Is a cleft in the anterior leaflet of an otherwise normal mitral valve an atrioventricular canal malformation?

Objectives. This study sought to ascertain the surgical anatomy of a cleft in the left atrioventricular (AV) valve.Background. Important morphologic differences exist between hearts with a cleft in the anterior leaflet of an otherwise normal mitral valve and those with a so-called cleft in the left AV valve when there is an AV septal defect, but it has been customary to link the lesions together on developmental grounds.Methods. Eight autopsied specimens with a cleft in the aortic (or anterior) leaflet of the mitral valve were studied in detail, and echocardiograms from 21 patients with such a cleft were compared with the specimens and with findings typical of the so-called partial AV canal and other forms of AV septal defect.Results. The structure and direction of the cleft, location of the papillary muscles within the left ventricle and AV junctional morphology of hearts with an otherwise normally structured mitral valve were significantly different from typical findings in hearts with AV septal defects.Conclusions. It is necessary to distinguish morphologically a cleft in an otherwise normally structured mitral valve in hearts with separate right and left AV junctions from the trifoliate left component of a common AV valve in hearts with an AV septal defect and a common AV junction because the disposition of the AV conduction tissues varies markedly between the lesions.     

Does chronic mitral regurgitation influence Doppler pressure half-time-derived calculation of the mitral valve area in patients with mitral stenosis?

Background

In patients with mitral stenosis (MS), Doppler pressure half-time (PHT) may be influenced by hemodynamic variables other than the anatomic mitral valve orifice narrowing. This study was undertaken to assess whether the presence of concomitant mitral regurgitation (MR) affects mitral valve area (MVA) estimation by PHT.

Methods

Consecutive patients (n = 166) with noncalcific MS, in sinus rhythm, were studied. Group 1 (n = 106) had no or mild MR, and group 2 (n = 60) had moderate or severe MR. MVA was assessed by using the PHT method and planimetry.

Results

There was a strong correlation between planimetry and PHT MVA in both groups (group 1: r = 0.86, P < .001; group 2: r = 0.73, P < .001). However, compared with planimetry MVA, PHT underestimated MVA by ≥20% in 18 patients (17%) in group 1 and 21 patients (35%) in group 2 (P < .01). Overestimation by ≥20% occurred in 12 patients (11%) in group 1 and in 7 (12%) in group 2. Group 2 subanalysis (group 2A: moderate MR, n = 16; group 2B: severe MR, n = 44) revealed that linear regression weakened with increasing severity of MR (group 2A: r = 0.824, P < .001, group 2B: r = 0.70, P < .001). PHT underestimation of MVA occurred in 31% and 36% of patients in Groups IIA and IIB, respectively (P = NS).

Conclusions

PHT appears to be reliable for estimating MVA in most patients with MS, even in the presence of MR. However, the presence of significant MR reduces the reliability of PHT-derived MVA, with underestimation of MVA in a significant number of subjects. The severity of MR has a direct impact on PHT-derived MVA.     

Is the mitral valve area flow-dependent in mitral stenosis? A dobutamine stress echocardiographic study

OBJECTIVES: The purpose of this study was to compare the effect of changes in flow rate on the mitral valve area (MVA) derived from two-dimensional echocardiographic planimetry and Doppler pressure half-time (PHT) methods in patients with mitral stenosis (MS). BACKGROUND: Dobutamine stress echocardiography has been proposed as a means of assessing the severity of MS. However, data regarding the effect of an increase in flow rate on MVA are limited. If MVA is indeed flow-dependent, this has important implications for the assessment of the severity of MS, particularly in the setting of reduced cardiac output (CO). METHODS: Dobutamine echocardiography was performed in 57 patients with isolated MS who were in sinus rhythm. The MVA was determined by planimetry and Doppler PHT methods. RESULTS: Cardiac output increased by > or =50% in 27 patients (group I) and by <50% in 30 patients (group II). In group I, the MVA by planimetry increased by only 10.6 +/- 2% and the MVA by PHT increased by 21.9 +/- 4.8%. These changes were similar to those observed in group II (10.7 +/- 3% and 14.8 +/- 4%, respectively; p = NS), despite a much smaller increase in CO. A clinically important change (from the severe to mild category) occurred in only one patient when using the PHT method and in none by planimetry. CONCLUSIONS: Changes in flow rate result in small but clinically insignificant changes in echocardiographic MVA measurement. These methods provide an accurate assessment of MS severity in a majority of patients, independent of changes in flow rate.     

Should a video-assisted mini-thoracotomy be the approach of choice for reoperative mitral valve surgery?

BACKGROUND AND AIM OF THE STUDY: Reoperative cardiac surgery carries a greater morbidity and mortality than primary cardiac surgery. The study aim was to compare perioperative outcomes in patients undergoing mitral valve surgery who had already undergone a previous cardiac operation using either a minimally invasive video-assisted (MIVA) mini-thoracotomy or a redo median sternotomy (MS). METHODS: Between January 1996 and June 2003, 71 consecutive patients with prior cardiac surgery underwent mitral valve surgery. Of these operations, 38 were MIVA procedures, performed through a 5-cm right anterior thoracotomy using voice-activated robotic camera control (AESOP 3000). Outcome was compared with results in 33 consecutive patients who underwent a standard redo MS. RESULTS: The MIVA and redo MS cohorts differed in preoperative ejection fraction (46 +/- 2% versus 55 +/- 2%; p = 0.004) and percentage of urgent operations (33 versus 8.3%; p = 0.01). Operative mortality was similar in both groups (5.7% and 5.9% respectively; p = 0.976), as were cardiopulmonary bypass, operating room, and ICU times. Postoperative intubation time was shorter in the MIVA group than in the redo MS group (29.1 +/- 8.9 versus 38.0 +/- 9.9 h; p = 0.008), and blood transfusion requirements were also reduced (2.9 +/- 0.6 versus 5.5 +/- 0.7 units; p = 0.001) respectively. Length of hospital stay was significantly less in the MIVA group (7.1 +/- 1.3 versus 11.2 +/- 1.1 days; p = 0.001). CONCLUSION: Minimally invasive video-assisted mitral valve operations may be performed safely and efficiently in patients with prior cardiac surgery. Demonstrated advantages include fewer red blood cell and blood product transfusions, as well as decreased intubation time and length of hospital stay.     

Dilated cardiomyopathy: a disease of the intercalated disc?

The contractile tissue of the heart is composed of individual cells, making specific cell-cell contacts necessary to ensure mechanical and electrochemical coupling during beating. These contact sites, termed the intercalated discs, have gained increased attention recently due to their potential involvement in cardiac disease. This article discusses how the intercalated discs are assembled during heart development and how they are affected in cardiomyopathy, with particular emphasis on dilated cardiomyopathy. A model is proposed to relate the alterations that are seen at a molecular level with changes in function observed in that kind of cardiac disease.     

Tricuspid annulus motion and mitral annulus motion: Anatomical intimacy causing a good correlation?

BACKGROUND:

Echocardiographic evaluation of the heart and its function, especially left ventricular systolic function, has great clinical importance. Systolic function can be measured using several methods, such as the amplitude of motion of the left atrioventricular plane (mitral annulus motion [MAM]) toward the apex during systole. Similarly, right ventricular systolic function can be measured using the motion of the right atrioventricular plane (tricuspid annulus motion [TAM]) toward the apex during systole.

OBJECTIVES:

Because the mitral and tricuspid annuli are situated close to each other in the fibrous skeleton between both ventricles and atria, one might think that a decrease in the amplitude of MAM would be followed by a decrease in the amplitude of TAM. The present study was developed to determinine if this anatomical intimacy causes a good correlation between the amplitudes of TAM and MAM.

METHODS:

Nineteen healthy subjects and 103 consecutive patients were included in the study and examined using echocardiography. The amplitudes of TAM and MAM were measured and the correlation between the amplitudes was calculated.

RESULTS:

In the 103 consecutive patients, a significant but relatively weak positive correlation was found between TAM and MAM amplitudes (Pearson’s correlation coefficient [r]=0.58; P<0.001). In the 19 healthy subjects, no significant correlation was found.

CONCLUSIONS:

Despite the anatomical intimacy of the annuli, the correlation between the amplitudes of TAM and MAM in consecutive patients was rather weak, and there was no correlation in healthy subjects. These findings could be due to anatomical and physiological differences between the right and left ventricles.