May age onset be relevant in the occurrence of left ventricular hypertrophy in Friedreich's ataxia?

BACKGROUND: Although heart involvement has been widely reported in Friedreich's ataxia (FA), which is the most prevalent of the spino-cerebellar degenerative diseases, the reason that cardiac abnormalities develop has not been yet established. HYPOTHESIS: The investigation was undertaken to study the prevalence and characteristics of cardiac abnormalities in patients with FA and to evaluate whether the presence of left ventricular hypertrophy could be predicted. METHODS: In all, 75 patients with FA and 16 patients with late onset FA (LOFA) disease were investigated for cardiac abnormalities using noninvasive methods. RESULTS: A significant (p < 0.01) difference in the age onset (9.8 +/- 3.9 years) was found in 31 of the 75 patients with FA (41%) who showed left ventricular hypertrophy (LVH) at echocardiographic examination compared with the remaining 44 patients with FA without LVH (12.6 +/- 4.3 years). Moreover, none of the 16 patients with LOFA (age onset 26.5 +/- 4.2 years) showed abnormalities at echocardiographic examination. A significant (p < 0.01) concordance in the familial distribution of hypertrophy was also found. CONCLUSION: These data suggest that the earlier the disease develops the more frequently LVH occurs.

Relation between diastolic perfusion time and coronary artery stenosis during stress-induced myocardial ischemia.

BACKGROUND: Experimental studies have demonstrated that during stress-induced myocardial ischemia, coronary obstruction and diastolic perfusion time are factors that limit subendocardial perfusion and correlate to degree of myocardial dysfunction. The relation between these two factors has not yet been investigated in humans. The aim of the present study was to assess the relation between diastolic perfusion time and degree of coronary stenosis during different types of stress tests. METHODS AND RESULTS: Nine patients with isolated and proximal stenosis of the left anterior descending coronary artery were selected. Patients underwent three different randomized stress tests (upright, supine bicycle stress test, and transesophageal atrial pacing). Diastolic perfusion time, heart rate (RR interval), and systolic and diastolic pressures were measured during the test and at the ischemic threshold (0.1-mV ST-segment depression). Angiographic measurements of coronary stenosis were evaluated by quantitative coronary angiography. At the ischemic threshold, significant differences among tests were found in heart rate (P < .05), systolic pressure (P < .001), and diastolic pressure (P < .05). In each stress test, diastolic perfusion time at the ischemic threshold was closely correlated with minimal stenosis diameter (r = .97; P < .001) and percent diameter stenosis (r = .92; P < .001) with no difference among the tests. In contrast, heart rate, rate-pressure product, and time to ischemic threshold were not significantly correlated with percent diameter stenosis and minimal stenosis diameter. No significant correlation was observed at the ischemic threshold between diastolic perfusion time and corresponding values of heart rate, despite the close correlation at rest (r = .95; P < .001). CONCLUSIONS: Despite differences in associated hemodynamic responses to various stress tests, a close relation exists between stenosis severity and diastolic perfusion time at the onset of stress-induced myocardial ischemia. Therefore, diastolic perfusion time at the ischemic threshold may be an indirect estimate of the hemodynamic significance of coronary stenosis.

Effects of intravenous digoxin on pulmonary venous and transmitral flows in patients with chronic heart failure of different degrees.

Acute effects of digoxin on diastole were evaluated noninvasively by combining data simultaneously obtained by Doppler echocardiograms (echo-Doppler) of transmitral and pulmonary venous flow curves in 38 patients with dilated and failing hearts, who had been stable for at least 7 days before the study. According to the resting ejection fraction (EF), patients were subdivided into Group 1 (EF < 30%: n = 20, mean EF values 23 +/- 8%) and Group 2 (EF > or = 30%: n = 18, mean EF values 40 +/- 3%). Significant differences were observed at rest between the two groups in both transmitral (shorter deceleration time and isovolumic relaxation time and increased peak E and E/A ratio in Group 1 vs. Group 2) and transpulmonary (reduced systolic forward component and systolic fraction of the flow curves in Group 1 compared with Group 2 and control subjects) parameters. Digoxin (1 mg subdivided into two doses, each infused over a 15-min period with 2 h between the doses) significantly modified the diastolic profile in Group 1 patients in the absence of statistically relevant changes in EF: a significant decrease of transmitral peak E (from 76 +/- 17 to 60 +/- 15 cm/s, p < 0.05) and E/A ratio (from 2.5 +/- 1 to 1.6 +/- 0.6; p < 0.05) and a significant lengthening of deceleration time (from 115 +/- 20 to 160 +/- 18 ms; p < 0.05) were detected.(ABSTRACT TRUNCATED AT 250 WORDS)

Site of myocardial ischemia as a determinant of postexercise blood pressure and heart rate response in coronary artery disease.

Forty patients with coronary artery disease and 15 normal subjects (group C) were studied to assess the influence of the site of stress-induced myocardial ischemia on cardiovascular response after exercise. Patients were divided in 2 groups according to myocardial thallium-201 scintigraphy: those with an anteroseptal reversible perfusion defect (group A; n = 24), and those with an inferoposterior reversible perfusion defect (group I; n = 16). All patients underwent serial bicycle exercise stress tests. The first 2 stress tests were interrupted when 0.1 mV of ST-segment depression was achieved (2,000 to 2,500 kg-m); a third test was stopped before the onset of ischemia (1,500 kg-m). Normal subjects performed stress tests at comparable work loads. At ischemic threshold, there was no difference in ejection fraction between groups A (65.5%) and I (67.3%). Mean values and recovery ratios of heart rate and systolic blood pressure were significantly higher in group A than in C and I during the recovery period of the 2,000 to 2,500 kg-m stress test. In contrast, no significant difference was observed among the groups in the 1,500 kg-m stress test, and between groups I and C in any stress test. The data show that in patients with the same degree of stress-induced impairment of ventricular function, the anterior site of ischemia leads to persistently higher values of heart rate and blood pressure after exercise, which are likely due to an enhanced adrenergic discharge.

Diastolic perfusion time and exercise posture in coronary artery disease patients: correlation with ST segment changes.

The relationship between either heart rate or diastolic time and ST segment depression has been evaluated during supine and upright exercise in 16 coronary artery disease patients. Diastolic perfusion time and ST segment depression were related by a linear regression, which was independent of exercise posture. The entity of ST segment depression was greater during supine than in upright exercise for the same heart rate. The assessment of the relationship between heart rate and diastolic perfusion time during two exercises showed that at the same heart rate, diastolic perfusion time was shorter in supine posture. In conclusion, the greater entity of ST segment depression induced by supine rather than upright exercise might be explained by the effect of supine posture on diastolic perfusion time.