Left ventricular function at rest and during exercise after aortic valve replacement in patients with aortic regurgitation

To determine the effect of aortic valve replacement on reversing abnormalities of left ventricular function in patients with aortic regurgitation, radionuclide cineangiography was used to study 16 symptomatic patients with aortic regurgitation before and 6 months after aortic valve replacement. Before operation, left ventricular ejection fraction was 46 ± 3 percent at rest (normal mean ± standard error of the mean 57 ± 1 percent; P < 0.001), and decreased to 37 ± 4 percent during exercise (normal 71 ± 2 percent; P < 0.001). After operation, ejection fraction rose to 58 ± 4 percent at rest, indistinguishable from the normal value, and during exercise was 53 ± 4 percent, increased (P < 0.001) from before operation but significantly (P < 0.001) subnormal. Thus, aortic valve replacement can improve but usually does not normalize left ventricular function during exercise in symptomatic patients with aortic regurgitation.     

Mitral valve replacement for isolated mitral regurgitation: Analysis of clinical course and late postoperative left ventricular ejection fraction

One hundred five patients underwent mitral valve replacement for relief of isolated mitral regurgitation between 1974 and 1979. There were 4 in-hospital deaths (4 percent) and 12 late deaths giving an 82 percent predicted 5 year survival rate. An age of 60 years or more at the time of surgery and a preoperative left ventricular ejection fraction of less than 0.40 were the only variables that correlated with decreased survival at 3 to 5 years after operation (p <0.05). Postoperatively, 87 (98 percent) of 89 long-term survivors were in New York Heart Association functional class I or II (68 in class I and 19 in class II). Survival did not differ between patients with porcine versus mechanical valve replacement, but patients with a mechanical valve had a greater incidence of postoperative cerebrovascular accident ($\text{8.6}\text{100}$ patient years) than did patients with a porcine valve (2.8/100 patient years) (p <0.002). Ejection fraction at rest was determined with multigated cardiac imaging 12 to 75 months post-operatively in 34 of 89 long-term survivors. The mean preoperative ejection fraction was 0.62 ± 0.09 (mean ± 1 standard deviation) and the mean postoperative ejection fraction was 0.50 ± 0.15 (p <0.001). When the preoperative value was compared with the postoperative value at rest the ejection fraction increased by 0.10 or more in 1 patient (3 percent), remained within ±0.09 of the preoperative value in 12 patients (35 percent) and decreased by 0.10 or greater in 21 patients (62 percent). Sixteen (94 percent) of 17 patients whose postoperative ejection fraction was greater than 0.50 were in functional class I postoperatively compared with 11 (65 percent) of 17 patients whose postoperative ejection fraction was 0.50 or less (p <0.05). No preoperative factor, including preoperative ejection fraction or cardiothoracic ratio, predicted the postoperative ejection fraction. A postoperative exercise ejection fraction was obtained in 29 patients, and an abnormal ejection fraction change with exercise (increase <0.05) was observed in 20 patients (69 percent). Patient age at the time of study correlated inversely with the change in ejection fraction from rest to exercise; no other variables were predictive.It is concluded that, in addition to age, only preoperative left ventricular function as measured by ejection fraction predicts survival in patients undergoing mitral valve replacement for isolated mitral regurgitation. Clinical recovery is good even though the majority of long-term survivors have a postoperative decrease in ejection fraction.     

Survival and functional results after valve replacement for aortic regurgitation from 1976 to 1983: impact of preoperative left ventricular function

Recent studies suggest that preoperative left ventricular function may no longer be an important determinant of survival or functional results after operation for aortic regurgitation because of improved operative techniques. To assess the effect of left ventricular function on prognosis in the current surgical era, we performed echocardiographic and radionuclide angiographic studies in 80 consecutive patients undergoing valve replacement from 1976 to 1983. No patient had associated coronary artery disease. For all patients, 5 year survival was 83 +/- 5%, significantly better than the 62 +/- 9% 5 year survival in our patients operated on from 1972 to 1976. Preoperative resting left ventricular ejection fraction (p less than .001), fractional shortening (p less than .001), and end-systolic dimension (p less than .01) were the most significant predictors of survival (univariate life-table analysis). Five year survival was 63 +/- 12% in patients with subnormal ejection fraction (n = 50) compared with 96 +/- 3% in those with normal ejection fraction (n = 30). Patients with subnormal left ventricular ejection fraction and poor exercise tolerance or prolonged duration of left ventricular dysfunction (greater than 18 months) comprised the high-risk subgroup (5 year survival 52 +/- 11%). Patients in this subgroup also had persistent left ventricular dysfunction after operation, with greater left ventricular end-diastolic dimensions and reduced ejection fraction (both p less than .001) compared with patients with normal preoperative left ventricular ejection fraction or a brief duration of left ventricular dysfunction (less than 14 months). Cold hyperkalemic cardioplegia was used for myocardial preservation in 46 patients.(ABSTRACT TRUNCATED AT 250 WORDS)     

Predictors of outcome for aortic valve replacement in patients with aortic regurgitation and left ventricular dysfunction: a change in the measuring stick

Although left ventricular function is generally regarded as a key determinant of prognosis in aortic regurgitation, predictors of outcome of aortic valve replacement based on this factor have recently been questioned. This study was performed to examine the role of indexes of left ventricular function in predicting the outcome of surgery in patients with aortic regurgitation and left ventricular dysfunction. Fourteen patients with aortic regurgitation with a preoperative ejection fraction of less than 0.55 (average 0.45 +/- 0.02) who underwent aortic valve replacement were studied. The patients had 82 (58%) of a possible 140 predictors of negative outcome preoperatively, but 12 of the 14 patients had a decrease in symptoms and an increase in ejection fraction into the normal range after operation (average postoperative ejection fraction 0.59 +/- 0.04). Although improvement occurred despite the presence of many negative predictors of outcome, there was a significant correlation between postoperative ejection fraction and eight of the tested preoperative predictors. Preoperative end-systolic dimension correlated best (r = -0.91) with postoperative ejection fraction. An end-systolic dimension of 60 mm correlated with a postoperative ejection fraction of 0.55. The results indicate that preoperative ventricular function is still an important determinant of outcome of aortic valve replacement for aortic regurgitation. However, current medical and surgical techniques permit a better prognosis in the presence of reduced ventricular function than was previously considered possible.     

Preoperative left ventricular function: minimal requirement for successful late results of valve replacement for aortic regurgitation

Postoperative survival and left ventricular function were studied in 62 patients who underwent aortic valve replacement for isolated, chronic aortic regurgitation between 1978 and 1985. The average follow-up period was 3.8 years. There were three in-hospital and six late deaths. Five (56%) of the nine postoperative deaths were of cardiac-related causes. The mean 7 year survival rate was 83 +/- 5%. Preoperative left ventricular end-systolic volume index was the most important indicator (p less than 0.001) for subsequent cardiac death. The 6.5 year survival rate was 92 +/- 4% for patients with an end-systolic volume index less than 200 ml/m2 compared with 51 +/- 16% for those whose index was greater than 200 ml/m2. None of the 48 patients with an end-systolic volume index less than 200 ml/m2 died of cardiac-related causes. Twenty-three of the 48 patients with an end-systolic volume index less than 200 ml/m2 (Group 1) and 6 of the 12 patients with a higher index (Group 2) underwent repeat catheterization 26 months postoperatively. Preoperative afterload, assessed by end-systolic wall stress, was elevated in both groups, but decreased postoperatively, becoming identical to the afterload in 20 normal control subjects. Although the preoperative ejection fraction was depressed in both groups, the great majority of patients in Group 1, compared with none in Group 2, exhibited normal ejection fraction postoperatively. Thus, in patients who recently underwent surgery for aortic regurgitation, satisfactory late results in both long-term survival and reversal of left ventricular dysfunction were obtained when the preoperative end-systolic volume index was less than 200 ml/m2.     

Reversal of left ventricular dilatation, hypertrophy, and dysfunction by valve replacement in aortic regurgitation

Although aortic valve replacement for aortic regurgitation relieves left ventricular volume overload, ventricular geometry does not consistently normalize. To assess the extent, determinants, and functional consequences of reversal of left ventricular dilatation and hypertrophy, 38 patients with severe aortic regurgitation were studied pre- and postoperatively by serial echocardiography and radionuclide cineangiography. Left ventricular end-diastolic dimension normalized in 58% of patients by 9 +/- 6 months postoperatively, at which time 50% of patients had normalized mass; cumulative normalization rose to 66% for end-diastolic dimension and 68% for left ventricular mass during further follow-up. All patients who had normalized end-diastolic dimension also had normal postoperative ejection fractions (mean 61 +/- 8%). In contrast, patients in whom the left ventricle remained dilated had a 42% prevalence of subnormal postoperative left ventricular ejection fraction. Preoperative left ventricular end-systolic dimension less than or equal to 55 mm identified 86% of patients in whom end-diastolic dimension normalized, whereas end-systolic dimension exceeded 55 mm in 81% of those with persistent dilatation; other proposed preoperative predictors of operative outcome correctly identified lower proportions (from 59% to 71%) of patients in whom left ventricular size did or did not normalize. In conclusion, aortic valve replacement resulted in normalized left ventricular chamber size and mass in two thirds of the patients selected for operation by current criteria; favorable geometric outcome is associated with persistence or recovery of normal left ventricular function.     

Early changes in left ventricular size and function after correction of left ventricular volume overload

The ability to predict early postoperative left ventricular size and function in patients with isolated aortic or mitral regurgitation was determined utilizing multigated blood pool imaging before and 2 to 4 weeks after valve replacement (aortic valve, 20 patients; mitral valve, 20 patients). Early postoperatively, ejection fraction decreased significantly (p <0.001) in both patient groups (from 0.55 ± 12 to 0.40 ± 0.14 [mean ± 1 standard deviation] in patients with aortic regurgitation and from 0.66 ± 0.09 to 0.48 ± 0.11 in patients with mitral regurgitation). The decrease in ejection fraction was associated with a large decrease in stroke volume with minimal or no change in end-systolic volume; it was unrelated to the preoperative ejection fraction. Early postoperative ejection fraction correlated best with preoperative end-systolic volume and was normal in 14 (67 percent) of 21 patients with a preoperative ejection fraction above 0.60; 4 (27 percent) of 15 patients with a preoperative ejection fraction of 0.50 to 0.60; and in 0 of 4 patients with a preoperative ejection fraction below 0.50 (p <0.05). In addition, a repeated scan in 16 patients late (1 to 2 years) after operation showed a further reduction in endsystolic volume in patients with aortic regurgitation with an increase in ejection fraction toward preoperative values. There was no significant change in patients with mitral regurgitation.End-diastolic volume decreased significantly (p <0.001) early postoperatively (from 162 ± 60 to 102 ± 41 ml/m² in patients with aortic regurgitation and from 131 ± 40 to 78 ± 30 ml/m² in patients with mitral regurgitation). This decrease was closely related to a decrease in stroke volume and was unrelated to preoperative ejection fraction. Early postoperative end-diastolic volume correlated best with the preoperative end-systolic volume. The major part of the reduction in end-diastolic volume occurred within 2 weeks of valve replacement.Removal of chronic left ventricular volume overload due to aortic or mitral regurgitation produces a decrease in ejection fraction and end-diastolic volume. The early reduction is in part a result of altered loading conditions and may not necessarily imply alterations in myocardial contractile function. The reduction in ejection fraction appears to persist in patients with mitral regurgitation.     

Afterload mismatch in aortic and mitral valve disease: implications for surgical therapy

In the management of patients with valvular heart disease, an understanding of the effects of altered loading conditions on the left ventricle is important in reaching a proper decision concerning the timing of corrective operation. In acquired valvular aortic stenosis, concentric hypertrophy generally maintains left ventricular chamber size and ejection fraction within normal limits, but in late stage disease function can deteriorate as preload reserve is lost and aortic stenosis progresses. In this setting, even when the ejection fraction is markedly reduced (less than 25%), it can improve to normal after aortic valve replacement, suggesting that afterload mismatch rather than irreversibly depressed myocardial contractility was responsible for left ventricular failure. Therefore, patients with severe aortic stenosis and symptoms should not be denied operation because of impaired cardiac function. In chronic severe aortic and mitral regurgitation, operation is generally recommended when symptoms are present, but whether to recommend operation to prevent irreversible myocardial damage in patients with few or no symptoms has remained controversial. In aortic regurgitation, left ventricular function generally improves postoperatively, even if it is moderately impaired preoperatively, indicating correction of afterload mismatch. Most such patients can be carefully followed by echocardiography. However, in some patients, severe left ventricular dysfunction fails to improve postoperatively. Therefore, when echocardiographic studies in the patient with severe aortic regurgitation show an ejection fraction of less than 40% (fractional shortening less than 25%) plus enlarging left ventricular end-diastolic diameter (approaching 38 mm/m2 body surface area) and end-systolic diameter (approaching 50 mm or 26 mm/m2), confirmation of these findings by cardiac catheterization and consideration of operation are advisable even in patients with minimal symptoms. In chronic mitral regurgitation, maintenance of a normal ejection fraction can mask depressed myocardial contractility. Pre- and postoperative studies in such patients have shown a poor clinical result after mitral valve replacement, associated with a sharp decrease in the ejection fraction after operation. This response appears to reflect unmasking of decreased myocardial contractility by mitral valve replacement, with ejection of the total stroke volume into the high impedance of the aorta (afterload mismatch produced by operation).(ABSTRACT TRUNCATED AT 400 WORDS)     

Impaired left ventricular function in chronic aortic valve disease: survival and function after replacement by Bj?rk-Shiley prosthesis.

Postoperative survival and left ventricular function were studied in 128 patients who underwent isolated aortic valve replacement by the Bj?rk-Shiley valve between 1973 and 1977. The average follow-up was 2.1 years. Patients with associated coronary artery disease or mitral valve disease were excluded. Preoperative ejection fraction ranged from 15-84%. Forty-two patients were restudied by cardiac catheterization 9.1 +/- 1.1 months (mean +/- SEM) after valve replacement. The hospital mortality was 11%. Preoperative type of valve lesion, functional class, cardiothoracic ratio, and ejection fraction (EF) had no significant effect on postoperative survival up to 4 years. After operation, left ventricular mass (LVMI) and peak systolic wall stress (PSWS) fell significantly, while EF and mean normalized systolic ejection rate (MNSER) increased in aortic stenosis and in aortic insufficiency. Neither in aortic stenosis nor in aortic insufficiency was there a significant relation between preoperative ejection fraction and postoperative LVMI, EF, MNSER and PSWS. We attributed this to a marked improvement of left ventricular function in patients with preoperative impaired ventricular function. Six patients with paravalvular leak to restudy has a significantly lower EF and MNSER, and a higher PSWS than patients without leak. Patients without leak had normal EF, MNSER and PSWS when compared with 10 normal persons, but LVMI remained moderately elevated. Postoperative transprosthetic gradient was 11.9 mm Hg (range 0-64 mm Hg). We conclude that impaired cardiac function is completely restored after aortic valve replacement by Bj?rk-Shiley valve, if valve function is good. Patients with impaired cardiac function preoperatively did not have a poorer prognosis after operation than patients with normal function.     

Long-term surgical prognosis of aortic valve diseases with pulmonary hypertension. Apropos of 34 cases]

Thirty-four patients underwent isolated aortic valve replacement with mean pulmonary artery pressures greater than 40 mmHg between 1972 and 1988. The aortic valve disease was stenotic in 10 cases, regurgitant in 14 cases and mixed in 10 cases. Thirty patients (88%) had invalidating cardiac failure (NYHA Classes III and IV). The mean preoperative ejection fraction was 44 +/- 15%. The hospital mortality was 17.6%. Ten patients died secondarily, five with terminal cardiac failure. The 5 year actuarial survival was 70 +/- 16%; the 10 year survival was 60 +/- 18% with an average follow-up of 115 +/- 61 months. None of the patients was lost to follow-up. Fifteen of the 18 survivors (83%) are asymptomatic or pauci-symptomatic after a follow-up of 126 +/- 62 months. Doppler echocardiography (n = 12) showed normal prosthetic valve function in 11 cases and aortic regurgitation in 1 case. Eight patients had tricuspid regurgitation with pulmonary artery systolic pressures less than 30 mmHg in 6 cases and between 30 and 40 mmHg in 2 cases. Severe pulmonary hypertension is therefore a poor early postoperative prognostic factor in aortic valve replacement surgery due to the associated left ventricular dysfunction. However, the long-term results are satisfactory: clinical improvement is usually related to a reduction of pulmonary hypertension.     

Left ventricular dynamics after aortic valve replacement: a long-term, combined radionuclide angiographic and ultrasonographic study

Between January 1985 and July 1990, we studied 71 patients at our institution who underwent aortic valve replacement for either aortic valve regurgitation (40 patients) or stenosis (31 patients). The following prostheses were implanted: 25 St. Jude Medical valves (bileaflet), 16 Bj?rk-Shiley (monoleaflet, tilting disc, 60 degrees convexo-concave), 16 Medtronic-Hall (monoleaflet, tilting disc), and 14 Starr-Edwards (caged ball). The patients were evaluated pre-and postoperatively by means of gated blood-pool scintigraphy and Doppler echocardiography. Postoperatively, each patient was studied at 6 months, 1 year, and then annually. The evaluations focused upon 1) scintigraphically assessed left ventricular performance indicators (end-diastolic and end-systolic volume, as well as resting and exercise ejection fraction) and 2) Doppler-derived hemodynamic indexes (peak and mean transvalvular pressure gradient, effective orifice area, regurgitant flow, and systolic wall stress). Early after aortic valve replacement, 55 (77.5%) of the patients had substantial symptomatic relief, with normal hemodynamic values both at rest and during exercise (New York Heart Association functional class I or II); another 6 patients (8.5%) maintained their preoperative status in those classes. Within a year after surgery, a majority of patients showed a significant reduction in left ventricular dimensions. The patients with preoperative aortic valve stenosis had a significantly reduced end-diastolic and end-systolic volume (p<0.05), a moderately reduced left ventricular mass index (p<0.01), and a significantly increased exercise ejection fraction (p<0.05); moreover, in all 31 of these cases, systolic wall stress returned to normal or lower-than-control values (p<0.005). The patients with preoperative aortic valve regurgitation had a significant reduction in end-diastolic and end-systolic volume (p<0.005), diastolic wall stress (p<0.005), and a significant increase in exercise ejection fraction (p<0.01); however, their left ventricular mass index was not significantly reduced. Optimal long-term survival was afforded by the St. Jude valve in the small size (21 mm) and the Starr-Edwards valve in the large size (27 mm). This study represents the first reported use of a serial, combined radionuclide and echocardiographic procedure for the follow-up of patients undergoing aortic valve replacement. During the 5(1/2)-year follow-up period, this combined technique proved highly accurate for collecting follow-up data, often complementing or correcting simple ultrasound results. This diagnostic approach enabled us to 1) obtain information comparable to or better than that provided by cardiac catheterization, 2) identify complications early, 3) differentiate between valvular and ventricular failure, and 4) suggest the valve of choice (not always that with the best hemodynamic performance) in patients with different cardiac variables. Further research is needed to confirm this study, the results of which could change many medical and surgical strategies for clinical management of the diseased aortic valve.     

Value of isometric exercise testing in the optimal timing of aortic valve replacement in aortic regurgitation

To evaluate the possible irreversibility of isometric exercise-inducedleft ventricular dysfunction in aortic regurgitation, we performedhandgrip exercise tests during cardiac catheterization on 17patients with chronic aortic regurgitation (AR-group), bothpreoperatively and one year after successful aortic valve replacement.Nine normal subjects served as a control group. Preoperatively, the ejection fraction decreased from 59 ±7% to 53 ± 8% (P<0.001) in the AR-group while it remainedunchanged in the control group during exercise. A positive correlationexisted between the changes in the ejection fraction duringpre- and postoperative exercise tests (r = 0.85, P < 0.001),which revealed that in patients with severely depressed ejectionfraction during the preoperative exercise test, the ventricularresponse to exercise was not totally corrected after surgery.The regression of left ventricular mass was also smaller inthe patients with most depressed ventricular response to exercisepreoperatively. As the isometric exercise-induced left ventricular dysfunctionappears to be partly irreversible, we conclude that the valvereplacement should perhaps be performed before stress-inducedventricular dysfunction has occurred. Non-invasive monitoringof ventricular response to exercise might be helpful in optimizingthe timing of valve replacement in aortic regurgitation.     

Early postoperative changes in left ventricular chamber size, architecture, and function in aortic stenosis and aortic regurgitation and their relation to intraoperative changes in afterload: a prospective two-dimensional echocardiographic study

We prospectively studied 16 patients with isolated aortic stenosis and eight with isolated aortic regurgitation undergoing aortic valve replacement, using two-dimensional echocardiography preoperatively, intraoperatively, and 41 +/- 7 days postoperatively to calculate the intraoperative change in afterload, quantify the postoperative changes in left ventricular chamber size, architecture, load and function, determine whether the postoperative left ventricular remodeling correlated with the intraoperative change in afterload in aortic stenosis and aortic regurgitation, and assess whether preoperative afterload excess precluded postoperative improvement in left ventricular function. Preoperative left ventricular mass, end-systolic meridional and circumferential wall stresses, ejection fraction, and stress-shortening relations in patients with aortic stenosis and aortic regurgitation were similar. However, our patients with aortic regurgitation had severe systolic dysfunction, with ejection fraction less than 55% in all but one patient, compared with only 10 of 16 patients with aortic stenosis. Left ventricular end-diastolic volume, mass/volume ratio, and chamber shape were significantly different in patients with aortic stenosis and aortic regurgitation (174 +/- 64 vs 294 +/- 140 ml, p less than .01; 1.81 +/- 0.63 vs 1.14 +/- 0.18, p less than .01; and 0.59 +/- 0.09 vs 0.69 +/- 0.09, p less than .05, respectively). Intraoperative end-systolic meridional and circumferential stresses fell significantly in patients with aortic stenosis but remained unchanged in those with aortic regurgitation. The changes in left ventricular volume and ejection fraction during early postoperative remodeling (6 weeks) correlated with the intraoperative change in afterload in patients with aortic stenosis. In contrast, there was no intraoperative change in afterload in patients with aortic regurgitation and no significant changes in left ventricular volume, architecture, or function at 6 weeks or at 6 months. The differences in left ventricular remodeling and changes in function between patients with aortic stenosis and aortic regurgitation in the early postoperative period most probably relates to the major difference in intraoperative reduction in afterload, although a contributory role may have been played by the preoperative left ventricular dysfunction in those with aortic regurgitation that was underestimated by measurement of ejection fraction.     

Myocardial structure and function in patients with aortic valve disease and their relation to postoperative results

Left ventricular angiographic studies were performed before and 6 months after aortic valve replacement with a Björk-Shiley prosthesis in 21 patients, 5 with aortic stenosis, 8 with mixed aortic valve lesions and 8 with aortic insufficiency. The degree of myocardial fibrosis and myocardial ultrastructural changes were evaluated from transmural needle biopsy specimens obtained from the left ventricular anterior free wall at operation. Twelve patients without heart disease served as control subjects for angiographic data. Patients with aortic valve disease had a significantly higher left ventricular mass before operation than control subjects and a lower ejection fraction and mean normalized systolic ejection rate. After operation left ventricular mass decreased considerably but did not reach normal level. Ejection fraction and mean normalized systolic ejection rate became normal in all patients with aortic valve disease. The percent fibrosis determined with morphometry was significantly higher in the subendocardium than in the subepicardium of pressure-overloaded hearts (predominant stenosis) (19 versus 13 percent) but equal in both layers of volume-overloaded hearts (predominant regurgitation) (19 versus 18 percent). Electron microscopy revealed significant intracell alterations of the nucleus, sarcomeres, mitochondria and cytoplasmic reticulum. When all patients, regardless of type of aortic valve lesion, were considered, there was no significant correlation before operation between percent fibrosis and ejection fraction (r 0.10) or mean normalized systolic ejection rate (r 0.02) but a significant inverse relation between left ventricular mass and ejection fraction (r 0.54) as well as mean normalized systolic ejection rate (r 0.49).These data suggest that (1) Depressed left ventricular function in aortic valve disease is associated with ultrastructural degenerative cell changes, but complete recovery of cardiac function after aortic valve replacement is not prevented by these changes. (2) Interstitial myocardial fibrosis is not a primary determinant of depressed cardiac function in aortic valve disease.     

Different rates of progression of heart valve defects

In order to determine the rate of progression in valvular heart disease, the records of patients with simple valve lesions and two cardiac catheterizations performed prior to surgery were examined retrospectively. In 53 patients (mitral regurgitation n = 16, aortic regurgitation n = 13, mitral stenosis n = 13, aortic stenosis n = 11) complete data were available. The time interval between the two studies averaged 47 +/- 24 months. In patients with mitral regurgitation left ventricular ejection fraction deteriorated significantly faster than in the other groups; the rate of left ventricular volume gain and rise in pulmonary pressure also tended to be higher in this group. The transvalvular gradient in aortic stenosis showed a highly significant increase during the observation period (56 +/- 26 mm Hg vs 78 +/- 29 mm Hg; p less than 0.01), however, left ventricular ejection fraction remained within normal limits. These data indicate that patients with mitral regurgitation should be followed closely prior to valve replacement.     

Myocardial structure in volume-overloaded hearts before and after valve replacement

The purpose of this study was to evaluate the histological characteristics of left ventricular muscle in volume-overloaded hearts. A preoperative biopsy was obtained in 31 patients: 14 with mitral regurgitation, 14 with aortic regurgitation and 3 with mitral regurgitation and aortic regurgitation. Postoperative tissue samples were available in 15 patients. Histological findings were correlated with echocardiographic and angiographic data before (preop) and one year after (postop) operation. Myocardial cell diameter was correlated with both the end-diastolic (r = 0.77, p less than 0.01) and end-systolic (r = 0.78, p less than 0.01) dimensions of the left ventricle, but was inversely correlated with the end-diastolic wall thickness-to-radius (h/R) ratio (r = -0.71, p less than 0.01). Percent fibrosis increased proportionally to the diameter (r = 0.42, p less than 0.05). For one year after operation, echocardiographic left ventricular dimensions and angiographic left ventricular volumes were significantly reduced (p less than 0.05), but in some patients postoperative values remained greater than normal. With regard to left ventricular morphology, myocardial cell diameter and interstitial fibrosis decreased significantly after valve replacement (p less than 0.05). However, the myocardial fiber remained hypertrophied and interstitial fibrosis remained above normal after surgery. Thus, postoperative ventricular dilatation was dependent upon the degree of myocardial fiber hypertrophy and interstitial fibrosis.     

Mitral valve surgery for dilated cardiomyopathy with mitral regurgitation

Outcomes of surgery for non-ischemic non-valvular dilated cardiomyopathy with associated mitral regurgitation were assessed in 8 consecutive patients who underwent 9 mitral valve operations between 2001 and 2004. Mitral valve replacement was performed when the coaptation depth exceeded 10 mm. Two patients initially underwent mitral valvuloplasty, and 6 underwent valve replacement. One patient had valve replacement soon after valvuloplasty. Transthoracic echocardiography was performed immediately before surgery, before discharge, and during follow-up. Transesophageal echocardiography was carried out intraoperatively to assess valvular and ventricular function. Postoperative mean functional class was significantly better than the preoperative value (2.4 +/- 0.7 vs. 3.3 +/- 0.7), and the improvement was sustained during follow-up (2.0 +/- 0.7). The ejection fraction and left ventricular end-diastolic dimension did not improve. One patient died without leaving hospital and two died during follow-up. The 2- and 4-year survival rates were 75.0% and 37.5%. Mitral valve surgery improved functional class without obvious changes in ejection fraction or left ventricular end-diastolic dimension.     

Relations of preoperative hemodynamics and coronary blood flow to improved left ventricular function after valve replacement for aortic regurgitation

In this study of the limits of reversibility of left ventricular function after aortic valve replacement for aortic regurgitation, measurements were made of pre- and postoperative coronary blood flow and left ventricular volumes. Eighteen patients who had undergone aortic valve replacement for pure aortic regurgitation using the Bj?rk-Shiley valve or the Bicerval valve were restudied an average of 8 +/- 3 months after surgery. Postoperative left ventricular end-systolic and end-diastolic volumes returned to near normal values. The slight left ventricular wall thickening apparent before surgery remained unchanged after surgery and, consequently, left ventricular mass, though somewhat reduced, remained abnormally high. Ejection fraction, which was low preoperatively, returned to normal postoperatively. Total coronary sinus blood flow decreased after surgery, but coronary sinus blood flow per 100 g of left ventricular mass increased. This recovery of coronary flow per unit mass was believed to cause the improvement in left ventricular function. A significant correlation was found between postoperative systolic function and preoperative left ventricular end-systolic and end-diastolic volumes, wall thickness and, especially, left ventricular mass, the latter indicating that, if preoperative left ventricular mass is less than 350 g/m2, postoperative improvement of systolic function is attainable. Another significant correlation was indicated by measurements of coronary sinus blood flow per 100 g of left ventricular mass. If this is greater than 35 ml/min before surgery, a postoperative improvement in systolic function to within the normal range may be expected.     

The value of rest and exercise radionuclide ventriculography as compared to echocardiography and angiography in the detection of left ventricular dysfunction in patients with chronic aortic regurgitation

Symptomatic patients with chronic aortic regurgitation and a left ventricular ejection fraction greater than 0.50, or forward cardiac index greater than 2.5 l/min/m2 at rest, have a much better survival rate than those with a depressed ejection fraction or cardiac index following aortic valve replacement. The annual mortality rate is approximately 2% for those with well preserved ventricular function versus 10% for those with depressed ventricular function at rest. This is in striking contrast to the situation that exists in patients with aortic stenosis, where the long-term survival is similar for those with a normal or depressed left ventricular ejection fraction or cardiac index at rest. Therefore, it would seem to be important to detect incipient left ventricular failure in patients with chronic aortic regurgitation and to intervene surgically before the left ventricular dysfunction becomes irreversible. In patients with a normal left ventricular ejection fraction at rest, maximal supine bicycle exercise testing with radionuclide ventriculography defines a group of patients with truly normal ventricular function (ejection fraction increases by greater than 0.05 ejection fraction units at peak exercise), and a group with incipient left ventricular dysfunction earlier than previously described variables (i.e., left ventricular ejection fraction at rest less than 0.50, left ventricular end-systolic volume index greater than 90 ml/m2, left ventricular end-systolic dimension greater than or equal to 5.5 cm, left ventricular shortening fraction less than or equal to 25%), and generally before the onset of symptoms.     

Left ventricular remodeling with intensive exercise after aortic valve replacement

The influence of regular exercise on cardiac remodeling after aortic valve replacement (AVR) is virtually unknown. The case is reported of a 49-year-old male patient who had undergone biological valve replacement for severe aortic regurgitation with reduced left ventricular ejection fraction (LVEF; 45%) and massive left ventricular dilation (left ventricular end-diastolic diameter (LVEDD) 96 mm), which had been recognized for at least three years before surgery. Starting with the normal postoperative cardiac rehabilitation, the patient subsequently intensified his regular endurance training, reaching a total of 9,500 km of cycling within one year. The LVEF (51%) and LVEDD (60 mm) were almost normalized within this period. This was accompanied by an increase in peak VO2, from 27 to 52 ml/min/kg, and in peak exercise capacity (bicycle ergometer) from 75 to 283 W. These findings indicate that even intensive endurance training after AVR seems to be feasible and safe, and may have a beneficial effect on postoperative cardiac remodeling.