QRS pattern in mitral stenosis

• 1.1. There are three types of electrocardiograms and vectorcardiograms seen with mitral stenosis (with or without mitral insufficiency): (a) the right ventricular type of anterior QRS loop which is the most common; (b) the combined hypertrophy type; and (c) the emphysema type or posterior QRS loop. This latter group has not been emphasized as having diagnostic significance for mitral stenosis. Eight examples of the posterior type are presented here.
• 2.2. Pathologic data give a basis for understanding the appearance of opposite electrical manifestations in a single disease state.
• 3.3. Although examples of both anterior and posterior types are emphasized in this paper, it is to be expected that mixtures exist. The recognition of the electrical patterns which result from a variety of “blends” is not difficult.
• 4.4. In the vectorcardiogram and electrocardiogram it may be possible to differentiate the posterior QRS loop of chronic lung disease from that of mitral stenosis.

     

The spectrum of pure mitral stenosis Hemodynamic studies in relation to clinical disability

The pathophysiology of mitral stenosis is reassessed, with special emphasis upon relation of physiologic variables to severity of symptoms and degree of disability. Data from 44 patients with pure mitral stenosis are presented. Cathetcrization of the left side of the heart was performed in all and catheterization of the right side of the heart in 25 patients.

Twenty-six patients were in Class I or II (American Heart Association Functional Classification) with mild symptoms or none at all, while 18 patients were in Class III with severe symptoms.

As expected, inverse relationships existed between left atrial pressure and mitral valve area (r = − 0.618), pulmonary arterial pressure and mitral valve area (r = − 0.575), and between mean mitral diastolic pressure gradient and mitral valve area (r = − 0.708). There was a positive relationship between cardiac index and mitral valve area (r = + 0.407). All correlation coefficients were significant to the 1 per cent level.

Seventeen of the 26 patients in Classes I and II had mitral valve areas of 1.5 cm², or less. This indicates that severe mitral stenosis can be found in a nearly asymptomatic state. All of the 18 Class III patients had valve areas of less than 1.5 cm². These two groups of patients with similar degree of valve narrowing were compared. Cardiac output was significantly (p < 0.01) reduced in both categories (2.81 L. min. M². for Classes I and II, and 2.82 L. min. M². for Class in patients). Left atrial pressure in the two groups, 18 and 19 mm. Hg, respectively, and mean diastolic pressure gradient, 11 and 13 mm. Hg, respectively, did not show significant differences. However, pulmonary arterial pressure, 22 mm. Hg in Classes I and II and 36 mm. Hg in Class II, as well as pulmonary arteriolar resistance, 105 compared to 425 dynes sec. cm. ⁻⁵, did allow a hemodynamic distinction between the two clinically different groups. These data suggest that the degree of pulmonary vascular disease is an important determinant of the symptoms of mitral stenosis.

For Class I and II patients, history, physical examination and radiographic studies did not allow an accurate prediction of the mitral valve size.

It is suggested that one of the earliest adaptive mechanisms to mitral blockade is a decrease in cardiac output and that this is not mediated, initially, through an elevated pulmonary vascular resistance, myocardial failure or atrial fibrillation. It is one of the means by which a patient with severe stenosis of the mitral valve may remain asymptomatic for prolonged periods of time.     

The vectorcardiographic quantitation of pulmonary hypertension in mitral stenosis

Hemodynamic data and vectorcardiographic (VCG) parameters were correlated in ninety-nine patients with mitral stenosis in order to quantitate the severity of pulmonary hypertension. Using spherical coordinate representation of VCG parameters as independent variables, multi-parameter regression equations were derived for estimating mean pulmonary artery pressure (PAm) and total pulmonary vascular resistance (TPR). The regression equations of this group of ninety-nine patients performed well when the patients were divided into specific subgroups based on horizontal plane morphology. The correlation co-efficients between estimated and measured values ranged from 0.71 to 0.81 for PAm and 0.68 to 0.80 for TPR. These regression equations were used to predict the PAm and TPR in a second set of 11 patients. The correlation co-efficients between the measured and predicted values for this group were 0.54 for PAm and 0.64 for TPR.     

Exercise Doppler echocardiography in patients with pure mitral stenosis

Exercise increases heart rate and cardiac output and is helpful in the determination of dynamic mitral gradient in patients with mitral stenosis. However exercise is difficult to perform during cardiac catheterization in a premedicated recumbent patient and is only feasible when the brachial approach is used. Therefore, in the haemodynamic laboratory, exercise has important practical limitations. In order to obtain similar information using a reproducible and non-invasive technique, we tested the feasibility of combined two-dimensional and continuous wave Doppler echocardiography during exercise in a selected number of patients with pure mitral stenosis and in sinus rhythm. Seven patients, ranging from 14 to 48 years (average: 35 +/- 13), underwent baseline two-dimensional and continuous wave Doppler examinations, repeated after 2 minutes of supine bicycle exercise at a workload of 25, 50, 75 watts. The following parameters were derived and averaged: mean velocity of flow across the mitral valve, mean mitral valve gradient, diastolic filling period and heart rate. The increase in mitral valve flow was from 1.5 +/- 0.3 to 2.2 +/- 0.5 m/s (p less than 0.001); the corresponding increase in mean pressure gradient was from 11 +/- 3 to 21 +/- 8 mmHg (p less than 0.001). The decrease in the diastolic filling period was from 424 +/- 170 to 272 +/- 73 msec (p less than 0.005). The increase in heart rate was from 60 +/- 10 to 100 +/- 18 beats/minute (p less than 0.001).(ABSTRACT TRUNCATED AT 250 WORDS)     

Global left ventricular function and regional wall motion in pure mitral stenosis-Left ventricular function in pure mitral stenosis

Global left ventricular function (LVF) and scgmental wall motion of the left ventricle are registered in 113 patients presenting a pure mitral stenosis (MS) and in a control group of 50 individuals. The segmental wall motion is measured on the end-diastolic-end-systolic frames of the left ventricle, obtained from right anterior oblique (RAO) monoplane cineangiography. Measurement of the segmental wall shortening is performed using the Stanford method. Group 1 includes 68 patients (60% of the total number of patients studied). These patients show no pathological contraction abnormality. In this group, the global LVF is not different from the control group. Group 2 includes 45 patients (40% of the total) for whom contraction abnormalities are present: anterior hypokinesis in 20% of the cases (anterior area mean shortening (AAS) = 18±8%; p<0.001 vs. group 1 and control group), and posterior hypokinesis in 20% of the cases (posterior area mean shortening (PAS) = 9.8 ±5.8%, p<0.001 vs. group 1 and control group). In this group, global LVF is impaired; ejection fraction (EF) = 0.57±0.1% (p<0.001 vs. group 1); velocity of circumferential fiber shortening (Vcf) = l±0.3 circ/s (p<0.001 vs. group 1); end-diastolic pressure (EDP) = 11±5 mmHg (p<0.01 vs. group 1). Segmental contraction abnormalities appear to be the main factor involved in the global LVF impairment. Segmental wall motion abnormalities could be related to subvalvular fibrosis, or LV filling difficulties, or principally, to a possible interplay between the right and the left ventricles.