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Biomedical subjects

B J Maron

Publications and source records attributed to B J Maron.

At least 19 recordsLinked to original sources
PubMed1979

Canine hypertrophic cardiomyopathy.

Necropsy findings in 10 dogs with naturally occurring cardiac disease closely resembled hypertrophic cardiomyopathy in human beings and cats. Each dog had marked cardiac hypertrophy, and 8 dogs had disproportionate thickening of the ventricular septum with respect to the left ventricular free wall (compared with dogs with normal hearts or with cardiac hypertrophy due to acquired or congenital heart disease). Ratios of septum to free wall thickness in the 10 dogs ranged from 1.1 to 1.5, and 6 had ratios greater than or equal to 1.3. Marked cardiac muscle cell disorganization in the ventricular septum, characteristic of human patients with hypertrophic cardiomyopathy, was found in only 2 of the 10 dogs. Death occurred while the dogs were under anesthesia during the course of operative procedures (5 dogs) or unexpectedly in animals without previous manifestations of cardiac disease (3 dogs). Four dogs had clinical signs of congestive heart failure, including 2 with marked cardiac decompensation. Two of these 4 dogs with heart failure and 1 dog that died during unrelated surgery, but without prior signs of heart disease, had electrocardiographic evidence of complete heart block.

Animals↗
PubMed1979

Hypertrophic cardiomyopathy and transmural myocardial infarction without significant atherosclerosis of the extramural coronary arteries.

Clinical and morphologic features of transmural myocardial infarction (associated with insignificant or absent atherosclerosis of the extramural coronary arteries) are described in seven patients with hypertrophic cardiomyopathy. Marked chronic congestive heart failure associated with supraventricular arrhythmias occurred in six of the seven patients, each of whom had no or mild left ventricular outflow tract obstruction under basal conditions. No patient had typical angina pectoris, and only one patient had clinically evident acute myocardial infarction. Infarction may have caused cardiac arrest in one other patient, but was "silent" in the remaining five patients. At necropsy, six of the seven patients had extensive myocardial scarring involving the ventricular septum, left ventricular free wall and one or both left ventricular papillary muscles; in four patients portions of the right ventricular wall were also scarred. Six patients had dilated ventricular cavities, including two who were known to have nondilated ventricular cavities earlier in their clinical course. It is concluded that transmural myocardial infarction in the absence of significant coronary atherosclerosis is a not uncommon finding (prevalence rate 15 percent) in a population of patients who had died from hypertrophic cardiomyopathy. Although transmural infarction is possibly a secondary event, it more likely contributes causally to the clinical deterioration of some patients with hypertrophic cardiomyopathy, leading to ventricular dilatation and progressive fatal cardiac failure.

Adolescent↗
PubMed1979

Nongenetically transmitted disproportionate ventricular septal thickening associated with left ventricular outflow obstruction.

Clinical, haemodynamic, and morphological features are described in 2 patients with disproportionate ventricular septal thickening, left ventricular outflow obstruction with systolic anterior motion of the anterior mitral leaflet, and either acquired or congenital heart disease. The disproportionate septal thickening in these patients appeared to be secondary to their underlying cardiac disease rather than a manifestation of genetically transmitted hypertrophic cardiomyopathy. One patient with combined aortic and mitral stenosis had severe systolic anterior motion of the anterior mitral leaflet and a residual large systolic pressure gradient between left ventricle and systemic artery after aortic valve replacement. In this patient the systolic anterior motion was evident in the presence of mitral valve stenosis. The other patient with mild aortic stenosis and a previously repaired coarctation of the aorta also had mild systolic anterior motion and a small subaortic systolic pressure gradient. Hence, these 2 patients demonstrate that disproportionate septal thickening secondary to acquired or congenital heart disease may be associated with left ventricular outflow obstruction and systolic anterior motion of the anterior mitral leaflet.

Adolescent↗
PubMed1979

Prevalence and characteristics of disporportionate ventricular septal thickening in infants with congenital heart disease.

Necropsy studies were performed in 125 infants, 2 years old or less, with a variety of congenital heart malformations. Disproportionate ventricular septal thickening (septal-to-left ventricular free wall thickness ratio greater than or equal to 1.3) was present in 31 (25%) of the 125 patients. In the majority of patients, an abnormal septal-to-free wall ratio did not appear to be a manifestation of genetically transmitted hypertrophic cardiomyopathy, since: 1) marked disorganization of septal myocardium (involving greater than or equal to 5% of the tissue section) was present in only five of the 31 patients with disproportionate septal thickening; and 2) echocardiographic studies in first degree relatives of four other patients with disproportionate septal thickening and normal septal architecture did not show asymmetric septal hypertrophy. The relatively high prevalence of septal-to-free wall ratios of 1.3 or greater in this population of infants with congenital heart disease appeared to be due in part to minor differerences in ventricular wall thicknesses (in patients with relatively thin absolute wall thicknesses) which may produce particularly large deviations from unity in septal-to-free wall ratio. Hence, 1) nongenetically transmitted disproportionate septal thickening is relatively common in infants with congenital heart diseases studied at necropsy: and 2) a septal-to-free wall ratio of greater than or equal to 1.3 cannot be used as the sole criterion for identifying associated hypertrophic cardiomyopathy in infants with other congenital heart diseases, particularly if marked absolute septal thickening is absent.

Cardiomegaly↗
PubMed1979

Prevalence of arrhythmias during 24-hour electrocardiographic monitoring and exercise testing in patients with obstructive and nonobstructive hypertrophic cardiomyopathy.

Many patients with hypertrophic cardiomyopathy die suddenly and unexpectedly, a significant number perhaps due to arrhythmia. Of 100 patients initially evaluated for signs or symptoms suggestive of heart disease or a family history of hypertrophic cardiomyopathy, 51 were selected solely because they met the echocardiographic criteria for the disease, and 49 patients were selected primarily because they had: 1) normal sinus rhythm despite left atrial enlargement, 2) a history of syncope, 3) a family history of premature death, or 4) a history of paroxysmal atrial fibrillation. All 100 patients were studied by 24-hour ambulatory electrocardiographic monitoring and 74 of them also underwent treadmill exercise testing. More than 50% of patients in repetitive ventricular premature depolarizations, including 19% who had ventricular tachycardia. Monitoring was superior to exercise testing for exposing these arrhythmias. Two patients experienced cardiac arrest within 2 months of monitoring; in each, monitoring had revealed ventricular tachycardia. Two patients with paroxysms of supraventricular tachycardia during monitoring developed fixed atrial fibrillation within 1 year. These preliminary observations suggest that monitoring may help identify patients at increased risk for significant arrhythmic events.

Adolescent↗
PubMed1979

Verapamil therapy: a new approach to the pharmacologic treatment of hypertrophic cardiomyopathy. I. Hemodynamic effects.

The hemodynamic effects of intravenous verapamil administration were examined in 27 patients with hypertrophic cardiomyopathy. Increasing doses of verapamil produced small increases in heart rate and cardiac output and a significant decrease in systolic blood pressure, but had no significance effect on mean pulmonary artery wedge pressure or left ventricular end-diastolic pressure. The highest dose of verapamil increased heart rate from 72 +/- 3 to 81 +/- 6 beats/min and reduced systolic blood pressure from 118 +/- 8 to 99 +/- 5 mm Hg (p less than 0.005). This dose decreased the basal left ventricular outflow tract gradient from 94 +/- 14 to 49 +/- 14 mm Hg and the average left ventricular outflow tract gradient during the Valsalva maneuver from 76 +/- 5 to 63 +/- 13 mm Hg, during amyl nitrite inhalation from 69 +/- 15 to 39 +/- 13 mm Hg, and during isoproterenol infusion from 108 +/- 29 to 70 +/- 21 mm Hg (p less than 0.01). These results indicate that verapamil can significantly decrease left ventricular outflow obstruction in patients with hypertrophic cardiomyopathy and thus may provide an important new therapeutic agent in the treatment of this disorder.

Adult↗
PubMed1979

Hypertrophic cardiomyopathy in the dog.

Clinical and necropsy findings in 10 dogs with a spontaneous primary hypertrophic cardiomyopathy are described. Each dog had marked cardiac hypertrophy, and 8 dogs had disproportionate thickening of the ventricular septum with respect to the left ventricular free wall (compared with dogs with normal hearts or with cardiac hypertrophy due to acquired or congenital heart disease). Septal:free wall thickness ratios in the 10 dogs ranged from 1.1 to 1.5; 6 had ratios greater than or equal to 1.3. However, marked cardiac muscle cell disorganization in the ventricular septum, characteristic of patients with hypertrophic cardiomyopathy, was present in only 2 of the 10 dogs. Death occurred most commonly while the dogs were under anesthesia during the course of operative procedures (5 dogs) or suddenly and unexpectedly in animals without previous symptomatic manifestations of cardiac disease (3 dogs). Four dogs had clinical signs of congestive heart failure, including 2 with marked cardiac decompensation. In addition, 2 of these 4 dogs with heart failure and 1 dog without previous symptoms (that died during a noncardiac operation) manifested complete heart block. It is conceivable that dogs with spontaneous hypertrophic cardiomyopathy may prove useful in the future investigations of the clinical, hemodynamic, and pathologic features of this disease in humans.

Animals↗
PubMed1978

Sudden death in patients with hypertrophic cardiomyopathy: characterization of 26 patients with functional limitation.

Sudden death is a recognized complication in symptomatic patients with hypertrophic cardiomyopathy. However, its occurrence in patients with no or transient previous cardiac symptoms presents a particularly challenging diagnostic and therapeutic dilemma. Therefore, 26 patients with hypertrophic cardiomyopathy whose death was the first definitive manifestation of cardiac disease were evaluated. Their ages ranged from 8 to 49 years (mean 18) and 23 were less than 25 years of age; 19 were male and 7 female. Of the 26 patients, 13 died during or immediately after moderate or severe physical exertion. Of 12 patients with previous cardiac catheterization, 6 had no or a small left ventricular outflow tract gradient under basal conditions and 6 had an outflow gradient of 50 mm Hg or greater. Left ventricular end-diastolic pressure was elevated in nine patients, and the ventricular septum was moderately to severely thickened (17 mm or more) in all patients. The electrocardiogram was abnormal in all 19 patients studied before death. Thus, sudden death may be the first definitive manifestation of cardiac disease in some patients with hypertrophic cardiomyopathy. Although the effects of patient selection in this study group cannot be excluded, sudden death was common in children and young adults and was often related to physical exertion; each patient showed a distinctly abnormal electrocardiogram and moderate to severe ventricular septal thickening.

Adolescent↗
PubMed1978

"Malignant" hypertrophic cardiomyopathy: identification of a subgroup of families with unusually frequent premature death.

Eight families were identified in which premature cardiac death due to hypertrophic cardiomyopathy occurred with unusual frequency. A total of 69 first degree relatives in the eight families were studied; 41 relatives had evidence of hypertrophic cardiomyopathy and 31 (75 per cent) died of their heart disease. Eighteen of these 31 patients were less than 25 years of age at the time of death. Death was sudden and unexpected in 23 of the 31 patients; in 15 of these 23 patients sudden death was the initial manifestation of cardiac disease. The remaining eight patients (seven were from two families) died after a chronic cardiac illness characterized by congestive heart failure, atrial fibrillation or thromboembolic events. Hence, premature cardiac death occurs frequently in certain families with hypertrophic cardiomyopathy. Such deaths are usually sudden, often occur in previously asymptomatic subjects and are common in children and young adults. These findings suggest that some families may manifest an unusually virulent expression of hypertrophic cardiomyopathy. Although this study cannot establish the precise prevalence with which "malignant" hypertrophic cardiomyopathy occurs, such families appear to be uncommon.

Adolescent↗
PubMed1978

Prevalence and characteristics of disproportionate ventricular septal thickening in patients with coronary artery disease.

Echocardiographic or necropsy studies were performed in 151 patients with coronary artery disease. Prevalence of disproportionate septal thickening (septal to free wall ratio greater than or equal to 1.3) was 11%. An abnormally increased septal-free wall ratio in these patients had two principal etiologies. First, it was a manifestation of genetically transmitted hypertrophic cardiomyopathy, as evidenced by disproportionate septal thickening in first degree relatives. Second, it was due to disproportionate septal thickening which did not appear to be a manifestation of genetically transmitted hypertrophic cardiomyopathy. This latter conclusion was suggested by negative echocardiographic studies in some families of patients with both coronary artery disease and disproportionate septal thickening. In addition, numerous disorganized cardiac muscle cells, characteristically present in patients with genetically transmitted hypertrophic cardiomyopathy, were absent from the septum of all patients with disproportionate septal thickening studied at necropsy. Although the mechanism responsible for this secondary type of disproportionate septal thickening is unknown, our results indicate that the presence of disproportionate septal thickening in a patient with coronary artery disease does not, per se, indicate the coexistence of genetically transmitted hypertrophic cardiomyopathy.

Coronary Disease↗