Prevalence and clinical outcome of mitral-valve prolapse

BACKGROUND

Mitral-valve prolapse has been described as a common disease with frequent complications. To determine the prevalence of mitral-valve prolapse in the general population, as diagnosed with the use of current two-dimensional echocardiographic criteria, we examined the echocardiograms of 1845 women and 1646 men (mean [+/-SD] age, 54.7+/-10.0 years) who participated in the fifth examination of the offspring cohort of the Framingham Heart Study.

METHODS

Classic mitral-valve prolapse was defined as superior displacement of the mitral leaflets of more than 2 mm during systole and as a maximal leaflet thickness of at least 5 mm during diastasis, and nonclassic prolapse was defined as displacement of more than 2 mm, with a maximal thickness of less than 5 mm.

RESULTS

A total of 84 subjects (2.4 percent) had mitral-valve prolapse: 47 (1.3 percent) had classic prolapse, and 37 (1.1 percent) had nonclassic prolapse. Their age and sex distributions were similar to those of the subjects without prolapse. None of the subjects with prolapse had a history of heart failure, one (1.2 percent) had atrial fibrillation, one (1.2 percent) had cerebrovascular disease, and three (3.6 percent) had syncope, as compared with unadjusted prevalences of these findings in the subjects without prolapse of 0.7, 1.7, 1.5, and 3.0 percent, respectively. The frequencies of chest pain, dyspnea, and electrocardiographic abnormalities were similar among subjects with prolapse and those without prolapse. The subjects with prolapse were leaner (P<0.001) and had a greater degree of mitral regurgitation than those without prolapse, but on average the regurgitation was classified as trace or mild.

CONCLUSIONS

In a community based sample of the population, the prevalence of mitral-valve prolapse was lower than previously reported. The prevalence of adverse sequelae commonly associated with mitral-valve prolapse in studies of patients referred for that diagnosis was also low.

C-Reactive protein predicts all-cause and cardiovascular mortality in hemodialysis patients

Hypoalbuminemia predicts death in dialysis patients. Although hypoalbuminemia has been attributed to malnutrition, evidence of inflammation (C-reactive protein [CRP] and cytokine levels) has recently been recognized to predict albumin concentration in dialysis patients. We measured CRP and albumin levels in October 1995 in 91 hemodialysis (HD) patients. During a 34-month follow-up period, we determined the incidence and cause of death. Patients were divided into four groups based on serum albumin levels (<3.5 [lowest quartile], 3.5 to 3.8, 3.9 to 4.0, and >4.0 g/dL [highest quartile]). Survival differed among the four groups (P = 0.0063). Patients with albumin levels greater than 4.0 g/dL had the greatest survival. Kaplan-Meier survival estimates of patients from varying CRP quartiles (<2.6, 2.6 to 5.2, 5.3 to 11.5, and >11.5 microg/mL) differed among the four groups (P < 0.0001). The group with the greatest CRP level (>11.5 microg/mL) had the lowest survival. Multivariate analysis using the Cox proportional hazards model showed that only CRP level (chi-square = 21.11; P < 0.0001) and age (chi-square = 5.44; P = 0.020) predicted death. Albumin level (chi-square = 0.16; P = 0.69) was not predictive. Only when CRP was excluded from the model did low serum albumin level (chi-square = 12. 04; P = 0.0004) predict death. CRP level (chi-square = 16.79; P < 0. 0001) and age (chi-square = 6.38; P = 0.012) also superceded albumin level (chi-square = 0.45; P = 0.51) in predicting cardiovascular mortality. Although values for blood urea nitrogen, creatinine, and normalized protein catabolic rate were significantly less among patients who died, these parameters, as well as cholesterol level and diabetes, were not important predictors of death in multivariate analysis. The acute-phase response or the cause of the acute-phase response is largely responsible for the effect of hypoalbuminemia on mortality in HD patients.

Insights from three-dimensional echocardiography into the mechanism of functional mitral regurgitation: direct in vivo demonstration of altered leaflet tethering geometry

BACKGROUND

Recent advances in three-dimensional (3D) echocardiography allow us to address uniquely 3D scientific questions, such as the mechanism of functional mitral regurgitation (MR) in patients with left ventricular (LV) dysfunction and its relation to the 3D geometry of mitral leaflet attachments. Competing hypotheses include global LV dysfunction with inadequate leaflet closing force versus geometric distortion of the mitral apparatus by LV dilatation, which increases leaflet tethering and restricts closure. Because geometric changes generally accompany dysfunction, these possibilities have been difficult to separate.

METHODS AND RESULTS

We created a model of global LV dysfunction by esmolol and phenylephrine infusion in six dogs. initially with LV expansion limited by increasing pericardial restraint and then with the pericardium opened. The mid-systolic 3D relations of the papillary muscle (PM) tips and mitral valve were reconstructed. Despite severe LV dysfunction (ejection fraction, 18+/-6%), only trace MR developed when pericardial restraint limited LV dilatation; with the pericardium opened, moderate MR accompanied LV dilatation (end-systolic volume, 44+/-5 mL versus 12+/-5 mL control, P<.001). Mitral regurgitant volume and orifice area did not correlate with LV ejection fraction and dP/dt (global function) but did correlate with changes in the tethering distance from the PMs to the anterior annulus derived from the 3D reconstructions, especially PM shifts in the posterior and mediolateral directions, as well as with annular area (P<.0005). By multiple regression, only changes in the PM-to-annulus distance independently predicted MR volume and orifice area (R2=.82 to .85, P=2x10(-7) to 6x10(-8)).

CONCLUSIONS

LV dysfunction without dilatation fails to produce important MR. Functional MR relates strongly to changes in the 3D geometry of the mitral valve attachments at the PM and annular levels, with practical implications for approaches that would restore a more favorable configuration.

Three-dimensional echocardiographic reconstruction of the mitral valve, with implications for the diagnosis of mitral valve prolapse

Mitral valve prolapse has been diagnosed by two-dimensional echocardiographic criteria with surprising frequency in the general population, even when preselected normal subjects are examined. In most of these individuals, however, prolapse appears in the apical four-chamber view and is absent in roughly orthogonal long-axis views. Previous studies of in vitro models with nonplanar rings have shown that systolic mitral annular nonplanarity can potentially produce this discrepancy. However, to prove directly that apparent leaflet displacement in a two-dimensional view does not constitute true displacement above the three-dimensional annulus requires reconstruction of the entire mitral valve, including leaflets and annulus. Such reconstruction would also be necessary to explore the complex geometry of the valve and to derive volumetric measures of superior leaflet displacement. A technique was therefore developed and validated in vitro for three-dimensional reconstruction of the entire mitral valve. In this technique, simultaneous real-time acquisition of images and their spatial locations permits reconstruction of a localized structure by minimizing the effects of patient motion and respiration. By applying this method to 15 normal subjects, a coherent mitral valve surface could be reconstructed from intersecting scans. The results confirm mitral annular nonplanarity in systole, with a maximum deviation of 1.4 +/- 0.3 cm from planarity. They directly show that leaflets can appear to ascend above the mitral annulus in the apical four-chamber view, as they did in at least one view in all subjects, without actual leaflet displacement above the entire mitral valve in three dimensions, thereby challenging the diagnosis of prolapse by isolated four-chamber view displacement in otherwise normal individuals. This technique allows us to address a uniquely three-dimensional problem with high resolution and provide new information previously unavailable from the two-dimensional images. This new appreciation should enhance our ability to ask appropriate clinical questions relating mitral valve shape and leaflet displacement to clinical and pathologic consequences.

MLH1 promoter hypermethylation is associated with the microsatellite instability phenotype in sporadic endometrial carcinomas

Microsatellite instability (MSI) has been detected in endometrial carcinomas occurring in women affected by hereditary nonpolyposis colorectal carcinoma (HNPCC) as well as in 20% of presumably sporadic endometrial tumors. While the MSI+ phenotype observed in endometrial tumors from HNPCC patients is attributed to germ line mutations in mismatch repair (MMR) genes, somatic mutations of known MMR genes are infrequent in MSI+ sporadic endometrial carcinomas. Recently, cytosine methylation of the MLH1 promoter region has been identified in a subset of MSI+ colon primary carcinomas and cell lines. We studied the MLH1 and MSH2 promoter methylation status in 29 presumably sporadic uterine endometrioid carcinomas (UECs), which had previously been characterized for the MSI phenotype and a subset for DNA MMR gene mutational status. We found that 13 (45%) of 29 cases of EC were hypermethylated in the 5' CpG island of MLH1. Hypermethylation of MSH2 was not observed. MLH1 was hypermethylated in 12 (92%) of 13 MSI+ tumors, while only 1 (6%) of 16 MSI- tumors (Fischer's exact test P<O.0001). Other tumor types we tested did not demonstrate MLH1 promoter hypermethylation. Our data suggest that hypermethylation of MLH1, but not of MSH2, is associated with the MSI phenotype in sporadic endometrial carcinomas.

Fusion of NUP214 to ABL1 on amplified episomes in T-cell acute lymphoblastic leukemia

In T-cell acute lymphoblastic leukemia (T-ALL), transcription factors are known to be deregulated by chromosomal translocations, but mutations in protein tyrosine kinases have only rarely been identified. Here we describe the extrachromosomal (episomal) amplification of ABL1 in 5 of 90 (5.6%) individuals with T-ALL, an aberration that is not detectable by conventional cytogenetics. Molecular analyses delineated the amplicon as a 500-kb region from chromosome band 9q34, containing the oncogenes ABL1 and NUP214 (refs. 5,6). We identified a previously undescribed mechanism for activation of tyrosine kinases in cancer: the formation of episomes resulting in a fusion between NUP214 and ABL1. We detected the NUP214-ABL1 transcript in five individuals with the ABL1 amplification, in 5 of 85 (5.8%) additional individuals with T-ALL and in 3 of 22 T-ALL cell lines. The constitutively phosphorylated tyrosine kinase NUP214-ABL1 is sensitive to the tyrosine kinase inhibitor imatinib. The recurrent cryptic NUP214-ABL1 rearrangement is associated with increased HOX expression and deletion of CDKN2A, consistent with a multistep pathogenesis of T-ALL. NUP214-ABL1 expression defines a new subgroup of individuals with T-ALL who could benefit from treatment with imatinib.

Synthesis of factor VIII antigen by cultured guinea pig megakaryocytes

Immunoprecipitates containing guinea pig Factor VIII antigen were prepared from guinea pig plasma with a cross-reacting rabbit anti-human Factor VIII. Monospecific antisera to guinea pig Factor VIII antigen were produced in rabbits by using these washed immunoprecipitates as immunogens. The resulting antisera to guinea pig Factor VIII antigen detected Factor VIII antigen in guinea pig plasma and inhibited the von Willebrand factor activity in guinea pig plasma. This antibody also detected Factor VIII antigen in a solubilized protein mixture prepared from isolated cultured guinea pig megakaryocytes. Cultured guinea pig megakaryocytes were labeled with radio-active leucine. By radioautography, 96.2% of the radio-activity was present in megakaryocytes. The radio-active Factor VIII antigen present in the solubilized cell protein mixture was isolated by immunoprecipitation and characterized by sodium dodecyl sulfate polyacrylamide gel electrophoresis. The results demonstrate that cultured guinea pig megakaryocytes synthesize Factor VIII antigen which contains the same polypeptide subunit (mol wt 200,000) present in guinea pig plasma Factor VIII antigen.

Age effects on lingual pressure generation as a risk factor for dysphagia

BACKGROUND

Tongue activity plays a crucial role in both oral and pharyngeal phases of swallowing. In this study, maximum lingual isometric and swallowing pressures were quantified in two groups of healthy men to investigate possible age effects on performance. Magnetic resonance images of the brain were also obtained to examine the relationship between age-related anatomical changes and swallowing function.

METHODS

Pressures were recorded at three lingual sites (tip, blade, and dorsum) during a maximal isometric task and during saliva swallows. Task order was randomized, and subjects performed three trails per placement site. Additionally, t2-weighted MRIs were obtained on 9 of the 10 young subjects (mean age = 25 years) and all 15 older subjects (mean age = 75 years).

RESULTS

Maximal isometric pressures were significantly greater for younger subjects at the tongue blade site (p = .002), whereas peak swallowing pressures remained similar across both age groups. Within-subject comparisons of maximum isometric to swallowing pressures, a measure of reserve capacity, revealed reduced difference scores at the tongue blade in the older group (p = .02). Older subjects exhibited significantly more cerebral atrophy (p = .001) and greater incidence of periventricular white matter lesions (p = .0001) than did younger subjects.

CONCLUSIONS

While swallowing pressures remain similar across the life span, overall pressure reserve declines with age. The implications are: (a) older people may be working harder to produce adequate swallowing pressures, and (b) age-related illness may put geriatric patients at higher risk for dysphagia, thus further complicating recovery.

Mechanism of ischemic mitral regurgitation with segmental left ventricular dysfunction: three-dimensional echocardiographic studies in models of acute and chronic progressive regurgitation

OBJECTIVES

This study aimed to separate proposed mechanisms for segmental ischemic mitral regurgitation (MR), including left ventricular (LV) dysfunction versus geometric distortion by LV dilation, using models of acute and chronic segmental ischemic LV dysfunction evaluated by three-dimensional (3D) echocardiography.

BACKGROUND

Dysfunction and dilation-both mechanisms with practical therapeutic implications-are difficult to separate in patients.

METHODS

In seven dogs with acute left circumflex (LCX) coronary ligation, LV expansion was initially restricted and then permitted to occur. In seven sheep with LCX branch ligation, LV expansion was also initially limited but became prominent with remodeling over eight weeks. Three-dimensional echo reconstruction quantified mitral apparatus geometry and MR volume.

RESULTS

In the acute model, despite LV dysfunction with ejection fraction = 23 +/- 8%, MR was initially trace with limited LV dilation, but it became moderate with subsequent prominent dilation. In the chronic model, MR was also initially trace, but it became moderate over eight weeks as the LV dilated and changed shape. In both models, the only independent predictor of MR volume was increased tethering distance from the papillary muscles (PMs) to the anterior annulus, especially medial and posterior shift of the ischemic medial PM, measured by 3D reconstruction (r2 = 0.75 and 0.86, respectively). Mitral regurgitation volume did not correlate with LV ejection fraction or dP/dt.

CONCLUSIONS

Segmental ischemic LV contractile dysfunction without dilation, even in the PM territory, fails to produce important MR. The development of MR relates strongly to changes in the 3D geometry of the mitral apparatus, with implications for approaches to restore a more favorable configuration.

Integrated mechanism for functional mitral regurgitation: leaflet restriction versus coapting force: in vitro studies

BACKGROUND

Functional mitral regurgitation in patients with ischemic or dilated ventricles has been related to competing factors: altered tension on the leaflets due to displacement of their papillary muscle and annular attachments, which restricts leaflet closure, versus global ventricular dysfunction with reduced transmitral pressure to close the leaflets. In vivo, however, geometric changes accompany dysfunction, making it difficult to study these factors independently. Functional mitral regurgitation also paradoxically decreases in midsystole, despite peak transmitral driving pressure, suggesting a change in the force balance acting to create a regurgitant orifice, with rising transmitral pressure counteracting forces that restrict leaflet closure. In vivo, this mechanism cannot be tested independently of annular contraction that could also reduce midsystolic regurgitation.

METHODS AND RESULTS

An in vitro model was developed that allows independent variation of papillary muscle position, annular size, and transmitral pressure, with direct regurgitant flow rate measurement, to test the hypothesis that functional mitral regurgitation reflects an altered balance of forces acting on the leaflets. Hemodynamic and echocardiographic measurements of excised porcine valves were made under physiological pressures and flows. Apical and posterolateral papillary muscle displacement caused decreased leaflet mobility and apical leaflet tethering or tenting with regurgitation, as seen clinically. It reproduced the clinically observed midsystolic decrease in regurgitant flow and orifice area as transmitral pressure increased. Tethering delayed valve closure, increased the early systolic regurgitant volume before complete coaptation, and decreased the duration of coaptation. Annular dilatation increased regurgitation for any papillary muscle position, creating clinically important regurgitation; conversely, increased transmitral pressure decreased regurgitant orifice area for any geometric configuration.

CONCLUSIONS

The clinically observed tented-leaflet configuration and dynamic regurgitant orifice area variation can be reproduced in vitro by altering the three-dimensional relationship of the annular and papillary muscle attachments of the valve so as to increase leaflet tension. Increased transmitral pressure acting to close the leaflets decreases the regurgitant orifice area. These results are consistent with a mechanism in which an altered balance of tethering versus coapting forces acting on the leaflets creates the regurgitant orifice.

The relationship of mitral annular shape to the diagnosis of mitral valve prolapse

The geometric or anatomic diagnosis of mitral valve prolapse, as opposed to the pathologic diagnosis of myxomatous valve disease, is based on the relationship of the mitral leaflets to the surrounding anulus. Current echocardiographic criteria for this diagnosis include leaflet displacement above the annular hinge points in any two-dimensional view; implicit in this equivalent use of intersecting views is the assumption that the mitral anulus is a euclidean plane. Prolapse by these criteria is found in a surprisingly large proportion of the general population. In most of these individuals, however, prolapse is present in the apical four-chamber view and absent in roughly orthogonal long-axis views of the left ventricle. This frequently observed discrepancy between leaflet-annular relationships in intersecting views suggests an underlying geometric property of the mitral apparatus that would produce the appearance of prolapse in one view without actual leaflet distortion. To address this possibility, a model of the mitral valve and anulus was constructed. When the model anulus was given a nonplanar, saddle-shaped configuration, the clinical observations were reproduced: the leaflets appeared to lie above the low points of the anulus in one plane, and below its high points in a perpendicular plane. Therefore, the appearance of mitral valve prolapse can occur without actual leaflet displacement above the most superior points of the mitral anulus if the anulus is nonplanar. To determine whether this pattern is reflected in the human mitral anulus, two-dimensional echocardiographic views of the mitral apparatus were obtained by rotation about the cardiac apex in 20 patients without evident annular or rheumatic valvular disease. In all cases the mitral anulus, as reconstructed from these views, had a nonplanar systolic configuration, with high points located anteriorly and posteriorly. This is consistent with the findings of other groups in animals, and would favor the appearance of prolapse in the four-chamber view and its absence in long-axis views that are oriented anteroposteriorly. This model can therefore explain the frequently observed discrepancy between leaflet-annular relationships in roughly orthogonal views. It challenges the assumption that the mitral anulus is planar as well as the diagnosis of prolapse in many otherwise normal individuals based on that assumption.

Reconsideration of echocardiographic standards for mitral valve prolapse: lack of association between leaflet displacement isolated to the apical four chamber view and independent echocardiographic evidence of abnormality

Mitral valve prolapse by current echocardiographic criteria can be diagnosed with surprising frequency in the general population, even when preselected normal subjects are examined. In most of these individuals, however, prolapse is present in the apical four chamber view and absent in roughly perpendicular long-axis views. Previous studies have shown that systolic annular nonplanarity can cause apparent prolapse in the four chamber view without actual leaflet displacement above the most superior points of the anulus, and there is evidence for such nonplanarity in vivo. It is then reasonable to ask whether superior leaflet displacement limited to the four chamber view has any pathologic significance or complications. The purpose of this study, therefore, was to address the following hypothesis: that patients with superior leaflet displacement confined to the four chamber view have no higher frequency of associated echocardiographic abnormalities than do patients without displacement in any view. Such abnormalities, which would provide independent evidence of mitral valve pathology or dysfunction, include leaflet thickening, left atrial enlargement and mitral regurgitation. Leaflet displacement was measured in the parasternal long-axis and apical four chamber views in 312 patients who were studied retrospectively and selected for the absence of forms of heart disease other than mitral valve prolapse. Leaflet thickness and left atrial size were measured and mitral regurgitation was graded. Patients with leaflet displacement limited to the four chamber view were no more likely to have associated abnormalities than were patients without displacement in any view (0 to 2% prevalence, p greater than 0.5). In contrast, patients with leaflet displacement in the long-axis view were significantly more likely to have associated abnormalities (12 to 24%, p less than 0.005), the frequency of which increased with the extent of leaflet displacement in that view (p less than 0.0001). These results suggest that displacement limited to the apical four chamber view is, in general, a normal geometric finding unassociated with echocardiographic evidence of pathologic significance.

Chordal cutting: a new therapeutic approach for ischemic mitral regurgitation

BACKGROUND

Mitral regurgitation (MR) conveys adverse prognosis in ischemic heart disease. Because such MR is related to increased leaflet tethering by displaced attachments to the papillary muscles (PMs), it is incompletely treated by annular reduction. We therefore addressed the hypothesis that such MR can be reduced by cutting a limited number of critically positioned chordae to the leaflet base that most restrict closure but are not required to prevent prolapse. This was tested in 8 mitral valves: a porcine in vitro pilot with PM displacement and 7 sheep with acute inferobasal infarcts studied in vivo with three-dimensional (3D) echo to quantify MR in relation to 3D valve geometry.

METHODS AND RESULTS

In all 8 valves, PM displacement restricted leaflet closure, with anterior leaflet angulation at the basal chord insertion, and mild-to-moderate MR. Cutting the 2 central basal chordae reversed this without prolapse. In vivo, MR increased from 0.8+/-0.2 to 7.1+/-0.5 mL/beat after infarction and then decreased to 0.9+/-0.1 mL/beat with chordal cutting (P<0.0001); this paralleled changes in the 3D leaflet area required to cover the orifice as dictated by chordal tethering (r(2)=0.76).

CONCLUSIONS

Cutting a minimum number of basal chordae can improve coaptation and reduce ischemic MR. Such an approach also suggests the potential for future minimally invasive implementation.

Somatic (craniocervical) tinnitus and the dorsal cochlear nucleus hypothesis

PURPOSE

Of all nonauditory sensory systems, only the somatosensory system seems to be related to tinnitus (eg, temporomandibular joint syndrome and whiplash). The purpose of this study is to describe the distinguishing characteristics of tinnitus associated with somatic events and to use these characteristics to develop a neurological model of somatic tinnitus.

MATERIALS AND METHODS

Case series.

RESULTS

Some patients with tinnitus, but no other hearing complaints, share several clinical features including (1) an associated somatic disorder of the head or upper neck, (2) localization of the tinnitus to the ear ipsilateral to the somatic disorder, (3) no vestibular complaints, and (4) no abnormalities on neurological examination. Pure tone and speech audiometry of the 2 ears is always symmetric and usually within normal limits. Based on these clinical features, it is proposed that somatic (craniocervical) tinnitus, like otic tinnitus, is caused by disinhibition of the ipsilateral dorsal cochlear nucleus. Nerve fibers whose cell bodies lie in the ipsilateral medullary somatosensory nuclei mediate this effect. These neurons receive inputs from nearby spinal trigeminal tract, fasciculus cuneatus, and facial, vagal, and glossopharyngeal nerve fibers innervating the middle and external ear.

CONCLUSIONS

Somatic (craniocervical) modulation of the dorsal cochlear nucleus may account for many previously poorly understood aspects of tinnitus and suggests novel tinnitus treatments.

Impact of impinging wall jet on color Doppler quantification of mitral regurgitation

BACKGROUND

In clinical color Doppler examinations, mitral regurgitant jets are often observed to impinge on the left atrial wall immediately beyond the mitral valve. In accordance with fluid dynamics theory, we hypothesized that a jet impinging on a wall would lose momentum more rapidly, undergo spatial distortion, and thus have a different observed jet area from that of a free jet with an identical flow rate.

METHODS AND RESULTS

To test this hypothesis in vivo, we studied 44 patients with mitral regurgitation--30 with centrally directed free jets and 14 with eccentrically directed impinging wall jets. Maximal color jet areas (cm2) (with and without correction for left atrial size) were correlated with mitral regurgitant volumes, flow rates, and fractions derived from pulsed Doppler mitral and aortic forward flows. The groups were compared by analysis of covariance. Mean +/- SD mitral regurgitant fraction, regurgitant volume, and mean flow rate averaged 37 +/- 17%, 3.06 +/- 2.65 l/min, and 147 +/- 118 ml/sec, respectively. The maximal jet area from color Doppler imaging correlated relatively well with the mitral regurgitant fraction in the patients with free mitral regurgitant jets (r = 0.74, p less than 0.0001) but poorly in the patients with impinging wall jets (r = 0.42, p = NS). Although the mitral regurgitant fraction was larger (p less than 0.05) in patients with wall jets (44 +/- 20%) than in those with free jets (33 +/- 15%), the maximal jet area was significantly smaller (4.78 +/- 2.87 cm2 for wall jets versus 9.17 +/- 6.45 cm2 for free jets, p less than 0.01). For the same regurgitant fraction, wall jets were only approximately 40% of the size of a corresponding free jet, a difference confirmed by analysis of covariance (p less than 0.0001).

CONCLUSIONS

Patients with mitral regurgitation frequently have jets that impinge on the left atrial wall close to the mitral valve. Such impinging wall jets are less predictable and usually have much smaller color Doppler areas in conventional echocardiographic views than do free jets of similar regurgitant severity. Jet morphology should be considered in the semiquantitative interpretation of mitral regurgitation by Doppler color flow mapping. Future studies of the three-dimensional morphology of wall jets may aid in their assessment.

Morbidity and mortality in elderly trauma patients

BACKGROUND

Despite an increasing incidence, relatively few studies have examined the factors that predict morbidity and mortality in older patients and several reports have found standard predictors such as the Injury Severity Score to be less useful in this patient population. Similarly, the effect of skeletal injury has not been examined with regard to complications and mortality. The purpose of this study was to review a large multicenter experience with elderly trauma patients to isolate factors that might predict morbidity and mortality. The potential effect of skeletal long-bone injury was of particular interest.

METHODS

The charts of all patients older than 60 years who were admitted to one of four Level I trauma centers after sustaining blunt trauma were reviewed. Mechanisms of injury included in the study were motor vehicle crash, pedestrian struck, fall from a height, and crush injury. Slip-and-fall injuries were excluded. A total of 326 patients met inclusion criteria. Variables studied included age, sex, mechanism of injury, Injury Severity Score (ISS), Revised Trauma Score, Glasgow Coma Scale (GCS) score, blood transfusion, fluid resuscitation, surgery performed (laparotomy, long-bone fracture stabilization, both), and timing of surgery. Outcome variables measured included incidence of adult respiratory distress syndrome, pneumonia, sepsis, myocardial infarction, deep venous thromboembolism, gastrointestinal complications, and death. chi2, logistic regression, t test, and nonparametric analyses were done as appropriate for the type of variable.

RESULTS

The average age of the patients was 72.2+/-8 years. Overall, 59 patients (18.1%) died, of whom 52 of 59 survived at least 24 hours. Statistical significance for continuous variables (p < 0.05) using univariate analysis was reached for the following factors for the patients who died: higher ISS (33.1 vs. 16.4), lower GCS score (11.5 vs. 13.9), greater transfusion requirement (10.9 vs. 2.9 U), and more fluid infused (12.4 vs. 4.9 L). Logistic regression analysis was performed to determine the factors that predicted mortality. They included (odds ratios and p values in parentheses) transfusion (1.11, p = 0.01), ISS (1.04, p = 0.008), GCS score (0.87, p = 0.007), and fluid requirement (1.06, p = 0.06). Regarding surgery, orthopedic surgery alone had an odds ratio of 0.53, indicating that orthopedic patients was less likely to die than patients who did not undergo any surgery. Patients who underwent only a general surgical procedure were 2.5 times more likely to die (p = 0.03) and patients who underwent both general and orthopedic procedures were 1.5 times more likely to die (p = 0.32) than patients who did not require surgery. Early (< or =24 hours) versus late (>24 hours) surgery for bony stabilization did not have a statistical effect on mortality (11% early vs. 18% late). Two patients in need of bony stabilization, however, died before these procedures were performed. With regard to complications, regression analysis revealed that ISS predicted adult respiratory distress syndrome, pneumonia, sepsis, and gastrointestinal complications; fluid transfusion predicted myocardial infusion; and need for surgery and transfusion requirements predicted sepsis. These complications, in turn, were significant risk factors for mortality. This large series of elderly patients demonstrates that mortality correlates closely with ISS and is influenced by blood and fluid requirements and by GCS score. The institution-specific mortality was the same when adjusted for ISS. The need for orthopedic surgery and the timing of the surgery was not a risk factor for systemic complications or mortality in this series.

CONCLUSION

Mortality is predicted by ISS and by complications in older patients. Seventy-seven percent of the orthopedic injuries were stabilized early, but the timing of surgery did not have any statistical effect on the incidence of complications or mortality. (ABSTRACT TRUNCA

Lateralized tinnitus studied with functional magnetic resonance imaging: abnormal inferior colliculus activation

Tinnitus, the perception of sound in the absence of external stimuli, is a common and often disturbing symptom that is not understood physiologically. This paper presents an approach for using functional magnetic resonance imaging (fMRI) to investigate the physiology of tinnitus and demonstrates that the approach is effective in revealing tinnitus-related abnormalities in brain function. Our approach as applied here included 1) using a masking noise stimulus to change tinnitus loudness and examining the inferior colliculus (IC) for corresponding changes in activity, 2) separately considering subpopulations with particular tinnitus characteristics, in this case tinnitus lateralized to one ear, 3) controlling for intersubject differences in hearing loss by considering only subjects with normal or near-normal audiograms, and 4) tailoring the experimental design to the characteristics of the tinnitus subpopulation under study. For lateralized tinnitus subjects, we hypothesized that sound-evoked activation would be abnormally asymmetric because of the asymmetry of the tinnitus percept. This was tested using two reference groups for comparison: nontinnitus subjects and nonlateralized tinnitus subjects. Binaural noise produced abnormally asymmetric IC activation in every lateralized tinnitus subject (n = 4). In reference subjects (n = 9), activation (i.e., percent change in image signal) in the right versus left IC did not differ significantly. Compared with reference subjects, lateralized tinnitus subjects showed abnormally low percent signal change in the IC contralateral, but not ipsilateral, to the tinnitus percept. Consequently, activation asymmetry (i.e., the ratio of percent signal change in the IC ipsilateral versus contralateral to the tinnitus percept) was significantly greater in lateralized tinnitus subjects as compared with reference subjects. Monaural noise also produced abnormally asymmetric IC activation in lateralized tinnitus subjects. Two possible models are presented to explain why IC activation was abnormally low contralateral to the tinnitus percept in lateralized tinnitus subjects. Both assume that the percept is associated with abnormally high ("tinnitus-related") neural activity in the contralateral IC. Additionally, they assume that either 1) additional activity evoked by sound was limited by saturation or 2) sound stimulation reduced the level of tinnitus-related activity as it reduced the loudness of (i.e., masked) the tinnitus percept. In summary, this work demonstrates that fMRI can provide objective measures of lateralized tinnitus and tinnitus-related activation can be interpreted at a neural level.

Echocardiographic predictors of left ventricular outflow tract obstruction and systolic anterior motion of the mitral valve after mitral valve reconstruction for myxomatous valve disease

OBJECTIVE

To determine predictors of systolic anterior motion and left ventricular outflow tract obstruction (SAM/LVOTO) after mitral valve repair (MVRep) in patients with myxomatous mitral valve disease.

BACKGROUND

Mechanisms for the development of SAM/LVOTO after MVRep have been described; however, predictors of this complication have not been explored. We hypothesize that pre-MVRep transesophageal echocardiography (TEE) can predict postrepair SAM/ LVOTO.

METHODS

Using TEE, the lengths of the coapted anterior (AL) and posterior (PL) leaflets and the distance from the coaptation point to the septum (C-Sept) were measured before and after MVRep in 33 patients, including 11 who developed SAM/LVOTO (Group 1) and 22 who did not (Group 2).

RESULTS

Group 1 patients had smaller AL/PL ratios (0.99 vs. 1.95, p < 0.0001) and C-Sept distances (2.53 vs. 3.01 cm, p = 0.012) prior to MVRep than those in Group 2. Resolution of SAM/LVOTO was associated with increases in AL/PL ratio and C-Sept distance. This reflects a more anterior position of the coaptation point in those who developed SAM/ LVOTO.

CONCLUSIONS

These data suggest that TEE analysis of the mitral apparatus can identify patients likely to develop SAM/LVOTO after MVRep for myxomatous valve disease. The findings are consistent with the concept that SAM of mitral leaflets is due to anterior malposition of slack mitral leaflet portions into the LVOT. The position of the coaptation point of the mitral leaflets is dynamic and a potential target and end point for surgical designs to prevent SAM/LVOTO post MVRep.

Echocardiographic measurement of right ventricular volume

The volume of the right ventricle can be determined angiographically from its projections in two mutually perpendicular planes. Echocardiographic techniques for measuring right ventricular volume, however, have been more difficult and less successful. In this study, a method was developed for calculating right ventricular volume from two intersecting cross-sectional echocardiographic views: the apical four-chamber and subcostal right ventricular outflow tract views. First, the areas and lengths of casts of 12 human right ventricles obtained at autopsy were directly measured in the chosen views. Actual cast volumes correlated best with a formula giving volume as 2/3 times the area in one view times the long axis in the other view. The degree of correlation was similarly high for calculations involving the area derived from either view and the length of the roughly orthogonal section. This relationship for right ventricular volume was then confirmed with two-dimensional echocardiographic images of hollow latex molds made from the casts (r = .95, p less than .0001). The significance of these findings is discussed in relation to angiographic results and models of the right ventricle.

Dynamics of mitral regurgitant flow and orifice area. Physiologic application of the proximal flow convergence method: clinical data and experimental testing

BACKGROUND

The proximal flow convergence method, a quantitative color Doppler flow technique, has been validated recently for calculating regurgitant flow and orifice area. We investigated the potential of the method as a tool to study different pathophysiological mechanisms of mitral valve incompetence by assessing the time course of regurgitant flow and orifice area and analyzed the implications for quantification of mitral regurgitation.

METHODS AND RESULTS

Fifty-six consecutive patients with mitral regurgitation of different etiologies were studied. The instantaneous regurgitant flow rate Q(t) was computed from color M-mode recordings of the proximal flow convergence region and divided by the corresponding orifice velocity V(t) to obtain the instantaneous orifice area A(t). Regurgitant stroke volume (RSV) was obtained by integrating Q(t). Mean regurgitant flow rate Qm was calculated by RSV divided by regurgitation time. Peak-to-mean regurgitant flow rates Qp/Qm and orifice areas Ap/Am were calculated to assess the phasic character of Q(t) and A(t). In the first 24 patients (group 1), computation of Qm and RSV from the color Doppler recordings was compared with the conventional pulsed Doppler method (r = .94, SEE = 29.4 mL/s and r = .95, SEE = 9.7 mL) as well as with angiography (rs = .93 and rs = .94, P < .001). The temporal variation of Q(t) and A(t) was studied in the next 32 patients (group 2): In functional regurgitation in dilated cardiomyopathy (n = 12), there was a constant decrease in A(t) throughout systole with an increase during left ventricular relaxation; Ap/Am was 5.49 +/- 3.17. In mitral valve prolapse (n = 6), A(t) was small in early systole, increasing substantially in midsystole, and decreasing mildly during left ventricular relaxation; Ap/Am was 2.48 +/- 0.26. In rheumatic mitral regurgitation (n = 14), a roughly constant regurgitant orifice area during most of systole was found in 4 patients. In the other patients there was significant variation of A (t) and the time of its maximum; Ap/Am was 1.81 +/- 0.56. ANOVA demonstrated that the differences in Ap/Am were related to the etiology of mitral regurgitation (P < .0001). To verify that the calculated variation in regurgitant orifice area during the cardiac cycle reflects an actual variation, the ability of the method to predict a constant orifice area throughout systole was tested experimentally in a canine model of mitral regurgitation. Five flow stages were produced by implanting fixed grommet orifices of different sizes into the anterior mitral leaflet. A constant regurgitant orifice area was correctly predicted throughout systole with a mean percent error of -1.8 +/- 4% (from -6.9% to +5.8%); the standard deviation of the individual curves calculated at 10% intervals during systole averaged 13.3% (from 3.6% to 19.6%). In addition, functional mitral regurgitation caused by ventricular dysfunction was produced pharmacologically in five dogs, and the color M-mode recordings of the proximal flow convergence region were obtained with the transducer placed directly on the heart instead of the chest, thus ruling out a significant effect of translational motion on the observed flow pattern. The pattern of regurgitant flow variation was identical to that observed in patients.

CONCLUSIONS

The proximal flow convergence method demonstrates that regurgitant flow and orifice area vary throughout systole in distinct patterns characteristic of the underlying mechanism of mitral incompetence. Therefore, in addition to the potential of the method as a tool to quantify mitral regurgitation, it allows analysis of the pathophysiology of regurgitation in the individual patient, which may be helpful in clinical decision making. Calculating mitral regurgitant flow rate and volume from the time-varying proximal flow field (ie, without assuming a constant orifice area that would produce overestimation in individual patients) provides excellent agreement with independent te

An integrated mechanism for systolic anterior motion of the mitral valve in hypertrophic cardiomyopathy based on echocardiographic observations

Although many mechanisms have been proposed to explain systolic anterior motion (SAM) of the mitral valve in hypertrophic cardiomyopathy, the precise mechanism of its onset and cessation remain undefined. The Venturi theory, based on increased flow velocity in a narrowed outflow tract, is widely accepted but fails to explain several important characteristics of SAM. It also neglects the potential role of drag forces generated by interposition of the leaflets into the path of ejection and of factors that would decrease the effectiveness of papillary muscle restraint. In order to obtain further insight into the mechanism of SAM, a detailed geometric study of the left ventricle and mitral apparatus was performed with cross-sectional echocardiography in three equal-sized groups of patients with hypertrophic cardiomyopathy and SAM, patients with hypertrophy and no anterior motion, and normal control subjects. A salient finding was that SAM began prior to ejection in patients with hypertrophic cardiomyopathy, which cannot be explained by the Venturi theory. Further, SAM began and was most prominent in the central portion of the leaflet as opposed to its lateral edges; this finding is not predicted by the Venturi mechanism. In addition to outflow tract narrowing, other structural changes unique to patients with SAM included anterior and inward displacement of the papillary muscles, anterior displacement of the mitral leaflets, and elongation of the mitral leaflets, which were, on the average, 1.5 to 1.7 cm longer than in the other subjects (p less than 0.0001). On the basis of these observations, an integrated mechanism for the initiation and resolution of SAM is proposed that would explain observed features such as onset before ejection and central prominence. This mechanism combines the effects of outflow tract narrowing with those of papillary muscle displacement. In particular, anterior and inward displacement of the papillary muscles can be predicted to alter the effectiveness of chordal support so that the central leaflet portions become relatively slack and are more readily displaced anteriorly. The altered distribution of chordal tension can also be predicted to orient the distal leaflets upward into the outflow tract at the onset of systole, prior to aortic valve opening, so that ventricular ejection will actually drag the interposed leaflets anteriorly. The resolution of SAM can be understood in terms of a reverse Venturi effect created by mitral regurgitation, as well as continued traction of the centrally displaced papillary muscles on the lateral leaflet margins.(ABSTRACT TRUNCATED AT 400 WORDS)

Papillary muscle displacement causes systolic anterior motion of the mitral valve. Experimental validation and insights into the mechanism of subaortic obstruction

BACKGROUND

Systolic anterior motion (SAM) of the mitral valve in hypertrophic cardiomyopathy (HCM) has generally been explained by a Venturi effect related to septal hypertrophy, causing outflow tract narrowing and high velocities. Patients with HCM, however, also have primary abnormalities of the mitral apparatus, including anterior and inward or central displacement of the papillary muscles, and leaflet elongation. These findings have led to the hypothesis that changes in the mitral apparatus can be a primary cause of SAM by altering the forces acting on the mitral valve and its ability to move in response to them. Despite suggestive observations, however, it has never been prospectively demonstrated that such changes can actually cause SAM.

METHODS AND RESULTS

To test this hypothesis in vivo, anterior papillary muscle displacement was created in 7 dogs studied by echocardiography, with controlled cardiac output and heart rate. In all 7 dogs, papillary muscle displacement caused SAM, with an outflow tract gradient (33 +/- 19 mm Hg) and mitral regurgitation in 6. As in patients with HCM, the mitral valve was displaced anteriorly and the coaptation point shifted toward the insertion of the leaflets, creating longer distal residual leaflets that moved anteriorly.

CONCLUSIONS

Primary changes in the mitral apparatus can cause SAM without septal hypertrophy. In this model, SAM appears to be determined by the ability of the leaflets to move anteriorly (papillary muscle displacement causing slack and increased residual leaflet length) and their interposition into the outflow stream by anterior displacement, determining the direction of this motion. Geometric factors observed in HCM and in patients with SAM without HCM can therefore play a primary role in causing SAM.

Prevalence of valvular regurgitation by Doppler echocardiography in patients with structurally normal hearts by two-dimensional echocardiography

The prevalence of valvular regurgitation in a large population with structurally normal hearts remains unknown. From the computer database of the echocardiography laboratory of the hospital, 7209 records containing results of both two-dimensional and Doppler echocardiographic examinations were identified, from which 867 (12%) with no structural abnormality on two-dimensional echocardiograms were obtained for analysis. Of these 867 records, 291 (34%) had evidence of regurgitation by Doppler technique in at least one cardiac valve. Mitral regurgitation was found in 167 (19%), tricuspid regurgitation in 151 (17%), pulmonic regurgitation in 45 (5%), and aortic regurgitation in 29 records (3%). Regurgitation of just one valve was the most common and occurred in 207 records (24%). This was followed by regurgitation of two valves (69 records, 8%), three valves (13 records, 2%), and four valves (two records, 0.2%). The prevalence of mitral, tricuspid, and aortic regurgitation was found to increase significantly with increasing age, as was the prevalence of regurgitation involving multiple valves. In 98% and 95% of mitral and tricuspid regurgitations, respectively, the jets were confined to the proximal one fourth of the atria, suggesting only trivial or mild regurgitation. Thus valvular regurgitation occurs not uncommonly in patients with structurally normal hearts referred for echocardiographic evaluation. These findings caution against the inappropriate diagnosis of clinical disease in the many patients who fall into this category. The increasing prevalence of valvular regurgitation with increasing age suggests that a wear-and-tear phenomenon rather than a congenital cause is involved in most instances.