heart disease;

Chronic primary mitral regurgitation

Severe MR: ❑ Etiologies: ❑ Severe MVP with loss of coaptation ❑ RHD with loss of central coaptation ❑ Prior IE ❑ Radiation induced leaflet thickening ❑ Left ventricular dilation ❑ Regurgitation fraction ≥ 50% ❑ Regurgitation volume ≥ 60ml ❑ Effective regurgitation orifice ≥ 0.4cm² ❑ Vena contracta ≥ 0.7cm

Progressive MR (Stage B): ❑ Etiologies: ❑ Severe MVP with normal coaptation ❑ RHD with loss of central coaptation ❑ Prior IE ❑ No Left ventricular dilation ❑ Regurgitation fraction < 50% ❑ Regurgitation volume < 60ml ❑ Effective regurgitation orifice < 0.4cm² ❑ Vena contracta < 0.7cm

Symptomatic (Stage D)

Asymptomatic (Stage C)

Initiate medical therapy: ❑ Vasodialators: ❑ Intravenous nitroprusside ❑ Hydralazine ❑ Beta blocker ❑ Diuretics ❑ Calcium channel blocker Mitral valve surgery: ❑ Mitral valve repair: ❑ Mostly preferred ❑ Mitral valve replacement: ❑ Mechanical valve in patients <65 years who have long-standing AF ❑ Bioprosthetic valves in patients with contraindications to warfarin Revascularisation: ❑ Concurrent coronary artery disease ❑ Revascularized at the time of mitral valve surgery Anticoagulation therapy: ❑ Warfarin: ❑ Target INR 2.5 (range 2.0 to 3.0) ❑ Rheumatic mitral valve disease who have a history of systemic embolism ❑ Left atrial thrombus ❑ Paroxysmal or chronic atrial fibrillation ❑ Aspirin: ❑ 75 to 100 mg/day ❑ Recurrent embolism despite adequate anticoagulation Endocarditis prophylaxis: ❑ Initiate infective endocarditis antimicrobial treatment

Mitral valve surgery: ❑ Performed in the following patients: ❑ LVEF 30 to ≤60% OR LVESD ≥ 40mm (Stage C2) ❑ LVEF >60% AND LVESD < 40mm (Stage C1) ❑ With likelihood of successful repair > 95% ❑ With expected mortality < 1% ❑ New onset AF OR PASP > 50mmHg (Stage C1) ❑ With likelihood of successful repair > 95% ❑ With expected mortality < 1% ❑ Mitral valve repair: ❑ Mostly preferred ❑ Mitral valve replacement: ❑ Mechanical valve in patients <65 years who have long-standing AF ❑ Bioprosthetic valves in patients with contraindications to warfarin Revascularization: ❑ Concurrent coronary artery disease ❑ Revascularized at the time of mitral valve surgery Periodic monitoring: ❑ In stage C1 patients with the following: ❑ With likelihood of successful repair < 95% ❑ With expected mortality > 1% ❑ Echocardiography: ❑ Every 6 months Anticoagulation therapy: ❑ Warfarin: ❑ Target INR 2.5 (range 2.0 to 3.0) ❑ Rheumatic mitral valve disease who have a history of systemic embolism ❑ Left atrial thrombus ❑ Paroxysmal or chronic atrial fibrillation ❑ Aspirin: ❑ 75 to 100 mg/day ❑ Recurrent embolism despite adequate anticoagulation Endocarditis prophylaxis: ❑ Initiate infective endocarditis antimicrobial treatment

Periodic monitoring: ❑ Clinical evaluation: ❑ Every 3-6 months ❑ Echocardiography: ❑ Every 6 months Anticoagulation therapy: ❑ Warfarin: ❑ Target INR 2.5 (range 2.0 to 3.0) ❑ Rheumatic mitral valve disease who have a history of systemic embolism ❑ Left atrial thrombus ❑ Paroxysmal or chronic atrial fibrillation ❑ Aspirin: ❑ 75 to 100 mg/day ❑ Recurrent embolism despite adequate anticoagulation Endocarditis prophylaxis: ❑ Initiate infective endocarditis antimicrobial treatment in case of valve involvement

Chronic Secondary Mitral Regurgitation

Shown below is an algorithm summarizing the approach to the management of chronic secondary mitral regurgitation..

AF: Atrial fibrillation; CAD: Coronary artery disease; HF: Heart failure; IE: Infective endocarditis; LV: Left ventricle; MR: Mitral regurgitation

Chronic secondary mitral regurgitation

Heart failure treatment: ❑ Click here for heart failure resident survival guide ❑ ACE inhibitors ❑ ARBs ❑ Beta blockers ❑ Intravenous inotropic drugs (dobutamine) ❑ Diuretictherapy ❑ IV vasodilators

CAD treatment: ❑ Click here for coronary artery disease medical therapy ❑ Aspirin ❑ ACE inhibitors ❑ Beta blockers ❑ Coronary angiography ❑ Click here for revascularization therapy

Cardiac resynchronization therapy: ❑ Cardiac resynchronization therapy with biventricular pacing: ❑ In functional MR patients with ventricular dyssynchrony ❑ Reduce LV end-systolic and end-diastolic dimensions ❑ Reduce mitral regurgitant jet area

Severe MR: ❑ Echo findings: ❑ Regional wall motion abnormalities with severe tethering of mitral leaflet ❑ Annular dilation with severe loss of central coaptation of the mitral leaflets ❑ LV dilation and systolic dysfunction due to primary myocardial disease ❑ Regurgitation fraction ≥ 50% ❑ Regurgitation volume ≥ 30ml ❑ Effective regurgitation orifice ≥ 0.2 cm²

Progressive MR (Stage B): ❑ Echo findings: ❑ Regional wall motion abnormalities with mild tethering of mitral leaflet ❑ Annular dilation with mild loss of central coaptation of the mitral leaflets ❑ LV dilation and systolic dysfunction due to primary myocardial disease ❑ Regurgitation fraction < 50% ❑ Regurgitation volume < 30ml ❑ Effective regurgitation orifice < 0.2 cm²

Stage D: Symptomatic (HF symptoms due to MR persist even after revascularization and medical therapy)

Stage C: Asymptomatic (HF and coronary ischemia symptoms respond to revascularization and medical herapy)

HF and coronary ischemia symptoms respond to revascularization and medical herapy

Mitral valve surgery: ❑ Mitral valve repair: ❑ Mostly preferred ❑ Mitral valve replacement: ❑ Mechanical valve in patients <65 years who have long-standing AF ❑ Bioprosthetic valves in patients with contraindications to warfarin Anticoagulation therapy: ❑ Warfarin: ❑ Target INR 2.5 (range 2.0 to 3.0) ❑ History of systemic embolism ❑ Left atrial thrombus ❑ Paroxysmal or chronic atrial fibrillation ❑ Aspirin: ❑ 75 to 100 mg/day ❑ Recurrent embolism despite adequate anticoagulation Endocarditis prophylaxis: ❑ Initiate infective endocarditis antimicrobial treatment

Periodic monitoring: ❑ Clinical evaluation: ❑ Every 3-6 months ❑ Echocardiography: ❑ Every 6 months Mitral valve surgery: ❑ Only in patients undergoing other cardiac surgery ❑ Mitral valve repair: ❑ Mostly preferred ❑ Mitral valve replacement: ❑ Mechanical valve in patients <65 years who have long-standing AF ❑ Bioprosthetic valves in patients with contraindications to warfarin Anticoagulation therapy: ❑ Warfarin: ❑ Target INR 2.5 (range 2.0 to 3.0) ❑ History of systemic embolism ❑ Left atrial thrombus ❑ Paroxysmal or chronic atrial fibrillation ❑ Aspirin: ❑ 75 to 100 mg/day ❑ Recurrent embolism despite adequate anticoagulation Endocarditis prophylaxis: ❑ Initiate infective endocarditis antimicrobial treatment for patients undergoing mitral valve surgery

Periodic monitoring: ❑ Clinical evaluation: ❑ Every 3-6 months ❑ Echocardiography: ❑ Every 6 months Mitral valve surgery: ❑ Only in patients undergoing other cardiac surgery ❑ Mitral valve repair: ❑ Mostly preferred ❑ Mitral valve replacement: ❑ Mechanical valve in patients <65 years who have long-standing AF ❑ Bioprosthetic valves in patients with contraindications to warfarin Anticoagulation therapy: ❑ Warfarin: ❑ Target INR 2.5 (range 2.0 to 3.0) ❑ History of systemic embolism ❑ Left atrial thrombus ❑ Paroxysmal or chronic atrial fibrillation ❑ Aspirin: ❑ 75 to 100 mg/day ❑ Recurrent embolism despite adequate anticoagulation Endocarditis prophylaxis: ❑ Initiate infective endocarditis antimicrobial treatment for patients undergoing mitral valve surgery

Diagnosis

Symptoms

• Acute mitral regurgitation causes the following symptoms:
  • Dyspnea
  • Orthopnea
  • Hypotension

• Chronic mitral regurgitation may have a prolonged asymptomatic interval phase until the heart decompensates and the symptoms of low cardiac output and pulmonary congestion start. By the time the symptoms develop, left ventricular dysfunction may have already occurred.

Physical Examination

• S₃ and S₄ may be heard on auscultation.
• A holosystolic murmur is heard in the apical region of the heart. MR murmur radiates to the axillary region. It may be soft, short and even absent. 70% of the cases of papillary muscle rupture have no murmur.

Holosystolic murmur of acute mitral regurgitation.	Holosystolic murmur of chronic mitral regurgitation.

Imaging

Transthoracic echocardiography

Echocardiographic findings indicating the presence of severe mitral regurgitation include:

• Regurgitant volume >60 ml
• Regurgitant fraction >55%
• Effective regurgitant orifice (ERO) (ratio of regurgitant flow volume to the velocity of the mitral insufficiency jet: ERO = Flow / Velocity) >0.4 cm²
• If the left ventricular and left atrial sizes are normal on echocardiography, mitral regurgitation is not severe.
• Central jets indicate the presence of a fairly normal mitral valve and therefore the mitral regurgitation is not severe.
• Wide eccentric jets indicate that the regurgitation is severe.
• Echocardiographic findings must match the symptoms, if they do not, perform transesophageal echocardiography (TEE) or cardiac catheterization. TTE can underestimate the magnitude of mitral regurgitation in patients with clinical signs of severe MR.

Treatment

Acute Severe Mitral Regurgitation

• Treatment of acute severe mitral regurgitation depends on the stability of the patient.If the patient is clinically stable, the treatment options are:
  • IV vasodilators, diuretics, antibiotics, anti-ischemic agents
  • Surgery is preferred in the following cases:
    • Endocarditis with progressive congestive heart failure
    • No response to antibiotics
    • Abscess formation
    • Recurrent embolization

• If the patient is clinically unstable , the treatment options are:
  • IV nitroprusside is used to maintain blood pressure. Inotropes are added when needed.
  • If medical therapy is not effective, an intra aortic balloon pump can be inserted to maintain hemodynamic stability.
  • Surgical treatment is usually indicated.
  • Knowledge of the etiology of the mitral regurgitation is important to know if the valve can be repaired or replaced.

Chronic Mitral Regurgitation

Why the Mitral valve is replaced Before Symptoms in Patients with Chronic Mitral Regurgitation

• Mitral regurgitation is a syndrome of pure volume overload whereas aortic regurgitation is a combination of both volume and pressure overload.
• Both syndromes are associated with an increase in preload.
• in mitral regurgitation, the afterload is reduced whereas in aortic regurgitation the afterload is increased. This is very important because when the mitral valve is repaired, there is no longer a reduction afterload and the left ventricle may fail due to an abrupt rise in the afterload. In aortic regurgitation, because the afterload is already increased chronically, replacement of the valve is not as likely to precipitate acute left ventricular failure due to an abrupt rise in afterload.

• By the time symptoms develop, there is already left ventricular dysfunction.
• Because of the low pressure system into which the blood is ejected into through the mitral valve, the ejection fraction is always high in mitral regurgitation. If the ejection fraction appears to be "normal", there is already decline in left ventricular function.
• There is no indication for vasodilator therapy in the absence of systemic hypertension in asymptomatic patients with preserved left ventricular function.

Indications for Surgery in Chronic Mitral Regurgitation

The indications for surgery in chronic mitral regurgitation are:

• Any symptoms - this is unlike mitral stenosis where surgeons operate on the heart when patients have class III or IV symptoms.
• Severe organic MR.
• Left ventricular dysfunction - ejection fraction <60% and end systolic diameter >40 mm².
• Surgery can be considered in asymptomatic patients in the following cases:
  • Truly severe MR
  • Low operative mortality
  • High chance of successful repair (e.g: posterior leaflet - MVP)

• Pre-operative ejection fraction has a prognostic impact in patients who undergo mitral valve repair or replacement. The lower the ejection fraction is, the higher the mortality is.

Do's

Don'ts

• Don't perform coronary angiography before valve surgery in patients who are hemodynamically unstable.
• Avoid coronary angiography in patients of acute coronary syndrome complicated by severe acute mitral regurgitation.

References

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