Tatsuji Naito

Evaluation of Right-Ventricular Function by Doppler Echocardiography in Patients with Chronic Respiratory Failure

In patients with chronic respiratory failure, right-ventricular function was non-invasively evaluated by Doppler echocardiography. A total of 31 patients (16 men, 15 women; mean age 65.8 ± 7.12 years) with pulmonary tuberculosis sequelae who had received home oxygen therapy during the preceding 6 or more months, were studied. Right-ventricular inflow and outflow waveforms were recorded, and right-ventricular function was evaluated using a new Doppler index combining systolic and diastolic function. On continuous wave Doppler echocardiography, estimated systolic pulmonary arterial pressure was calculated from the gradient between the right atrium and right ventricle. There was no correlation between the new Doppler index and systolic pulmonary arterial pressure, and some patients showed high index values despite low systolic pulmonary arterial pressure. The new Doppler index facilitated evaluation of ventricular function irrespective of right-ventricular afterload.

Left Ventricular Mass and Global Function in Essential Hypertension after Antihypertensive Therapy

This study compares left ventricular global function in 55 patients (25 with hypertrophy and 30 without hypertrophy) with essential hypertension, whose blood pressure had been stable for longer than 1 year, with that in 35 healthy subjects. Left ventricular global function was calculated using the echocardiographic Doppler index as described by Tei et al. (Tei index). No significant differences were observed in echocardiographic left ventricular systolic function between the three groups. Left ventricular global function differed significantly between the three groups, however, suggesting impaired left ventricular global function even in the absence of left ventricular hypertrophy. Similar changes were observed in the ratio of peak velocity of atrial systole to peak velocity of early diastole during left ventricular inflow waveform (A/E), indicating that this disorder mainly reflects impaired left ventricular diastolic function. Unlike A/E, the Tei index is not affected by increasing age, and, therefore, is appropriate for evaluating left ventricular global function in hypertensive patients, most of whom are middle-aged or older. This index may be useful for determining treatment strategy and evaluating treatment effects.

Monitoring of Nocturnal Oxygen Desaturation Using Pulse Oximeter and Apnomonitor in Patients with Chronic Pulmonary Disease

The relationship between the degree of nocturnal oxygen desaturation (NOD) and pulmonary hemodynamics, pulmonary function tests, and resting awake blood gases was evaluated in patients with chronic pulmonary diseases (CPD). The severity of NOD correlated with the degree of impairment of pulmonary hemodynamics, but not with pulmonary function tests or resting awake blood gases. NOD was markedly alleviated by oxygen inhalation in CPD patients who did not develop sleep apnea.

Ventilatory and pulmonary vascular responses to acute hypoxia are nonuniform in healthy man

The present study was undertaken to examine the pulmonary vascular and ventilatory responses to acute hypoxia in healthy individuals. Pulmonary hemodynamics and minute ventilation (VE) were serially measured during inhalation of 13% O2 for 15 min. There was a wide variability in the pulmonary vascular response to acute hypoxia, and a significant negative correlation between the initial increase in VE after the start of hypoxia (delta VE) and the percent increase in mean pulmonary arterial pressure (r = -0.646; p < 0.01). The fall in arterial oxygen tension significantly decreased in response to an increase in delta VE. These results support the view that a blunted ventilatory response to acute hypoxic stimulation enhances alveolar hypoxia, thereby favoring the constriction of pulmonary vasculature. Thus, our results suggest that the ventilatory response to acute hypoxia plays a significant role in the pulmonary vascular response to acute hypoxia.

Pulsed Doppler Echocardiographic Assessment of Changes in Pulmonary Artery Pressure during Oxygen Breathing

To validate the use of pulsed Doppler echocardiography in detecting changes in pulmonary artery pressure (PAP), several parameters of flow velocity profiles of the right ventricular outflow tract were compared with changes in PAP and pulmonary vascular resistance measured directly by cardiac catheterization. The study was performed in 33 patients with chronic pulmonary disease (chronic obstructive pulmonary disease or pulmonary fibrosis) or pulmonary thromboembolism, during room air and 100% oxygen breathing. Inhalation of 100% oxygen for 15 min significantly reduced PAP in patients with mild pulmonary hypertension (20 < or = mean PAP < or = 24 mm Hg; control: 21.3 +/- 1.3, O2: 17.9 +/- 2.2 mm Hg, p < 0.05) and those with severe pulmonary hypertension (mean PAP > or = 25 mm Hg; control 44.9 +/- 16.8, O2: 35.4 +/- 13.5 mm Hg, p < 0.05). It also significantly reduced the pulmonary vascular resistance and cardiac output in both groups. The ratio of acceleration time to right ventricular ejection time (AT/RVET), a parameter measured by Doppler echocardiography, correlated significantly with mean PAP during room air (r = 0.73, p < 0.0001) and oxygen breathing (r = 0.64, p < 0.0001). Furthermore, AT/RVET increased significantly in patients with mild pulmonary hypertension and those with severe pulmonary hypertension. Our results suggest that the Doppler technique provides a clinically useful, noninvasive index for assessing changes in PAP during oxygen breathing in patients with pulmonary hypertension complicating chronic pulmonary disease or pulmonary thromboembolism.