Opening snap and isovolumic relaxation period in relation to mitral valve flow in patients with mitral stenosis. Significance of A2--OS interval

Left ventricular diastolic function in mitral stenosis

The assessment of left ventricular (LV) function in the setting of mitral stenosis (MS) has been critically examined for decades. Accurate assessment of aberrations in diastolic function is important as these subjects often present with signs and symptoms of heart failure and pulmonary congestion that cannot be solely explained by the severity of mechanical obstruction. Echocardiographic evaluation of diastolic dysfunction includes an evaluation of reduced LV compliance, diminished restoring forces, and enhanced stiffness, which are challenging in the setting of MS owing to altered hemodynamic loading. Conventional echocardiographic and Doppler measures offer limited information. Novel assessments employing speckle tracking echocardiography are relatively less studied. A more comprehensive assessment including clinical evaluation, identification of concomitant disorders, and comorbidities is particularly warranted in older subjects with degenerative MS to suspect diastolic dysfunction and arrive at optimal medical therapy or intervention. This review provides an overview of etiological, pathophysiological, echocardiographic, and invasive assessment of diastolic dysfunction in the setting of MS, with specific focus on strengths and limitations of available echocardiographic and Doppler techniques.

Doppler estimation of left ventricular filling pressures in patients with mitral valve disease

BACKGROUND

Conventional Doppler measurements have limitations in the prediction of left atrial pressure (LAP) in patients with mitral valve disease (MVD), given the confounding effect of valve area, left ventricular (LV) relaxation, and stiffness. However, the time interval between the onset of early diastolic mitral inflow velocity (E) and annular early diastolic velocity (Ea) by tissue Doppler imaging (TDI), T(E-Ea), which is well related to the time constant of LV relaxation (tau) in canine and clinical studies, is not subject to these variables. We therefore undertook this study to test its usefulness in a patient population.

METHODS AND RESULTS

Two-dimensional Doppler and TDI echocardiography were performed simultaneously with right-heart catheterization in 51 consecutive patients (mean+/-SD age, 64+/-11 years) with MVD: 35 with moderately severe to severe mitral regurgitation (MR) and 16 with moderate to severe mitral stenosis (MS). Among several Doppler measurements, only the mitral E/A ratio, isovolumetric relaxation time (IVRT), and pulmonary venous Ar duration had significant relations with mean pulmonary capillary wedge pressure (PCWP). The ratio of IVRT to T(E-Ea) (for MR, r=-0.92; for MS, r=-0.88; both P<0.001) and the ratio of IVRT to tau (for MR, r=-0.74; for MS, r=-0.85; both P<0.001) had the best correlations with PCWP. In 54 repeat studies, including those performed after MV repair or replacement, these ratios tracked well the changes in PCWP and readily identified changes in mean PCWP by > or =5 mm Hg. A similar correlation was noted in 13 patients with atrial fibrillation (r=-0.92, P<0.01) and in a prospective group of 14 patients with MR (r=-0.93, P<0.001).

CONCLUSIONS

The ratio of IVRT to T(E-Ea) or to tau can be readily applied for estimating mean PCWP in patients with MVD and can track changes in PCWP after valve surgery.

Cardiovascular applications of the Doppler technique: A long way from birth to scientific acceptance

Analysis of the early developments of cardiac Doppler illustrates a gap, frequently encountered in science, between initial concepts and final acceptance. Acceptance may only emerge as a result of multidisciplinary collaboration and fruitful dialogue between physicians, physiologists, physicists, and engineers. By 1980, after a good deal of trial and error and a long period of incremental improvement, the majority of the theoretic and scientific issues had been defined. The explosive development of Doppler techniques can now intervene to sweep aside the medical community's scepticism.

Right and left isovolumic ventricular relaxation time intervals compared in patients by means of a single-pulsed Doppler method

Right and left isovolumic ventricular relaxation time intervals measurements were obtained as follows: from the peak R wave on the electrocardiogram to either the mitral or the tricuspid pulsed Doppler flow trace onset minus the R to end-ejection zero flow crossing of the subaortic (left side) or pulmonary (right side) D flow trace time interval. A ratio was calculated as a percent difference duration between both isovolumic ventricular relaxation time intervals. The aim was to compare isovolumic ventricular relaxation time interval values in 42 healthy controls and to study the changes induced by heart diseases in 27 patients with (1) controlled hypertension without left ventricular hypertrophy, (2) hypertrophic cardiomyopathy, and (3) Cor pulmonale. Mean values of isovolumic ventricular relaxation time intervals significantly differed at paired and unpaired studies, with right isovolumic ventricular relaxation time intervals shorter than those of the left side in all groups (p < 0.001) except for patients with Cor pulmonale. Isovolumic ventricular relaxation time intervals did not correlate with heart rate and moderately correlated with left ventricular mass and age. No significant difference was found between healthy controls and patients with controlled hypertension. Significant changes were found in patients with hypertrophic cardiomyopathy and Cor pulmonale versus healthy controls for both isovolumic ventricular relaxation time intervals. However, significant changes in the ratio were only found in patients with Cor pulmonale (p < 0.005) because of abnormal similar values for both isovolumic ventricular relaxation time intervals. This Doppler method enabled, for the first time, serial comparison of isovolumic ventricular relaxation time intervals with a homologous method. Both isovolumic ventricular relaxation time intervals significantly lengthened with age and with left ventricular indexed mass, but their ratio remained insignificantly changed except for patients with Cor pulmonale. The concomitant right and left isovolumic ventricular relaxation time intervals lengthening in patients with hypertrophic cardiomyopathy and Cor pulmonale suggests interdependence of both ventricles through the septum. This makes recommendable systematic comparison of both sides. The calculation of a ratio, free from the effect of factors intervening on isovolumic ventricular relaxation time intervals, may, in addition, be of diagnostic help.

Mitral stenosis: mitral dome excursion at M1 and the mitral opening snap--the concept of reciprocal heart sounds

The dynamics of the delayed accentuated mitral component (M1) of the first heart sound and the MOS were studied in 11 patients with mitral stenosis of varying severity. Echophonocardiographic (M-mode and 2D) studies were performed with analysis of LA dimensions, dynamics, and mitral valve excursion at the time of M1 and MOS. LA area and length, mitral annular diameter, and mitral dome area (from anulus plane to fused valve tip) and length were measured at M1 and MOS. Significant dynamic increases in mitral dome area and length occurred from M1 to MOS, with less striking but consistent increases in LA area, LA length, and mitral annular diameter. Conversely, mitral dome area and length decreased significantly from MOS to M1, with less striking but consistent decreases in LA area, LA length, and mitral annular diameter. Frame-by-frame video tape analysis showed that dome movement was separate from anulus motion. Mitral dome descent into the left ventricle terminated at MOS and reversal of dome motion terminated at M1. The conformational and dimensional changes that terminated abruptly at MOS reversed and terminated abruptly in a reciprocal manner at the time of the delayed, accentuated M1. When considered in light of known hemodynamic, pressure pulse, and imaging correlates in mitral stenosis, these observations strengthen the hypothesis that the mechanisms involved in the production of M1 and MOS in mitral stenosis are paired or reciprocal in nature, and the delayed, accentuated M1 and the MOS of mitral stenosis are reciprocal cardiovascular sounds.

Extent of mitral calcific deposits determined by cineangiography in mitral stenosis and their effect on valve motion, hemodynamics and clinical signs

The relation between the degree of leaflet calcium in a stenotic mitral valve and several parameters of valve mobility, hemodynamics and clinical signs was determined in 105 patients with relatively pure mitral stenosis (MS). The amount of mitral valve calcific deposits was determined by grading cineangiograms. Compared to 71 patients with no or minimal valvular calcium, the 23 patients with heavy valve leaflet calcium were significantly older, more likely to be men and more likely to be in atrial fibrillation. These patients also had a significant reduction of valve mobility in that their M-mode measurements of valve excursion and rate of valve opening were significantly reduced compared to those of patients without heavy valvular calcium. Two-dimensional echocardiograms also documented a significant reduction in valve mobility and progressive restriction in doming of the anterior mitral leaflet as the level of calcium increased. The prevalence of an opening snap was significantly decreased in patients with heavy vs no or light valvular calcium, and patients without an opening snap had reduced valve mobility. However, a considerable number of patients with moderate to heavy valve calcium retained an opening snap.

[Existence of asymptomatic changes in left ventricular function in the diabetic. Noninvasive study]

49 diabetics (D) (26 IDD and 23 NIDD) were compared to 32 controls (C). Absence of ischemic cardiopathy (IC) was confirmed by routine investigations and noninvasive cardiovascular techniques, including an exercise ECG using 12 leads and a thallium 201 scintigraphy. Our results show: a) a prolonged mean isovolumetric relaxation time (IVRT) as studied by the M mode echocardiography and phonomechanography: D = 0,10 sec +/- 0,04; C = 0,05 sec +/- 0,02; p less than 0,0001; b) a reduced mean EF slope: D = 97,48 +/- 37,08 mm / sec; C = 125,68 +/- 34,35; p less than 0,005; c) a high mean Weissler index (ratio of PEP to LVET): D = 40 +/- 0,08; C = 33 +/- 0,05; p less than 0,01. IVRT and EF slope abnormalities are related to increased myocardial stiffness and impaired LV compliance. In the absence of changes in preload and afterload, the high Weissler index reflects impaired contractility of the myocardium. These abnormalities are related neither to the duration of diabetes nor to the presence or severity of the complications. With the M mode echocardiography, mean diastolic and systolic thickness of the septum is greater in D with retinopathy than in C (p less than 0,005 and p less than 0,03 respectively); mean diastolic and systolic thickness of the posterior wall is greater in NIDD than in C (p less than 0,001 and p less than 0,025). We conclude that there is evidence of left ventricular functional abnormalities specific to diabetes and unrelated to IC and hypertension. Our findings support the hypothesis that they may be due to metabolic disorders and/or myocardial microangiopathy.

Isovolumic relaxation period in man

Isovolumic relaxation period (IRP) was measured noninvasively from the onset of the aortic component of the second heart sound on the phonocardiogram to the point of separation of the mitral leaflets on the echocardiogram. IRP was measured in 83 patients with different cardiac diseases. The duration of IRP was 58 +/- 11 msec. in normal subjects. It was prolonged in hypertension (p < 0.001), HOCM (p < 0.001), in aortic stenosis (p < 0.05), and aortic incompetence (p < 0.001), and was shortened in congestive cardiomyopathyl (p < 0.05) and mitral stenosis (p < 0.01). In patients with coronary artery disease and normal over-all systolic LV function, IRP was prolonged (p < 0.001); IRP was shortened in four patients with coronary disease who had severe LV dysfunction and severe additional mitral incompetence. IRP was related to systemic blood pressure, percentage shortening of the LV in systole, and to the mitral EF slope. It tended to increase with increasing heart rate and a regression equation was developed for predicting IRP in relation to blood pressure and heart rate in normal sbjects. There was no relation to the PR-Ac time or to isovolumic contraction time. IRP is a useful measurement of LV dynamics in early diastole.

Aortic root and left atrial wall motion. An echocardiographic study

The echocardiographically recorded movement of the aortic root was studied by analysing the relation between posterior aortic wall motion and other intracardiac events. The systolic anterior movement of the aortic root continued beyond aortic valve closure and in cases with mitral regurgitation began significantly earlier than in normal subjects. The diastolic rapid posterior movement began after mitral valve opening but did not occur in patients with mitral stenosis. The total amplitude of aortic root motion was increased in patients with mitral regurgitation, diminished in cases of mitral stenosis, and was normal with aortic regurgitation. In patients with atrioventricular block an abrupt posterior movement followed the P wave of the electrocardiogram irrespective of its timing in diastole. These observations correlate with the expected changes in left atrial volume during the cardiac cycle both in the normal subjects and patients with heart disease. The results support the hypothesis that phasic changes in left atrial dimension are largely responsible for the echocardiographically observed movement of the aortic root and indicate a potential role for echocardiography in the analysis of left atrial events.