Cross sectional echocardiographic identification of hypoplastic left heart syndrome and differentiation from other causes of right ventricular overload

To identify the echocardiographic features that can be used to distinguish between hypoplastic left heart syndrome and other causes of right ventricular overload in the sick neonate cross sectional echocardiographic studies of 10 neonates with hypoplastic left heart syndrome were analysed and compared with those in 15 neonates with other causes of right ventricular overload and 15 normal controls. Left ventricular and right ventricular cavity dimensions and the shape and size of the mitral valve annulus and aortic root were recorded and presented both as absolute values (mm) and corrected for body surface area (mm/m2). Logistic regression was used to produce a classification rule to estimate the probability of a neonate having hypoplastic left heart syndrome. The diameter of the mitral valve annulus was the single most discriminative variable. There was, however, considerable overlap of all the calculated features between neonates with hypoplastic left heart syndrome and those with other causes of right ventricular overload. The diagnosis of hypoplastic left heart syndrome should not be based on any one single echocardiographic feature but the general appearance of abnormal left heart valves, small cavity dimensions, and the size of the mitral valve annulus.     

Prevalence of Fabry disease in a predominantly hypertensive population with left ventricular hypertrophy

Background

Patients with Fabry disease (FD) develop progressive left ventricular hypertrophy (LVH). In screening studies in patients with LVH, the prevalence of FD ranges from 0 to 12%. This variability is attributable to different factors like diverging inclusion and exclusion criteria, the evaluation of selected populations and suboptimal screening methods.In this study, we aimed to determine the prevalence of FD in an unselected population of everyday clinical practice presenting LVH, defined as a maximal end-diastolic septal or posterior wall thickness ≥ 13 mm, without exclusion of patients with arterial hypertension or valvular pathology, and using optimal screening methods.

Methods

In adult males, a two-tier approach was used; α-Galactosidase A (aGAL A) activity was measured using a dried bloodspot test (DBS) and diagnosis was confirmed by mutation analysis of the GLA gene. In females, mutation analysis was the primary screening tool.

Results

362 men and 178 women were screened. Six patients were diagnosed with a genetic sequence alteration of the GLA gene. One man had a novel mutation, GLA p.Ala5Glu (c.44C > A), presenting as classical FD. Another man and three women had the previously described GLA p.Ala143Thr (c.427G > A) mutation, which generally presents as an attenuated phenotype. One woman had a novel sequence alteration c.639 + 6A > C, which appeared to be a polymorphism. All true Fabry patients had arterial hypertension (AHT), and one had hypertrophic obstructive cardiomyopathy (HOCM).

Conclusions

In a group of unselected patients with LVH, we found a prevalence of Fabry disease of 0.9%. AHT or type of hypertrophy should not be an exclusion criterion for screening for FD.     

Cross sectional echocardiographic identification of hypoplastic left heart syndrome and differentiation from other causes of right ventricular overload.

To identify the echocardiographic features that can be used to distinguish between hypoplastic left heart syndrome and other causes of right ventricular overload in the sick neonate cross sectional echocardiographic studies of 10 neonates with hypoplastic left heart syndrome were analysed and compared with those in 15 neonates with other causes of right ventricular overload and 15 normal controls. Left ventricular and right ventricular cavity dimensions and the shape and size of the mitral valve annulus and aortic root were recorded and presented both as absolute values (mm) and corrected for body surface area (mm/m2). Logistic regression was used to produce a classification rule to estimate the probability of a neonate having hypoplastic left heart syndrome. The diameter of the mitral valve annulus was the single most discriminative variable. There was, however, considerable overlap of all the calculated features between neonates with hypoplastic left heart syndrome and those with other causes of right ventricular overload. The diagnosis of hypoplastic left heart syndrome should not be based on any one single echocardiographic feature but the general appearance of abnormal left heart valves, small cavity dimensions, and the size of the mitral valve annulus.     

Sensitivity of electrocardiographic criteria for left ventricular hypertrophy according to type of cardiac disease

The sensitivity of 30 electrocardiographic criteria for left ventricular (LV) hypertrophy, isolated or combined, was examined to determine the relation to the underlying disease. Patients with coronary artery disease (CAD), systemic hypertension, valvular heart disease and cardiomyopathy were evaluated. A cardiac partition technique was used to define ventricular hypertrophy. Single electrocardiographic criteria often showed high sensitivity for 1 disease state, but not for others. Precordial voltage criteria were most sensitive for those with hypertensive and valvular disease. A QRS axis of more than -30 degrees occurred most often in patients with CAD. Both left atrial abnormality and abnormal T-wave inversion of more than 1 mm in V6 occurred with a high sensitivity in general; however, T-wave inversion of more than 1 mm in V6 had a low sensitivity in cardiomyopathy. Methods using combinations of various electrocardiographic criteria improved sensitivity. Using these methods, sensitivity of the electrocardiogram for LV hypertrophy was excellent for patients with systemic hypertension and valvular heart disease and acceptable by usual standards for patients with CAD and cardiomyopathy. Because the use of a single criterion is often ineffective, methods using multiple electrocardiographic criteria to detect LV hypertrophy are recommended when the patients under study have diverse cardiac diseases.     

Electrocardiographic criteria of left ventricular hypertrophy in left bundle-branch block.

In order to determine whether the electrocardiographic criteria of left ventricular hypertrophy apply in the presence of left bundle-branch block we studied 79 cases of intermittent left bundle-branch block and compared the QRS voltage and axis before and after its onset. Cases of incomplete left bundle-branch block were excluded. There was a statistically significant correlation between pre- and post-left bundle-branch block values of R or S wave voltage in leads I, V1, V2, V5, and V6, the Sokolow index (R V5 or V6 + S V1), and the QRS axis. There was a statistically significant reduction in R wave voltage in leads I, V5, and V6, an increase in S wave voltage in V1 and V2, and leftward shift of QRS axis, but the Sokolow index remained unchanged, after the onset of left bundle-branch block. The Sokolow criteria for left ventricular hypertrophy apply satisfactorily even in the presence of left bundle-branch block, though specificity is low, but QRS axis is unhelpful.     

Electrocardiographic criteria of left ventricular hypertrophy in left bundle-branch block.

In order to determine whether the electrocardiographic criteria of left ventricular hypertrophy apply in the presence of left bundle-branch block we studied 79 cases of intermittent left bundle-branch block and compared the QRS voltage and axis before and after its onset. Cases of incomplete left bundle-branch block were excluded. There was a statistically significant correlation between pre- and post-left bundle-branch block values of R or S wave voltage in leads I, V1, V2, V5, and V6, the Sokolow index (R V5 or V6 + S V1), and the QRS axis. There was a statistically significant reduction in R wave voltage in leads I, V5, and V6, an increase in S wave voltage in V1 and V2, and leftward shift of QRS axis, but the Sokolow index remained unchanged, after the onset of left bundle-branch block. The Sokolow criteria for left ventricular hypertrophy apply satisfactorily even in the presence of left bundle-branch block, though specificity is low, but QRS axis is unhelpful.     

Electrocardiographic criteria of left ventricular hypertrophy and unipolar aVR lead

The introduction of data processing techniques into the interpretation of electrocardiograms and the rapid progress towards automatization require a multiplication of the criteria of decision and an exact evaluation of their performance. The ECG diagnosis of left ventricular hypertrophy depends on a large number of parameters. Only the aVR lead has not been fully exploited to date. This study proposes a corrected measurement of S in aVR, with an amplitude of S aVRc greater than or equal to 11 mm being the parameter with the best performance and the best predictability.     

心电图电压标准诊断左室肥大价值的研究

目的 评价临床上最常用的几项心电图电压标准诊断左室肥大（LVH）的价值及性别差异。方法 选择1999—2003年我院体检及住院患者499例，依据超声心动图测定的左室重量指数（LVMI）分为正常组（男210饲，女83例）和左室肥大组（男126例，女80例）。计算各项电压标准诊断左室肥大的敏感性、特异性和准确率，并比较各项电压标准诊断左室肥大的性别差异。结果 各项电压标准诊断左室肥大的特异性均〉95％,在单项指标中，Rvs〉2．5my标准的敏感性和准确率分别为62．8％和85．1％，明显高于Rvs及RaVL电压标准。在复合指标中，Comell指数和Sokolow指数诊断左室肥大的敏感性和准确率明显高于R4＋Sm指标。男、女性采用相同的电压阈值，其诊断性能存在明显性别差异。结论 Cornell指数、Sokolow指数及Rv5电压标准是诊断左宣肥大较好的指标。男、女性采用不同的电压阈值标准，可望进一步改善目前心电图诊断左室肥大的性能。     

Determinants of sensitivity and specificity of electrocardiographic criteria for left ventricular hypertrophy

Numerous electrocardiographic criteria, which are largely dependent on fixed voltage thresholds, have been proposed for the diagnosis of left ventricular hypertrophy (LVH). Electrocardiographic criteria for LVH were examined in 4,684 subjects of the Framingham Heart Study who underwent echocardiographic study for LVH. Echocardiographic LVH was detected in 290 men (14.2%) and 465 women (17.6%). Electrocardiographic features of LVH were present in 2.9% of men (60/2,042) and 1.5% of women (39/2,642). The overall sensitivity of the electrocardiographic diagnosis of LVH was 6.9%, whereas specificity was 98.8%. Sensitivity of the electrocardiogram (ECG) for LVH was marginally lower in women than in men (5.6% vs. 9.0%, p = 0.075). Obesity was inversely associated with sensitivity (p less than 0.05, both sexes combined, sex-adjusted). Smoking was also inversely related to sensitivity (p = 0.001, both sexes combined, sex-adjusted). In contrast, sensitivity of the ECG increased with age (p less than 0.001, both sexes combined, sex-adjusted). These findings suggest that electrocardiographic detection of LVH can be improved by incorporating information about noncardiac factors that impact on electrocardiographic sensitivity for LVH, presumably by attenuating QRS voltage. New strategies that take into consideration sex, age, smoking status, and obesity might improve the sensitivity of the ECG without diminishing specificity.     

Myocardial oxygen supply in left ventricular hypertrophy and coronary heart disease.

Coronary arteriolar dilation adjusts blood flow according to local fluctuating metabolic needs of the myocardium. Because of high extravascular compression during systole, the subendocardial layer of the left ventricle is especially dependent on the duration and the perfusion pressure of the diastolic period. In patients with obstructive coronary artery disease, regional arteriolar dilation is utilized to compensate for focal arterial stenoses. Coronary blood flow may be compensated with the patient at rest, but loss of reserve arteriolar dilation limits further adjustment to superimposed transient increases in metabolic needs. Subendocardial perfusion in the region supplied by the stenosed artery is especially vulnerable to shortened diastolic time during tachycardia. In patients with chronic aortic valve disease, the metabolic rate of the left ventricle is increased in proportion to the increases in myocardial mass and work. Coronary blood flow and metabolic rate per gram of the hypertrophied myocardium are normal when the patient is at rest, at the expense of diminished coronary arteriolar reserve. High tissue pressure relative to the diastolic perfusion pressure probably contributes to the diffuse subendocardial ischemia that occurs in these patients during tachycardia.