Progress in mitral and aortic regurgitation

The assessment of left ventricular diastolic function: guidance and recommendations from the British Society of Echocardiography

Impairment of left ventricular (LV) diastolic function is common amongst those with left heart disease and is associated with significant morbidity. Given that, in simple terms, the ventricle can only eject the volume with which it fills and that approximately one half of hospitalisations for heart failure (HF) are in those with normal/'preserved' left ventricular ejection fraction (HFpEF) (Bianco et al. in JACC Cardiovasc Imaging. 13:258-271, 2020. 10.1016/j.jcmg.2018.12.035), where abnormalities of ventricular filling are the cause of symptoms, it is clear that the assessment of left ventricular diastolic function (LVDF) is crucial for understanding global cardiac function and for identifying the wider effects of disease processes. Invasive methods of measuring LV relaxation and filling pressures are considered the gold-standard for investigating diastolic function. However, the high temporal resolution of trans-thoracic echocardiography (TTE) with widely validated and reproducible measures available at the patient's bedside and without the need for invasive procedures involving ionising radiation have established echocardiography as the primary imaging modality. The comprehensive assessment of LVDF is therefore a fundamental element of the standard TTE (Robinson et al. in Echo Res Pract7:G59-G93, 2020. 10.1530/ERP-20-0026). However, the echocardiographic assessment of diastolic function is complex. In the broadest and most basic terms, ventricular diastole comprises an early filling phase when blood is drawn, by suction, into the ventricle as it rapidly recoils and lengthens following the preceding systolic contraction and shortening. This is followed in late diastole by distension of the compliant LV when atrial contraction actively contributes to ventricular filling. When LVDF is normal, ventricular filling is achieved at low pressure both at rest and during exertion. However, this basic description merely summarises the complex physiology that enables the diastolic process and defines it according to the mechanical method by which the ventricles fill, overlooking the myocardial function, properties of chamber compliance and pressure differentials that determine the capacity for LV filling. Unlike ventricular systolic function where single parameters are utilised to define myocardial performance (LV ejection fraction (LVEF) and Global Longitudinal Strain (GLS)), the assessment of diastolic function relies on the interpretation of multiple myocardial and blood-flow velocity parameters, along with left atrial (LA) size and function, in order to diagnose the presence and degree of impairment. The echocardiographic assessment of diastolic function is therefore multifaceted and complex, requiring an algorithmic approach that incorporates parameters of myocardial relaxation/recoil, chamber compliance and function under variable loading conditions and the intra-cavity pressures under which these processes occur. This guideline outlines a structured approach to the assessment of diastolic function and includes recommendations for the assessment of LV relaxation and filling pressures. Non-routine echocardiographic measures are described alongside guidance for application in specific circumstances. Provocative methods for revealing increased filling pressure on exertion are described and novel and emerging modalities considered. For rapid access to the core recommendations of the diastolic guideline, a quick-reference guide (additional file 1) accompanies the main guideline document. This describes in very brief detail the diastolic investigation in each patient group and includes all algorithms and core reference tables.

The effect of cardiac properties on arterial pulse waves: An in-silico study

This study investigated the effects of cardiac properties variability on arterial pulse wave morphology using blood flow modelling and pulse wave analysis. A lumped-parameter model of the left part of the heart was coupled to a one-dimensional model of the arterial network and validated using reference pulse waveforms in turn verified by comparison with in vivo measurements. A sensitivity analysis was performed to assess the effects of variations in cardiac parameters on central and peripheral pulse waveforms. Results showed that left ventricle contractility, stroke volume, cardiac cycle duration, and heart valves impairment are determinants of central waveforms morphology, pulse pressure and its amplification. Contractility of the left atrium has negligible effects on arterial pulse waves. Results also suggested that it might be possible to infer left ventricular dysfunction by analysing the timing of the dicrotic notch and cardiac function by analysing PPG signals. This study has identified cardiac properties that may be extracted from in vivo central and peripheral pulse waves to assess cardiac function.

Atypical Presentation of Acute Mitral Regurgitation Secondary to Papillary Muscle Rupture

Acute mitral regurgitation (MR) is a life-threatening condition presenting with severe decompensated heart failure due to sudden retrograde blood flow into the left atrium. The causes are broadly classified into ischemic and non-ischemic. Rapid and accurate diagnosis of acute MR and its potential causes is essential. This case uniquely highlights an atypical presentation of severe MR secondary to papillary muscle rupture without a known, identifiable cause. Therefore, suspicion of acute MR should be high if clinical symptoms are present, even without known risk factors, due to the high morbidity and mortality associated with delayed management.

Mitral repair with leaflet preservation versus leaflet resection and ventricular reverse remodeling from a randomized trial

OBJECTIVES

In the Canadian Mitral Research Alliance (CAMRA) Trial CardioLink-2 leaflet resection versus preservation techniques for posterior leaflet prolapse was investigated and no difference was shown in their effect on mean mitral gradient at peak exercise at 12 months postoperatively. The purpose of this subanalysis was to evaluate the effect of the 2 strategies on left ventricular (LV) reverse remodeling after repair.

METHODS

A total of 104 patients were randomized to either a leaflet resection or leaflet preservation strategy. Echocardiograms, performed at baseline (preoperative), predischarge, and 12 months postoperatively, were analyzed in a blinded fashion at a core laboratory.

RESULTS

All patients underwent successful mitral repair. At discharge, 3 patients showed moderate mitral regurgitation, whereas the remainder showed mild or less regurgitation. Compared with the baseline echocardiogram, the indexed end diastolic volume was reduced at the discharge echocardiogram (P < .0001) and was further reduced at the 12-month echocardiogram (P = .01). In contrast, the indexed end systolic volume did not significantly change from baseline assessed at the predischarge echocardiogram (P = .32) but improved at 12 months postoperatively (P < .0001), resulting in a corresponding improvement in ejection fraction at 12 months (P < .0001). The type of mitral repair strategy had no significant effect on LV reverse remodeling trends.

CONCLUSIONS

The mitral repair strategies used did not influence postoperative LV reverse remodeling, which occurred in stages. Although LV end diastolic dimensions recovered before discharge, improvements in LV end systolic dimension were evident 12 months after repair.

Usefulness of Mitral Regurgitant Volume Quantified Using Magnetic Resonance Imaging to Predict Left Ventricular Remodeling After Mitral Valve "Correction"

MRI studies have shown a tight correlation between mitral regurgitant volume and left ventricular end-diastolic volume (LV EDV) in patients with primary chronic mitral regurgitation (MR). They have also shown a tight correlation between regurgitant volume and the decrease in LVEDV following mitral valve surgery. The purpose of this study is to validate an empiric calculation that can be used preoperatively to predict the amount of left ventricular remodeling following mitral valve correction. This is a prospective multicenter study of 63 (61 ± 13 years, male 65%) patients who underwent an MRI before and after mitral valve correction. Pre and postmitral valve correction ventricular volumes and ejection fractions were quantified. The predicted change in LV EDV was empirically calculated as mitral regurgitant volume/left ventricular ejection fraction. The observed change in LV EDV was compared to the predicted change in LV EDV. The LVEDV decreased in 61 (97%) patients following mitral valve correction (237 ± 66 ml vs 164 ± 46 ml, p <0.0001). Correlation between the observed and predicted change in LVEDV was good for the entire cohort (r = 0.77, p <0.0001) and excellent in patients with <10 ml of residual MR (r = 0.87, p <0.0001). This tight correlation was seen in both patients with primary (0.86, p <0.0001) and secondary MR (0.97, p <0.0001) and <10 ml of residual MR. Multivariate predictors of LV remodeling were MR volume, primary MR, and LVESV. In conclusion cardiac MRI volumetric measurements accurately predict LV remodeling following mitral valve correction. This finding supports the notion that MRI accurately quantifies the severity of chronic mitral regurgitation and a cardiac MRI should be strongly considered before mitral valve correction.

Eukaryotic elongation factor 2 (eEF2) kinase/eEF2 plays protective roles against glucose deprivation-induced cell death in H9c2 cardiomyoblasts

During the development of cardiac hypertrophy, glucose deprivation (GD) associated with coronary microvascular rarefaction is caused, leading to cardiomyocyte death. Phosphorylation (inactivation) of eukaryotic elongation factor 2 (eEF2) by eEF2 kinase (eEF2K) inhibits protein translation, a highly energy consuming process, which plays protective roles against nutrient deprivation-induced cell death. We previously showed that eEF2 phosphorylation was increased in isolated heart from several cardiac hypertrophy models. In this study, we investigated whether eEF2K/eEF2 mediates the inhibition of cardiomyocyte death under GD condition. In H9c2 rat cardiomyoblasts cultured with serum-free medium, GD significantly augmented eEF2 phosphorylation and signals related to autophagy [increase of microtubule-associated protein 1 light chain 3 (LC3)-II to LC3-I ratio] and apoptosis (cleavage of caspase-3) as determined by Western blotting. GD induced cell death, which was augmented by eEF2K gene knockdown using a small interfering RNA. eEF2K gene knockdown significantly augmented GD-induced cleavage of caspase-3 and apoptotic nuclear condensation as determined by 4', 6-diamidino-2-phenylindole staining. In contrast, eEF2K gene knockdown significantly inhibited GD-induced increase of LC3-II to LC3-I ratio and autophagosome formation as determined by an immunofluorescence staining. An inhibitor of autophagy, 3-methyladenine or bafilomycin A1 significantly augmented GD-induced cleavage of caspase-3. Further, eEF2K gene knockdown significantly inhibited GD-induced phosphorylation of adenosine monophosphate-activated protein kinase (AMPK)α and its downstream substrate, unc-51 like autophagy activating kinase (ULK)1. An inhibitor of AMPK, dorsomorphin significantly inhibited GD-induced increase of LC3-II to LC3-I ratio. In conclusion, we for the first time revealed that eEF2K/eEF2 axis under GD condition mediates the inhibition of apoptotic H9c2 cell death at least in part via promotion of autophagy through AMPKα/ULK1 signaling pathway.

Acute mitral regurgitation

The diagnosis of acute mitral regurgitation (MR) is often missed or delayed because the clinical presentation is substantially different from that in patients with chronic MR. Management of acute MR depends on the specific aetiology of valve dysfunction and there is a lack of consensus on the optimal therapeutic approach in many patients. In particular, management of secondary MR due to acute ischaemia is challenging because of unique mechanisms of valve incompetence compared with chronic ischaemic MR. Another clinical challenge is management of acute MR due to transient systolic anterior motion of the mitral valve in the acute phase of Takotsubo cardiomyopathy, which commonly resolves within a few weeks. Additionally, iatrogenic MR induced by intraventricular devices is a recently recognised aetiology of acute MR. Acute primary MR typically requires early surgical intervention, for example, with a flail leaflet or endocarditis, because of acute cardiovascular decompensation with an abrupt increase in left atrial pressure. In an emergency situation and high surgical risk, a percutaneous mitral valve edge-to-edge repair is an alternative therapeutic option. Firm diagnosis of the severity and aetiology of acute MR is necessary for proper decision making, including timing and types of surgical intervention.

Left ventricular remodelling in chronic primary mitral regurgitation: implications for medical therapy

Surgical repair or replacement of the mitral valve is currently the only recommended therapy for severe primary mitral regurgitation. The chronic elevation of wall stress caused by the resulting volume overload leads to structural remodelling of the muscular, vascular and extracellular matrix components of the myocardium. These changes are initially compensatory but in the long term have detrimental effects, which ultimately result in heart failure. Understanding the changes that occur in the myocardium due to volume overload at the molecular and cellular level may lead to medical interventions, which potentially could delay or prevent the adverse left ventricular remodelling associated with primary mitral regurgitation. The pathophysiological changes involved in left ventricular remodelling in response to chronic primary mitral regurgitation and the evidence for potential medical therapy, in particular beta-adrenergic blockers, are the focus of this review.

Papillary muscle rupture following acute myocardial infarction: Anatomic, echocardiographic, and surgical insights

Papillary muscle (PM) rupture is a rare complication of acute myocardial infarction which carries an excessive mortality rate. Optimal outcomes require rapid diagnosis and prompt surgical referral, and in this regard, echocardiography plays a crucial role. Comprehensive echocardiographic examination of the patient with PM rupture consists of identification of the ruptured PM segment, visualization of flail mitral valve segment(s), evaluation of mitral regurgitation severity, and assessment of left ventricular systolic function. This article discusses anatomic and echocardiographic features as well as the surgical management of PM rupture.

Cardiothoracic surgical emergencies in the intensive care unit

Patients with cardiothoracic surgical emergencies are frequently admitted to the ICU, either prior to operative intervention or after surgery. Recognition and appropriate timing of operative intervention are key factors in improving outcomes. A collaborative team approach with the cardiothoracic service is imperative in managing this patient population.

Clinical impact of aortic regurgitation after transcatheter aortic valve replacement: insights into the degree and acuteness of presentation

OBJECTIVES

The aim of this study was to determine the impact of the degree of residual aortic regurgitation (AR) and acuteness of presentation of AR after transcatheter aortic valve replacement (TAVR) on outcomes.

BACKGROUND

The degree of residual AR after TAVR leading to excess mortality remains controversial, and little evidence exists on the impact of the acuteness of presentation of AR.

METHODS

A total of 1,735 patients undergoing TAVR with balloon-expandable or self-expanding valves were included. The presence and degree of AR were evaluated by transthoracic echocardiography; acute AR was defined as an increase in AR severity of ≥1 degree compared with pre-procedural echocardiography.

RESULTS

Residual AR was classified as mild in 761 patients (43.9%) and moderate to severe in 247 patients (14.2%). The presence of moderate to severe AR was an independent predictor of mortality at a mean follow-up of 21 ± 17 months compared with none to trace (adjusted hazard ratio [HR]: 1.81, 95% confidence interval [CI]: 1.32 to 2.48; p < 0.001) and mild AR (adjusted HR: 1.68, 95% CI: 1.27 to 2.24; p < 0.001) groups. There was no increased risk in patients with mild AR compared with those with none to trace AR (p = 0.393). In patients with moderate to severe AR, acute AR was observed in 161 patients (65%) and chronic AR in 86 patients (35%). Acute moderate to severe AR was independently associated with increased risk of mortality compared with none/trace/mild AR (adjusted HR: 2.37, 95% CI: 1.53 to 3.66; p < 0.001) and chronic moderate to severe AR (adjusted HR: 2.24, 95% CI: 1.17 to 4.30; p = 0.015) [corrected]. No differences in survival rate were observed between patients with chronic moderate to severe and none/trace/mild AR (p > 0.50).

CONCLUSIONS

AR occurred very frequently after TAVR, but an increased risk of mortality at ∼2-year follow-up was observed only in patients with acute moderate to severe AR.

Blood volume measurement by hemodilution: association with valve disease and re-evaluation of the Allen Formula

BACKGROUND

Total blood volume (TBV) assessment is central to the management of cardiac surgical patients with cardiopulmonary bypass (CPB). The widely accepted Allen Formula lacks accuracy in estimating TBV in these patients. Moreover, the impact of commonly encountered cardiac disease states on TBV has not been systematically investigated. The aim of this study was to determine TBV by hemodilution (TBVHD) for patients with valve disease, compare TBVHD to algorithms frequently used during cardiac surgery and to modify the Allen Formula to better fit today's patient population.

METHODS

TBVHD was prospectively measured upon initiation of CPB. Ninety-six patients were grouped into 4 cohorts by preoperative diagnosis and compared to Allen and weight-based formulae in a univariate analysis: mitral regurgitation (MR), coronary artery disease requiring bypass surgery (CABG) and aortic stenosis (AS) ± CABG. The independent effects of height and weight on TBV were correlated to the original Allen Formula by multiple linear regression.

RESULTS

Patients with MR had significantly larger TBVHD compared to patients with AS, CABG or both. The smallest TBVHD was found in the patients with AS and CABG. The modified Allen Formula had an excellent model fit (R(2) = 0.88 and R(2) = 0.95 for males and females, respectively; p<0.001) while the classic formula overestimated TBV by 30% in males and females. For males, height impacted TBV calculations the most whereas weight was the predominant determinant in females.

CONCLUSION

Blood volume assessment via the Allen Formula or bodyweight overestimated TBV in cardiac surgical patients, with potential implications on their management. The assumption that MR frequently presents with increased intravascular volume was confirmed whereas AS patients with coronary disease had a relatively smaller TBV. Lastly, a modified Allen Formula to better reflect today's patient population was derived to reproducibly improve accuracy in mathematical estimates of TBV.

Mitral regurgitation: current trends in diagnosis and management

Mitral regurgitation is the most prevalent heart valve disorder in the United States. Individuals with mitral regurgitation may be asymptomatic or may present with dyspnea, orthopnea, fatigue, and/or heart rhythm disturbances. Long-standing mitral regurgitation causes chronic left ventricular volume overload, which leads to left ventricular dilation and contractile dysfunction. Without treatment, mitral regurgitation results in biventricular failure and death. Echocardiography is the preferred diagnostic test to assess the presence and severity of mitral regurgitation. Mitral valve surgery, the only effective treatment for patients with severe mitral regurgitation, is recommended early in the course of the disease to prevent the development of heart failure. Early recognition of mitral regurgitation and timely referral for mitral valve surgery significantly improve symptoms and long-term survival.

Valvular heart disease: diagnosis and management

Valvular heart disease (VHD) encompasses a number of common cardiovascular conditions that account for 10% to 20% of all cardiac surgical procedures in the United States. A better understanding of the natural history coupled with the major advances in diagnostic imaging, interventional cardiology, and surgical approaches have resulted in accurate diagnosis and appropriate selection of patients for therapeutic interventions. A thorough understanding of the various valvular disorders is important to aid in the management of patients with VHD. Appropriate work-up for patients with VHD includes a thorough history for evaluation of causes and symptoms, accurate assessment of the severity of the valvular abnormality by examination, appropriate diagnostic testing, and accurate quantification of the severity of valve dysfunction and therapeutic interventions, if necessary. It is also important to understand the role of the therapeutic interventions vs the natural history of the disease in the assessment of outcomes. Prophylaxis for infective endocarditis is no longer recommended unless the patient has a history of endocarditis or a prosthetic valve.

Usefulness of NT-proBNP in the assessment of patients with aortic or mitral regurgitation

BACKGROUND

Recent application of brain natriuretic peptide and N-terminal prohormone brain natriuretic peptide (NT-proBNP) in cardiac valvular disease is very promising.

AIMS

To test the usefulness of NT-proBNP in the assessment of patients with aortic or mitral regurgitation.

PATIENTS AND METHODS

Sixty-seven patients - 23 with aortic and 12 with mitral regurgitation vs. 32 controls - were examined by color Doppler echocardiography, cardiopulmonary exercise testing, Minnesota Living with Heart Failure Questionnaire (MLWHFQ) and plasma NT-proBNP assay at rest (T0) and after maximal physical exercise (T1).

RESULTS

NT-proBNP was significantly higher in patients than in controls, both at T0 (298 +/- 85 vs. 46 +/- 11 pg/ml; P < 0.01) and at T1 (366 +/- 106 vs. 50 +/- 12 pg/ml; P < 0.01). MLWHFQ score was significantly higher in patients (19 +/- 3 vs. 1 +/- 0.6; P < 0.001) with a significant inverse correlation with VO2max (r = -0.538, P < 0.001) and a direct correlation with NT-proBNP (T0: r = 0.415, P < 0.01; T1: r = 0.458, P < 0.01). NT-proBNP was inversely correlated with VO2max (T0: r = -0.444, P < 0.001; T1:r = -0.428, P < 0.001) and directly correlated with left atrial diameter (T0: r = 0.370, P < 0.01; T1: r = 0.409, P = 0.001), and left ventricular mass index (r = 0.279, P < 0.01, and r = 0.272, P < 0.01). No correlations were found between echocardiographic parameters of valvular disease severity and VO2max, NT-proBNP and MLWHFQ.

CONCLUSIONS

NT-proBNP is useful in the assessment of the cardiac functional damage secondary to mitral and aortic regurgitation.

Imaging the heart valves using ECG-gated 64-detector row cardiac CT

Multi-detector row cardiac CT imaging demonstrates clinical usefulness in valvular heart disease, for which CT has not been traditionally used. Electrocardiographic (ECG)-gated CT coronary angiography also has an established clinical role with an increasingly solid evidence base, and the same data set in these patients also provides valuable information about chamber and valvular structure and function; this information should also be considered when interpreting cardiac CT and non-ECG gated thoracic imaging. Although true flow data cannot be achieved using CT, as with echocardiography and MRI, there are a number of imaging features that may be used when interpreting and inferring valve pathology. This article discusses the role of currently available imaging modalities and the rationale for cardiac CT, while focusing on the CT interpretation of valvular heart disease with respect to the relevant pathophysiology and management options that have importance to the radiologist. A suggested method of post-processing image review is provided with reference to a variety of normal and pathological pictorial illustrations.

Blood Volume Assessment in the Diagnosis and Treatment of Chronic Heart Failure

Symptoms of intravascular volume overload and increased cardiac filling pressures in the systemic and pulmonary venous circulations are among the most common complaints in patients with chronic heart failure (CHF). The clinical utility of physical examination for estimation of intravascular volume status in patients with CHF is limited due to poor specificity and sensitivity of most signs of congestion. Direct measurement of blood volume with radioisotope techniques is FDA-approved and has been shown to be closely associated with invasive measurements of cardiac filling pressures in patients with CHF. Unrecognized volume overload is common in CHF patients and is associated with adverse clinical outcomes. Additional work is needed to determine the clinical utility of serial blood volume measurements in the management of patients with CHF.

Elongation Index as a New Index Determining the Severity of Left Ventricular Systolic Dysfunction and Mitral Regurgitation in Patients with Congestive Heart Failure

The shape of the left ventricle is an important echocardiographic feature of left ventricular dysfunction. Progression of the mitral regurgitation and consequent left ventricular remodeling is unpredictable in heart failure. Elongation index is an index of left ventricular sphericity. The surface area of the elongated ventricle is larger than that of a spherical one. The objective of this study was to assess the relation between elongation index and the degree of mitral regurgitation along with noninvasive indices of left ventricular function. Thirty-two patients (21 male, 11 female, mean age: 57 +/- 6 yrs) with congestive heart failure and mitral regurgitation were included. Patients were stratified into three groups according to vena contracta width as having mild (n = 11), moderate (n = 11) and severe mitral regurgitation (n = 10). The elongation index (EI) was considered as equal to {[(left ventricular internal area-measured) - (theoretical area of the sphere with measured left ventricular volume)]/(theoretical area of the sphere with measured left ventricular volume)}. Ejection fractions by the modified Simpson rule, dP/dt and sphericity index (SI) were also recorded. The relationship between (EI), ejection fraction, dP/dt and SI reached modest statistical significance (p < 0.05). When the EI and SI were compared, the correlation was also significant (p < 0.01). The areas under the receiver operator curve of EI and SI for discriminating dP/dt < 1000 mm Hg/s were 0.833 and 0.733, respectively. In conclusion, the elongation, which defines the shape of the left ventricle, might be related to the systolic function of the left ventricle and the degree of the mitral regurgitation. Further studies are needed to demonstrate its use in other clinical entities.

Subvalvular Alterations Promote Increased Mitral Valve Regurgitation in Progressive Dilated Cardiomyopathy

BACKGROUND

Alterations in transmitral pressure, valve structure, subvalvular geometry, and abnormal myocardial function have all been implicated in the pathophysiology of functional/progressive mitral valve regurgitation (MR). In this study, we hypothesized that a relatively small structural lesion to the mitral valve apparatus predisposes to severe MR in the setting of progressive left ventricular dilation. While examining this hypothesis, an additional purpose of this study was to determine the extent of papillary muscle (PM) distortion and mitral annular dilation with increasing MR resulting from progressive dilated cardiomyopathy.

METHODS AND RESULTS

Mild MR was produced via a limited, fixed structural lesion to the mitral valve apparatus of 8 dogs (20 to 22 kg). Incremental tachypacing induced left ventricular dilation over an 8-month period. The pacer was deactivated and the dogs followed for an additional 6 weeks. Echocardiographic measurements demonstrated significant cardiac remodeling (left ventricular end diastolic diameter) and MR progression with a 54% increase in left ventricular end diastolic diameter and a 44% increase in MR jet area (P < .05). Tachypacing induced decreases in left ventricular ejection fraction recovered nearly to baseline levels by 6 weeks after pacing cessation. Nevertheless, left ventricular dilation persisted and MR remained severe after pacing cessation. There was a significant increase in the short axis PM segment length and PM angular separation from baseline (6.28 +/- 0.83 versus 4.02 +/- 0.56 cm and 99.7 +/- 2.6 versus 90.1 +/- 3.2 deg, respectively, P < .05) with no change in mitral annulus circumference (8.71 +/- 0.70 versus 8.15 +/- 0.35 cm, P = NS).

CONCLUSION

Progressive MR severity in nonischemic dilated cardiomyopathy resulted from changes in left ventricular shape and altered papillary muscle geometries and does not require mitral annulus dilation or a reduced left ventricular ejection fraction.

Asymptomatic valvular disease: who benefits from surgery?

Routine physical examination and noninvasive imaging frequently lead to the diagnosis of valvular heart disease in asymptomatic patients. The decision to proceed to surgical repair or replacement is based on an informed evaluation of the risks of surgery versus those encountered with a nonoperative course. In determining whether symptoms are present, stress testing may be helpful, as many patients with significant valvular lesions have a tendency to limit their daily physical exertion to levels that do not provoke symptoms. The two most feared consequences of conservative management, sudden death and permanent myocardial damage, are rare in asymptomatic patients with severe aortic stenosis or regurgitation. Surgery for asymptomatic aortic stenosis is performed only for certain high-risk subsets of patients, including those with left ventricular dysfunction, ventricular arrhythmia, and critically small valves. Asymptomatic patients with aortic regurgitation and mitral regurgitation should undergo surgery if they have systolic dysfunction or marked ventricular enlargement.

Is measurement of plasma brain natriuretic peptide levels a useful test to detect for surgical timing of valve disease?

BACKGROUND

The optimal timing of valve surgery is very important. In patients who are severely symptomatic, the marked improvement in symptomatic status observed following successful valve surgery. However, in patients with no or only mild symptoms, the decision is more difficult. The aim of this retrospective study was to determine whether the measurement of plasma brain natriuretic peptides (BNP) levels is useful to decide surgical timing for valve disease.

METHODS

Fifty-one patients with valve disease underwent single valve surgery (mitral stenosis, MS, 13; mitral regurgitation, MR, 16; aortic stenosis, AS, 14; aortic regurgitation, AR, 8 patients). Blood samples, echocardiographic and cardiac catheterization data were obtained before operation and echocardiographic examination were performed after 1-year of operations.

RESULTS

In patients subjected to single heart valve surgery, plasma BNP mean levels were 214.6+/-48.5 pg/ml. In plasma BNP levels, there was only significant difference between MS and AS group (MS 67.5+/-9.7 vs. AS 314.3+/-112.0 pg/ml, P=0.04). There were no relationships between plasma BNP levels and pre-operative cardiac functions. After 1-year of the valve surgery, NYHA functional class was reduced in 36 patients (70.6%) and plasma BNP levels before the surgery significantly correlated with post-operative NYHA functional class.

CONCLUSIONS

In this retrospective study, patients with high plasma BNP levels significantly impaired the improvement of clinical symptoms after surgery. We have suggested that plasma BNP levels is useful for detecting asymptomatic valvular disease, and is a clinical marker useful in determining the optimal surgical timing.

Correlation of echo-Doppler aortic valve regurgitation index with angiographic aortic regurgitation severity

We assessed aortic regurgitation (AR) severity by utilizing multiple echo-Doppler variables in comparison with AR severity by aortic root angiography. Patients were divided into 3 groups: mild, moderate, and severe. An AR index (ARI) was developed, comprising 5 echocardiographic parameters: ratio of color AR jet height to left ventricular outlet flow diameter, AR signal density from continuous-wave Doppler, pressure half-time, left ventricular end-diastolic diameter, and aortic root diameter. There was a strong correlation between AR severity by angiography and the calculated echo-Doppler ARI (r = 0.84, p = 0.0001). As validated by aortic angiography, the ARI is an accurate reflection of AR severity.

Indications for surgery for aortic regurgitation

Aortic valve replacement for isolated aortic regurgitation (AR) is usually not indicated unless the regurgitation is severe. However, not all patients with severe AR require aortic valve replacement. This review focuses on the causes of AR and the pathophysiology of acute versus chronic AR, and the attendant adaptive mechanisms of the left ventricle that ultimately determine their different natural histories. Aortic valve surgery must be performed in a timely manner to prevent cardiac death, ameliorate symptoms, and limit late postoperative excess mortality.