Anesthesia for patients with mitral regurgitation

INTRODUCTION — 

In resource-abundant countries, mitral regurgitation (MR) is a common valve lesion that may occur from a variety of etiologies (figure 1):

●Primary causes (ie, intrinsic disease of the mitral leaflets or subvalvular apparatus; eg, mitral valve prolapse, infective endocarditis)

●Secondary causes (eg, ischemic heart disease [postinfarction or ischemic] or cardiomyopathy) which usually cause left ventricular or atrial enlargement and dilation of the mitral annulus

●Dynamic processes (eg, MR caused by systolic anterior motion [SAM] of the mitral valve associated with dynamic left ventricular outflow tract [LVOT] obstruction that occurs in some patients with hypertrophic cardiomyopathy [HCM], other causes of left ventricular hypertrophy, or stress [takotsubo] cardiomyopathy)

The prevalence of significant MR increases with age, as illustrated by a population study in which more than 9 percent of adults ≥75 years old had moderate to severe MR (table 1) [1].

This topic will discuss hemodynamic and anesthetic management of patients with MR during noncardiac surgical procedures or open cardiac surgical procedures involving the mitral valve.

Anesthetic management for percutaneous interventions to treat MR (eg, transcatheter edge-to-edge mitral valve repair) is discussed separately. (See "Anesthesia for percutaneous cardiac valve interventions", section on 'Transcatheter edge-to-edge mitral repair'.)

Anesthetic considerations for patients with MR during labor and delivery are discussed separately. (See "Anesthesia for labor and delivery in high-risk heart disease: Specific lesions", section on 'Regurgitant lesions'.)

OVERVIEW OF MITRAL REGURGITATION

Primary MR

Chronic primary MR — Primary MR is caused by abnormality in one or more of the four components of the valve apparatus (leaflets, chordae tendineae, papillary muscles, and mitral annulus). Causes of primary MR include degenerative disease (mitral valve prolapse), valve destruction (eg, infective endocarditis), and rheumatic valve disease.

Severe MR causes the following hemodynamic changes:

●Left atrial and pulmonary vascular effects – Chronic MR with chronic volume overload of the left atrium (LA) is accompanied by elevated LA pressure and LA enlargement with associated risk of atrial dysrhythmias, particularly atrial fibrillation (AF). If MR is severe, increased pulmonary venous pressure causes elevations in pulmonary artery pressure (PAP, and may result in vascular changes with increased pulmonary vascular resistance (PVR) [2].

●Left ventricular size and function – Severe chronic MR causes chronic left ventricular (LV) volume overload. In this setting, the LV ejection fraction typically overestimates intrinsic LV systolic function because a portion of each ejection volume flows into the low-pressure LA chamber rather than against the high impedance of the aorta [3]. Thus, if preoperative estimates of LV ejection fraction are reduced, it is likely that significant ventricular dysfunction is present.

Symptoms of heart failure (HF) in patients with severe mitral (or aortic) regurgitation typically manifest as excessive fatigue with gradual onset of dyspnea during exertion, due to a gradual decrease in forward cardiac output and an increase in pulmonary congestion. Severe physical deconditioning may be present in patients who limit their physical activity because of symptoms interfering with ability to exercise or even to perform normal daily activities (table 2).

For chronic MR, the prevalence, etiology, pathophysiology, stages, and indications for percutaneous or surgical intervention are discussed in separate topics (table 3) [4,5]:

●(See "Pathophysiology and natural history of chronic mitral regurgitation".)

●(See "Clinical manifestations and diagnosis of chronic mitral regurgitation".)

●(See "Chronic primary mitral regurgitation: General management".)

●(See "Chronic primary mitral regurgitation: Indications for intervention".)

●(See "Chronic primary mitral regurgitation: Choice of intervention".)

Acute primary MR — Primary MR can also be caused by acute processes such as chordae or papillary muscle rupture, valve destruction or perforation with endocarditis, rheumatic fever, or mechanical injury (trauma or iatrogenic injury). (See "Acute mitral regurgitation in adults: Clinical presentation and diagnosis" and "Acute mitral regurgitation: Management".)

Secondary MR

Chronic secondary MR — Chronic secondary or functional MR may be either ischemic or non-ischemic in origin:

●Ischemic heart disease (caused by prior myocardial infarction [MI] and/or myocardial ischemia) with segmental and/or global LV systolic dysfunction, often with LV and mitral annular dilation. (See "Treatment of ischemic cardiomyopathy".)

●Dilated cardiomyopathy, typically with LV dilation and global LV systolic dysfunction with mitral annular dilation. (See "Causes of dilated cardiomyopathy".)

Chronic secondary MR is sometimes further classified as ventricular functional mitral regurgitation and atrial functional mitral regurgitation. In the former, there is incomplete coaptation of the leaflets due to left ventricular dilatation or infarction. In the latter, left atrial enlargement, often from diastolic dysfunction or atrial fibrillation, results in mitral annulus enlargement and incomplete leaflet coaptation. In contrast to primary MR, the mitral leaflet appears quite normal. The prevalence, etiology, pathophysiology, stages of MR severity, and indications for percutaneous or surgical intervention for chronic secondary MR are discussed in separate topics:

●(See "Pathophysiology and natural history of chronic mitral regurgitation".)

●(See "Clinical manifestations and diagnosis of chronic mitral regurgitation".)

●(See "Chronic secondary mitral regurgitation: General management and prognosis".)

●(See "Chronic secondary mitral regurgitation: Intervention".)

Acute secondary MR — Acute secondary MR may occur in the setting of regional wall motion abnormality due to myocardial infarction (MI) or myocardial ischemia due to mitral leaflet tethering resulting from papillary muscle excess angulation or displacement. (See "Acute mitral regurgitation in adults: Clinical presentation and diagnosis", section on 'Etiology'.)

Dynamic MR with SAM — Dynamic MR may occur in patients with systolic anterior motion (SAM) of the mitral valve with hypertrophic cardiomyopathy (HCM) accompanied by LV outflow tract (LVOT) obstruction, other causes of left ventricular hypertrophy, or stress cardiomyopathy. (See "Acute mitral regurgitation in adults: Clinical presentation and diagnosis", section on 'Nonischemic causes'.)

PREOPERATIVE ASSESSMENT AND MANAGEMENT

General approach — Preanesthetic assessment for cardiac or noncardiac surgery involves reviewing the cardiology consultant’s assessment of the chronicity and severity of MR and associated hemodynamic alterations (which determines the stage of chronic MR), concomitant cardiac valve disease, and concomitant cardiac disease (eg, coronary artery disease and heart failure) [4,6,7].

Chronic MR

Cardiac surgery — Preanesthetic assessment is described above, including assessment of stage of chronic primary (table 3) or secondary MR (table 4). Other aspects of preoperative assessment for elective cardiac surgery are discussed separately. (See "Overview of preoperative evaluation and management for cardiac surgery in adults".)

●For chronic primary MR – Indications and techniques for interventions in patients with chronic primary MR are discussed in separate topics:

•(See "Chronic primary mitral regurgitation: Indications for intervention".)

•(See "Chronic primary mitral regurgitation: Choice of intervention", section on 'Surgical valve repair versus replacement'.)

●For chronic secondary MR – Indications and techniques for interventions in patients with chronic secondary MR are discussed in separate topics.

•(See "Chronic secondary mitral regurgitation: Intervention", section on 'Choice of mitral surgical procedure'.)

•(See "Surgical procedures for severe chronic mitral regurgitation".)

Some patients undergoing other types of cardiac surgery (eg, coronary artery bypass grafting [CABG] for ischemic heart disease) also have severe chronic MR. Indications for a concomitant mitral valve replacement or a repair procedure are discussed separately. (See "Chronic secondary mitral regurgitation: Intervention", section on 'Indications for mitral valve intervention'.)

Noncardiac surgery — For patients with MR who are undergoing noncardiac surgery, a separate topic reviews history and physical examination, cardiac diagnostic studies, optimization of coexisting medical conditions, as well as indications for mitral valve intervention prior to elective surgery. (See "Noncardiac surgery in patients with mitral or aortic regurgitation", section on 'Chronic mitral regurgitation'.)

Acute MR — Acute symptomatic severe MR is a cardiovascular emergency. The suddenly increased LA pressure may cause "flash" pulmonary edema, acute right heart failure, or cardiogenic shock. Treatment of acute MR requires urgent intensive medical stabilization. Mechanical circulatory support such as insertion of an intraaortic balloon pump (IABP) before surgery or a coronary intervention may be beneficial by reducing LV afterload and increasing diastolic coronary arterial blood flow. These issues are discussed separately. (See "Acute mitral regurgitation: Management", section on 'Medical stabilization'.)

Patients with acute severe MR caused by disruption of the mitral valve apparatus (eg, ruptured papillary muscle) are generally managed with urgent or emergency surgical repair. Transcatheter catheter repair is an option for selected patients with very high surgical risk. These issues are discussed separately. (See "Acute mitral regurgitation: Management".)

Anesthetic considerations for emergency cardiac surgery are discussed in a separate topic. (See "Anesthesia for emergency cardiac surgery".)

Dynamic MR — For patients with systolic anterior motion (SAM) of the mitral valve, left ventricular outflow tract obstruction, and dynamic MR, the associated condition (hypertrophic cardiomyopathy [HCM], other cause of left ventricular hypertrophy, or stress [takotsubo] cardiomyopathy) is identified and treated. (See "Acute mitral regurgitation in adults: Clinical presentation and diagnosis", section on 'Etiology' and "Acute mitral regurgitation: Management" and "Acute mitral regurgitation: Management", section on 'For systolic anterior motion (SAM) of the mitral valve'.)

Preanesthetic medication management — Medication management before noncardiac surgery in patients with acute or chronic MR may include:

●Cardiovascular medications – Chronically administered cardiovascular medications for management of cardiac risk or arrhythmias (eg, beta blockers, calcium channel blockers, statins, amiodarone) are typically continued in the perioperative period [4,6]. Details regarding perioperative management of these cardiovascular medications are available elsewhere:

•(See "Perioperative medication management", section on 'Cardiovascular medications'.)

•(See "Perioperative management of heart failure in patients undergoing noncardiac surgery", section on 'Preoperative management'.)

●Antiplatelet and anticoagulant medications – In patients with an indication for aspirin therapy, aspirin is typically continued.

Management of chronic anticoagulant therapy in patients with atrial fibrillation (AF) balances thromboembolic risk and bleeding risk to determine the optimal timing of anticoagulant interruption and whether to use bridging anticoagulation. Patients undergoing urgent or emergency surgery after recent administration of anticoagulant therapy may require urgent anticoagulant reversal to prevent or treat severe bleeding. Such patients are not appropriate candidates for a neuraxial technique. Further discussion is available in separate topics. (See "Perioperative management of patients receiving anticoagulants" and "Neuraxial anesthesia/analgesia techniques in the patient receiving anticoagulant or antiplatelet medication".)

Perioperative management of other chronically administered medications is discussed separately. (See "Perioperative medication management".)

Premedication — Heavy premedication is avoided in patients with severe MR, although small incremental doses of a short-acting IV benzodiazepine (eg, midazolam 1 to 2 mg) may be administered in the immediate preoperative period if necessary to avoid or treat anxiety.

HEMODYNAMIC MANAGEMENT

Key goals and issues — Key principles for hemodynamic management of patients with mitral regurgitation (MR) depend on the cause:

●Primary MR – Hemodynamic management of patients with primary MR is summarized in the table (table 5), with details described below. (See 'Parameters for primary and secondary MR' below.)

●Secondary MR – Hemodynamic management of patients with secondary MR due to ischemic heart disease or dilated cardiomyopathy includes the following considerations in addition to hemodynamic management as discussed below (see 'Parameters for primary and secondary MR' below):

•With ischemic heart disease – For patients with ischemic heart disease, anesthetic and hemodynamic management must include considerations for the underlying ischemic heart disease (table 6), as well as considerations for MR. Details are discussed in a separate topic. (See "Anesthesia for noncardiac surgery in patients with ischemic heart disease".)

•With cardiomyopathy – For patients with cardiomyopathy, anesthetic and hemodynamic management must include considerations for associated heart failure (table 7), as well as considerations for MR. Details are discussed in a separate topic. (See "Anesthesia for noncardiac surgery in patients with heart failure".)

●Dynamic MR – Hemodynamic management for patients with dynamic MR secondary to systolic anterior motion of the mitral valve (SAM) differs markedly from that for either primary MR or secondary functional MR. Inotropes are avoided in patients with dynamic MR since enhanced contractility is likely to increase the severity of MR. Beta blocker therapy (if tolerated) may reduce the associated left ventricular outflow obstruction and thus reduce MR. (See "Acute mitral regurgitation: Management", section on 'For systolic anterior motion (SAM) of the mitral valve'.)

Hemodynamic and anesthetic management of patients with hypertrophic cardiomyopathy (HCM) are discussed in the table (table 8), and separately. (See "Anesthesia for patients with hypertrophic cardiomyopathy undergoing noncardiac surgery".)

Parameters for primary and secondary MR

Heart rate

●Primary MR – For patients with primary MR, maintain a normal to fast heart rate (HR) of 80 to 95 beats per minute (bpm) to reduce regurgitation into the left atrium (LA) during systole. However, excessive tachycardia (eg, due to poorly controlled ventricular rate in a patient with atrial fibrillation [AF]) is avoided.

Avoid bradycardia in this setting. Glycopyrrolate 0.2 mg may be administered and repeated if necessary to treat bradycardia. If associated with hypotension, bradycardia may be treated with bolus doses of ephedrine 5 mg. If these agents are ineffective, a low-dose infusion of dobutamine, epinephrine, or dopamine may be initiated (table 9). (See "Perioperative arrhythmias", section on 'Sinus bradycardia'.)

●Secondary MR – Some patients with secondary MR may present with a lower HR since they have received preoperative beta blocker therapy (table 7). For patients with secondary MR due to ischemic heart disease, a target HR around of 55 to 80 bpm is generally optimal to reduce the risk of provoking ischemia (table 6).

Heart rhythm — Although sinus rhythm (SR) is hemodynamically optimal, many patients with chronic MR have AF. Supraventricular tachyarrhythmias (SVT) including AF are generally better tolerated in patients with primary MR than in those with aortic stenosis (AS) or mitral stenosis (MS). However, SVT with a rapid ventricular response may result in hemodynamic instability requiring pharmacologic rate control or cardioversion. (See "Atrial fibrillation: Overview and management of new-onset atrial fibrillation".)

Afterload (systemic vascular resistance) — Control of hypertension is important in patients with MR because elevated systemic vascular resistance (SVR) may worsen regurgitant flow into the LA and decrease cardiac output (CO).

●Primary MR – In this setting, prevent significant increases in SVR by maintaining a low to normal systolic blood pressure (BP) of approximately 100 to 120 mmHg, or within 20 percent of baseline, since higher systolic BP increases regurgitant flow and decreases forward flow. Elevations in BP are prevented by ensuring continuation of chronically administered antihypertensive medications, adequate depth of anesthesia intraoperatively, and effective postoperative analgesia. If necessary, a vasodilator such as sodium nitroprusside or clevidipine may be administered by continuous infusion to decrease SVR and systolic BP (table 9 and table 10).

●Secondary MR – For patients with secondary MR, management of systolic BP is particularly challenging. Many patients with secondary MR have coexisting coronary artery disease with a risk of developing myocardial ischemia. Hemodynamic management involves ensuring adequate BP to optimize oxygen delivery to the myocardium while limiting myocardial oxygen demand (table 6). Adequate BP is necessary to maintain adequate coronary perfusion pressure and myocardial oxygen supply during diastole. However, acute increases in systolic BP are avoided or treated since these may increase regurgitant flow into the LA and decrease forward flow, and may also increase myocardial oxygen demand. A reasonable approach is to maintain systolic BP and mean arterial pressure (MAP) close to preoperative values throughout the perioperative period. (See "Anesthesia for noncardiac surgery in patients with ischemic heart disease", section on 'Prevention of ischemia'.)

●MR with left ventricular (LV) systolic dysfunction – LV systolic dysfunction is more commonly present in patients with secondary MR than with primary MR. For hypotension in a patient with chronic MR and reduced LV ejection fraction, reasonable treatment options include continuous infusion of an inodilator such as milrinone and/or a beta-adrenergic inotropic agent such as dobutamine (table 9). Addition of or substitution with a low-dose epinephrine infusion may be necessary to maintain adequate BP in some patients.

Pure alpha-adrenergic agonists (eg, phenylephrine) are generally avoided. However, if a vasopressor agent is needed, cautious adjustment (ie, in small doses or with incremental adjustments) is required, with close monitoring to avoid a sudden increase in afterload and/or bradycardia, which may worsen MR and further reduce CO.

Preload (intravascular volume) — Maintain preload while attempting to avoid volume overload.

Most patients with primary or secondary MR are receiving chronic diuretic therapy and may present to the operating room with relative hypovolemia. This is treated with fluid administration in 100 to 250 mL increments to restore and maintain optimal intravascular volume, with assessment of the hemodynamic response and respiratory status after each increment. Aggressive fluid administration is avoided due to risk of fluid overload and pulmonary edema.

In some cases, a patient with primary or secondary MR presents to the operating room with hypervolemia and pulmonary edema. This is generally treated with an intravenous (IV) nitroglycerin infusion (table 10) and/or diuretic administration (eg, furosemide 10 to 20 mg) to reduce preload. Nitroglycerin may be particularly useful in patients with ischemic MR and evidence of hypervolemia and pulmonary edema.

Contractility — Avoid doses of drugs that might cause significant depression of myocardial contractility (eg, high doses of propofol or volatile anesthetic agents).

If continuous infusion of an inotropic agent is necessary for a patient with MR and severe ventricular systolic dysfunction, an inodilator such as milrinone or dobutamine is typically selected (table 9). Occasionally, in a patient with hypotension, infusion of low-dose epinephrine may be necessary.

Pulmonary artery pressure — Elevated pulmonary artery pressure (PAP) with or without elevated pulmonary vascular resistance (PVR) is common in patients with chronic severe MR [8]. In this setting, avoid hypoxemia, hypercarbia, and metabolic acidosis, which increase PVR and thus cause or exacerbate pulmonary hypertension (PH) [8].

Considerations for concomitant cardiac conditions — Many patients with mitral valve disease have a combination of stenosis and regurgitation in a single cardiac valve, disease of more than one valve, or coexisting coronary disease (see "Valvular heart disease in older adults"). In such cases, optimal hemodynamic management depends on which of the lesions is predominant and which hemodynamic changes are likely to be most deleterious (table 11). A reasonable approach for a patient who is hemodynamically stable and compensated in the preoperative period is to target preoperative HR and BP intraoperatively.

As an example, some patients present with a combination of MR and mitral stenosis (MS) [9,10]. Hemodynamic targets for such patients take the differing requirements for each lesion into consideration (table 12 and table 5). Typically, a normal HR (eg, 70 to 80 bpm), normal or low to normal SVR, and normal contractility are optimal [6,11,12].

Additional anesthetic and hemodynamic considerations are applicable for patients with MR and other underlying cardiac disease:

●Ischemic heart disease (table 6) – (See "Anesthesia for noncardiac surgery in patients with ischemic heart disease".)

●Cardiomyopathy (table 7) – (See "Anesthesia for noncardiac surgery in patients with heart failure".)

ANESTHETIC MANAGEMENT FOR NONCARDIAC SURGERY

General approach — The choice of anesthetic techniques and agents is based on requirements for accomplishing the surgical procedure, as well as the hemodynamic goals for primary mitral regurgitation (MR) or similar goals for secondary MR (which in some cases is caused by ischemic heart disease). Regardless of which technique is selected, pain-induced tachycardia and hypertension are avoided. Hypertension with increased systemic vascular resistance (SVR) exacerbates both MR and myocardial ischemia, and tachycardia also exacerbates ischemia (table 6 and table 5).

Sedation with monitored anesthesia care — Management of monitored anesthesia care (MAC) with or without a peripheral nerve block for patients with primary MR due to any etiology is similar to that for patients with other types of cardiac valve pathology (eg, aortic stenosis) (see "Anesthesia for patients with aortic stenosis", section on 'Sedation with monitored anesthesia care'), or ischemic heart disease (see "Anesthesia for noncardiac surgery in patients with ischemic heart disease", section on 'Local anesthesia with monitored anesthesia care'). It is particularly important to avoid oversedation with consequent hypoventilation, hypercapnia, and hypoxemia to prevent increases in pulmonary vascular resistance (PVR) or exacerbation of ischemia.

Neuraxial anesthesia — For patients with primary or secondary MR, gradual afterload reduction with neuraxial anesthesia can be beneficial to decrease MR severity. However, preload should be maintained [6]. Patients who had undergone aggressive diuresis in the preoperative period are at risk for hypotension immediately after placement of a neuraxial block due to hypovolemia and vasodilation caused by the sympatholysis (see "Overview of neuraxial anesthesia", section on 'Cardiovascular'). This is managed with incremental fluid boluses of 100 to 250 mL, and with small bolus doses of ephedrine 5 to 10 mg and/or phenylephrine 40 to 100 mcg.

General anesthesia

Monitoring

●Intra-arterial catheter – An intra-arterial catheter may be placed for major procedures, particularly in patients with fluid overload and pulmonary congestion.

●Transesophageal echocardiography – Monitoring with transesophageal echocardiography (TEE) may be helpful if a major vascular, orthopedic, or abdominal procedure is planned, particularly if the patient has coexisting coronary artery disease or if the severity of MR is uncertain.

Severity of MR is qualitatively estimated with color-flow Doppler to assess regurgitant jet size (ie, the length and area of the regurgitant jet in the left atrium, and the magnitude of the aliased portion), as well as the eccentricity of the jet (image 1 and table 13). In addition, the width of the vena contracta should be measured because it is easy to acquire, is reproducible, and is relatively independent of ventricular loading conditions (movie 1). (See "Transesophageal echocardiography in the evaluation of mitral valve disease", section on 'Severity of mitral regurgitation'.)

Also, volume status, vascular resistance, degree of regurgitation, and both right and left regional and global ventricular function can be continuously monitored with TEE during surgery. (See "Intraoperative transesophageal echocardiography for noncardiac surgery".)

Anesthetic agents and techniques — Considerations for selecting anesthetic agents and techniques are similar for patients with MR and aortic regurgitation (AR). Details are discussed separately. (See "Anesthesia for patients with aortic regurgitation", section on 'Anesthetic agents and techniques'.)

ANESTHETIC MANAGEMENT FOR CARDIAC SURGERY

General considerations for cardiac surgery — General considerations for anesthetic management of patients undergoing open cardiac surgery with cardiopulmonary bypass (CPB) are discussed in separate topics:

●General preoperative considerations – (See "Overview of preoperative evaluation and management for cardiac surgery in adults".)

●Intraoperative considerations

•(See "Anesthesia for cardiac surgery: General principles".)

•(See "Initiation of cardiopulmonary bypass".)

•(See "Management of cardiopulmonary bypass".)

•(See "Weaning from cardiopulmonary bypass".)

•(See "Intraoperative problems after cardiopulmonary bypass".)

●Early postoperative considerations – (See "Postoperative care after cardiac surgery".)

Prebypass hemodynamic management — Key principles for hemodynamic management during the prebypass period for patients with MR are summarized in the table (table 5).

Additional considerations apply to patients with secondary MR due to ischemic heart disease (table 6).

Other hemodynamic considerations may be relevant for patients with other coexisting cardiac pathology. Examples include:

●MR with coronary artery disease (CAD) – Many patients with MR have coexisting coronary artery disease [13,14]. These patients are particularly prone to develop myocardial ischemia in the prebypass period. Hemodynamic management involves ensuring adequate systemic blood pressure (BP) to optimize oxygen delivery to the myocardium while limiting myocardial oxygen demand (table 6). (See "Anesthesia for coronary artery bypass grafting surgery".)

●MR with tricuspid regurgitation – Patients who develop right-sided heart failure and tricuspid regurgitation often have pulmonary hypertension. Chronically administered pulmonary vasodilator agents are continued during the perioperative period. (See "Anesthesia for noncardiac surgery in patients with pulmonary hypertension or right heart failure".)

Prebypass TEE assessment — Prebypass (and postbypass) transesophageal echocardiography (TEE) assessment is indicated for cardiac valve surgical procedures [15,16]. Details for performing the intraoperative TEE examination for patients undergoing cardiac surgical procedures for MR are discussed in a separate topic. (See "Transesophageal echocardiography in the evaluation of mitral valve disease", section on 'Role of intraoperative transesophageal echocardiography'.)

Chronic mitral regurgitation — Prior to CPB, the TEE examination is focused on quantification of MR severity, the mechanism causing MR and whether the valve can be repaired or should be replaced, presence of pathology in other cardiac valves, and status of left ventricular (LV) and right ventricular (RV) function.

Severity of chronic MR is semi-quantitatively estimated with color-flow and pulsed-wave Doppler to assess regurgitant jet size (length, area), and eccentricity (image 1 and table 13) [17]. If the MR jet is eccentric, the jet may be visualized on edge, which may result in underestimation of jet size.

●Systolic reversal of flow in one or more pulmonary veins can be seen in severe MR [18].

●The width of the vena contracta should be measured since it is easy to acquire, is reproducible, and is relatively independent of ventricular loading conditions (movie 1). This measurement is made at the narrowest neck of the MR jet, obtained in a mid-esophageal four-chamber view [17].

●In addition, the proximal isovelocity surface area (PISA) method can be helpful in quantitation of effective regurgitant orifice area (EROA) or regurgitant volume but can lead to underestimation in patients with eccentric jets. Quantitative Doppler using the continuity equation can also be used to determine the EROA and regurgitant volume if aortic regurgitation is not present.

●Other echocardiographic signs of severe MR include a peak E velocity >1.2 m/second and a dense continuous wave Doppler MR jet signal.

However, alterations in ventricular loading conditions can alter the severity of MR, resulting in MR severity estimates that are not typical for the patient [19]. For example, MR severity is typically underestimated after induction of general anesthesia due to decreases in sympathetic tone and LV afterload, and MR severity can vary considerably during surgery [17,20]. Thus, if intraoperative confirmation of severity is critically important, assessment should be performed during hemodynamic conditions approximating the patient's preoperative baseline. Transient use of a vasopressor agent such as phenylephrine may be necessary to restore the BP to baseline levels [20]. (See "Transesophageal echocardiography in the evaluation of mitral valve disease", section on 'Severity of mitral regurgitation'.)

TEE examination of mitral valve structure includes assessment of the anterior leaflet, posterior leaflet, papillary muscles, chordae tendineae, and mitral valve annulus (figure 2) [17].

For patients with primary MR, intraoperative three-dimensional (3D) TEE enables detailed study of valve morphology and quantitative analysis of annular size and leaflet dimensions important to the repair of degenerative mitral valves (resulting in mitral valve prolapse, partial flail, or flail leaflet).

●Carpentier's classification of mitral valve regurgitation is often used as a common language for the echocardiographer and surgeon in assessing the etiology of MR and the likelihood of successful repair. Type 1 lesions (with normal leaflet motion) and type 2 lesions (excessive leaflet motion) are typically more amenable to operative repair than type 3 lesions (restricted leaflet motion) [17,21].

●Repair is less likely to be successful if there is extensive calcification or degeneration of a leaflet or annulus, significant mitral stenosis, prolapse of more than one-third of the leaflet tissue, or extensive chordal fusion, calcification, or papillary muscle rupture [17].

●Other assessments include:

•Estimation of the risk of post-repair systolic anterior motion (SAM) of the mitral valve.

•Determination of the correct annuloplasty device size.

•Determination of the largest size mitral valve prosthesis that will fit in the patient (based on inter-trigonal distance) in case the repair fails.

•Determination of the precise location of the left circumflex coronary artery relative to the location of annular sutures.

Further discussion is available in other topics:

●(See "Transesophageal echocardiography in the evaluation of mitral valve disease", section on 'Role of intraoperative transesophageal echocardiography'.)

●(See "Chronic primary mitral regurgitation: Choice of intervention", section on 'Surgical valve repair versus replacement'.)

●(See "Rheumatic mitral stenosis: Overview of management", section on 'Concomitant indication for cardiac surgery'.)

The other cardiac valves are also examined individually, with particular attention to whether significant tricuspid regurgitation (TR) or aortic regurgitation (AR) is present.

In addition, the LV is examined for regional wall motion abnormalities that may be associated with ischemic MR, or global LV dysfunction due to ischemia, or LV dilation due to chronic volume overload [22,23]. The RV is examined for possible dilation and dysfunction due to chronic pulmonary hypertension.

Acute mitral regurgitation — Prior to CPB, the TEE examination is focused on the mechanism causing acute MR, determination of whether the valve is likely repairable, hemodynamics (including Doppler estimation of cardiac output [CO] through the left ventricular outflow tract), and status of LV and RV function. Other valve lesions are also evaluated.

In acute MR, the regurgitant jet velocity may be lower, the jet area may not be large, and the jet is often markedly eccentric, all of which may contribute to underestimating the degree of regurgitation. Quantitation of MR severity is also attempted, although the above-described methods for quantifying chronic severe MR (table 13) may not apply to acute MR. Presence of the combination of a flail leaflet or ruptured papillary muscle, pulmonary vein systolic flow reversal, and a hyperdynamic LV with low systemic output by Doppler suggests acute severe MR, even in the absence of a large regurgitant jet [24]. Since patients with acute MR frequently present with hypotension (even prior to induction of general anesthesia), high left atrial (LA) pressure, and an eccentric MR jet, color-flow Doppler imaging may not detect a large regurgitant jet in the LA despite the presence of pulmonary vein systolic flow reversal [24]. (See "Acute mitral regurgitation in adults: Clinical presentation and diagnosis", section on 'Echocardiography'.)

Surgical techniques — Open mitral valve repair or replacement is usually achieved through a midline sternotomy, followed by the establishment of CPB and opening of the LA to repair or replace the valve. The left atriotomy may be made posteriorly at the interatrial groove, or the LA can be entered across the interatrial septum via a right atriotomy. Regardless of the atriotomy approach, bicaval venous cannulation is recommended to create a bloodless operating field and provide adequate venous drainage for CPB.

If mitral valve replacement is necessary, either a bioprosthetic or mechanical mitral valve may be implanted, as discussed separately. (See "Choice of prosthetic heart valve for surgical aortic or mitral valve replacement".)

Concomitant procedures may be performed at the time of open cardiac surgery to treat MR. Examples include:

●Concomitant coronary artery bypass grafting (CABG) surgery for patients with an indication for coronary artery revascularization. CABG is commonly indicated in patients with secondary MR and coronary artery disease. (See "Chronic secondary mitral regurgitation: Intervention", section on 'Concurrent mitral valve surgery and CABG'.)

●Concomitant tricuspid valve repair for patients with severe TR [8]. (See "Tricuspid regurgitation: Management and prognosis", section on 'At the time of left-sided valve surgery'.)

●Selected patients with atrial fibrillation (AF) are candidates for left atrial appendage (LAA) exclusion/excision to reduce the risk of thromboembolism and/or surgical AF ablation to reduce the risk of recurrent AF. (See "Atrial fibrillation: Left atrial appendage occlusion" and "Atrial fibrillation: Surgical ablation".)

After completion of the procedure, the LA is closed, and air is removed from the left heart prior to removal of the aortic cross-clamp. After the cross-clamp is removed, the heart is reperfused, and the patient is weaned from CPB. During weaning, removal of residual air is guided by TEE monitoring.

Postbypass TEE assessment — Specific highlights for postbypass transesophageal echocardiography (TEE) after mitral valve repair or replacement are described below.

●After any mitral valve procedure – Immediately after weaning from CPB, TEE is used to assess results of all surgical interventions while the patient is still in the operating room. The following aspects are emphasized after any open mitral valve surgery (see "Anesthesia for cardiac surgery: General principles", section on 'Postbypass TEE examination'):

•Confirm removal of all residual air prior to weaning from CPB. Details are explained in a separate topic. (See "Anesthesia for cardiac surgery: General principles", section on 'Postbypass TEE examination'.)

•Assess left and right ventricular function. In some cases, acute LV or RV failure may occur in some patients during attempted weaning from CPB.

•Following separation from CPB, hemodynamic parameters are typically corrected to baseline levels prior to completing assessment of valve function, thereby reducing risk for underestimating any residual MR.

•Check for incidental injury to adjacent cardiac structures (eg, damage to the aortic valve causing AR or to the circumflex artery causing inferolateral LV regional wall motion abnormalities) [17].

●After mitral valve repair

•Assessment of residual MR – A repaired mitral valve is interrogated for residual MR immediately after weaning from CPB. If significant residual MR is present, the mechanism causing it is identified (eg, inadequate repair, systolic anterior motion of the mitral valve [SAM], which is discussed below, or a paravalvular leak around an annuloplasty ring) [17]. With the aid of TEE interrogation of the repaired valve, residual MR is assessed while addressing any hemodynamic conditions that may be causing or exacerbating the MR (as discussed below for SAM). The surgeon and cardiac anesthesiologist must then jointly decide whether the residual MR is significant, and if so, whether further attempts to repair the mitral valve are feasible, or replacement of the mitral valve will be necessary. Postbypass hemodynamics must be considered in evaluating the adequacy of the repair, since hypotension may lead to erroneous underestimation of MR severity. Thus, BP should be normalized before final surgical decisions are made.

•Assessment for SAM – After a mitral valve repair procedure that includes preservation of the anterior leaflet (particularly repair for mitral valve prolapse), it is also important to assess and document the presence of SAM with left ventricular outflow tract (LVOT) obstruction [17,25-27]. On TEE examination, SAM is identified when the mitral leaflets are drawn anteriorly into the LVOT during systole, causing LVOT obstruction and concomitant MR. The LVOT obstruction can be identified by Doppler color flow mapping, and the resulting gradient can be quantified with spectral Doppler interrogation. Notably, LVOT obstruction is exacerbated by LV "underfilling" (ie, hypovolemia) and by positive inotropic agents. If SAM does not resolve after volume loading and withdrawal of inotropic agents, then revision of the mitral valve repair or mitral valve replacement is likely necessary [17]. If further surgical revisions to repair the native valve are unsuccessful, then mitral valve replacement is usually required.

•Assessment of transmitral gradient – The transmitral gradient should also be assessed after mitral valve repair [27]. If the transmitral gradient is significantly elevated (eg, mean gradient >6 mmHg) and the elevation is not caused by a high output state, then re-repair or replacement of the valve may be necessary [28].

●After mitral valve replacement – After mitral valve replacement, TEE is used to rule out paravalvular leak, abnormal prosthetic leaflet mobility, or a high gradient across the mitral prosthesis indicating a stuck leaflet.

Postbypass management — Postbypass problems that may be evident while the patient is still in the operating room include:

●Left ventricular dysfunction – Typically, patients with preoperative LV impairment will require inotropic support during the immediate postbypass period. Treatment is described separately. (See "Intraoperative problems after cardiopulmonary bypass", section on 'Left ventricular dysfunction'.)

●Right ventricular dysfunction – Also, acute refractory right heart failure with a high pulmonary vascular resistance (PVR) may occur in some patients during attempted weaning from CPB [8]. Inodilator agents such as milrinone may be employed, often with concomitant use of norepinephrine to avoid excessive systemic vasodilatation. Treatment is described separately. (See "Intraoperative problems after cardiopulmonary bypass", section on 'Right ventricular dysfunction'.)

●Arrhythmias – Arrhythmias, particularly AF, are common in the postbypass and postoperative periods. Treatment includes synchronized cardioversion (especially if sinus rhythm was present before CPB), administration of amiodarone if cardioversion is unsuccessful [29], and correction of potassium and magnesium levels to high-normal values. (See "Intraoperative problems after cardiopulmonary bypass", section on 'Arrhythmias' and "Intraoperative problems after cardiopulmonary bypass", section on 'Metabolic abnormalities'.)

●Bleeding – Bleeding is a common complication after open cardiac valve surgical procedures. Strategies to achieve hemostasis are described separately. (See "Achieving hemostasis after cardiac surgery with cardiopulmonary bypass", section on 'Achieving hemostasis and management of bleeding'.)

●Other complications – A rare surgical complication after mitral valve replacement is disruption of atrioventricular continuity. This complication is more likely in the setting of severe mitral annular calcification and is associated with risk of intractable bleeding and high mortality rates. (see "Management and prognosis of mitral annular calcification", section on 'Mitral valve surgery')

SOCIETY GUIDELINE LINKS — 

Links to society and government-sponsored guidelines from selected countries and regions around the world are provided separately. (See "Society guideline links: Cardiac valve disease" and "Society guideline links: Perioperative cardiovascular evaluation and management".)

SUMMARY AND RECOMMENDATIONS

●Overview of mitral regurgitation (MR)

•Chronic MR – Chronic primary MR (due to intrinsic disease of the mitral leaflets or mitral valvular apparatus) or secondary MR (due to ischemic heart disease or cardiomyopathy) leads to chronic volume overload of the left atrium (LA). This is associated with LA enlargement, elevated LA pressure, and atrial dysrhythmias (typically, atrial fibrillation [AF]). Pulmonary artery pressure may be significantly increased at rest or with exercise with severe MR. (See 'Chronic primary MR' above and 'Chronic secondary MR' above.)

•Acute MR – Acute primary MR (due to chordae or papillary muscle rupture, valve destruction or perforation with endocarditis, rheumatic fever, or mechanical injury) or acute secondary MR (due to mitral leaflet tethering due to myocardial infarction or ischemia) suddenly increases LA pressure, often with "flash" pulmonary edema, acute right heart failure, and cardiogenic shock requiring emergency treatment. (See 'Acute primary MR' above and 'Acute secondary MR' above.)

•Dynamic MR – Dynamic MR occurs in some patients with left ventricular outflow tract (LVOT) obstruction with systolic anterior motion (SAM) of the mitral valve due to hypertrophic cardiomyopathy, stress cardiomyopathy, or other causes of left ventricular hypertrophy. Anesthetic management is discussed in a separate topic (table 8). (See "Anesthesia for patients with hypertrophic cardiomyopathy undergoing noncardiac surgery".)

●Preoperative assessment and management

•Chronic MR – Prior assessments of severity, chronicity, and other cardiac valve pathology are reviewed.

-Noncardiac surgery – History and physical examination, cardiac diagnostic studies, optimization of coexisting medical conditions, and indications for mitral valve intervention prior to elective noncardiac surgery are discussed separately. (See "Noncardiac surgery in patients with mitral or aortic regurgitation", section on 'Chronic mitral regurgitation'.)

-Cardiac surgery – The mechanism causing MR and whether there is associated mitral stenosis (MS), pathology of other cardiac valves, coronary artery disease, heart failure, or concomitant pulmonary hypertension are noted. Other aspects of preoperative assessment are discussed separately. (See "Overview of preoperative evaluation and management for cardiac surgery in adults".)

•Acute MR – Acute MR requires emergency cardiac surgery. Preanesthetic assessment is discussed separately. (See "Anesthesia for emergency cardiac surgery", section on 'Preoperative considerations'.)

•Preanesthetic medication management – Other topics review perioperative management of commonly administered chronic medications:

-(See "Perioperative medication management", section on 'Cardiovascular medications'.)

-(See "Perioperative management of patients receiving anticoagulants".)

-(See "Perioperative management of heart failure in patients undergoing noncardiac surgery", section on 'Preoperative management'.)

-(See "Anesthesia for noncardiac surgery in patients with pulmonary hypertension or right heart failure", section on 'Management of chronic medications'.)

•Premedication – If premedication for anxiety is needed, small incremental doses of midazolam (eg, 1 to 2 mg) may be administered. (See 'Premedication' above.)

●Hemodynamic management

•Primary and secondary MR – Hemodynamic management for primary MR is summarized in the table (table 5). (See 'Parameters for primary and secondary MR' above.)

•Other concomitant valve pathology – For combined MR and MS or disease of more than one valve, optimal hemodynamic management depends on which lesion is predominant and which hemodynamic changes are likely to be most deleterious (table 11). (See 'Considerations for concomitant cardiac conditions' above.)

•MR with ischemic heart disease – Additional considerations are noted in the table and in a separate topic (table 6). (See "Anesthesia for noncardiac surgery in patients with ischemic heart disease".)

•MR with dilated cardiomyopathy – Additional considerations are noted in the table and in a separate topic (table 7). (See "Anesthesia for noncardiac surgery in patients with heart failure".)

●Anesthetic management for noncardiac surgery – Choice of anesthetic techniques and agents is based on requirements for accomplishing the surgical procedure, as well as hemodynamic goals for MR. (See 'Anesthetic management for noncardiac surgery' above and 'Hemodynamic management' above.)

•Neuraxial anesthesia – Gradual afterload reduction with neuraxial anesthesia can be beneficial to decrease MR severity. However, preload should be maintained. (See 'Neuraxial anesthesia' above.)

•General anesthesia

-Monitoring – An intra-arterial catheter and monitoring with transesophageal echocardiography (TEE) are helpful for major surgical procedures. (See 'Monitoring' above.)

-Anesthetic agents and techniques – Considerations for selecting anesthetic agents and techniques are similar for patients with MR or aortic regurgitation (AR), as discussed separately. (See "Anesthesia for patients with aortic regurgitation", section on 'Anesthetic agents and techniques'.)

●Anesthetic management for cardiac surgery

•Prebypass hemodynamic management – Key principles are summarized in the table (table 5). (See 'Prebypass hemodynamic management' above.)

•Prebypass TEE assessment

-Chronic MR – Details for TEE examination of the mitral valve are discussed above and in a separate topic. (See 'Chronic mitral regurgitation' above and "Transesophageal echocardiography in the evaluation of mitral valve disease", section on 'Role of intraoperative transesophageal echocardiography'.)

All cardiac valves are examined individually, with particular attention to whether significant tricuspid regurgitation (TR) or AR is present.

Also, the left ventricle (LV) is examined for regional wall motion abnormalities, global LV dysfunction associated with ischemic MR, or LV dilatation due to chronic volume overload. The right ventricle (RV) is examined for dilation and dysfunction due to chronic pulmonary hypertension.

-Acute MR – TEE examination focuses on mitral valve structure, the mechanism causing acute MR, whether the valve can be repaired, and LV and RV function. (See 'Acute mitral regurgitation' above.)

•Surgical techniques – (See 'Surgical techniques' above.)

•Postbypass TEE assessment – Specific highlights for postbypass TEE assessment include (see 'Postbypass TEE assessment' above):

-Mitral valve repair – Assess for residual MR, systolic anterior motion (SAM) with LVOT obstruction, or a transmitral gradient.

-Mitral valve replacement – Rule out paravalvular leak, abnormal prosthetic leaflet mobility, or a high gradient across the mitral prosthesis indicating a stuck leaflet.

•Postbypass management – Common postbypass problems include LV or RV dysfunction, arrhythmias, and bleeding. (See 'Postbypass management' above.)