Mitral regurgitation in coronary heart disease

Development and Validation of Artificial Intelligence-based Method for Diagnosis of Mitral Regurgitation from Chest Radiographs

Purpose

To develop an artificial intelligence-based model to detect mitral regurgitation on chest radiographs.

Materials and Methods

This retrospective study included echocardiographs and associated chest radiographs consecutively collected at a single institution between July 2016 and May 2019. Associated radiographs were those obtained within 30 days of echocardiography. These radiographs were labeled as positive or negative for mitral regurgitation on the basis of the echocardiographic reports and were divided into training, validation, and test datasets. An artificial intelligence model was developed by using the training dataset and was tuned by using the validation dataset. To evaluate the model, the area under the curve, sensitivity, specificity, accuracy, positive predictive value, and negative predictive value were assessed by using the test dataset.

Results

This study included a total of 10 367 images from 5270 patients. The training dataset included 8240 images (4216 patients), the validation dataset included 1073 images (527 patients), and the test dataset included 1054 images (527 patients). The area under the curve, sensitivity, specificity, accuracy, positive predictive value, and negative predictive value in the test dataset were 0.80 (95% CI: 0.77, 0.82), 71% (95% CI: 67, 75), 74% (95% CI: 70, 77), 73% (95% CI: 70, 75), 68% (95% CI: 64, 72), and 77% (95% CI: 73, 80), respectively.

Conclusion

The developed deep learning-based artificial intelligence model may possibly differentiate patients with and without mitral regurgitation by using chest radiographs.Keywords: Computer-aided Diagnosis (CAD), Cardiac, Heart, Valves, Supervised Learning, Convolutional Neural Network (CNN), Deep Learning Algorithms, Machine Learning Algorithms Supplemental material is available for this article. © RSNA, 2022.

2020 ACC/AHA Guideline for the Management of Patients With Valvular Heart Disease: Executive Summary: A Report of the American College of Cardiology/American Heart Association Joint Committee on Clinical Practice Guidelines

AIM

This executive summary of the valvular heart disease guideline provides recommendations for clinicians to diagnose and manage valvular heart disease as well as supporting documentation to encourage their use.

METHODS

A comprehensive literature search was conducted from January 1, 2010, to March 1, 2020, encompassing studies, reviews, and other evidence conducted on human subjects that were published in English from PubMed, EMBASE, Cochrane, Agency for Healthcare Research and Quality Reports, and other selected database relevant to this guideline. Structure: Many recommendations from the earlier valvular heart disease guidelines have been updated with new evidence and provides newer options for diagnosis and treatment of valvular heart disease. This summary includes only the recommendations from the full guideline which focus on diagnostic work-up, the timing and choice of surgical and catheter interventions, and recommendations for medical therapy. The reader is referred to the full guideline for graphical flow charts, text, and tables with additional details about the rationale for and implementation of each recommendation, and the evidence tables detailing the data considered in developing these guidelines.

Subclinical carotid atherosclerosis predicts all-cause mortality and cardiovascular events in obese patients with negative exercise echocardiography

BACKGROUND

Obesity is a major health problem due to its high prevalence. The relationship between obesity and cardiovascular disease is unclear. Some studies agree that certain conditions associated with obesity, such as physical inactivity or cardiovascular risk factors, are responsible for cardiovascular risk excess among obese people. Carotid intima-media thickness and carotid plaques (CP) have been associated with cardiovascular adverse events in healthy populations, and recent data suggest a higher prevalence of subclinical carotid atherosclerosis in obese and metabolically unhealthy patients. However, there are no studies correlating subclinical atherosclerosis and adverse events (AE) in obese subjects.

AIM

To determine the association between carotid disease and AE in obese patients with negative exercise echocardiography (EE).

METHODS

From January 1, 2006 to December 31, 2010, 2000 consecutive patients with a suspicion of coronary artery disease were submitted for EE and carotid ultrasonography. Exclusion criteria included previous vascular disease, left ventricular ejection fraction < 50%, positive EE, significant valvular heart disease and inferior to submaximal EE. An AE was defined as all-cause mortality, myocardial infarction and cerebrovascular accident. Subclinical atherosclerosis was defined as CP presence according to Manheim and the American Society of Echocardiography Consensus.

RESULTS

Of the 652 patients who fulfilled the inclusion criteria, 226 (34.7%) had body mass indexes ≥ 30 kg/m2, and 76 of them (33.6%) had CP. During a mean follow-up time of 8.2 (2.1) years, 27 AE were found (11.9%). Mean event-free survival at 1, 5 and 10 years was 99.1% (0.6), 95.1% (1.4) and 86.5% (2.7), respectively. In univariate analysis, CP predicted AE [hazard ratio (HR) 2.52, 95% confidence interval (CI) 1.17-5.46; P = 0.019]. In multivariable analysis, the presence of CP remained a predictor of AE (HR 2.26, 95%CI 1.04-4.95, P = 0.041). Other predictors identified were glomerular filtration rate (HR 0.98, 95%CI 0.96-0.99; P = 0.023), peak metabolic equivalents (HR 0.83, 95%CI 0.70-0.99, P = 0.034) and moderate mitral regurgitation (HR 5.02, 95%CI 1.42-17.75, P = 0.012).

CONCLUSION

Subclinical atherosclerosis defined by CP predicts AE in obese patients with negative EE. These patients could benefit from aggressive prevention measures.

Concomitant mitral valve surgery in patients with moderate ischemic mitral regurgitation undergoing coronary artery bypass grafting

Background

The clinical benefits of a concomitant mitral valve (MV) surgery in patients with moderate ischemic mitral regurgitation (iMR) undergoing coronary artery bypass grafting (CABG) remain controversial.

Methods

The study involved 710 patients (mean age, 65.0±8.9 years; 504 males) with moderate iMR undergoing CABG between 1990 and 2015. Of these, 116 (16.3%) patients underwent a concomitant MV surgery (MVS; replacement in 10, repair in 106) and 594 (83.7%) underwent CABG only. Clinical and echocardiographic outcomes were compared before and after adjustment with the use of propensity score (PS) analyses.

Results

Early mortality occurred in 22 (3.7%) and 13 (11.2%) patients in CABG-only and CABG with MVS group, respectively (P=0.001). After adjustment, CABG with MVS group showed significantly increased risks of early death (P<0.001), low cardiac output syndrome (LCOS) (P=0.001) and surgical bleeding (P=0.014). During a median follow-up of 78.0 months (quartile 1-3, 33.6-115.9 months), overall mortality occurred in 286 (40.3%) patients. The addition of an MV surgery showed an increased risk of overall mortality [hazard ratio (HR), 1.34; 95% confidence interval (CI), 0.99-1.80; P=0.055], which became comparable 1 year after surgery on landmark survival analysis (HR, 0.94; 95% CI, 0.64-1.39; P=0.772). Improved left ventricular (LV) ejection fraction and LV reverse remodeling were observed in both groups without significant intergroup differences.

Conclusions

The addition of a concomitant MV surgery increased the risk of early mortality and complications in patients with moderate iMR undergoing CABG. In long-term clinical and echocardiographic outcomes, a concomitant MV surgery seemed to confer no significant clinical benefits.

Baseline mitral regurgitation predicts outcome in patients referred for dobutamine stress echocardiography

A number of parameters recorded during dobutamine stress echocardiography (DSE) are associated with worse outcome. However, the relative importance of baseline mitral regurgitation (MR) is unknown. The aim of this study was to assess the prevalence and associated implications of functional MR with long-term mortality in a large cohort of patients referred for DSE. 6745 patients (mean age 64.9 ± 12.2 years) were studied. Demographic, baseline and peak DSE data were collected. All-cause mortality was retrospectively analyzed. DSE was successfully completed in all patients with no adverse outcomes. MR was present in 1019 (15.1%) patients. During a mean follow up of 5.1 ± 1.8 years, 1642 (24.3%) patients died and MR was significantly associated with increased all-cause mortality (p < 0.001). With Kaplan-Meier analysis, survival was significantly worse for patients with moderate and severe MR (p < 0.001). With multivariate Cox regression analysis, moderate and severe MR (HR 2.78; 95% CI 2.17-3.57 and HR 3.62; 95% CI 2.89-4.53, respectively) were independently associated with all-cause mortality. The addition of MR to C statistic models significantly improved discrimination. MR is associated with all-cause mortality and adds incremental prognostic information among patients referred for DSE. The presence of MR should be taken into account when evaluating the prognostic significance of DSE results.

Characteristics of coronary artery disease among patients with atrial fibrillation compared to patients with sinus rhythm

BACKGROUND

With a high prevalence of coronary artery disease (CAD) among patients with atrial fibrillation (AF), CAD is one of the main risk factors for AF. However, little is known about the characteristics of CAD in AF patients, especially whether a specific anatomical distribution of coronary artery stenoses might predispose an individual to AF via atrial ischemia remains speculative. To address this issue, we evaluated the potential associations between angiographic characteristics of CAD and AF.

METHODS

In this single-center retrospective analysis, 796 consecutive patients with confirmed CAD and AF (CAD-AF) and 785 patients with CAD and sinus rhythm (CAD-SR) were enrolled. Clinical characteristics and angiographic findings were compared between groups in stable CAD and during acute myocardial infarction (MI).

RESULTS

Mitral valve disease and chronic heart failure were significantly more common in CAD-AF than in CAD-SR. Clinical condition in CAD-AF was significantly more severe as indicated by New York Heart Association/World Health Organization functional class. Left ventricular ejection fraction was reduced in CAD-AF, reflecting the marked fraction of patients with ischemic cardiomyopathy. No association between anatomical characteristics of CAD and AF was found. However, CAD-AF seemed to be associated with a higher CAD severity (p = 0.06). Additionally, CAD-AF with MI showed a significantly higher number of diseased coronary vessels.

CONCLUSION

The anatomical distribution of coronary artery stenoses does not contribute to AF in CAD patients. However, AF is linked to a higher CAD severity, which might predispose individuals to AF by driving ischemic heart disease and changes in left ventricular function.

[Surgical treatment of ishemic mitral regurgitation: repair, replacement or revascularization alone?]

INTRODUCTION

Treatment of ischemic mitral regurgitation in patients that require revascularization of myocardium is still debatable.

OBJECTIVE

The aim of this study was to compare three surgical approaches: valve repair and revascularization; valve replacement and revascularization, and revascularization alone.

METHODS

In 2006 and 2007 at the Institute for Cardiovascular Diseases, Clinical Centre of Serbia, Belgrade, 1,040 patients with coronary disease underwent surgery. Forty-three patients (4.3%) had also mitral insufficiency 3-4+. The patients were examined clinically, echocardiographically and haemodynamically. In group I there were 14 (32.3%) patients, in group II 16 (37.2%) patients and in group III 3 (30.5%) patients. Ninety-three per cent of patients were classified as New York Heart Association (NYHA) class III and IV, and three (7%) patients had congestive heart weakness with ejection fraction < or =30%. The decision as to surgical procedure was made by the surgeon. Postoperatively, patients were checked clinically and echocardiographically after 3, 6 and 12 months. The follow-up period was approximately 15 months (8-20).

RESULTS

Hospital mortality for the whole group was 6.9% (3 patients). In group I mortality was 14.2% (2 patients), in group II 6.25% and in group III there was no mortality. Long term results, up to 15 months, showed 100% survival in groups I and II, and in group III one patient died (7.7%).

CONCLUSION

Short term results upto 30 days were best in group III, but longer term results were better in groups I and II.

Acute geometric changes of the mitral annulus after coronary occlusion: a real-time 3D echocardiographic study

We performed real-time 3D echocardiography in sixteen sheep to compare acute geometric changes in the mitral annulus after left anterior descending coronary artery (LAD, n=8) ligation and those after left circumflex coronary artery (LCX, n=8) ligation. The mitral regurgitation (MR) was quantified by regurgitant volume (RV) using the proximal isovelocity surface area method. The mitral annulus was reconstructed through the hinge points of the annulus traced on 9 rotational apical planes (angle increment=20 degrees). Mitral annular area (MAA) and the ratio of antero-posterior (AP) to commissure-commissure (CC) dimension of the annulus were calculated. Non-planar angle (NPA) representing non-planarity of the annulus was measured. After LCX occlusion, there were significant increases of the MAA during both early and late systole (p<0.01) with significant MR (RV: 30+/-14 mL), while there was neither a significant increase of MAA, nor a significant MR (RV: 4+/-5 mL) after LAD occlusion. AP/CC ratio (p<0.01) and NPA (p<0.01) also significantly increased after LCX occlusion during both early and late systole. The mitral annulus was significantly enlarged in the antero-posterior direction with significant decrease of non-planarity compared to LAD occlusion immediately after LCX occlusion.

[A simplified method of continuous-wave Doppler noninvasive assessment of ventricular relaxation in mitral insufficiency]

INTRODUCTION AND OBJECTIVES

The minimum value of dP/dT is a parameter of diastolic function that can be estimated noninvasively by analyzing the profile of velocity of the mitral regurgitant jet, recorded by continuous-wave Doppler. This estimation requires a complex analysis of the curves that impedes its practical use. Our objective was to validate a simplified method to estimate noninvasively the value of dP/dTmin when mitral regurgitation exists. We calculated the pendient of the profile of velocity of the curve of mitral regurgitation during its deceleration, between 3 and 1.5 m/s, an interval that defines a difference in pressure using the formula delta p = (4v2(1) - 4v2(2)). We divided this interval by the time needed by the jet to decelerate from 3 to 1.5 m/s, obtaining the rate of pressure decay, in mmHg/s.

METHODS

We provoked mitral regurgitation in five pigs and registered dP/dT and the curve velocity of mitral regurgitation simultaneously, by micromanometer-tipped catheter and continuous-wave Doppler, respectively. The rate of pressure decay was calculated on the mitral regurgitation curve.

RESULTS

We obtained 29 simultaneous registers. The coefficient for the correlationship between dP/dT and the rate of pressure decay was with an r value of 0.62 (p < 0.0001). The rate of pressure decay underestimated systematically the value of dP/dT. Intra and interobserver variability of TDP was 9 and 11%, respectively.

CONCLUSIONS

This study validates a simplified method to estimate dP/dT noninvasively, with acceptable correlation with invasive measurements and adequate reproducibility.

[Double post-acute myocardial infarction complication: rupture of the interventricular septum and acute mitral insufficiency]

We present a case of double post acute myocardial infarction complication: ventricular septal defect and acute and severe mitral insufficiency. As a consequence of the delay in the diagnosis, the patient developed pulmonary hypertension with values at the systemic level. The patient underwent surgery in order to close the ventricular septal defect and aneurysmectomy, resulting in posterior regression of mitral insufficiency and pulmonary circuit values became normal. The ethology, diagnosis, evolution and treatment of this exceptional association of acute post myocardial infarction complications are discussed.

Pathogenesis of mitral regurgitation in acute myocardial infarction: importance of changes in left ventricular shape and regional function

The pathogenesis of mitral regurgitation (MR) was determined by quantitative echocardiography in 188 patients with acute myocardial infarction (AMI) within 48 hours after admission. MR was classified, by using color Doppler, as significant (grades 3 to 4) or trivial (grades 0 to 2). Left ventricular (LV) function (global and regional), volume, and shape, as well as mitral valvular features, were measured and analyzed by stepwise logistic regression. Significant MR occurred in 25 (13%) patients. Univariately, recurrent infarction (p < 0.01), LV dilation (p < 0.001) and sphericity (p < 0.001), inferoposterolateral asynergy (p < 0.001), mitral annular dilatation (p < 0.005), and mitral leaflet restriction (p < 0.05) were associated with significant MR. In regression analysis, only recurrent infarction (odds ratio 5.08), LV sphericity index (odds ratio 1.12), and inferoposterolateral asynergy (odds ratio 6.07) were independently associated with significant MR, whereas none of the mitral valvular features examined had an independent association. In conclusion, changes in LV shape and regional function and not mitral valvular changes are prime determinants of significant MR after AMI.

Intensity of murmurs correlates with severity of valvular regurgitation

PURPOSE

To evaluate the relationship between the intensity of murmurs and severity of mitral and aortic regurgitation.

PATIENTS AND METHODS

Consecutive patients with chronic isolated aortic (n = 40) or mitral (n = 170) regurgitation undergoing echocardiographic quantitation of regurgitation between 1990 and 1991 were studied. Regurgitant volume and fraction were measured using two simultaneous methods (quantitative Doppler echocardiography and quantitative two-dimensional echocardiography); the intensity of the regurgitant murmur (grade 0 to 6) was noted by physicians unaware of the study.

RESULTS

Correlations between murmur intensity and regurgitant volume and fraction were good in aortic regurgitation (r = .60 and r = .67, respectively; P < 0.001) and mitral regurgitation (r = .64 and r = .67, respectively; P < 0.001) but weaker (r = .47 and r = .45, respectively) in the subset of mitral regurgitation of ischemic or functional cause. Murmur intensity grades > or = 3 for aortic regurgitation and > or = 4 for mitral regurgitation predicted severe regurgitation (regurgitant fraction > or = 40%) in 71% and 91% of patients, respectively. Murmur grades < or = 1 for aortic regurgitation and < or = 2 for mitral regurgitation predicted "not severe" regurgitation in 100% and 88% of patients, respectively. Murmur grades 2 for aortic regurgitation and 3 for mitral regurgitation were not correlated to degree of regurgitation. The severity of regurgitation was the most powerful determinant of intensity of murmur.

CONCLUSIONS

Murmur intensity correlates well with the degree of chronic organic aortic and mitral regurgitation, and can be used as a predictor of regurgitation severity and as a simple guideline for diagnostic testing in these patients.

Pathogenesis of acute ischemic mitral regurgitation in three dimensions

Changes in the geometric and intravalvular relationships between subunits of the ovine mitral valve were measured before and after acute posterior wall myocardial infarction in three dimensions by means of sonomicrometry array localization. In 13 sheep, nine sonomicrometer transducers were attached around the mitral anulus and to the tip and base of each papillary muscle. Five additional transducers were placed on the epicardium. Snares were placed around three branches of the circumflex coronary artery. One to 2 weeks later, echocardiograms, dimension measurements, and left ventricular pressures were obtained before and after the coronary arteries were occluded. Data were obtained from seven sheep. Coronary occlusion infarcted 32% of the posterior left ventricle and produced 2 to 3+ mitral regurgitation by Doppler color flow mapping. Multidimensional scaling of dimension measurements obtained from sonomicrometry transducers produced three-dimensional spatial coordinates of each transducer location throughout the cardiac cycle before and after infarction and onset of mitral regurgitation. After posterior infarction, the mitral anulus enlarges asymmetrically along the posterior anulus, and the tip of the posterior papillary muscle moves 1.5 +/- 0.3 mm closer to the posterior commissure at end-systole. The posterior papillary muscle also elongates 1.9 +/- 0.3 mm at end-systole. The left ventricle enlarges asymmetrically and ventricular torsion along the long axis changes. The development of postinfarction mitral regurgitation appears to be the consequence of multiple small changes in ventricular shape and contractile deformation and in the spatial relationship of mitral valvular subunits.

Continuous wave Doppler echocardiography for noninvasive assessment of left ventricular dP/dt and relaxation time constant from mitral regurgitant spectra in patients

OBJECTIVES

We previously demonstrated experimentally that the mitral regurgitant velocity spectrum can be used to estimate left ventricular pressure throughout systole and may provide a new noninvasive method for estimating maximal dP/dt and the relaxation time constant. This study was designed to test this method in patients.

BACKGROUND

The maximal first derivative of left ventricular pressure (dP/dt) and the time constant of left ventricular isovolumetric relaxation (tau) are important variables of left ventricular function, but the need for invasive measurement with high fidelity catheters has limited their use in clinical cardiology.

METHODS

Twelve patients with mitral regurgitation were studied. The Doppler mitral regurgitant velocity spectrum was recorded simultaneously with micromanometer left ventricular pressure tracings in all patients. The regurgitant velocity profiles were digitized and converted to ventriculoatrial (VA) pressure gradient curves using the simplified Bernoulli equation and differentiated into instantaneous dP/dt. The relaxation time constant (tau) was calculated assuming a zero pressure asymptote from catheter left ventricular pressure decay (tau c) and from the Doppler-derived VA gradient curve with corrections. Two methods were used to correct the Doppler gradient curve to better approximate the left ventricular pressure decay before calculating the relaxation time constant: 1) adding an arbitrary 10 mm Hg (tau 10), and 2) adding the actual mean pulmonary capillary pressure (tau LA).

RESULTS

The Doppler-derived maximal positive dP/dt (1,394 +/- 302 mm Hg/s [mean +/- SD]) correlated well (r = 0.91) with the catheter-derived maximal dP/dt (1,449 +/- 307 mm Hg/s). Although the Doppler-derived negative maximal dP/dt differed slightly from catheter measurement (1,014 +/- 289 vs. 1,195 +/- 354 mm Hg/s, p < 0.01), the correlation between Doppler and catheter measurements was similarly good (r = 0.89, p < 0.0001). The correlation between tau 10 and tau c was excellent (r = 0.93, p < 0.01), but the Doppler-derived tau 10 (50.0 +/- 11.0 ms) slightly underestimated the catheter-derived tau c (55.5 +/- 12.8 ms, p < 0.01). This slight underestimation could be corrected by adding the actual pulmonary capillary wedge pressure to the Doppler gradient curve.

CONCLUSIONS

Doppler echocardiography provides an accurate and reliable method for estimating left ventricular maximal positive dP/dt, maximal negative dP/dt and the relaxation time constant (tau) in patients with mitral regurgitation.

Techniques and results of mitral valve repair for ischemic mitral regurgitation

Mitral regurgitation (MR) may start during the acute phase of myocardial infarction and it may increase, decrease, or remain unchanged as the necrotic muscle is replaced by fibrous tissue and remodeling of the ventricle takes place. Acute infarction can cause MR because of rupture of papillary muscle (PM) head or dysfunction of the PM and underlying ventricular wall. When MR is due to rupture of a single PM head and the surrounding muscle is not extensively infarcted, it is possible to suture the PM head in place with pledget sutures or to use other techniques of repair of flair leaflets such as chordal transfer or chordal replacement. When MR is due to extensive necrosis of the PM and the ventricular wall, it is safer to replace the mitral valve with preservation of the chordae tendineae. Correction of MR by means of valve repair in patients with healed myocardial infarction is frequently possible when the cause of MR is determined by Doppler echocardiography. The most common cause of MR is incomplete closure of the mitral valve due to apical displacement of the PM. Prolapse of the leaflets is rare in patients with healed myocardial infarction. Mitral annuloplasty decreases or abolishes MR in most cases when lack of coaptation of the leaflets is the problem. Transient ischemia can also cause MR. Successful myocardial revascularization either by angioplasty or coronary artery bypass often cures episodic ischemic MR.

Effect of thrombolysis on acute mitral regurgitation during evolving myocardial infarction. Experience from the Thrombolysis in Myocardial Infarction (TIMI) Trial

OBJECTIVES

This study was undertaken to determine whether early successful thrombolysis can reverse infarct-associated mitral valve dysfunction.

BACKGROUND

Mitral regurgitation is a common complication of acute myocardial infarction and has been shown to adversely affect both short- and long-term prognosis. Although anecdotal reports have suggested that reperfusion of the infarct-related artery may restore normal function to the mitral valve, this theory has not been subjected to formal investigation.

METHODS

Patients with total or partial obstruction of the infarct-related artery received intravenous thrombolytic therapy with either streptokinase or recombinant tissue-type plasminogen activator within 7 h of symptom onset (mean 4.8 h) as part of the Thrombolysis in Myocardial Infarction (TIMI) Phase I trial. Repeat coronary angiography assessed arterial patency at 90 min and 10 days after attempted reperfusion. The presence and severity of mitral regurgitation were determined by contrast ventriculography both before thrombolysis and before hospital discharge.

RESULTS

Overall, 21 (16%) of the 132 study patients exhibited mitral regurgitation on either their initial or their predischarge ventriculogram. The proportion of infarct-related arteries found to be patent (TIMI flow grade 2 or 3) was statistically similar in patients with and without mitral regurgitation during each angiographic evaluation period (initial, 90 min and 10 days). Although coronary artery perfusion increased overall during sequential measurement (mean TIMI grade was 0.4 +/- 0.6 initially, 1.5 +/- 1.3 at 90 min and 2.2 +/- 1.0 at 10 days), the pattern of reperfusion observed could not predict an increase or decrease in regurgitant severity (p = NS). Early mitral regurgitation resolved in 57% of patients by 10 days, but this resolution appeared independent of the presence or absence of improved coronary perfusion (60% vs. 50%). The development of new regurgitation during the recovery period (6%) was also unrelated to improved perfusion (7% vs. 4%).

CONCLUSIONS

Acute mitral regurgitation developing during myocardial infarction shows frequent changes in its presence or severity during the 1st 10 days, appears independent of coronary artery patency both early and late after thrombolysis and cannot be reliably treated by improving arterial perfusion with thrombolytic agents.

Mitral regurgitation following first-time acute myocardial infarction--early and late findings by Doppler echocardiography

A total of 61 patients with first-time mild to moderate acute myocardial infarction and no reinfarction within the following 2 months were studied prospectively by Doppler echocardiography before hospital discharge and after 2 months to evaluate the prevalence of mitral regurgitation. Twenty-one age-matched healthy subjects served as controls. At baseline, the prevalence of Doppler-recorded mitral regurgitation was 74% and 29% in patients and controls, respectively. In the patients, the regurgitant flow measured by color flow Doppler was 1.04 cm2 (range 0.2-8 cm2) and occupied 7.5% (range 2-45%) of the left atrial area. Corresponding figures for controls were 0.35 cm2 (0.1-0.6) and 2.4% (0.7-4.5), respectively. On continuous wave Doppler, most patients (33/45) had Doppler signals similar to those of healthy controls. The prevalence of mitral regurgitation was about the same in anterior and inferior infarction (75 and 72% respectively). In the patients, the prevalence was similar after 2 months (79%) with minor changes in the Doppler characteristics of the regurgitation (regurgitant flow 1.12 cm2 and occupying 8.1% of left atrial area). The study demonstrates that in a group of patients with first-time mild to moderate myocardial infarction the prevalence of Doppler-recorded mitral regurgitation is high and mild in severity in the majority of the cases. The changes remain almost similar even after 2 months.

Interventricular septal rupture complicating acute myocardial infarction: from pathophysiologic features to the role of invasive and noninvasive diagnostic modalities in current management

Rupture of the interventricular septum is a serious complication of acute myocardial infarction, accounting for 5% of deaths due to acute infarction. The septal perforation most frequently occurs during the first week after the infarction. The majority of these patients present with at least two-vessel coronary artery disease, and most cases have a total occlusion of the infarct-related artery. The degree of associated right ventricular damage is clinically important. Unpredictable hemodynamic deterioration can rapidly develop in 80% of the patients, and mortality with medical therapy alone exceeds 90%. Because the preoperative hemodynamic status of these patients appears to be a major determinant for survival, accurate diagnosis, urgent management, and early operative correction are necessary to avoid a catastrophic clinical outcome. Traditionally, diagnostic procedures included first, the insertion of a pulmonary artery catheter for recording of pressures, sequential oximetry, and calculation of the shunt's magnitude and the cardiac output followed by left ventriculography and coronary arteriography for angiographic demonstration of the shunt and the coronary anatomy. Currently, optimal utilization of color flow Doppler and two-dimensional and transesophageal echocardiography offers a significant clinical advantage and can be used to shorten the time spent on diagnosis, evaluation, and management prior to the urgent surgical repair. The elimination of time-consuming diagnostic tests can contribute to further improvement in the survival rate.

Noninvasive measurement of the time constant of left ventricular relaxation using the continuous-wave Doppler velocity profile of mitral regurgitation

BACKGROUND

The time constant of isovolumic relaxation (tau) is an important parameter of ventricular diastolic function, but the need for invasive measurement with high-fidelity catheters has limited its use in general clinical cardiology. The Doppler mitral regurgitant velocity spectrum can be used to estimate left ventricular (LV) pressure throughout systole and may provide a new noninvasive method for estimating tau.

METHODS AND RESULTS

Mitral regurgitation was produced in nine dogs, and ventricular relaxation was adjusted pharmacologically and with hypothermia. High-fidelity ventricular pressures were recorded, and tau was calculated from these hemodynamic data (tau H) assuming a zero-pressure asymptote. Continuous-wave mitral regurgitant velocity profiles were obtained, and the ventriculo-atrial (VA) pressure gradient was calculated by the simplified Bernoulli equation; tau was calculated from the Doppler data from the time of maximal negative dP/dt until LV-LA pressure crossover. Three methods were used to correct the Doppler VA gradient to better approximate the LV pressure before calculating tau: 1) adding actual LA V wave pressure (to yield tau LA); 2) adding 10 mm Hg (tau 10); and 3) no adjustment at all (actual VA gradient used to calculate tau 0). The agreement between tau H and the three Doppler estimates of tau was assessed by linear regression and by the mean and standard deviation of the error between the measurements (delta tau). the measurements (delta tau). tau H ranged from 29 to 135 msec. Without correction for LA pressure, the Doppler estimate of tau seriously underestimated tau H: tau 0 = 0.30 tau H + 9.4, r = 0.79, delta tau = -35 +/- 18 msec. This error was almost completely eliminated by adding actual LA pressure to the VA pressure gradient: tau LA = 0.92 tau H + 7.6, r = 0.95, delta tau = 2 +/- 7 msec. Addition of a fixed LA pressure estimate of 10 mm Hg to the VA gradient yielded an estimate that was almost as good: tau 10 = 0.89 tau H + 4.9, r = 0.88, delta tau = -2 +/- 12 msec. In general, tau was overestimated when actual LA pressure was below this assumed value, and vice versa. Numerical analysis demonstrated that assuming LA pressure to be 10 mm Hg should yield estimates of tau accurate to +/- 15% between true LA pressures of 5 and 20 mm Hg.

CONCLUSIONS

This study demonstrates that the Doppler mitral regurgitant velocity profile can be used to provide a direct and noninvasive measurement of tau. Because mitral regurgitation is very common in cardiac patients, this method may allow more routine assessment of tau in clinical and research settings, leading to a better understanding of the role of impaired ventricular relaxation in diastolic dysfunction and the effect of therapeutic interventions.

Cardiac evaluation

Over the past decade there has been a dramatic, rapid development of new imaging modalities used in the evaluation of the cardiac patient. These newer techniques are frequently complex and specialized in their application and interpretation. Nonetheless, the prevalence of cardiac disease in the United States, and the wide application of these diagnostic tests, mandate that the well-rounded clinician has a basic understanding of the utility of these diagnostic modalities. Unfortunately, the burgeoning field of cardiac imaging seems at times to overshadow our most important basic diagnostic tools, namely, the history, physical exam, chest radiograph, and electrocardiogram (ECG). This review will attempt to impart a basic understanding of the newer cardiac diagnostic tests and their utility in various disease states. Emphasis on the importance of the basic clinical exam and the precise integration of specific diagnostic tests into the cardiac evaluation will be emphasized. The article will deliver a basic review of exercise treadmill testing, echocardiography, radionuclide imaging techniques, magnetic resonance imaging, and cardiac catheterization. It is hoped that this review will impart to the noncardiologist clinician a basic understanding of the cardiovascular diagnostic techniques so that an accurate, precise, cost-effective, efficient diagnostic plan for the patient with cardiovascular disease can be developed and applied.

Treatment of severe mitral regurgitation caused by ischemic papillary muscle dysfunction: indications for coronary angioplasty

The aim of this study was to evaluate the prognosis and functional outcome of mitral regurgitation caused by ischemic papillary muscle dysfunction with respect to treatment, and to determine the role of coronary angioplasty in this context. Thirty patients with severe ischemic mitral regurgitation were followed up for 33 +/- 3 months. Thirteen patients were treated medically (group I) and 17 patients underwent surgery or angioplasty (group II). The 3-year survival was 59.5% (45.6% in group I and 70.2% in group II). Angioplasty was only used in paroxysmal mitral regurgitation caused by papillary muscle ischemia. This technique resulted in spectacular immediate results in three patients with pulmonary edema caused by mitral regurgitation during myocardial ischemia. Surgical correction of mitral regurgitation should be considered without delay if angioplasty is not feasible or if the regurgitation is permanent or severe. Widening the indications of surgery or angioplasty should result in an improvement of the prognosis of these high-risk patients.

Mechanism of ischemic mitral regurgitation. An experimental evaluation

BACKGROUND

Papillary muscle dysfunction (PMD) has been implicated in the pathogenesis of ischemic mitral regurgitation (MR). We hypothesized that ischemic MR is not caused by PMD and/or dysfunction of the myocardial regions from where the papillary muscles arise but is related to reduction in global left ventricular (LV) function. To test this hypothesis, three groups of dogs were studied.

METHODS AND RESULTS

In group 1 dogs (n = 8), varying degrees of regional and global LV dysfunction were produced. In group 2 dogs (n = 7), the circulation to the papillary muscles was isolated from that of the rest of the LV. Dysfunction of one or both papillary muscles was produced without producing global LV dysfunction. Global LV dysfunction was also produced while keeping papillary muscle function intact. The degree of MR (assessed using contrast echocardiography) was correlated in both groups of dogs with thickening of the papillary muscles and regional and global LV function. In the group 3 dogs (n = 6), the spatial distribution of blood flow within each papillary muscle was determined during ischemia by using radiolabeled microspheres. Thickening of the papillary muscles was assessed at three different levels along their lengths and was correlated with average blood flow at these levels. In group 1 dogs, MR was noted only when global LV function was affected and its severity correlated inversely with global LV function (r = -0.84 with peak positive LV dP/dt and r = -0.95 with global LV thickening, respectively). In comparison, there was poor correlation between MR and anterior and posterior papillary muscle thickening (r = -0.38 and r = -0.49, respectively). In group 2 dogs, MR did not occur in the presence of either PMD or akinesia of the immediately adjacent LV myocardium. MR occurred only when global LV dysfunction was produced (with the papillary muscle function intact), and its severity correlated inversely with global LV function (r = -0.92 with LV dP/dt and r = -0.86 with global LV thickening, respectively). There was poor correlation between the degree of MR and thickening of the anterior and posterior papillary muscles (r = -0.24 and r = -0.38, respectively). In both groups of dogs, MR was associated with incomplete mitral leaflet closure (IMLC), and the severity of MR correlated linearly with the degree of IMLC (r = 0.98). MR was never associated with mitral valve prolapse. In the group 3 dogs, despite more inhomogeneous flow during ischemia to the anterior compared with the posterior papillary muscle, mean thickening of these muscles was similar (3 +/- 10% and 3 +/- 4%, respectively). Furthermore, there was minimal variability in thickening between different parts of the muscles (3 +/- 2% and 5 +/- 3%, respectively).

CONCLUSIONS

It is concluded that PMD and/or dysfunction of the immediately adjacent LV myocardium does not result in MR. MR occurs during ischemia only when global LV function is affected, even when thickening of the papillary muscles and the immediately adjacent LV remains intact. MR in this situation is related to IMLC; the greater the degree of IMLC, the greater the MR. These findings suggest that the mechanism of ischemic MR is not related to PMD. There may also be important therapeutic implications of these findings.

Evaluation of transient mitral regurgitation in coronary artery disease

The pathoanatomy and factors associated with transient mitral regurgitation (MR) induced by myocardial ischemic stress are unknown. Changes in valvular and ventricular parameters during transient, stress-induced MR in patients with coronary artery disease were investigated, and the clinical characteristics of these patients were identified. Color flow Doppler echocardiography was used to quantify the MR color area, the coaptation point of the mitral leaflets, the mitral valve anulus diameter, and left ventricular volumes and wall motion in 42 patients before and immediately after exercise echocardiography (group 1, n = 27), or before and during percutaneous transluminal coronary angioplasty (PTCA) (group 2, n = 15). Of the 27 patients with exercise echocardiography, 4 developed new, transient MR (group 1B) and 9 had MR both at rest and during exercise (group 1C). Of the 15 patients with PTCA, 7 developed new MR (group 2B). New MR (groups 1B and 2B) was associated with more severe stress-induced ventricular dyskinesia (p less than 0.05) than was seen in patients with chronic MR (group 1C) or in patients without MR, and occurred predominantly in patients with left anterior descending or right coronary artery stenoses. Stress-induced MR was not associated with changes in blood pressure or in mitral valve anulus diameter, nor with the development of mitral valve prolapse. It was associated with apical displacement of the mitral leaflets in patients in group 1B and C (p less than 0.05). New MR flow areas were significantly smaller than those in patients with chronic MR (p less than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Intraoperative transesophageal Doppler color flow imaging used to guide patient selection and operative treatment of ischemic mitral regurgitation

BACKGROUND

Intraoperative transesophageal Doppler color flow imaging (TDCF) affords the opportunity to assess mitral valve competency immediately before and after cardiopulmonary bypass (CPB). The purpose of this study was to assess the utility of TDCF to assist in the selection and operative treatment of ischemic mitral regurgitation (MR).

METHODS AND RESULTS

Two hundred forty-six patients undergoing surgery for ischemic heart disease were prospectively studied. All had preoperative cardiac catheterization. Catheterization and pre-CPB TDCF were discordant in their estimation of MR in 112 patients (46%). Compared with patients in whom both techniques agreed in estimation of MR, patients with discordance in MR were more likely to have had unstable clinical syndromes at the time of catheterization (79% versus 40%, p less than 0.05) or to have received thrombolytics (16% versus 8%, p less than 0.05). Pre-CPB TDCF resulted in a change in the operative plan with respect to the mitral valve in 27 patients (11%). Because less MR was found by TDCF than catheterization, 22 patients had only coronary bypass grafting when combined coronary bypass and mitral valve surgery had been planned. Because more MR was found by TDCF than catheterization, five patients had combined coronary bypass and mitral valve surgery when coronary bypass alone had been planned. Unsatisfactory results noted by TDCF following mitral valve surgery in five patients resulted in immediate corrective surgery. Cox regression analysis identified residual MR at the completion of surgery to be an important predictor of survival (chi 2 = 21.4) after surgery--more important than patient age (chi 2 = 8.3) or left ventricular ejection fraction (chi 2 = 5.3).

CONCLUSIONS

These results indicate that TDCF is useful in guiding patient selection and operative treatment of ischemic MR and that in such patients, intraoperative TDCF should be performed routinely.

Noninvasive estimation of the instantaneous first derivative of left ventricular pressure using continuous-wave Doppler echocardiography

BACKGROUND

The complete continuous-wave Doppler mitral regurgitant velocity curve should allow reconstruction of the ventriculoatrial (VA) pressure gradient from mitral valve closure to opening, including left ventricular (LV) isovolumic contraction, ejection, and isovolumic relaxation. Assuming that the left atrial pressure fluctuation is relatively minor in comparison with the corresponding LV pressure changes during systole, the first derivative of the Doppler-derived VA pressure gradient curve (Doppler dP/dt) might be used to estimate the LV dP/dt curve, previously measurable only at catheterization (catheter dP/dt).

METHODS AND RESULTS

This hypothesis was examined in an in vivo mitral regurgitant model during 30 hemodynamic stages in eight dogs. Contractility and relaxation were altered by inotropic stimulation and hypothermia. The Doppler mitral regurgitant velocity spectrum was recorded along with simultaneously acquired micromanometer LV and left atrial pressures. The regurgitant velocity profiles were digitized and converted to VA pressure gradient curves using the simplified Bernoulli equation. The instantaneous dP/dt of the VA pressure gradient curve was then derived. The instantaneous Doppler-derived VA pressure gradients, instantaneous Doppler dP/dt, dP/dtmax, and -dP/dtmax were compared with corresponding catheter measurements. This method of estimating dP/dtmax from the instantaneous dP/dt curve was also compared with a previously proposed Doppler method of estimating dP/dtmax using the Doppler-derived mean rate of LV pressure rise over the time period between velocities of 1 and 3 m/sec on the ascending slope of the Doppler velocity spectrum. Both instantaneous Doppler-derived VA pressure gradients (r = 0.95, p less than 0.0001) and Doppler dP/dt (r = 0.92, p less than 0.0001) correlated well with corresponding measurements by catheter during systolic contraction and isovolumic relaxation (pooled data). The Doppler dP/dtmax (1,266 +/- 701 mm Hg/sec) also correlated well (r = 0.94) with the catheter dP/dtmax (1,200 +/- 573 mm Hg/sec). There was no difference between the two methods for measurement of dP/dtmax (p = NS). Although Doppler -dP/dtmax was slightly lower than the catheter measurement (961 +/- 511 versus 1,057 +/- 540 mm Hg/sec, p less than 0.01), the correlation between measurements by Doppler and catheter was excellent (r = 0.93, p less than 0.0001). The alternative method of mean isovolumic pressure rise (896 +/- 465 mm Hg/sec) underestimated the catheter dP/dtmax (1,200 +/- 573 mm Hg/sec) significantly (on average, 25%; p less than 0.001).

CONCLUSIONS

The present study demonstrated an accurate and reliable noninvasive Doppler method for estimating instantaneous LV dP/dt, dP/dtmax, and -dP/dtmax.

Mitral valve replacement combined with coronary artery operation: determinants of early and late results

Mitral valve replacement combined with coronary artery bypass grafting has been reported as being associated with a higher mortality than either mitral valve replacement or coronary artery bypass grafting alone. Cause of mitral valve disease and severity of mitral regurgitation have been reported as related to mortality. To study the correlation of the cause of mitral valve disease and severity of mitral regurgitation to hospital mortality and long-term survival, we analyzed the results of 135 patients undergoing mitral valve replacement and coronary artery bypass grafting between June 1974 and August 1989. The hospital mortality was 11.8% (16/135). Fifteen preoperative and operative variables were tested for correlation with hospital or late mortality using univariate tests and multivariate regression. Advanced age (greater than 60 years), New York Heart Association functional class, and wall motion score were independently associated with hospital mortality (p less than 0.05). The cause of mitral valve disease and severity of mitral regurgitation were not related to hospital mortality or long-term survival (p greater than 0.05). The follow-up rate was 96.6% for the hospital survivors (115/119). Mean follow-up was 52.6 +/- 4.1 months. There were 35 late deaths. Survival was 91.9%, 89.9%, 78%, and 49.9% at 1, 2, 5, and 10 postoperative years, respectively. Preoperative New York Heart Association functional class and use of catecholamines during the postoperative intensive care period were independently related to late survival (p less than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Acute mitral regurgitation due to short periods of ischemia during percutaneous transluminal coronary angioplasty: an angiographic study

The frequency and severity of mitral regurgitation were investigated during a short period of ischemia (60 seconds) in patients undergoing elective percutaneous transluminal coronary angioplasty of single vessel disease. Thirty patients showed stenoses in the left anterior descending artery, 3 patients in the circumflex artery and 1 patient in the right coronary artery. Only patients with global and regional normal left ventricular function, and without collaterals reaching or filling the target vessel, were enrolled in the study. All patients suffered pain during occlusion of the vessel. Signs of mitral regurgitation of grade 1 could be documented angiographically in 9 patients and of grade 2 in 4 patients. In no patient mitral regurgitation of grades 3 or 4 was seen. A highly significant (P less than 0.001) decrease of global, as well as regional, left ventricular function could be documented during ischemia in all patients. The breakdown of wall motion was more pronounced in patients with mitral regurgitation, and reached statistical significance (P less than 0.05) in the apical and anterolateral segments. All patients with mitral regurgitation showed extended severely hypokinetic or akinetic wall segments adjacent to the anterior papillary muscle. There were no angiographic signs of mitral valvar prolapse or dilation of the mitral annulus. We concluded that transient mitral regurgitation is common during short periods of ischemia in humans, but of only minimal degree in the setting of single vessel disease. The mechanism is different from mechanisms in chronic ischemic incompetence of the mitral valve.

A new method for estimating left ventricular dP/dt by continuous wave Doppler-echocardiography. Validation studies at cardiac catheterization

In this study, we explored the use of continuous wave Doppler-echocardiography guided by color Doppler flow-mapping as a method for noninvasively calculating the rate of pressure rise (RPR) in the left ventricle. Continuous wave Doppler determination of the velocities in mitral regurgitant jets allows calculation of instantaneous pressure gradients between the left ventricle and the left atrium. Left atrial pressure variations in early systole can be considered negligible; therefore, the rising segment of the mitral regurgitation velocity curve should reflect left ventricular pressure increase. We studied 50 patients (mean age, 51 years; range, 25-66 years) in normal sinus rhythm with color Doppler-proven mitral regurgitation and compared the Doppler-derived left ventricular RPR with peak dP/dt obtained at cardiac catheterization. Doppler studies were performed simultaneously with cardiac catheterization in 11 patients and immediately before in the remaining cases. Two points were arbitrarily selected on the steepest rising segment of the continuous wave mitral regurgitation velocity curve (point A, 1 m/sec, point B, 3 m/sec), and the time interval (t) between them was measured. Following the Bernoulli relation, the pressure rise between points A and B is 32 mm Hg (4vB2-4vA2) and the RPR is 32 mm Hg/t. Results showed a linear correlation between the Doppler RPR and peak dP/dt (r = 0.87, SEE = 316 mm Hg/sec). The RPR in the left ventricle can be derived from the continuous wave Doppler mitral regurgitation velocity curve.

Acute ventricular septal rupture. Angiographic-morphologic features and clinical assessment

Twenty patients with acute ventricular septal rupture underwent cardiac catheterization. Prior to catheterization, 17 patients were in Killip class 3-4. Mean cardiac index and cardiac output were 2.03 +/- 0.81 L/min/m2 and 3.55 +/- 1.33 L/min, respectively. Based on a recent pathologic description of septal rupture, we encountered by angiography and during surgery, two morphologic types of rupture: simple type which appears as a direct through-and-through communication between the ventricles, and complex type which presents hemorrhagic tracts in the septum with the opening into the ventricles at different levels. Considering the management of patients with septal rupture and the clinical outcome in our series, it is suggested that there is a need to minimize invasive angiographic procedures prior to early surgical correction of the ruptured septum.

Effect of electrical stimulus parameters on the development and propagation of action potentials in short excitable fibres

Intracellular action potentials (IAPs) produced by short fibres in response to their electrical stimulation were analysed. IAPs were calculated on the basis of the Hodgkin-Huxley (1952) model by the method described by Joyner et al. (1978). Principal differences were found in processes of activation of short (semilength L less than 5 lambda) and long fibres under near-threshold stimulation. The shorter the fibre, the lower was the threshold value (Ithr). Dependence of the latency on the stimulus strength (Ist) was substantially non-linear and was affected by the fibre length. Both fibre length and stimulus strength influenced the IAP amplitude, the instantaneous propagation velocity (IPV) and the site of the first origin of the IAP (and, consequently, excitability of the short fibre membrane). With L less than or equal to 2 lambda and Ithr less than or equal to Ist less than or equal to 1.1Ithr, IPV could reach either very high values (so that all the fibre membrane fired practically simultaneously) or even negative values. The latter corresponded to the first origin of the propagated IAP, not at the site of stimulation but at the fibre termination or at a midpoint. The characters of all the above dependencies were unchanged irrespective of the manner of approaching threshold (variation of stimulus duration or its strength). Reasons for differences in processes of activation of short and long fibres are discussed in terms of electrical load and latency. Applications of the results to explain an increased jitter, velocity recovery function and velocity-diameter relationship are also discussed.

Valvular heart disease: clinical approach to acute decompensation of left-sided lesions

Acute valvular heart disease is often life-threatening. The diagnosis of acute valvular decompensation is made by attention to the physical assessment and appropriate use of diagnostic techniques. Recent advances in valvular heart disease have centered around noninvasive diagnostics. Doppler echocardiography can accurately diagnose and quantify stenotic and regurgitant lesions; its use with M-mode and two-dimensional echocardiography makes these the noninvasive diagnostic procedures of choice. Acute decompensation is often related to preexisting critical aortic or mitral stenosis, or more commonly, acute severe regurgitation. Although of different etiologies, acute mitral and aortic regurgitation are associated with similar diagnostic and therapeutic modalities. Emergency treatment consists of vasodilator and, possibly, inotropic therapy. However, definitive therapy generally requires surgical intervention.