Operative Outcomes with Myxomatous Mitral Valve Repair: Experience with 586 Patients.

INTRODUCTION: American Heart Association (AHA) guidelines recommend mitral valve repair for myxomatous mitral regurgitation whenever possible to prevent LV dysfunction and early mortality. Here we review our early operative outcomes with mitral valve repair for myxomatous mitral regurgitation. METHODS: We collected data from 586 consecutive patients that underwent mitral repair for myxomatous disease at the Prince Henry and Prince of Wales Hospitals Sydney between 1997 and 2012. All patients had pre- and postoperative transthoracic echocardiograms. RESULTS: In the first 30 days postoperatively there were five deaths (0.9%), four strokes (0.7%) and five transient ischaemic attacks (TIAs) (0.9%). Repair involved resection in 55.5%, neochordal reconstruction in 41.6%, and in 2.9% a combination of both. There was increasing use of neochordae since 2006. At discharge 99% had mitral regurgitation (MR) ≤ mild and ≤ trivial in 79.5%. For posterior leaflet disease neochordae had improved MR at discharge compared with resection (85% vs 78%, P<0.05). Preoperative triscupid regurgitation (TR) and pulmonary hypertension > mild were associated with a greater degree of MR at discharge (P<0.05) for reasons that are unclear. CONCLUSION: We have shown excellent early results for mitral repair with very low operative mortality and excellent freedom from significant MR. Successful mitral repairs with low morbidity have resulted in a pattern of early referral in keeping with the current guidelines.

The role of transthoracic echocardiography in excluding left sided infective endocarditis in Staphylococcus aureus bacteraemia.

In all patients with Staphylococcus aureus bacteraemia a transoesophageal echocardiogram is recommended to exclude infective endocarditis. We determined that a finding of normal to trivial valvular regurgitation on transthoracic echocardiogram in these patients significantly reduced the probability of infective endocarditis. Furthermore, in the absence of embolic phenomena the likelihood of infective endocarditis was less than 2%. This probability could be further reduced if the echocardiogram was performed greater than 5 days after the bacteraemia. Therefore, in the assessment of patients with S. aureus bacteraemia a transoesophageal echocardiogram is not always required to exclude infective endocarditis.

Lp(a) and conventional risk profiles predict the severity of coronary stenosis in high-risk hospital-based patients.

AIMS: To explore predictive power of Lp(a), of conventional lipoprotein profiles and their carrier proteins, and of biometric measurements, for the presence and severity of angiographically documented coronary disease in high-risk patients, and to compare risk profiles in men and women. METHODS: We determined coronary artery disease (CAD) risk factors in 1308 Australian Caucasian patients (313 women and 995 men) aged < or =65 years who consecutively underwent coronary angiography. RESULTS: In univariate analyses of the risk factors, lipid profiles, Lp(a), cigarette smoking, diabetes, hypertension and obesity were all higher in men and women with CAD and changed significantly with the number of significantly diseased vessels (> or =50% luminal obstruction). When stepwise logistic regression analysis was applied, age (OR 1.06, 95% CI: 1.04-1.09), TC/HDL-C (OR 1.29, 95% CI: 1.15-1.45), male gender (OR 2.64, 95% CI: 1.67-4.16), hyperLp(a) (> or =300 mg/L) (OR 2.09, 95% CI: 1.42-3.07), lifetime smoking dose (OR 1.02, 95% CI: 1.01-1.03), diabetes (OR 2.19, 95% CI: 1.14-4.18) and waist/hip ratio (OR 14.53, 95% CI: 1.21-174.90) were predictive of the disease. Both Lp(a) levels and percentage of hyperLp(a) increased linearly with the number of significantly diseased vessels. When the analyses were conducted in men and women separately, hyperLp(a), TC/HDL-C, lifetime smoking dose and age remained as significant predictors in both groups but the waist/hip ratio was only predictive in women. CONCLUSIONS: As Lp(a) is an independent predictor of the occurrence and extent of coronary stenosis and relevant to treatment options, we suggest that it should be measured routinely in the coronary risk profile assessment of high-risk patients.

Relationship between total plasma homocysteine, polymorphisms of homocysteine metabolism related enzymes, risk factors and coronary artery disease in the Australian hospital-based population.

Modest elevations of circulating homocysteine are common in patients with vascular disease. We explored interrelations between total plasma homocysteine levels and mutations in genes for three key enzymes in methionine-homocysteine metabolism. Methyltetrahydrofolate reductase (MTHFR) 677C-->T, cystathionine beta synthase (CBS) 68-bp insertion at exon 8, and methionine synthase (MS) 2756A-->G were typed in 685 Australian caucasian patients aged < or =65 years with and without angiographically documented coronary artery disease (CAD). We also assessed associations between homocysteine levels and extracellular superoxide dismutase (EC-SOD) and other CAD risk factors. There were significant correlations between plasma total homocysteine, and EC-SOD (r = 0.170, p = 0.001 for men; r = 0.241, p = 0.003 for women) and LDL (r = 0.153, p = 0.001 for men; r = 0.132, p = 0.081 for women). Levels were also significantly higher among patients with unstable angina (15.30+/-0.44 micromol/l for men, 14.44+/-0.74 micromol/l for women) than those without angina (13.98+/-0.38 micromol/l for men, 13.41+/-0.98 micromol/l for women) or with stable angina (14.00+/-0.37 micromol/l for men, 12.88+/-0.71 micromol/l for women). There were no significant associations between the levels and the presence or severity of CAD. The mutant MTHFR homozygotes tended to have higher levels and those with the MS and CBS mutations tended to have lower levels. We conclude that there is a significant correlation between plasma homocysteine levels and EC-SOD suggesting that elevated homocysteine may exert oxidative stress and that levels are associated with unstable angina, but not the occurrence or extent of coronary stenosis. The contributions to total plasma homocysteine levels of the common mutations of genes coding for the enzymes controlling homocysteine metabolism are modest.

The frequency of a common mutation of the methionine synthase gene in the Australian population and its relation to smoking and coronary artery disease.

BACKGROUND: Modest elevations in levels of circulating homocysteine are common in patients with vascular disease. Methionine synthase is a vitamin B12-dependent enzyme catalysing the re-methylation of homocysteine to methionine; reduced methionine synthase activity results in elevated level of homocysteine. DESIGN: A case-control study. METHODS: We explored the frequency and distribution of a 2756A-->G (D919G) mutation of the methionine synthase gene, detected by polymerase chain reaction genotyping, in 745 Australian Caucasian patients aged < or = 65 years (550 men and 195 women) with and without angiographically documented coronary artery disease (CAD). RESULTS: The frequency distributions of AA, AG and GG genotypes were 61.9%, 33.8% and 4.3%, respectively, and were in Hardy-Weinberg equilibrium. There was no correlation between the methionine synthase mutation and CAD from simple chi2 comparison. However, the interactive term of life-time smoking dose with methionine synthase genotypes was predictive of both the number of significantly diseased vessels (> or =50% luminal obstruction; chi2 = 12.518, P=0.0019), and the presence or absence of significant CAD (chi2=7.045, P=0.027). A stepwise logistic regression analysis showed that smokers who were also GG homozygotes had more severe CAD compared with smokers of other genotypes. The methionine synthase genotypes were not associated with any of the other established CAD risk factors assessed in our study. CONCLUSIONS: We conclude that the methionine synthase 2756A-->G mutation is common, with homozygosity occurring in approximately 4% of white Australians, and that it has an interactive effect with life-time smoking dose to increase the severity of CAD. Smokers who are also GG homozygotes have additionally elevated CAD risk.

Thromboembolic risks of left atrial thrombus detected by transesophageal echocardiogram.

Patients with left atrial thrombus are considered at high risk for thromboembolic events. The actual prognosis of these patients and the features most predictive of future events are unclear. We performed transesophageal echocardiograms in 2,894 patients over a 6 1/2-year period; 94 (age 69 +/- 11 years, 59 men, 83 in atrial fibrillation) were found to have left atrial thrombus. The thrombi were considered mobile in 45 patients and 33 patients had thrombus with a maximum dimension > or = 1.5 cm. Seven of the 94 patients with prosthetic valves were excluded from follow-up analysis. Over a follow-up period of 25.3 +/- 19.2 months, 17 patients had suffered a stroke or embolic event (event rate 10.4% per year) and 27 had died (mortality 15.8% per year). Cox proportional hazard regression analysis identified a maximum thrombus dimension > or = 1.5 cm (RR 19, p = 0.002), history of thromboembolism (RR 4.2, p = 0.038), and mobile thrombus (RR 5.3, p = 0.02) as predictors of subsequent thromboembolism. Moderate or severe left ventricular dysfunction was the only significant predictor of death (RR 2.9, p = 0.04). Gender, age, warfarin therapy at follow-up, atrial fibrillation, location (cavity vs appendage) of thrombus, and spontaneous echocardiographic contrast were not significant. Aggressive antithrombotic therapy may be indicated in these high-risk patients.

Three-dimensional reconstruction of the flow in a human left heart by using magnetic resonance phase velocity encoding.

Intraventricular flows have been correlated with disease and are of interest to cardiologists as a possible means of diagnosis. This study extends a method that use magnetic resonance (MR) to measure the three-dimensional nature of these flows. Four coplanar, sagittal MR slices were located that spanned the left ventricle of a healthy human. All three velocity components were measured in each slice and 18 phases were obtained per beat. With use of the MR magnitude images, masks were created to isolate the velocity data within the heart. These data were read into the software package, Data Visualizer, and the data from the four slices were aligned so as to reconstruct the three-dimensional volume of the left ventricle and atrium. By representing the velocity in vectorial form, the three-dimensional intraventricular flow field was visualized. This revealed the presence of one large line vortex in the ventricle during late diastole but a more ordered flow during early diastole and systole. In conclusion, the use of MR velocity acquisition is a suitable method to obtain the complex intraventricular flow fields in humans and may lead to a better understanding of the importance of these flows.

Selection of patients for transesophageal echocardiography after stroke and systemic embolic events. Role of transthoracic echocardiography.

BACKGROUND AND PURPOSE: This study examined whether patients suffering from stroke and other systemic embolic events may be selected for transesophageal echocardiography on the basis of clinical and transthoracic echocardiographic findings. METHODS: We performed transthoracic and transesophageal echocardiography on 824 patients after stroke and other suspected embolic events. Patients were classified into group A if they were in sinus rhythm and had a normal transthoracic echocardiogram. Group B consisted of all other patients. Transesophageal echocardiographic findings of left atrial spontaneous contrast, left atrial thrombus, complex aortic atheroma, and interatrial septal anomalies were correlated with clinical and transthoracic echocardiographic results. RESULTS: Transesophageal echocardiography detected at least one potential source of embolism in 399 patients (49%): spontaneous contrast in 214 patients (26%), left atrial thrombus in 54 (7%), complex atheroma in 111 (13%), and interatrial septal anomalies in 126 (15%). In group A (n = 236), only 3 (1%) had spontaneous contrast, 11 (4.6%) had complex atheroma, and none had left atrial thrombus. In group B (n = 588), 211 patients (36%, P < .001) had spontaneous contrast, 54 (9.2%, P < .001) had atrial thrombus, and 100 (17%, P < .001) had complex atheroma. Interatrial septal anomalies were detected in similar proportions of patients (18% in group A versus 14% in group B). Left atrial spontaneous echo contrast, thrombus, and complex atheroma were significantly more prevalent in older patients, but interatrial septal anomalies were more prevalent in younger patients irrespective of transthoracic echocardiographic findings. Multivariate analysis identified both an abnormal transthoracic echocardiogram and patient age to be independent predictors of transesophageal echocardiographic findings of left atrial spontaneous echo contrast, left atrial thrombus, or complex atheroma. CONCLUSIONS: Transesophageal echocardiography has a low yield for left atrial spontaneous contrast, left atrial thrombus, or complex aortic atheroma in patients with normal transthoracic echocardiogram and sinus rhythm and in younger patients. Interatrial septal anomalies are more prevalent in younger patients. Transthoracic echocardiogram should be performed in patients after stroke or systemic embolic events as a noninvasive screening tool. We recommend transesophageal echocardiogram for patients with abnormal transthoracic echocardiogram and in younger patients when the finding of a patent foramen ovale may contribute to patient management.

Resolution of left atrial spontaneous echocardiographic contrast after percutaneous mitral valvuloplasty: implications for thromboembolic risk.

Left atrial spontaneous echocardiographic contrast (SEC) is an important marker of increased thromboembolic risk in patients with mitral stenosis. To evaluate the effect of percutaneous transseptal mitral valvuloplasty (PTMV) on SEC, we performed transesophageal echocardiography 1 day before and 3 months after PTMV on 88 consecutive patients. SEC was present in 65 (74%) patients before PTMV and was associated with absence of moderate or severe mitral regurgitation (p = 0.01), a smaller valve area (p = 0.02), an older age (p = 0.04), and atrial fibrillation (p = 0.05). At 3 months, PTMV resulted in a mean absolute and relative increase in valve area of 0.54 +/- 0.36 cm2 and 53% +/- 43%, respectively. SEC resolved in 37 patients but persisted in 28 (32%) patients at the 3-month study. The absolute and relative increase of valve area and worsened mitral regurgitation after PTMV were predictors of resolution of SEC, with the relative increase in valve area being the only significant predictor on multivariate analysis. PTMV frequently results in resolution of SEC, which may have important implications in reducing the thromboembolic risk in these patients.

Prognostic implications of left atrial spontaneous echo contrast in nonvalvular atrial fibrillation.

OBJECTIVES: This study examined the influence of left atrial spontaneous echo contrast on the subsequent stroke or embolic event rate and on survival in patients with nonvalvular atrial fibrillation. BACKGROUND: Left atrial spontaneous echo contrast is associated with atrial fibrillation and a history of previous stroke or other embolic events. However, the prognostic implications of spontaneous contrast in patients with nonvalvular atrial fibrillation are unknown. METHOD: The study group comprised 272 consecutive patients with nonvalvular atrial fibrillation undergoing transesophageal echocardiography. Clinical and echocardiographic data were collected at baseline, and patients were prospectively followed up, and all strokes, other embolic events and deaths were documented. The relation between spontaneous contrast at baseline and subsequent stroke, other embolic events and survival was analyzed. RESULTS: Left atrial spontaneous echo contrast was detected at baseline in 161 patients (59%). The mean follow-up was 17.5 months. The stroke or other embolic event rate was 12%/year (15 strokes, 3 transient ischemic attacks, 2 peripheral embolisms) in patients with, compared with 3%/year (5 strokes) in patients without, baseline spontaneous contrast (p = 0.002). In 149 patients without previous thromboembolism, the event rate was 9.5%/year in patients with and 2.2%/year in patients without spontaneous contrast (p = 0.003). There were 25 deaths in patients with and 11 deaths in patients without spontaneous contrast. Patients with spontaneous contrast had significantly reduced survival (p = 0.025). On multivariate analysis, spontaneous contrast was the only positive predictor (odds ratio 3.5, p = 0.03) and warfarin therapy on follow-up the only negative predictor (odds ratio 0.23, p = 0.02) of subsequent stroke or other embolic events. CONCLUSIONS: Transesophageal echocardiography can risk stratify patients with nonvalvular atrial fibrillation by identifying left atrial spontaneous echo contrast. These patients have both a significantly higher risk of developing stroke or other embolic events and a reduced survival, and they may represent a subgroup in whom the risk/benefit ratio of anticoagulation may be most favorable.

Role of transoesophageal echocardiography in the diagnosis and management of aortic root abscess.

OBJECTIVE: To assess and compare the roles of transthoracic and transoesophageal echocardiography in the diagnosis and management of an aortic root abscess. DESIGN: To select patients with echocardiographic diagnosis of aortic valve endocarditis with and without an aortic root abscess and correlate this with a retrospective review of surgical and necropsy data. SETTING: Tertiary referral centre at a university teaching hospital. PATIENTS AND METHODS: 34 patients with confirmed aortic valve endocarditis were treated over a four and a half year period. All patients underwent both transthoracic and transoesophageal echocardiography with 17 patients having biplane or multiplane imaging. RESULT: 11 patients (32%) had an aortic root abscess. Transthoracic echocardiography identified four cases of aortic root abscess whereas transoesophageal echocardiography correctly detected all 11 cases and also detected complications including mitral aortic intervalvar fibrosa fistula in two patients and right atrial involvement in another two patients. Only biplane imaging was able to show an anterior aortic root abscess in one patient and the circumferential involvement of the aortic annulus in another two patients. All patients with an aortic root abscess were treated surgically after transoesophageal echocardiographic diagnosis. After operation, prosthetic aortic regurgitation was present in seven patients and a repeat operation was performed in three patients. Only transoesophageal echocardiography detected a postoperative aorto-right atrial fistula in two patients and recurrence of the root abscess in another. There were five deaths in hospital (45%). CONCLUSIONS: Compared with transthoracic echocardiography, transoesophageal echocardiography was more sensitive and more specific for the early diagnosis of aortic root abscess and its complications and facilitated both the preoperative and postoperative management of these patients. Biplane and multiplane imaging provide additional diagnostic information. All patients with suspected aortic valve endocarditis should have an early transoesophageal echocardiographic study.

Semiautomated method for noise reduction and background phase error correction in MR phase velocity data.

Background phase distortion and random noise can adversely affect the quality of magnetic resonance (MR) phase velocity measurements. A semiautomated method has been developed that substantially reduces both effects. To remove the background phase distortion, the following steps were taken: The time standard deviations of the phase velocity images over a cardiac cycle were calculated. Static regions were identified as those in which the standard deviation was low. A flat surface representing an approximation to the background distortion was fitted to the static regions and subtracted from the phase velocity images to give corrected phase images. Random noise was removed by setting to zero those regions in which the standard deviation was high. The technique is demonstrated with a sample set of data in which the in-plane velocities have been measured in an imaging section showing the left ventricular outflow tract of a human left ventricle. The results are presented in vector and contour form, superimposed on the conventional MR angiographic images.

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)

Assessment of postreperfusion myocardial hemorrhage using proton NMR imaging at 1.5 T.

BACKGROUND: Intramyocardial hemorrhage occurs frequently after reperfusion of acute myocardial infarction. However, its significance has not yet been established, mainly because of the lack of methods for detecting such hemorrhage. The following ex vivo study was carried out to assess the potential of nuclear magnetic resonance (NMR) imaging to detect and quantitate postreperfusion intramyocardial hemorrhage. METHODS AND RESULTS: Sixteen adult mongrel dogs underwent 3 hours of coronary occlusion followed by 1 hour of reperfusion, and three dogs underwent 4 hours of occlusion without reperfusion. Radiolabeled microspheres and 51Cr-labeled red blood cells were used to assess flow and evaluate the extent of hemorrhage. These results were later compared with both NMR and histology. Spin-echo NMR imaging was performed on the excised hearts using a 1.5-T system. Macroscopic assessment of the sliced myocardium revealed the existence of hemorrhage in 14 of the 16 dogs that underwent reperfusion but in none of those with occlusion only. In all 16 dogs with reperfusion, zones of increased signal intensity (SI) ratio (1.68 +/- 0.41 compared with control, p less than 0.05) were seen in regions relating to the distribution of the occluded coronary artery, whereas in 13 of the 16 dogs, areas of decreased SI within the zone of increased SI ratio (0.81 +/- 0.16 compared with control, p less than 0.05) were also seen, corresponding to regions with macroscopic hemorrhage. In contrast, in the three dogs without reperfusion, no macroscopic hemorrhage was observed, and likewise, no NMR zones of reduced SI were detected. Hemorrhage size by NMR (decreased SI zones), correlated well with hemorrhage size calculated from tissue slices (r = 0.96, SEE = 0.92%, p less than 0.01), or by 51Cr labeling (r = 0.78, SEE = 1.5, p = 0.1). In the reperfusion group, T2 relaxation times in the infarcted hemorrhagic zone (58 +/- 9 msec) were significantly lower than the infarcted zones without hemorrhage (98 +/- 13 msec, p less than 0.001). In contrast, when compared with control (964 +/- 72 msec), T1 relaxation times were significantly increased in both infarct zones, either with (1,284 +/- 176 msec) or without (1,266 +/- 103 msec) hemorrhage. The selective shortening of T2 relaxation times in the hemorrhagic regions is consistent with the paramagnetic effects of deoxyhemoglobin. CONCLUSIONS: NMR imaging may provide a noninvasive approach for the detection and quantitation of intramyocardial hemorrhage. This observation may provide a means to further characterize pathological processes associated with acute myocardial infarction and assess the role of myocardial hemorrhage after reperfusion therapy.

Embolization of a left atrial ball thrombus during transesophageal echocardiography.

We report a case of systemic embolization of a left atrial ball thrombus during transesophageal echocardiography (TEE). A 49-year-old man with rheumatic mitral stenosis and atrial fibrillation underwent TEE to evaluate a transient cerebral ischemic attack. TEE demonstrated a free-floating left atrial thrombus. Disappearance of the thrombus during the study occurred after tachycardia and was associated with acute hemiplegic stroke and an absent radial pulse. The possible mechanism of embolization and the implications for the selection and management of patients undergoing TEE are discussed.

The effect of postinfarction intramyocardial hemorrhage on transverse relaxation time.

1H NMR imaging has been used to define zones of myocardial infarction (MI), which appear as areas of relatively increased signal intensity (SI). However, zones of decreased SI have been observed within or around the areas of infarction in NMR images acquired at high magnetic fields. To determine the cause of these areas of reduced SI, ex vivo spin-echo 1H NMR imaging at 1.5 T was performed in eight dogs following 72 h of coronary artery occlusion. In all dogs, a zone of increased SI (122 +/- 7% compared to control myocardium; P less than 0.01) was observed in the territory of the occluded coronary artery. In seven of the dogs, additional zones were also seen, within or around the central zone of increased SI, which displayed SI that was reduced in comparison with the local enhanced intensity, but was similar to the intensity of normal myocardium (97 +/- 7% compared to control; P = NS). Gross inspection and histological assessment of sliced myocardium disclosed hemorrhage in these regions characterized by locally decreased NMR SI. Image-derived calculation of T2 in the various infarct regions revealed a significant shortening of T2 in the hemorrhagic infarct zones characterized by decreased SI, in comparison with the nonhemorrhagic infarct zones characterized by increased SI (59 +/- 7 ms vs 73 +/- 10 ms, P less than 0.05). No difference was found, however, between the observed T2's of hemorrhagic infarct and of control tissue (57 +/- 4 ms). Using a biexponential analysis of T2 from the hemorrhagic infarct zones, the intrinsic T2 of water protons affected by hemorrhage was determined to be 43 +/- 9 ms, significantly reduced in comparison with the values obtained with the standard monoexponential fit. The reduction in T2 in the hemorrhagic zone is consistent with the paramagnetic effects of deoxyhemoglobin associated with intramyocardial hemorrhage. Thus the apparent T2, measured in hemorrhagic infarct tissue, represents the result of an averaging effect of infarct and hemorrhage on T2 relaxation times. These observations improve our understanding of the changes in NMR SI within the infarcted regions, and may provide a noninvasive method for the detection and quantitative assessment of intramyocardial hemorrhage.

Nuclear magnetic resonance imaging for assessment and follow-up of patients with valve disease.

Nuclear magnetic resonance (NMR) imaging now offers a powerful means of assessing a variety of clinically important parameters in patients with valvular heart disease. NMR approaches will probably be most useful in patients with chronic valvular regurgitation, in which there continues to be uncertainty regarding the optimum timing for surgical intervention. In these patients it is possible to simultaneously assess both the valvular regurgitation and the resulting changes in myocardial structure and function. In patients with aortic stenosis, NMR can be applied to the assessment of left ventricular mass, both before and after valvuloplasty or valve replacement. In mitral stenosis, NMR may be applied to the assessment of right ventricular volumes and function. NMR may be used for the detection of prosthetic valve regurgitation when Doppler studies are equivocal. Finally, NMR imaging may be applied in patients with congenital or aortic root disease to evaluate valvular function in addition to diagnostic assessment of such patients. The future development of isotropic three-dimensional acquisition approaches, ultrafast imaging strategies, automated surface detection techniques, and more rapid function and flow analysis could considerably enhance the use of the current NMR approaches. The application of spectroscopic techniques could provide a means of monitoring myocardial metabolic abnormalities in ventricles exposed to chronic overload. Meanwhile, in patients with valvular regurgitation and stenosis, it would seem timely to initiate long-term serial NMR studies to further define natural history and the effects of various medical regimens and to ultimately help determine optimum medical and interventional regimens.

Interstudy reproducibility of biplane cine nuclear magnetic resonance measurements of left ventricular function.

Cine nuclear magnetic resonance (NMR) imaging, as a noninvasive and high-resolution imaging modality, has been shown to be reliable for determining absolute left ventricular (LV) volumes and ejection fraction. A relatively new gradient echo cine NMR approach using 2 orthogonal long-axis planes (2- and 4-chamber) aligned with the true axes of the left ventricle has been previously developed and validated against radiographic biplane LV cineangiography. The aim of the present investigation was to determine the reproducibility of this more rapid cine NMR approach for the measurement of LV volumes and ejection fraction. Eighteen normal subjects underwent 2 cine NMR studies, on different days, using a 1.5-tesla clinical imaging system. Studies were analyzed on-line and blindly by 2 independent observers. Intraobserver error was also determined in a blinded manner. Mean values of measurements determined by this method in this group of normal subjects were end-diastolic volume (120 +/- 20 ml), end-systolic volume (39 +/- 9 ml) and ejection fraction (67 +/- 4%). Paired analysis of data revealed no significant bias between interstudy, interobserver or intraobserver measurements, except for interobserver end-diastolic volume, where the first observer measurements were slightly elevated (5.6 +/- 7.8 ml) compared with the second. This resulted in a small difference in ejection fraction (1.7 +/- 2.3%) between observers. The absolute variation between measurements (square root of variance components) was low for all interstudy, interobserver and intraobserver comparisons: end-diastolic volume was less than +/- 6.7 ml, end-systolic volume less than +/- 3.5 ml and ejection fraction less than +/- 2.4%.(ABSTRACT TRUNCATED AT 250 WORDS)