Asymmetric septal hypertrophy (ASH): the unifying link in the IHSS disease spectrum. Observations regarding its pathogenesis, pathophysiology, and course

Emerging Themes in Genetics of Hypertrophic Cardiomyopathy: Current Status and Clinical Application

Hypertrophic cardiomyopathy (HCM), defined clinically by the presence of unexplained left ventricular hypertrophy (LVH), with wall thickness ≥ 1.5 cm, is a phenotype in search of a diagnosis, which is most often a genetically determined, cardiac exclusive, or systemic disorder. Familial evaluation and genetic testing are required for definitive diagnosis. The role of genetic findings in predicting development of disease, outcomes, and increasingly to guide management is evolving with access to larger data sets. The specific mutation and sex of the patient are important determinants that ultimately are likely to guide management. The genetic/familial evaluation is influenced by the accuracy of the clinical diagnosis and the extent/expertise of the genetic laboratory. Genetic testing in a patient with unexplained LVH without systemic manifestations will yield a definite/likely pathogenetic mutation in a sarcomere (30%-50%), regulatory/functional (10%-15%) or metabolic/syndromic (< 5%) gene associated with Mendelian inheritance. The importance of oligo- and polygenic determinants, usually in the absence of Mendelian inheritance, is under investigation with important implications, particularly related to familial evaluation and definition of risk of disease development in relatives of probands. The results of genetic testing are increasingly important in management strategies related to the use of the implantable cardioverter defibrillator for prevention of sudden death, use of myosin inhibitors for refractory symptoms in patients with and without outflow tract obstruction, and-on the immediate horizon-gene therapy. This review will focus on genetic and outcome data in sarcomeric HCM, and minor causative genes with robust evidence of their association will also be considered.

Does papillary muscle free strain has predictive value in risk stratification of patients with hypertrophic cardiomyopathy?

BACKGROUND

Papillary muscle free strain has not been evaluated previously in hypertrophic cardiomyopathy (HCMP) patients. Our aim was to evaluate free papillary muscle free strain in HCMP patients and to find whether it has a value for prediction of sudden cardiac death (SCD) risk score.

METHODS

Transthoracic echocardiography with tissue Doppler imaging, 2-D speckle tracking imaging (STI) of 55 HCMP patients and 45 controls were performed. HCMP patients were further divided into two groups according to their SCD risk score. Patients with risk score of less than 6 points constituted low/intermediate risk group, whereas patients with risk score of greater or equal to 6 points constituted high risk group.

RESULTS

Interventricular septum, posterior wall, and left ventricular mass index were significantly higher, whereas mitral E/A ratio was significantly lower in HCMP patients compared to controls. Longitudinal apical 4C, 2C, 3C, global longitudinal LV strain, anterolateral papillary muscle (ALPM), posteromedial papillary muscle (PMPM) free strain were significantly reduced in HCMP group compared to control group. Global longitudinal strain and ALPM free strain were significantly lower in patients with high SCD risk score (-14.6 (-17.4 - -13.1) vs -11.6 (-13.2 - -10.1), p = 0.001 and -17.1 (-20.3 - -14.0) vs -9.2 (-12.6 - -7.5), p<0.001, respectively. Global longitudinal strain and ALPM free strain were statistically significantly correlated with SCD risk score (r = 0.480, p<0.001 and r = 0.462, p<0.001, respectively). Global longitudinal strain value of -12.60% had a sensitivity of 73.3% and specificity of 82.5% for predicting high SCD risk score (AUC: 0.787, 95% CI: 00.643-0.930, p = 0.001). ALPM free strain value of -12.95% had 66.7% sensitivity and 77.5% specificity for predicting high SCD risk score (AUC: 0.766, 95% CI: 0.626-0.905, p = 0.003).

CONCLUSION

Papillary muscle free strain was reduced in HCMP patients. It might be used in risk stratification of these patients.

Myocardial bridging in adult with hypertrophic cardiomyopathy: Imaging findings with coronary computed tomography angiography

Myocardial bridgin in an adult with hypertrophic cardiomyopathy is a rare congenital coronary artery anomaly. It is often detected incidentally, and its true incidence in the general population is not known. Myocardial bridging may cause compression of a coronary artery, and it has been suggested that myocardial ischemia may result. Symptoms of myocardial bridging in the adult with hypertrophic cardiomyopathy are syncope, palpitations, dyspnea, and chest pain. Also, arrhythmia and myocardial infarction can be seen; these can cause sudden death, especially in athletes and young people. We present a case of a 48-year-old male with hypertrophic cardiomyopathy and myocardial bridging detected by coronary computed tomography angiography who complained of chest pain.

The Remarkable 50 Years of Imaging in HCM and How it Has Changed Diagnosis and Management: From M-Mode Echocardiography to CMR

The almost 50-year odyssey of cardiac imaging in hypertrophic cardiomyopathy (HCM), revisited and described here, has been remarkable, particularly when viewed in the timeline of advances that occurred during a single generation of investigators. At each step along the way, from M-mode to 2-dimensional echocardiography to Doppler imaging, and finally over the last 10 years with the emergence of high-resolution tomographic cardiac magnetic resonance (CMR), evolution of the images generated by each new technology constituted a paradigm change over what was previously available. Together, these advances have transformed the noninvasive diagnosis and management of HCM in a number of important clinical respects. These changes include a more complete definition of the phenotype, resulting in more reliable clinical identification of patients and family members, defining mechanisms (and magnitude) of left ventricular outflow obstruction, and novel myocardial tissue characterization (including in vivo detection of fibrosis/scarring); notably, these advances afford more precise recognition of at-risk patients who are potential candidates for life-saving primary prevention defibrillator therapy. This evolution in imaging as applied to HCM has indelibly changed cardiovascular practice for this morphologically and clinically complex genetic disease.

Cross-sectional echocardiographic assessment of aortic obstruction

Cross-sectional echocardiographic features of aortic obstruction occurring at multiple levels of the left ventricular outflow tract are discribed. Specific pathologic entities considered include coarctation of the aorta, supravalvular, valvular, and discrete subvalvular aortic stenosis, as well as functional or idiopathic hypertrophic subaortic stenosis. At each of these levels the cross-sectional method permits direct visualization of the obstructing lesion, it's morphologic characteristics, and extent. In addition the relationship of the area of obstruction to more normal surrounding areas of the outflow tract can be assessed. Studies at the supravalvular and valvular levels indicate the direct imaging of the stenotic area may permit estimation of severity. At the subvalvular level the patterns of development of functional obstruction can be examined and the mechanisms of this type of obstruction further illucidated. Finally in addition to direct visualization of individual areas of obstruction it is possible to detect or exclude areas of concommittant obstruction at other levels of the outflow tract. Cross-sectional echocardiography therefore represents a rapid, non-invasive method for visualizing the location, extent, severity, and dynamic nature of lesions producing obstruction to left ventricular outflow.

Cardiomyopathy in childhood and adult life, with emphasis on hypertrophic cardiomyopathy

Over 60 entries in the genetic catalog have cardiomyopathy features--32 autosomal dominant, 35 autosomal recessive and X-linked. Over 40 present in, or can have survival into, adult life. Major clinicopathologic categories of these cardiomyopathic disorders included: sudden death (13 entities); cardiac conduction disturbance important feature; associated myopathy or motor dysfunction; storage diseases with cardiac involvement; cardiac amyloidoses; and, other categories. Genes, abnormality of which can cause hypertrophic cardiomyopathy (HCM), have been identified on chromosomes 1, 14 and 15, the locus on chromosome 14 involving the B-myosin heavy chain gene, but at least one unidentified locus is known to exist and there is a suggestive locus on chromosome 16, so that HCM is not a single disease but a group of disorders with clinicopatholopic similarities. To investigate these aspects of HCM in some detail, sixty-six patients with "sharply demarcated" differential myocardial fiber bundle hypertrophy (DMBH), considered to be of significant degree, from a pediatric autopsy data base of approximately 8,000 cases, were reviewed. Twenty-three of the patients died suddenly, without antecedent significant cardiac dysfunction, seven had clinical congestive heart failure of varying duration, three were stillborn, six showed evidence of aspiration of amniotic sac content (three had history of fetal distress), five had ischemic bowel disease, three (two with clinical cerebral palsy and one with Ondine's curse syndrome) had cerebral atrophy and sclerosis and one had extensive more acute encephalomalacia, and a variety of other major "causes of death" were present. Whether all infants and children with DMBH meeting the criteria used, who do not have congenital heart disease, have dominant hypertrophic cardiomyopathy (HCM) cannot be established by studies of this type, but the "concentration" of a gene or genes for HCM in pediatric autopsy series because the strong effect of HCM on life expectancy is relevant to this possibility. The data raise the question that stillbirth, fetal distress with aspiration of amniotic sac content, ischemic bowel disease and cerebral atrophy and sclerosis may be hitherto underappreciated features of HCM in childhood, and that patients with HCM may be peculiarly liable to die with certain types of septic shock, such as acute meningococcemia. In the material of this study, sudden death was statistically more frequent in females than in males in childhood (p < .029).

Analysis of transmural trend of myocardial integrated ultrasound backscatter for differentiation of hypertrophic cardiomyopathy and ventricular hypertrophy due to hypertension

OBJECTIVES

This study was undertaken to differentiate hypertrophic cardiomyopathy from hypertensive hypertrophy using a newly developed M-mode format integrated backscatter imaging system capable of calibrating myocardial integrated backscatter with the power of Doppler signals from the blood.

BACKGROUND

Myocardial integrated ultrasound backscatter changes in patients with hypertrophic cardiomyopathy; however, it is unknown whether ultrasound myocardial tissue characterization may be useful in differentiating hypertrophic cardiomyopathy from hypertensive hypertrophy.

METHODS

Calibrated myocardial integrated backscatter and its transmural gradient were measured in the septum and posterior wall in 31 normal subjects, 13 patients with hypertensive hypertrophy and 22 patients with hypertrophic cardiomyopathy. The gradient in integrated backscatter was determined as the ratio of calibrated integrated backscatter in the endocardial half to that in the epicardial half of the myocardium.

RESULTS

Cyclic variation of integrated backscatter was smaller and calibrated myocardial integrated backscatter higher in patients with hypertrophied hearts than in normal subjects, but there were no significant differences in either integrated backscatter measure between patients with hypertensive hypertrophy and those with hypertrophic cardiomyopathy. Transmural gradient in myocardial integrated backscatter was present only in patients with hypertrophic cardiomyopathy (5.0 +/- 1.8 dB [mean +/- SD] for the septum; 1.2 +/- 1.6 dB for the posterior wall).

CONCLUSIONS

Hypertrophic cardiomyopathy and ventricular hypertrophy due to hypertension can be differentiated on the basis of quantitative analysis of the transmural gradient in integrated backscatter.

Doppler evidence that true left ventricular-to-aortic pressure gradients exist in hypertrophic cardiomyopathy

The etiology of systolic left ventricular-to-aortic pressure gradients in hypertrophic cardiomyopathy is still controversial. While cavity obliteration has been proposed by some investigators as the cause for recording of a high left ventricular systolic pressure, the concept of left ventricular outflow tract obstruction has received more experimental support. To investigate further whether left ventricular pressure truly exceeds aortic pressure and implies obstruction, we studied, with imaging and Doppler echocardiographic techniques, five patients with asymmetric septal hypertrophy and systolic anterior movement of the mitral valve occasionally causing it to abut upon the septum. All had outflow tract pressure gradients (peak 85 +/- 10 mm Hg) and trace to mild mitral regurgitation. Continuous wave Doppler study recorded peak flow velocities in the outflow tract (4.6 +/- 0.3 m/sec), and mitral regurgitant (mean 6.6 +/- 0.3 m/sec) jets. Aortic systolic and diastolic blood pressures were measured by cuff sphygmomanometry, and simultaneous carotid pulse tracings were recorded. The magnitude of systolic aortic pressure was determined at the time of peak velocity in the mitral regurgitant jet. Since the peak systolic pressure gradient across the mitral valve (left ventricular minus left atrial pressure) should equal 4 times the square of the peak velocity (V) in the mitral regurgitant jet, peak left ventricular systolic pressure should equal 4 x V2 plus the height of left atrial pressure at the time of peak mitral regurgitant velocity. In each case, calculations were made assuming an upper normal left atrial pressure of 10 mm Hg.(ABSTRACT TRUNCATED AT 250 WORDS)

Localized septal hypertrophy: part of the spectrum of hypertrophic cardiomyopathy or an incidental echocardiographic finding?

In a prospective study of the results of 5582 consecutive two-dimensional echocardiographic examinations, hypertrophy of a localized region of the basal ventricular septum was identified in 26 patients. Proven diagnoses were coronary disease in five patients, coronary plus valvular disease in three, valvular disease in seven, and miscellaneous in four. Localized septal hypertrophy was the only cardiac diagnosis in seven patients. The ratio of the thickness of the hypertrophied area to that of the adjacent septum was greater than or equal to 1.7 (mean 1.93 +/- 0.19) in all patients. The ration of the length of the hypertrophied portion (mean 0.34 +/- 06) to the length (apex to base) of the septum was less than 0.39 in all but one patient. Although the mitral valve tended to be more anterior than expected in 20, other features of hypertrophic cardiomyopathy were generally lacking. Of four patients undergoing left ventricular angiography, the bulge was identified in only one in whom cranial-caudal angulation was added to the 60-degree left anterior oblique view. An autopsy was performed in one patient; the hypertrophy was identified, although results of microscopic examination showed no fiber disarray. These data suggest that, in most instances, localized septal hypertrophy is an incidental echocardiographic finding. The diagnosis of hypertrophic cardiomyopathy should generally not be made on the basis of this feature alone.

Estimation of regional stress in the left ventricular septum and free wall: an echocardiographic study suggesting a mechanism for asymmetric septal hypertrophy

Although asymmetric septal hypertrophy is noted in a wide variety of cardiac disorders, its cause remains unclear. One possible mechanism is that the septum is subjected to greater systolic stress because of its flatter (more eccentric) contour. This was investigated noninvasively in nine subjects by estimation of regional myocardial stress from measurements of blood pressure by cuff sphygmomanometry and by echocardiographic examinations of left ventricular shape and dimensions. Analysis of left ventricular cavity shape showed that both the free and septal walls were elliptical, but the septum was more eccentric than the free wall. Using a conceptual model to determine changes in regional systolic stress, the theoretical rate of increase in regional stress relative to pressure (delta S/delta P) was significantly greater in the septum compared to the free wall. Increased hypertrophy of the septum to normalize this increased delta S/delta P may be the cause of asymmetric septal hypertrophy in many disorders associated with elevated left ventricular pressure.

The relation of age to the thickness of the interventricular septum, the posterior left ventricular wall and their ratio

We obtained echocardiographic measurements of interventricular septal and posterior left ventricular wall thickness in 100 apparently normal subjects in whom there was no evidence or history of coronary artery disease, hypertension or prolapsing mitral valve. Subjects were divided into five age groups of 20-29, 30-39, 40-49, 50-59 and 60-70 years and there were 20 subjects in each group. Measurements of interventricular septum and posterior left ventricular wall thickness were made in each subject at both mitral and sub-mitral levels at the time of Q wave inscription, and the measurements were related to body surface area. The interventricular septum increased from a median of 8.3 mm in the age group 20-29 to 11.2 mm in the group 60-70, whereas the posterior left ventricular wall increased from 7.5 mm to 9.8 mm. The difference in the medians between the groups 20-29 and 60-70 was statistically significant for both interventricular septum and posterior left ventricular wall (P less than 0.02). Our data showed that interventricular septal, posterior left ventricular wall thickness measurements and their ratio should be related to age in order to assess their significance.

Long-term study of the ultrastructural changes of myocardium in patients undergoing cardiac surgery, with more than 10 years follow-up

The myocardium from 44 patients undergoing open cardiac surgery was studied to determine if alterations demonstrable with the electron microscope could be related to prognosis. Planimetric methods were used to evaluate myofibrils, Golgi, mitochondria, myelin figures, other organelles, and intracellular space in order to achieve as objective a measurement as possible. Morphologic changes were graded and correlated with clinical findings and results after long-term follow-up. Factors evaluated in terms of survival included patient age, degree and extent of valvular disease, the presence of coronary artery disease, and degenerative changes of the myocardium as demonstrated ultrastructurally. Patients dying, of cardiac causes, within the first 5 years, had a higher ultrastructural grade than those surviving for more than 10 years. Statistical analysis, using stepwise regression methods, demonstrated a highly significant correlation (P less than 0.001) between cardiac ultrastructural integrity and prognosis. The addition of age to the prediction model was also significant (P less than 0.04), using the two variable models, EM grade and age were, similarly, highly significant (P less than 0.001).

Angled interventricular septum on echocardiography: anatomic anomaly or technical artifact?

An acutely angled interventricular septum has been reported to constitute a distinct two-dimensional echocardiographic geometric pattern that may permit a false M-mode echocardiographic recording of asymmetric septal hypertrophy. In light of experience suggesting that the angle between the aortic root and interventricular septum varied with the intercostal space of the transducer, 45 subjects were prospectively studied by two-dimensional and M-mode echocardiography. Parasternal long- and short-axis views were obtained from two to four intercostal spaces in each subject. Two-dimensional echographic cursor-generated M-mode echocardiograms were obtained from the long-axis views; interventricular septal and left ventricular posterior wall thickness was measured from both the two-dimensional and M-mode echocardiograms. On two-dimensional echocardiography, the angle between the aortic root and septum became more acute as a progressively lower intercostal space was used (p less than 0.001). Although no change in septal thickness was apparent, the septal thickness significantly increased as a progressively lower intercostal space was used. On M-mode echocardiography, 21 subjects (47%) demonstrated asymmetric septal hypertrophy (septal/posterior wall thickness ratio greater than 1.3) from at least one intercostal space, but this was confirmed by the two-dimensional technique in only 4 subjects (9%). Thus, a two-dimensional echocardiographic recording of an angled interventricular septum can be produced by positioning the transducer in a low intercostal space, and caution must be used in the interpretation of asymmetric septal hypertrophy on M-mode echocardiograms. Two-dimensional echocardiography is a useful means of identifying subjects with apparent asymmetric septal hypertrophy that often may be the result of a technical artifact.

Two forms of hypertrophic cardiomyopathy distinguished by inheritance of HLA haplotypes and left ventricular outflow tract obstruction

In this study we have performed human leukocyte antigen (HLA)-A and B typing on nine patients with hypertrophic cardiomyopathy (HCM) and their relatives. Four patients had relatives who also had the disease. HLA typing of the familial form of HCM revealed a very close association of a given HLA-A,B haplotype with the occurrence of the disease. All four patients who had affected relatives had obstruction of left ventricular outflow (LVOT), while four patients with unaffected relatives did not have obstruction. One additional patient with obstruction and without familial incidence was an only child and had few living relatives. Thus, HCM can be divided into two subtypes: a familial form linked to the HLA-A,B system, which may be related to obstructive type, and a sporadic form not linked to HLA antigens. These data confirm the existence of at least two separate forms of hypertrophic cardiomyopathy. The study also confirms their existence in the Japanese population, with a completely different gene pool than the population from the southeastern United States in whom the observation was initially described.

Left ventricular emptying dynamics in patients with asymmetric septal hypertrophy and concentric hypertrophic cardiomyopathy

We studied the dynamics of left ventricular (LV) emptying in 8 patients with asymmetric septal hypertrophy (ASH), 6 patients with concentric hypertrophic cardiomyopathy (CHC), and 6 normal controls. Four patients with ASH had resting systolic gradients greater than 20 mmHg, all had significant post premature ventricular contraction (PVC) systolic pressure gradients. LV volume (V) was obtained by frame-by-frame analysis of cineangiograms. End-diastolic volume was similar for all groups; end-systolic volume was significantly less in ASH and CHC patients than in normals. Maximum dV/dt was similar in ASH and CHC, and significantly greater than normals. Total systolic contraction time (SCT), i.e., time from peak volume to last cine frame at minimum volume, was similar for all groups, but the time required to eject 90% of stroke volume (90%T), as a fraction of SCT, was shorter for ASH (0.52 +/- 0.07) and CHC patients (0.51 +/- 0.05) than normals (0.67 +/- 0.07) (p less than 0.05 vs myopathy groups). In the sinus beat following a PVC, however, this ratio decreased significantly in normals and CHC patients, but did not change in ASH patients. We conclude that ASH and CHC have similar exaggerated systolic LV ejection dynamics in the basal state; the failure of ASH patients with post-PVC systolic outflow gradient to reduce 90% T/SCT post PVC may reflect obstruction to LV emptying.

Left ventricular myotomy. Physiologic approach to surgical therapy for IHSS

Twenty patients were operated on for idiopathic hypertrophic subaortic stenosis (IHSS) between 1966 and 1980. All were in New York Heart Association functional class 3 or 4, and 17 had overt congestive failure. The mean resting gradient across the left ventricular (LV) outflow tract preoperatively was 78 mm Hg. Seventeen patients underwent transaortic LV myotomy, one had mitral valve replacement (MVR), and two patients with rheumatic mitral insufficiency (MI) and IHSS underwent myotomy and MVR. There was one operative death (5 percent). Mean follow-up was 5.8 years. Eighteen of 19 survivors were improved to class 1 or 2. One patient whose gradient and symptoms were not relieved by myotomy was improved by myectomy and MVR. The MI was abolished or reduced by myotomy in ten of 13 patients. There were six late deaths, five of which are known or assumed to be cardiac related. We concluded that LV myotomy is a safe and effective technique for surgical management of IHSS. Left ventricular myectomy, MVR, or both are indicated in selected cases.

Congestive heart failure in adults. Six considerations in systematic diagnosis

There are two key clinical questions to be answered in any patient with documented congestive heart failure. First, what is the underlying etiology? Second, what exacerbating factors are present? The ECG, the echocardiogram, and chest x-ray films may provide important diagnostic clues. The mode of presentation (acute vs chronic) is also of major importance. Attention should be paid to treatable or reversible factors, including infective endocarditis, occult aortic stenosis, recurrent pulmonary emboli, and chronic constrictive pericarditis. Finally, the possibility of unrecognized congenital heart disease (eg, atrial septal defect) should not be overlooked.

Histopathological specificity of hypertrophic obstructive cardiomyopathy. Myocardial fibre disarray and myocardial fibrosis

The topography and specificity of fibre disarray and fibrosis in hypertrophic obstructive cardiomyopathy were determined in a histological study comprising 40 necropsy hearts--10 with hypertrophic cardiomyopathy, 10 with congestive cardiomyopathy, 10 with aortic valve stenosis, and 10 normal hearts. Seven standard regional sections were sampled from each heart and graded "double-blind" (tissue location and disease entity) for severity and extent of fibre dissarray and four distinct types of myocardial fibrosis. Statistical comparison of the severity and distribution of indices of fibre disarray and fibrosis within each group and between the normal and the disease groups showed that fibre disarray and fibrosis were qualitatively non-specific for hypertrophic cardiomyopathy. However, when fibre disarray was quantified (1) it was significantly increased in hypertrophic cardiomyopathy and allowed separation of hearts with hypertrophic cardiomyopathy from normal hearts and from those with congestive cardiomyopathy and aortic stenosis, (2) it did not vary significantly among sections of the left ventricle (that is, between the septum and the free wall) in hypertrophic cardiomyopathy, (3) it was closely associated with plexiform fibrosis, and (4) it varied independently of wall and septal thickness. Though the histogenesis of fibre disarray is unknown, it probably represents an exaggeration of a non-specific common pathway for many diverse pathophysiological processes.

The pediatric spectrum of dynamic left ventricular obstruction

Twenty-one pediatric patients with echocardiographic and/or hemodynamic evidence of dynamic left ventricular obstruction are presented in order to examine the pathophysiologic mechanisms of this disorder. Neonates commonly had transient hypertrophic cardiomyopathy related to hypertension or to being infants of diabetic mothers. Infants with D-transposition of the great arteries sometimes developed signs of subpulmonic dynamic obstruction. Older children and adolescents had either classic findings of IHSS or concentric left ventricular hypertrophy. The spectrum of hypertrophic cardiomyopathy appears to be broader in pediatric patients than in adults.

Idiopathic hypertrophic subaortic stenosis. I. Interventricular septum during the systolic contraction

Biplane left ventricular cineangiographies in 4 patients with typical obstructive idiopathic hypertrophic subaortic stenosis (IHSS) and in control patients with normal left ventricles were analysed. In the protruding hypertrophic muscular interventricular septum of IHSS a markedly reduced shortening occurs in either direction during the systolic contraction. It does not bend towards the right ventricle. It is suggested that the septum of IHSS acts as a suspender during the systolic contraction, thereby accounting for the fast stroke volume ejection and the high ejection fraction of IHSS.

Hypertrophic obstructive cardiomyopathy and coronary artery spasm

Three patients had hypertrophic obstructive cardiomyopathy and coronary artery spasm. The clinical diagnosis of hypertrophic obstructive cardiomyopathy, in all patients, was confirmed by echocardiography and angiography. Significant spasm of the right coronary artery was demonstrated in each patient by selective coronary arteriography. One patient had atherosclerotic obstructive three vessel disease, while the other two showed no evidence of any fixed organic narrowing of the coronary arteries. ST segment elevation in the inferior ECG leads was documented in two of the patients in association with coronary spasm.

ECG pattern of left ventricular hypertrophy in nonobstructive hypertrophic cardiomyopathy: the significance of the mid-precordial changes

A review of electrocardiograms from 33 patients with nonobstructive hypertrophic cardiomyopathy was made. In 22 patients there was noted a high QRS voltage, depression of the ST segment, and inversion of the T wave, satisfying the diagnostic criteria of left ventricular hypertrophy with the abnormal changes not only extending to the midprecordial leads but showing the most striking abnormal changes in Lead V4 in 20 patients. The frontal plane electrical axis was normal (around 60 degrees), with the most remarkable changes in Lead II. In the VCG, the magnitude of the QRS loop was increased and directed anteriorly and to the left, and the T loop was deviated posteriorly and to the right opposite the QRS loop. The asymmetric septal and apical hypertrophy was noted on echocardiography and/or angiocardiography. The coronary arteries were normal without significant obstruction in selective coronary angiography. It was postulated that the asymmetric septal and apical hypertrophy was reflected in this ECG pattern. The recognition of this ECG pattern provides pertinent information in the clinical detection of nonobstructive HCM.

Coexistence of asymmetric septal hypertrophy and aortic valve disease in adults

Echocardiography detected asymmetric septal hypertrophy (ASH) in five of 200 adults being assessed for aortic valve surgery. Four of these were among 119 patients with dominant aortic stenosis, which was severe in three. ASH was confirmed at the time of aortic valve replacement in two of these patients; the third declined operation. The finding of ASH in only one of 81 patients with free aortic reflux is consistent with chance association. While the same explanation could apply to the higher prevalence in those with aortic stenosis, it may be that a long-standing pressure overload can trigger inappropriate septal hypertrophy in predisposed individuals.

Relationship between hypertension and angina pectoris

1 Many factors are of importance in the relationship between angina pectoris and hypertensive heart disease. Vascular resistance modifies the oxygen supply, whereas the oxygen demand is influenced by the systolic and diastolic BPs, the diastolic filling time and wall tension, the duration of systole and transmural pressure and the sympathetic stimulation to the heart. 2 The treatment of angina pectoris in patients with hypertensive heart disease should aim to reduce myocardial ischaemia, and it is suggested that beta-adrenoceptor antagonists are most suitable, as they reduce BP, heart rate and myocardial contractility and thus oxygen demand.

Mitral valve replacement using a porcine xenograft for treatment of IHSS--A case report

Recently we treated a 24-year-old female IHSS patient by mitral valve replacement, using a porcine xenograft valve. Following surgery, clinical manifestations improved markedly and postoperative cardiac catheterization revealed that the pressure gradient between left ventricle and aorta had dropped to a minimum compared with the pre-operative value of 104 mmHg and end-diastolic pressure of the left ventricle had returned to normal level.

Incidence of thyroid disease in cases of hypertrophic cardiomyopathy

The investigative findings of patients considered to have possible hypertrophic cardiomyopathy were examined, and 31 of these fulfilling defined criteria for the disease were reviewed in detail, with emphasis on thyroid abnormalities. Four patients had a history of thyroid disease (13%). Explanations considered for the apparent association were the effects of hyperthyroidism on normal, or more probably, incipiently abnormal myocardium.

Dynamic left ventricular outflow tract obstruction and systolic anterior motion of the mitral valve in the absence of asymmetric septal hypertrophy

Systolic anterior motion of the anterior mitral valve leaflet and asymmetric septal hypertrophy are the principal components of the dynamic subaortic stenosis in hypertrophic obstructive cardiomyopathy. Mitral valve systolic anterior motion without septal hypertrophy or left ventricular outflow tract obstruction has been described, but asymmetric septal hypertrophy is supposedly a consistent feature of dynamic subaortic stenosis. We describe two patients with syncope, chest pain and the typical systolic murmur of hypertrophic subaortic stenosis whose echocardiograms showed mitral valve systolic anterior motion but not asymmetric septal hypertrophy. Normal septal thickness on echo was confirmed by intravenous indocyanine green to identify the right septal endocardium. At catheterization, left ventricular outflow tract gradients were provoked, and neither patient had interventricular septal hypertrophy on biventricular cineangiography. These findings in two cases suggest that mitral valve systolic anterior motion can be the only definable anatomic abnormality associated with symptomatic dynamic left ventricular outflow tract obstruction and that asymmetric septal hypertrophy is not a necessary component of this condition.