Timing of operation for chronic aortic regurgitation

Echocardiographic Markers of Early Left Ventricular Dysfunction in Asymptomatic Aortic Regurgitation: Is It Time to Change the Guidelines?

BACKGROUND

The ideal timing for surgery in asymptomatic chronic aortic regurgitation (AR) remains unclear. New thresholds for left ventricular ejection fraction (LVEF), left ventricular (LV) indexed end-systolic volume (iESV), and global longitudinal strain (GLS) have been associated with mortality in these patients. These represent markers of early LV dysfunction.

OBJECTIVES

The authors sought to assess the relationship between these markers (LVEF <60%, iESV ≥45 mL/m2, and GLS worse than -15%) and mortality, comparing them to Class I/IIa American College of Cardiology/American Heart Association guideline recommendations and absence of any of these.

METHODS

A total of 673 asymptomatic patients with chronic clinically significant (≥ moderate-severe) AR between 2004 and 2019 at a single referral center were retrospectively analyzed. The primary study outcome was all-cause mortality.

RESULTS

Mean age was 57 ± 17 years, 97 (14%) were female, 293 (45%) had hypertension, and 273 (41%) had an abnormal number of valve cusps. Aortic valve replacement was performed in 281 (48%) patients, and 69 (10%) died while under surveillance (without aortic valve replacement). LVEF <60% was present in 296 (44%) patients, 122 (25%) of 482 had GLS worse than -15%, and 261 (39%) had iESV ≥45 mL/m2. Mortality under surveillance was highest when Class I/IIa recommendations were present (HR: 4.22; 95% CI: 2.15-8.29), followed by the presence of 1 or more markers of early LV dysfunction (HR: 2.18; 95% CI: 1.21-3.92); no markers was used as the reference (all, P < 0.05). LVEF showed the strongest association with mortality, statistically slightly better than GLS and iESV. In the absence of Class I/IIa recommendations, 1 marker of early LV dysfunction was associated with higher, although not statistically significant, mortality compared with no markers (P = 0.063), followed by 2 markers; highest mortality was when all 3 markers were present (HR: 5.46; 95% CI: 2.51-11.90; P < 0.001).

CONCLUSIONS

Patients with asymptomatic clinically significant chronic AR incur a survival penalty when Class I/IIa guideline recommendations are attained. In patients without these recommendations, at least 2 markers of early LV dysfunction identify those with higher mortality risk who may benefit from early surgery.

Mitral regurgitation: anatomy is destiny

Mitral regurgitation (MR) occurs when any of the valve and ventricular mitral apparatus components are disturbed. As MR progresses, left ventricular remodelling occurs, ultimately causing heart failure when the enlarging left ventricle (LV) loses its conical shape and becomes globular. Heart failure and lethal ventricular arrhythmias may develop if the left ventricular end-systolic volume index exceeds 55 ml/m2. These adverse changes persist despite satisfactory correction of the annular component of MR. Our goal was to describe this process and summarize evolving interventions that reduce the volume of the left ventricle and rebuild its elliptical shape. This 'valve/ventricle' approach addresses the spherical ventricular culprit and offsets the limits of treating MR by correcting only its annular component.

The hemodynamic effects of acute aortic regurgitation into a stiffened left ventricle resulting from chronic aortic stenosis

Acute aortic regurgitation (AR) post-chronic aortic stenosis is a prevalent phenomenon occurring in patients who undergo transcatheter aortic valve replacement (TAVR) surgery. The objective of this work was to characterize the effects of left ventricular diastolic stiffness (LVDS) and AR severity on LV performance. Three LVDS models were inserted into a physiological left heart simulator. AR severity was parametrically varied through four levels (ranging from trace to moderate) and compared with a competent aortic valve. Hemodynamic metrics such as average diastolic pressures (DP) and reduction in transmitral flow were measured. AR index was calculated as a function of AR severity and LVDS, and the work required to make up for lost volume due to AR was estimated. In the presence of trace AR, higher LVDS had up to a threefold reduction in transmitral flow (13% compared with 3.5%) and a significant increase in DP (2-fold). The AR index ranged from ∼42 to 16 (no AR to moderate AR), with stiffer LVs having lower values. To compensate for lost volume due to AR, the low, medium, and high LVDS models were found to require 5.1, 5.5, and 6.6 times more work, respectively. This work shows that the LVDS has a significant effect on the LV performance in the presence of AR. Therefore, the LVDS of potential TAVR patients should be assessed to gain an initial indication of their ability to tolerate post-procedural AR.

[Surgery of aortic regurgitation with reduced left ventricular function]

BACKGROUND

Aortic valve replacement improves clinical symptoms and left ventricular systolic function in patients with chronic aortic regurgitation despite a higher surgical risk. The objective of this study is to determine if left ventricular function will be normalized after surgery.

PATIENTS AND METHOD

This retrospective study included 40 patients (nine females and 31 males) with chronic aortic regurgitation and left ventricular systolic dysfunction who were evaluated by echocardiography Doppler. Were included patients with left ventricular ejection fraction less or equal to 45%. Ages ranged from 18 to 77 years (mean = 46.4 ± 12.6 years). Preoperatively, six patients (15%) were asymptomatic, ten (25%) were in NYHA II, half (50%) in NYHA III and four (10%) in NYHA IV. The mean preoperative ejection fraction (EF) was 36.2 ± 2%. The mean end systolic and diastolic dimensions were 61.7 ± 8.5 mm and 78.9 ± 9.7 mm respectively. Aortic regurgitation was quantified grade III in sixteen patients (40%) and grade IV in twenty-four (60%).

RESULTS

Thirty-seven patients underwent aortic valve replacement and three Bentall operations. Hospital mortality was 7.5% (3/40). The mean follow-up period was 69.7 months. All survivor patients were investigated. Out of these, five were lost and 32 were controlled. Symptomatic improvement was noted in most of the survivors. Sixty percent (24/40) were severely symptomatic before and only 6.25% (2/32) during follow-up. The ejection fraction increased significantly after surgery (36.2 ± 2% in preoperative period vs. 55.2 ± 10% in postoperative period, P < 0.02). Left ventricular diameters decreased significantly also. Survival rates were 3-year 94%, 5-year 91% and 7-year 89%.

CONCLUSION

Despite reduced left ventricular systolic function, aortic valve replacement in chronic aortic regurgitation was associated with acceptable operative risk. Surgery improves functional status, symptoms and ejection fraction in most patients.

Surgical ventricular restoration for the treatment of heart failure

Heart failure (HF) is an emerging epidemic affecting 15 million people in the USA and Europe. HF-related mortality was unchanged between 1995 and 2009, despite a decrease in the incidence of cardiovascular disease. Conventional explanations include an aging population and improved treatment of acute myocardial infarction and HF. An adverse relationship between structure and function is the central theme in patients with systolic dysfunction. The normal elliptical ventricular shape becomes spherical in ischemic, valvular, and nonischemic dilated cardiomyopathy. Therapeutic decisions should be made on the basis of ventricular volume rather than ejection fraction. When left ventricular end-systolic volume index exceeds 60 ml/m², medical therapy, CABG surgery, and mitral repair have limited benefit. This form-function relationship can be corrected by surgical ventricular restoration (SVR), which returns the ventricle to a normal volume and shape. Consistent early and late benefits in the treatment of ischemic dilated cardiomyopathy with SVR have been reported in >5,000 patients from various international centers. The prospective, randomized STICH trial did not confirm these findings and the reasons for this discrepancy are examined in detail. Future surgical options for SVR in nonischemic and valvular dilated cardiomyopathy, and its integration with left ventricular assist devices and cell therapy, are described.

Aortic and mitral regurgitation: quantification using moving slice velocity mapping

Comprehensive assessment of the severity of valvular insufficiency includes quantification of regurgitant volumes. Previous methods lack reliable slice positioning with respect to the valve and are prone to velocity offsets due to through-plane motion of the valvular plane of the heart. Recently, the moving slice velocity mapping technique was proposed. In this study, the technique was applied for quantification of mitral and aortic regurgitation. Time-efficient navigator-based respiratory artifact suppression was achieved by implementing a prospective k-space reordering scheme in conjunction with slice position correction. Twelve patients with aortic insufficiency and three patients with mitral insufficiency were studied. Aortic regurgitant volumes were calculated from diastolic velocities mapped with a moving slice 5 mm distal to the aortic valve annulus. Mitral regurgitant flow was indirectly assessed by measuring mitral inflow at the level of the mitral annulus and net aortic outflow. Regurgitant fractions, derived from velocity data corrected for through-plane motion, were compared to data without correction for through-plane motion. In patients with mild and moderate aortic regurgitation, regurgitant fractions differed by 60% and 15%, on average, when comparing corrected and uncorrected data, respectively. Differences in severe aortic regurgitation were less (7%). Due to the large orifice area of the mitral valve, differences were still substantial in moderate-to-severe mitral regurgitation (19%). The moving slice velocity mapping technique was successfully applied in patients with aortic and mitral regurgitation. The importance of correction for valvular through-plane motion is demonstrated.

Timing of surgery in chronic aortic regurgitation

When deciding on therapy for aortic regurgitation (AR), it is imperative to distinguish between acute and chronic AR. Symptoms and echocardiographic findings are essential in distinguishing acute from chronic AR and in assessing the severity. Vasodilators have been shown to be helpful in treating patients with chronic severe AR. The timing of aortic valve replacement in chronic severe AR remains controversial. Symptoms, left ventricular function, and response to exercise have been shown to be the most important prognostic indicators.

[Nuclear cardiology: technical bases and clinical applications]

Although the role of nuclear cardiology is currently well consolidated, the addition of new radiotracers and modern techniques makes it necessary to continuously update the requirements, equipment and clinical applications of these isotopic tests. The characteristics of the radioisotopic drugs and examinations presently used are explained in the first part of this text. In the second, the indications of them in diagnostic and prognostic evaluation of the different coronary diseases are presented.

Heart motion adapted cine phase-contrast flow measurements through the aortic valve

A method for magnetic resonance cine velocity mapping through heart valves with adaptation of both slice offset and angulation according to the motion of the valvular plane of the heart is presented. By means of a subtractive labeling technique, basal myocardial markers are obtained and automatically extracted for quantification of heart motion at the valvular level. The captured excursion of the basal plane is used to calculate the slice offset and angulation of each required time frame for cine velocity mapping. Through-plane velocity offsets are corrected by subtracting velocities introduced by basal plane motion from the measured velocities. For evaluation of the method, flow measurements downstream from the aortic valve were performed both with and without slice adaptation in 11 healthy volunteers and in four patients with aortic regurgitation. Maximum through-plane motion at the aortic root level as calculated from the labeled markers averaged 8.9 mm in the volunteers and 6.5 mm in the patients. The left coronary root was visible in 2-4 (mean: 2.2) time frames during early diastole when imaging with a spatially fixed slice. Time frames obtained with slice adaptation did not contain the coronary roots. Motion correction increased the apparent regurgitant volume by 5.7 +/- 0.4 ml for patients with clinical aortic regurgitation, for an increase of approximately 50%. The proposed method provides flow measurements with correction for through-plane motion perpendicular to the aortic root between the valvular annulus and the coronary ostia throughout the cardiac cycle. Magn Reson Med 42:970-978, 1999.

Chronic aortic regurgitation. Role of medical therapy and optimal timing for surgery

Aortic valve replacement should be performed once significant symptoms develop. Lacking important symptoms, operation should also be performed in patients with aortic regurgitation who manifest consistent and reproducible evidence of either LV contractile dysfunction at rest or extreme LV dilation. Noninvasive imaging techniques should play a major role in this evaluation. An important clinical decision, such as recommending aortic valve replacement in the asymptomatic patient, should not be based on a single echocardiographic or radionuclide angiographic measurement alone. When these data consistently indicate impaired contractile function at rest or extreme LV dilation on repeat measurements, however, operation is indicated in the asymptomatic patient. This strategy should reduce the likelihood of irreversible LV dysfunction in these patients and enhance long-term postoperative survival.

Doppler evaluation of aortic regurgitation in children

Doppler indexes have been used successfully to determine the severity of aortic regurgitation (AR) in adults but have not been evaluated systematically in children. To evaluate the accuracy of specific Doppler echocardiographic indexes in assessing the degree of AR in children, 30 children underwent 2-dimensional and Doppler echocardiography within 24 hours of angiography. Patients were divided into 4 groups based on the degree of angiographic AR. Color Doppler jet width, short-axis jet area, jet length, and maximum jet area were measured. AR slope was measured using continuous-wave Doppler. Flow in the abdominal aorta was evaluated using pulsed Doppler. Doppler indexes were compared with the angiographic grade of AR. Jet width and short-axis jet area were significantly different between groups and showed strong correlation with the angiographic grade. Holodiastolic flow reversal in the abdominal aorta separated 1+ to 2+ from 3+ to 4+ AR (100% sensitivity and 100% negative predictive value for 3+ to 4+ AR). Jet length, maximum jet area, and the ratio of reverse to forward abdominal aortic velocity time integrals correlated with angiography but showed little difference between groups that differed by only 1 angiographic grade. AR slope did not correlate with the angiographic grade. We conclude that in children, color Doppler jet width, short-axis jet area, and holodiastolic abdominal aortic flow reversal are the best predictors of angiographic severity. Use of these indexes may obviate the need for angiography to determine the degree of AR in children.

Quantifying aortic regurgitation by using the color Doppler-imaged vena contracta: a chronic animal model study

BACKGROUND

The aim of the present study was to evaluate the accuracy of determining aortic effective regurgitant orifice area (EROA) and aortic regurgitant volume by using the color Doppler-imaged vena contracta (CDVC).

METHODS AND RESULTS

Twenty-nine hemodynamically different states were obtained pharmacologically in eight sheep with surgically induced aortic regurgitation. Instantaneous regurgitant flow rates (RFRs) were obtained with aortic and pulmonary electromagnetic flowmeters (EFMs), and aortic EROAs were determined from EFM RFRs divided by continuous wave Doppler velocities. Color Doppler-derived EROAs were estimated by measuring the maximal diameters of the CDVC. Peak and mean RFRs and regurgitant volumes per beat were calculated from vena contracta area continuous wave diastolic Doppler velocity curves. Peak EFM-derived RFRs varied from 1.8 to 13.6 (6.3+/-3.2) L/min (range [mean+/-SD]), mean RFRs varied from 0.7 to 4.9 (2.7+/-1.3) L/min, regurgitant volumes per beat varied from 7.0 to 48.0 (26.9+/-12.2) mL/beat, and the regurgitant fractions varied from 23% to 78% (55+/-16%). EROAs determined by using CDVC measurements correlated well with reference EROAs obtained by using the EFM method (r=.91, SEE=0.07 cm2). Excellent correlations and agreements between peak and mean RFR and regurgitant volumes per beat as determined by Doppler echocardiography and EFM were also demonstrated (r=.95 to .96).

CONCLUSIONS

Our study indicates that the CDVC method can be used to quantify both aortic EROAs and regurgitant flow rates.

Quantitative Stress Echocardiography in Chronic Aortic and Mitral Regurgitation

It was the purpose of the present study to prove the feasibility and reliability of quantitative stress-echocardiography as an alternative method to radionuclide angiography (RNA) in chronic regurgitant valvular lesions. Echocardiography and RNA are most commonly used to obtain various left ventricular (LV) morphometric and functional parameters that have been postulated to predict long-term prognosis in patients with aortic and mitral valvular regurgitation. Supine bicycle ergometry with a workload ranging from 25-250 Watts was used to evaluate stress dependent LV volumes and ejection fractions (EFs) in patients with pure aortic (n = 18) and mitral regurgitation (n = 14). Most patients (23/32) underwent simultaneous right heart catheterization. Echocardiographic EFs were validated by RNA with good correlations (r = 0.81, P < 0.01). Patients with aortic regurgitation and functional class I/II (9), had a significant increase in EF during exercise (60%-67%, P < 0.001) and a reduction in end-systolic volume (71-52 mL, P < 0.01). In comparison, patients with class III symptoms (9), had a drop in EF (53%-49%, P < 0.01), had larger baseline end-systolic volume (104 mL, P = NS), which did not decrease during stress (104 vs 107 mL, P = NS). In patients with chronic mitral regurgitation baseline and exercise EF did not differ between class I/II (6) and class III (8), however, mildly symptomatic patients increased from 57%-67%, (P < 0.01) versus patients in class III (65% vs 69%, P = NS). Stroke volume index was not different at baseline (44 vs 33 mL/m(2), P = NS); however, there were significant differences during exercise (70 vs 41 mL/m(2), P = 0.05). Quantitative stress-echocardiography is a noninvasive and safe alternative method to RNA, which allows reliable calculation of stress dependent LV volumes and EF. Determination of end-systolic volumes may be of additional prognostic value. The combination of a high baseline EF and low stroke volume index with the inability to improve during exercise might reflect early stages of impaired LV function in patients with severe mitral regurgitation.

Estimating myocardial damage and the need for surgery in patients with valvular heart disease by Tl-201 SPECT

Left ventricular myocardial disorders due to volume overload were investigated by Tl-201 myocardial SPECT (Tl-201 SPECT) in patients with aortic or mitral regurgitation, and its utility for timing cardiac valve replacement was studied. There were significant correlations between Tl-201 scores and electrocardiographic changes and the New York Heart Association classification. There also were favorable correlations between Tl-201 scores and the left ventricular end-diastolic dimension and between Tl-201 scores and left ventricular ejection fraction, and a close relationship between the presence of a left ventricular myocardial disorder and left ventricular diameter. These results suggest that myocardial perfusion abnormalities and left ventricular myocardial disorders may accompany left ventricular dilatation owing to volume overload. After valve replacement, left ventricular end-diastolic dimension normalized, and Tl-201 scores improved slightly, suggesting normalization of myocardial perfusion. When moderate or more severe Tl-201 defects are present on Tl-201 SPECT images, in addition to inverted Tl-201 waves on the electrocardiogram or a left ventricular end-diastolic dimension of 65 mm or more, cardiac valve replacement should be considered.

Evaluation of eccentric aortic regurgitation by color Doppler jet and color Doppler-imaged vena contracta measurements: an animal study of quantified aortic regurgitation

To evaluate the utility of measurements of the color Doppler jet area, jet length, and width of the color Doppler-imaged vena contracta (the smallest flow diameter in any part of the flow acceleration field) as methods for quantifying aortic regurgitation (AR), eight sheep with surgically induced AR were studied. AR was quantified as peak and mean regurgitant flow rates, regurgitant stroke volumes, and regurgitant fractions as determined with pulmonary and aortic electromagnetic flow probes and flowmeters balanced against each other. Simple linear regression analysis between the maximal color jet areas, jet length, and flowmeter data showed only moderately good correlation (jet area: 0.42 < or = r < or = 0.57, SEE = 2.85 cm2; jet length: 0.42 < or = r < or = 0.59, SEE = 1.23 cm). In contrast, the width of color Doppler-imaged vena contracta was a better indicator of the severity of AR on the basis of the electromagnetic flowmeter methods (0.73 < or = r < or = 0.90, SEE = 0.15 cm). Therefore the color Doppler jet length and jet area methods have limited use for determining AR, whereas the width of the color Doppler-imaged vena contracta can be used for quantifying the severity of AR.

Combined rest and exercise electrocardiographic repolarization findings in relation to structural and functional abnormalities in asymptomatic aortic regurgitation

The relationship of combined rest and exercise electrocardiographic (ECG) repolarization abnormalities to left ventricular geometry and function was examined in 48 patients with asymptomatic chronic pure aortic regurgitation and no recent use of digitalis. Echocardiographic and radionuclide cineangiographic findings were compared in groups defined by the presence or absence of the "strain" pattern of repolarization abnormality on the resting ECG and also by the presence or absence of standard positive repolarization changes during upright treadmill exercise ( > 0.1 mV additional horizontal or downsloping ST depression). These hierarchic groups demonstrated trends toward progressively abnormal left ventricular dimensions, mass, wall stress, and change in ejection fraction with exercise. Although the presence of the strain pattern on the resting ECG alone was most strongly correlated with underlying functional and geometric abnormalities, an abnormal exercise test response was independently associated with abnormal left ventricular systolic dimension. The large group of patients with no symptoms and normal resting repolarization had only 0% to 4% prevalences of markedly increased systolic dimension (> 55 mm), reduced ejection fraction at rest (< 45%), or reduced ejection fraction during exercise (< 40%), whereas the small group of patients with abnormal resting repolarization and a positive exercise test response had 50% to 83% prevalences of these findings. These data suggest a possible role for rest and exercise ECG in the serial evaluation of patients with aortic regurgitation.

Severity of Aortic Regurgitation Assessed by Digital Image Processing of Doppler Spectral Recordings

Visual estimates of the intensity of the regurgitant signal (RS) obtained by continuous-wave (CW) Doppler has been used as an indicator of the severity of aortic regurgitation (AR). This study was designed to test this concept quantitatively using digital image processing methods. Twenty-one patients with AR were studied, 14 of whom had concomitant mitral valve disease. Patients with aortic stenosis were excluded. By angiography, 10 patients had mild (grade 1 or 2), 5 had moderate (grade 3), and 6 severe (grade 4) AR. We digitized three well-defined AR envelopes and calculated the mean pixel intensity (MPI) of the RS and the systolic flow signal (SFS) using an offline computer analysis system developed in our laboratory. To negate the effects of different gain settings, the ratio of RS to SFS (RS/SFS ratio) was compared to angiographic grade of AR. Thus, each patient served as his own control. The mean RS/SFS ratio was 0.54 +/- 0.42 SD (range 0.46-0.59) for mild AR, 0.76 +/- 0.71 SD (range 0.65-0.82) for moderate AR, and 0.84 +/- 0.52 (range 0.77-0.92) for severe AR. This RS/SFS ratio correlated well with angiographic severity of AR (r = 0.9). A ratio of <0.6 identified patients with mild AR and >0.6 correlated with moderate-to-severe AR. We conclude that the ratio of the regurgitant to systolic flow CW Doppler signal is an accurate noninvasive indicator of AR severity. (ECHOCARDIOGRAPHY, Volume 13, May 1996)

Aortic regurgitation complicated by extreme left ventricular dilation: long-term outcome after surgical correction

OBJECTIVES

This study sought to determine the outcome of aortic valve replacement for aortic regurgitation complicated by extreme left ventricular dilation.

BACKGROUND

Aortic valve replacement has been recommended in aortic regurgitation with extreme left ventricular dilation (diastolic dimension >/= 80 mm), but extreme left ventricular dilation raises concern about irreversible left ventricular dysfunction.

METHODS

Thirty-one patients with a preoperative echocardiographic diastolic dimension >/= 80 mm (group 1) undergoing operation for severe isolated aortic regurgitation between 1980 and 1989 were compared with 188 patients with a diastolic dimension <80 mm operated on during the same period (group 2).

RESULTS

Preoperatively, extreme left ventricular dilation was seen only in male patients and was associated with a reduced ejection fraction (43 +/- 12% vs. 53 +/- 11% [mean +/- SD], p < 0.0001). The postoperative outcome of group 1 was compared with that of male patients in group 2 (group 2M, n = 144). The operative mortality rates for groups 1 and 2M were 0% and 5.6%, respectively (p = 0.35). Late survival in operative survivors was similar in groups 1 and 2M, but compared with expected survival, an excess mortality was observed for group 1 (p = 0.024). Preoperative ejection fraction, but not diastolic dimension, independently predicted late survival and postoperative ejection fraction. Postoperatively, groups 1 and 2M showed a similar improvement in ejection fraction, but persistent left ventricular enlargement was more frequent in group 1.

CONCLUSIONS

Extreme left ventricular dilation due to aortic regurgitation is observed in male patients and is frequently associated preoperatively with a reduced ejection fraction but is not a marker of irreversible left ventricular dysfunction. Operative risk and late postoperative survival are acceptable in these patients, although a late excess mortality, predicted best by preoperative ejection fraction, is observed. Therefore, extreme left ventricular dilation is not a contraindication to operation, which should be performed before left ventricular dysfunction occurs.

Clinical outcome of severe asymptomatic chronic aortic regurgitation: a long-term prospective follow-up study

One hundred one patients with asymptomatic chronic severe aortic regurgitation and normal ejection fraction were monitored for up to 10 years (mean 55.4 +/- 33.5 months). Predefined surgical indications were the development of cardiac symptoms or the documentation of impaired basal left ventricular function. During the follow-up period there were no cardiac deaths; 14 patients needed surgery, 8 because of development of symptoms and 6 because of left ventricular impairment. The risk of surgery was 12% at 5 years and 24% at 10 years. Baseline end-systolic diameter > 50 mm and radionuclide ejection fraction < 60% were independent predictors or either cardiac symptoms or left ventricular dysfunction. In patients needing surgery, a pattern of progressive left ventricular dilatation was demonstrated. There were no deaths during surgery, and echocardiographic and radionuclide parameters normalized in the first year of follow-up. Our data confirm that the prognosis of severe aortic regurgitation in patients with no symptoms is good and that the occurrence of asymptomatic left ventricular dysfunction is an uncommon event. Surgery can be safely postponed until the appearance of cardiac symptoms or the documentation of left ventricular dysfunction at rest.

Asymptomatic aortic regurgitation: indications for operation

Left ventricular (LV) systolic function is an important determinant of long-term prognosis in patients with chronic aortic regurgitation. In patients undergoing aortic valve replacement (AVR), those with preoperative LV dysfunction have a greater risk of postoperative congestive heart failure and death than do those in whom preoperative LV systolic function is normal. Patients with preoperative LV dysfunction are not a homogeneous group, however, but may be further stratified according to risk on the basis of the severity of symptoms, exercise intolerance, and temporal duration of LV dysfunction. Hence, asymptomatic patients with reproducible and definite evidence of impaired LV function should undergo operation without waiting for the development of symptoms or more severe LV dysfunction. Among asymptomatic patients with normal LV systolic function (normal ejection fraction and fractional shortening), the prognosis is excellent with only a gradual rate of deterioration during conservative, nonoperative management. The long-term follow-up experience of such patients indicates that the annual mortality rate is less than 0.5% and that less than 4% per year require AVR because symptoms or LV dysfunction at rest develop. Patients likely to require operation over a 10-year period because symptoms or LV dysfunction develop can be identified on the basis of age, severity of LV dilatation by echocardiography, and progressive change in LV dimensions or resting ejection fraction during the course of serial follow-up studies. Patients at risk of sudden death before surgery is performed may be identified by extreme LV dilatation (diastolic dimension > 80 mm, systolic dimension > 55 mm).(ABSTRACT TRUNCATED AT 250 WORDS)

Spontaneous variability of ventricular function in patients with chronic heart failure. The Western Enoximone Study Group and the REFLECT Investigators

PURPOSE

The spontaneous variation of the left and right ventricular ejection fractions (LVEF and RVEF) was evaluated in patients with chronic heart failure receiving only digoxin and diuretics over a 12-week interval.

PATIENTS AND METHODS

Fifty-one patients with stable heart failure were studied with radionuclide angiography. A baseline evaluation and a 12-week follow-up study were performed. Heart failure therapy consisted of digoxin and diuretics alone during this time.

RESULTS

The mean baseline LVEF (n = 51) was 27.2 +/- 9.5 (range: 7 to 50) and the LVEF after 12 weeks was 27.6 +/- 9.7 (range: 11 to 53; p = NS versus baseline). Mean RVEF (n = 19) was 31.9 +/- 11.3 at baseline and 30.3 +/- 11.3 (range: 14 to 50; p = NS versus baseline) after 12 weeks. Although there was no significant change in mean LVEF or RVEF in this group of patients, individual patients demonstrated considerable spontaneous variation. Individual LVEF values changed from 0 to 26 ejection fraction percentage points (mean of individual changes = 5.6 +/- 5.5). Individual RVEF determinations over the 12-week period varied by 0 to 15 percentage units (mean = 5.6 +/- 4.9). Thirty-five percent of patients had an absolute change in LVEF greater than 5 and 37% of patients had an absolute change of RVEF greater than 5. Even after deletion of the two worst outliers from the LVEF and RVEF data, a change in LVEF greater than 13 and a change in RVEF greater than 11% units were necessary to exclude spontaneous variation as a likely cause for the observed changes (95% confidence limits). No relationship between a change in the individual patient's LVEF or RVEF was found when these values were compared with exercise time, systolic or diastolic blood pressure, heart rate, or degree of baseline left or right ventricular dysfunction.

CONCLUSION

In patients with heart failure, large (greater than 5) spontaneous changes in LVEF and RVEF may be seen in over one third of patients during a 12-week period. This variability should be considered when the ejection fraction is used as an index of improved or worsened cardiac function. The use of the LVEF and RVEF to assess interventions or therapy for heart failure should be interpreted with caution.

Rapid assessment of aortic regurgitation and left ventricular function using cine nuclear magnetic resonance imaging and the proximal convergence zone

In patients with aortic regurgitation (AR), knowledge of the severity of AR, and the degree of left ventricular (LV) dysfunction are important for optimal management. Previous nuclear magnetic resonance (NMR) studies to assess these parameters used multiple tomographic planes that are time-consuming to obtain and analyze, and thus not cost-effective. In addition, these studies assessed the severity of AR by looking simply at the size of the regurgitant jet, a parameter that relates only poorly to regurgitant volume. The present study evaluates a rapid, single-plane, cine NMR approach (scan time < 10 minutes), and a new grading system for AR that is based on the presence, size and persistence of not only the regurgitant jet, but also the zone of proximal signal loss. Compared with color Doppler echocardiography (n = 42), the NMR approach detected AR with a specificity of 100% and a sensitivity of 95%. NMR regurgitant jet area correlated well with color Doppler regurgitant jet area (n = 20; r = 0.81; p < 0.01), but did not discriminate well between all grades of AR as compared with x-ray contrast aortography (n = 14). Using the new NMR grading criteria, AR grade by NMR was in accordance with aortographic grade in 12 patients, differing by only 1 grade in the remaining 2 patients. NMR grade was in accordance within 1 grade of Doppler in all patients compared (n = 20). LV volumes and ejection fraction using this single-plane approach correlated well with a previously validated, NMR biplane approach (r > 0.87; n = 18).(ABSTRACT TRUNCATED AT 250 WORDS)

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.

The changing unnatural history of valvular regurgitation

In the past 15 years three major advancements have improved the lot of our patients with left-sided valvular regurgitation. First, the concept that mitral and aortic regurgitation were similar volume overloading lesions has changed. Mitral regurgitation constitutes a nearly pure volume overload wherein the excess volume is ejected against relatively low pressure into the left atrium. On the other hand, aortic regurgitation represents a combined pressure and volume overload in which the excess volume being pumped is ejected against the relatively high pressure of the aorta. These differences in loading between mitral and aortic regurgitation produce a different response to operation. Afterload reduction after correction of aortic regurgitation increases ejection performance if it was decreased preoperatively. Conversely, afterload increases after mitral valve replacement, decreasing ejection performance. These differences make the left ventricle in mitral regurgitation less tolerant of preoperative dysfunction than the left ventricle in aortic regurgitation. Second, with respect to aortic regurgitation, reproducible indexes have been developed that identify when left ventricular dysfunction is present, leading to earlier operation in an attempt to avoid permanent ventricular dysfunction. In turn, earlier operation has led to a fall in operative mortality rate and an almost universal increase in left ventricular function if it was depressed preoperatively. Third, with regard to mitral regurgitation, recognition of the importance of the mitral valve apparatus in maintaining left ventricular function has led to an increased emphasis on chordal preservation during mitral valve operations.(ABSTRACT TRUNCATED AT 250 WORDS)

Criteria for the accurate interpretation of changes in left ventricular ejection fraction and cardiac volumes as assessed by rest and exercise gated radionuclide angiography

Although serial left ventricular ejection fraction and volumetric measurements using gated radionuclide angiography are commonly used to evaluate clinical changes and therapeutic outcomes in individual patients, criteria are not available for accurately interpreting whether a change in any of these hemodynamic measurements is clinically meaningful. Accordingly, the magnitude of inherent variability among sequential measurements of hemodynamic variables assessed by gated radionuclide angiography was investigated in a double-blind placebo-controlled fashion in 39 patients during two placebo periods separated by 6 weeks. All patients analyzed had remained clinically stable during the study period. Although the mean values for all hemodynamic variables between the two placebo periods were minimally changed, the differences in individual patients were striking. Criteria were developed to allow meaningful interpretation of changes in hemodynamic variables by estimating the likelihood that an observed change is due to variability alone. On the basis of this analysis of placebo radionuclide angiographic data, variation due to chance alone is unlikely to account for all variability if a change observed between the two rest gated studies in a patient is greater than or equal to 7% units for left ventricular ejection fraction, greater than or equal to 45 ml/m2 for end-diastolic volume index, greater than or equal to 35 ml/m2 for end-systolic volume index, greater than or equal to 20 ml/m2 for stroke volume index and greater than or equal to 1.25 liters/min per m2 for cardiac index. An observed 4% unit change in left ventricular ejection fraction (increase or decrease) after a medical intervention in an individual patient occurs by random variation greater than 25% of the time.(ABSTRACT TRUNCATED AT 250 WORDS)

Mechanisms for left ventricular systolic dysfunction in aortic regurgitation: importance for predicting the functional response to aortic valve replacement

To test the hypothesis that the combined use of the time-varying elastance concept and conventional circumferential stress-shortening relations would elucidate differential mechanisms for left ventricular systolic dysfunction in severe, chronic aortic regurgitation and therefore predict the functional responses to aortic valve replacement, 31 control patients and 37 patients with aortic regurgitation were studied. The studies included micromanometer left ventricular pressure determinations, biplane contrast cineangiograms under control conditions and radionuclide angiograms under control conditions and during methoxamine or nitroprusside infusions with right atrial pacing. The patients with aortic regurgitation were classified into three groups: Group I had normal Emax and stress-shortening relations, Group II had abnormal Emax but normal stress-shortening relations and Group III had abnormal Emax and stress-shortening relations. The left ventricular end-diastolic and end-systolic volumes showed a progressive increase and the ejection fraction showed a progressive decrease from Group I to III; these values differed from those in the control patients (p less than 0.001). In Group I, there was a decrease in left ventricular volumes (p less than 0.05) but no significant change in ejection fraction (61 +/- 7% versus 63 +/- 4%) after aortic valve replacement. In contrast, in Group II, reduction in left ventricular volumes (p less than 0.01) was associated with an increase in ejection fraction from 50 +/- 8% to 64 +/- 11% (p less than 0.01). Finally, in Group III, reduction in left ventricular volumes (p less than 0.05) was associated with a further decrement in ejection fraction from 35 +/- 13% to 30 +/- 13%. Group I patients had compensated adequately for chronic volume overload. However, Group II had left ventricular dysfunction that was associated with an increase in the left ventricular volume/mass ratio compared with that in the control patients and Group I (p less than 0.05 for both), suggesting inadequate hypertrophy and assumption of spherical geometry. Finally, irreversible myocardial dysfunction had supervened in Group III. In conclusion, a combined analysis of left ventricular chamber performance using the time-varying elastance concept and myocardial performance using conventional circumferential stress-shortening relations provides complementary information that elucidates differential mechanisms for left ventricular systolic dysfunction and therefore predicts the functional response to aortic valve replacement.

Maximal oxygen uptake in severe aortic regurgitation: a different view of left ventricular function

Respiratory gas exchange was used to assess left ventricular (LV) function in 22 patients with severe aortic regurgitation (19 men and three women, aged 18 and 70 years, mean 49 years). Anaerobic threshold and symptom-limited maximal oxygen consumption (VO2 max) were measured during treadmill exercise, and the results were compared with conventional echocardiographic and radionuclide indices of LV systolic function. The results were considered with respect to the patients' New York Heart Association functional class. Both rest and exercise LV ejection fractions were variable, but the mean results were similar in all classes. The echocardiographic indices of LV cavity dimensions, fractional shortening, radius/thickness ratio, and systolic wall stress also showed a wide range but with similar mean results in each class. In contrast, VO2 max and anaerobic threshold showed a relationship to functional class. VO2 max was 32.4 +/- 3.4 ml/kg/min in age-matched control subjects; in the patients it was 27.9 +/- 4.7 in class I, 24.7 +/- 5.7 in class II, and 14.2 +/- 2 in the combined class III/IV. Results in patients in classes I and II were similar, but both groups were significantly different from control subjects (p less than 0.05) and from patients in class III/IV (p less than 0.01). About half of the patients with moderate LV dysfunction (judged by reduced VO2 max) were asymptomatic, and LV function was impaired in 4 of 10 patients in class I. Thus, unlike conventional indices of LV function, VO2 max appeared capable of distinguishing patients with moderate-to-severe LV dysfunction from those with little or no LV dysfunction. Measurement of respiratory gas exchange appears to be a valid and useful supplementary means of assessing LV function in severe aortic regurgitation. Further long-term evaluation is required.

Clinical evaluation of a prospective protocol for the timing of surgery in chronic aortic regurgitation

Out of 160 prospectively followed patients with aortic regurgitation, the clinical courses of 53 patients with pure, severe, and chronic aortic regurgitation and without coronary artery disease who were selected for surgery on the basis of predefined criteria is discussed. Surgical criteria were either unequivocal symptoms or documentation of impaired left ventricular dysfunction (defined as angiographic ejection fraction of less than 50% plus and end-systolic volume index greater than 60 ml/m2). According to preoperative status, patients were divided as follows: 11 asymptomatic patients (group A), 30 patients with moderate (classes II to III) symptoms (group B), and 12 patients with dyspnea at rest and pulmonary edema when first seen (group C). Surgical mortality was one patient (from group C). Late death occurred in four patients (one from group B, three from group C). At the end of follow-up (minimum 1 year, mean 3.6 years) 41 patients were in functional class I, four patients in class II, and one patient in class III. All patients except one in functional classes II and III belonged to group C. Before surgery, patients from groups A and B had similar ventricular dimensions and ejection fractions, whereas patients from group C had larger end-systolic diameters and volumes and lower ejection fractions. End-diastolic and end-systolic diameters decreased significantly at 1 and 2 years after surgery. Patients from group C continued to have dilated hearts as did those patients from groups A and B who had preoperative end-systolic diameters greater than 55 mm.(ABSTRACT TRUNCATED AT 250 WORDS)

Management of asymptomatic chronic aortic regurgitation with left ventricular dysfunction: a decision analysis

STUDY OBJECTIVE

To determine the optimal strategy for the timing of aortic valve replacement in patients with chronic, severe aortic regurgitation with left ventricular dysfunction.

DESIGN

Decision analysis comparing early surgery (timed at the onset of left ventricular dysfunction) with delayed surgery (timed at the onset of symptoms) using data from the literature and expert opinion for variables in a representative case scenario (40-year-old man with bicuspid aortic valve disease).

SETTING

Tertiary care center doing valve replacement surgery.

MEASUREMENTS AND MAIN RESULTS

The early-surgery approach was preferred based on quality-adjusted life years. Sensitivity analysis showed that the result was not affected by the following variables within their derived ranges: rate of symptom development after onset of left ventricular dysfunction for the delayed-surgery approach, perioperative mortality for both approaches, and occurrence of major nonfatal stroke or congestive heart failure for both approaches. Although the decision was sensitive to the yearly postoperative mortality rates, the delayed-surgery operative mortality rate had to be almost as low as the early-surgery rate to change the preference to the delayed-surgery approach. The preference could also change if survival were much more important to the patient in the first five years than after five years or if the patient disliked living on anticoagulants enough to value a year on anticoagulants as worth only 80% of a year not on anticoagulants.

CONCLUSION

This decision analysis provides quantitative support for the impression that patients similar to the case scenario do better with surgery timed at the onset of ventricular dysfunction than with surgery delayed until symptoms develop. It thus supports the practice of following these patients noninvasively in order to time surgery.

Mechanical pathophysiology of some heart diseases: a theoretical model study

Sarcomere dynamics are related to the global left ventricular (LV) function in some representative pathological states, by using a theoretical model which combines sarcomere function, LV fibrous structure and geometry with the haemodynamic loading conditions. The analysis shows that pressure (concentric) hypertrophy due to hypertension or aortic stenosis is associated with an increase of the normal endocardial-to-epicardial gradient(s) of oxygen demand, which may be one of the causes for the development of endocardial fibrosis. The analysis also indicates that sarcomere shortening is relatively normal in compensated volume (eccentric) hypertrophy. Mitral stenosis demonstrates a case of decreased LV function, secondary to a chronic decrease in LV end diastolic volume, with sarcomeres that operate at their lowest length range. Conversely, the sarcomere function is depressed in cardiomyopathy; the heart's pumping function is maintained by appropriate adjustment mechanisms. However, the sarcomeres show minimal shortening and function at their highest length range with low (or zero) functional reserve. The study thus provides a quantitative tool that relates global LV function to local sarcomere dynamics in various pathological states.

Chronic severe aortic regurgitation: a prospective follow-up of 60 asymptomatic patients

Sixty asymptomatic patients (age 26 +/- 10 years) with chronic severe aortic regurgitation were followed prospectively for 2.4 +/- 1.4 years. Based on previous echocardiographic end-systolic dimension (ESD) and angiographic ejection fraction (EF) correlations, the cohort was divided into group A (21 patients) with ESD greater than or equal to 48 mm and group B (39 patients) with ESD less than 48 mm. Group B had a faster ESD progression (NS) and 19 crossed over to group A. Thirteen patients, all with ESD greater than 48 mm, reached designated end points. One died of cerebral embolism and 12 (age 31.4 +/- 10.6 years) required aortic valve replacement (AVR). Of these, 9 of 12 were asymptomatic and 11 of 12 had significant left ventricular dysfunction (LVD). The preoperative ESD of 51.9 +/- 4.1 mm fell to 38.4 +/- 3.6 mm (p less than 0.001) postoperatively and the EF of 43.7 +/- 4.16 increased to 64.9 +/- 5.9 (p less than 0.001). We found (1) the progression was faster than in other series; (2) ESD greater than 48 mm was associated with significant progression; and (3) patients with EF above 40% showed no residual LVD after AVR.

Effects of unloading and positive inotropic interventions on left ventricular function in asymptomatic patients with chronic severe aortic insufficiency

The effect of an unloading (nifedipine, 20 mg sublingually) and of a combined unloading and positive inotropic intervention (nifedipine plus digoxin, 0.5 mg intravenously) on left ventricular performance was assessed in 48 patients with chronic severe aortic insufficiency. The left ventricular pump function-myocardial contractility relation (ejection fraction, EF vs. peak arterial pressure to end-systolic volume ratio, PAP/ESV), and the pump function-afterload relation (EF vs. mean systolic wall stress, MWS) were constructed by means of quantitative M-mode and two-dimensional echocardiography. In patients with normal control pump function (n = 14), nifedipine markedly decreased MWS, moving the patients to a new, more advantageous EF-MWS relation. In the 34 patients with abnormal pump function, the myocardial contractility level was the mean factor conditioning the response to pharmacological intervention. Patients with a value of PAP/ESV greater than 2.5 (n = 22) had normalization of EF after nifedipine and were upgraded to a more advantageous outlook for left ventricular mechanics EF-MWS and EF-PAP/ESV relations. Of the 12 patients without normalization of EF after nifedipine, only the 4 patients with PAP/ESV greater than 2 had normalization of pump function indices after combined administration of nifedipine and digoxin.