Echocardiographic Assessment and Systolic Time Interval Measurements in the Evaluation of Severe Hypertension in Nigerian Africans*

Introduction: Systolic Time Interval (STI) is a simple,noninvasive and precise technique to assess left ventricular (LV) function. It measures aortic Pre-Ejection Period (PEP) over Left Ventricular Ejection Time (LVET) from echocardiogram. Thyrotoxicosis will enhance LV function and cause reduction of STI. This study was perform to measure the changes of STI after administration of high dose L-thyroxine and to determine the correlation between high dose L-thyroxine administration and STI. Materials and Method: A Total of 22 patients were screened. Those with cardiac diseases and high Framingham risk score were excluded. Nine patients were started on high dose L-thyroxine (7x their usual dose) once a week during the month of Ramadan.Thyroid hormones ( T3,T4,TSH)Â and STI (PEP/LVET) were measured at baseline and within 24 hrs after high dose L-thyroxine ingestion. Results: All patients have normal thyroid hormones level and normal cardiac function at baseline. The median dose (mcg) of L-thyroxine was 600 (437.5,700) while the median level of fT4 (pmol/L) was 17.43(12.38,20.8). Despite the significant increment of fT4 after Lthyroxine ingestion [baseline 13.21(8.19,14.63) vs high dose 17.43(12.38,22.55) p; 0.011] there was no significant change in STI [baseline 0.3(0.2,0.4) vs high dose 0.28(0.26,0.45) p; 0.513]. There was no correlation found between the dose of Lthyroxine and STI (r=0.244 , p;0.526). Conclusion: Administration of high dose Lthyroxine did not significantly alter STI despite significant increment of fT4 level unlike the naturally occurring thyrotoxicosis.Therefore ‘exogenous’ administration of high dose L-thyroxine is cardiac safe.

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QUINIDINE PROLONGS SYSTOLIC TIME INTERVAL

InPharma ◽

10.1007/bf03285044 ◽

1977 ◽

Vol 79 (1) ◽

pp. 15-15

Keyword(s):

Time Interval ◽

Systolic Time Interval ◽

Systolic Time

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Utility of M-Mode Echocardiography for Early Identification of Infants with Persistent Pulmonary Hypertension of the Newborn

PEDIATRICS ◽

10.1542/peds.68.4.515 ◽

1981 ◽

Vol 68 (4) ◽

pp. 515-525 ◽

Cited By ~ 1

Author(s):

Lilliam M. Valdes-Cruz ◽

Golde C. Dudell ◽

Angelo Ferrara ◽

Barbara J. Nickles

Keyword(s):

Pulmonary Hypertension ◽

Pulmonary Disease ◽

Early Identification ◽

Clinical Deterioration ◽

Persistent Pulmonary Hypertension ◽

Time Interval ◽

Ejection Time ◽

Systolic Time Interval ◽

Systolic Time ◽

Ventricular Ejection Time

The clinical syndrome of persistent pulmonary hypertension of the newborn (PPHN) still carries high mortality in spite of improved neonatal care. The purpose of this prospective study was to assess the utility of M-mode echocardiography for the early identification of infants with PPHN prior to clinical deterioration. Echocardiograms of 51 infants who needed fractional inspiratory oxygen (FIO2) ≥0.25 to maintain adequate Pao2 within 36 hours of life were compared to those of 115 healthy full-term and preterm newborns. Of the 51 infants, ten had elevated systolic time interval ratios of both ventricles simultaneously (ventricular pre-ejection period to ventricular ejection time [RPEP/RVET ≤0.50, LPEP/LVET ≤0.38J]). All of these newbrns had PPHN that was manifest clinically by 11 to 30 hours of age. The echocardiographic findings preceded clinical deterioration by at least one to five hours in all cases. The other 41 infants had clinical courses consistent with uncomplicated pulmonary disease. These data indicate that systolic time interval ratios, although not accurate measures of pulmonary arterial pressure and/or pulmonary vascular resistance, permit early identification of infants with PPHN and separation from others with uncomplicated pulmonary disease.

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Systolic Time Interval Characteristics in Children with Duchenne's Progressive Muscular Dystrophy

PEDIATRICS ◽

10.1542/peds.70.6.958 ◽

1982 ◽

Vol 70 (6) ◽

pp. 958-964

Author(s):

Shyamal K. Sanyal ◽

Ralph C. Tierney ◽

P. Syamasundar Rao ◽

Samuel E. Pitner ◽

Stephen L. George ◽

...

Keyword(s):

Heart Rate ◽

Muscular Dystrophy ◽

Normal Control ◽

Left Ventricular ◽

Time Interval ◽

Systolic Time Interval ◽

Control Subjects ◽

Systolic Time ◽

Ventricular Ejection Time ◽

Duchenne's Muscular Dystrophy

Systolic time interval (STI) characteristics of 17 boys with Duchenne's muscular dystrophy (DMD) were compared with those of 80 normal boys who served as control subjects. The heart rate decreased linearly with age in normal control subjects (r = -.47, P < .01). By contrast, heart rate was significantly higher in patients with DMD (P <.001) and tended to increase further with age. Each STI variable for normal control subjects increased significantly with age (P ≤ .01); QII, left ventricular ejection time (LVET), and pre-ejection period (PEP), in addition, decreased with increasing heart rate (P ≤ .05). In dystrophic patients QII and LVET decreased with increasing heart rate (P < .001) but were not influenced by age. None of the other STI values in dystrophic patients was significantly influenced by either age or heart rate. Mean QII, LVET, and QI were shorter and PEP, isometric contraction time (ICT), and PEP/LVET ratio were longer (P < .001) for DMD patients than for normal control subjects. In 13/17 patients, QII and LVET were below the 95% confidence interval of the normal mean, whereas PEP, ICT, and PEP/LVET exceeded the upper limits of normal in 8, 9, and 11 patients, respectively. For dystrophic patients, the difference (Δ) between the observed values and those predicted from regression equations for normal control subjects was lower for QII, LVET, and QI (P < .01) but higher for PEP (P < .04), ICT, and PEP/LVET ratio (P < .001). Δ QII and Δ LVET increased with age (P = .001 and .032, respectively). Duchenne's muscular dystrophy is thus documented to be associated with substantial alterations in STI characteristics that suggest a compromise of global left ventricular performance. Some of these abnormalities increase with age, probably reflecting the progressive cardiomyopathy characteristic of this disease.

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