Left Ventricular Ejection Rate Research Articles

94 SYSTOLIC LEFT VENTRICULAR AND AORTIC BLOOD FLOW RE-Q4 SPONSE TO INCREASING SYSTEMIC VASCULAR RESISTANCE

Classical indices of myocardial performance may be insensitive to changes in myocardial reserve when native afterload is reduced The objective of this study was to examine the response of left ventricular and regional aortic blood flow to changes in systemic vascular resistance(SVR) in a canine model using combined gated pulsed doppler echocardiography(GPDE) and a non-imaging cardiac probe(NICP). SVR was augmented by continuous methoxamine infusion and calculated by standard thermodilution techniques in 5 animals (3-5kg). Aortic blood flow was evaluated by GPDE interrogation of the thoracic aorta. Systolic aortic blood flow was described by the mean velocity and the frequency time integral partitioned into the first and latter two-thirds of systole. The left ventricular ejection rate and stroke volume were measured simultaneously by NICP. Increasing SVR resulted in a pansystolic reduction in the mean ejection rate of the left ventricle and mean systolic aortic flow velocity. A normal reciprocal relationship was present for the first and latter two-thirds of left ventricular and aortic systolic blood flow as measured by percent change of stroke volume. This baseline relationship persisted with increasing SVR. In conclusion, combined GPDE and NICP can provide an effective means to noninvasively evaluate left ventricular performance and regional aortic blood flow changes with augmentation of afterload.

Immediate hemodynamic effects of a dopamine-receptor agonist (fenoldopam) in patients with essential hypertension.

Systemic, splanchnic, and renal hemodynamics, intravascular volume, and reflexive and endocrine changes were measured before and after a single dose of fenoldopam, a novel antihypertensive agent that acts through stimulation of specific dopamine receptors. A 13% reduction in mean arterial pressure was mediated by a fall in total peripheral resistance association with an increase in cardiac index, heart rate, stroke volume, left ventricular ejection rate, and circumferential fiber shortening. Renal blood flow increased, thereby reducing the renal vascular resistance by more than 40%. In contrast, splanchnic hemodynamics failed to change. Likewise, there were no changes in intravascular volume, plasma renin activity, or norepinephrine, serum aldosterone, or prolactin levels.

Hypertrophic obstructive cardiomyopathy. Effects of acute and chronic verapamil treatment on left ventricular systolic and diastolic function.

Changes in left ventricular systolic and diastolic function and outflow gradient were evaluated in patients with obstructive hypertrophic cardiomyopathy after intravenous acute treatment with verapamil (15 patients) and after six months of oral chronic treatment (11 patients). All patients had severe symptoms despite beta blockade, and the condition of all but two improved appreciably after chronic treatment with verapamil. Resting left ventricular outflow tract gradient decreased in six of 15 patients after intravenous verapamil, and in five of 11 patients after long term treatment, but there was no change in provocable gradients nor any correlation between changes in gradient and improvement in symptoms. Left ventricular ejection rate did not change after intravenous or oral treatment. End systolic pressure/end systolic volume index remained unchanged after oral verapamil treatment. Whereas left ventricular total stroke volume index and end diastolic volume index increased without any significant change in left ventricular end diastolic pressure, indicating improved left ventricular diastolic function. In some patients the left ventricular diastolic pressure-volume curve shifted downwards or to the right or both. These findings suggest that improvement in symptoms with verapamil in patients with obstructive hypertrophic cardiomyopathy is unlikely to be related to changes in left ventricular outflow gradient or in systolic function and may be related to improved diastolic function.

Effects of dobutamine on left ventricular performance and myocardial metabolic demands in patients with ischemic heart disease.

Sixteen patients with coronary artery disease undergoing cardiac catheterization were studied. Eleven had previous infarcts and the patients were divided into two groups: In group I were 7 patients with no left ventricular dysfunction, no increase in ventricular size, or symptoms of congestive failure; group II included 9 patients with ventricular dysfunction, increased ventricular size, and 7 of the 9 had congestive failure. Each patient underwent a continuous infusion of dobutamine from 2.5 to 10 micrograms/kg min-1 with dosage increments of 2.5 micrograms/kg at 15-minute intervals. Systemic and coronary hemodynamic measurements were obtained at the end of the 5 and 10 micrograms/kg min-1 infusion doses. Left ventricular performance improved (higher cardiac index, left ventricular stroke work index and mean systolic ejection rate, and lower left ventricular end-diastolic pressure), while heart rate, mean arterial pressure, and coronary sinus blood flow increased after dobutamine in the 16 patients. While patients in both groups had a rise in cardiac index, a reduction in left ventricular end-diastolic pressure, an unchanged mean arterial pressure and a rise in coronary blood flow, only patients in group I had a significant increase in heart rate, and only patients in group II had significant increases in left ventricular stroke work index and mean systolic ejection rate, and a significant reduction in systemic vascular resistance. Left ventricular oxygen consumption did not increase significantly in either group. However, 5 patients showed a decreased myocardial lactate extraction after 10 micrograms/kg min-1 of intravenous dobutamine, 3 from group I and 2 from group II.(ABSTRACT TRUNCATED AT 250 WORDS)

Immediate hemodynamic effects of a new calcium-channel blocking agent (nitrendipine) in essential hypertension

The immediate hemodynamic effects of a new calcium-channel blocking agent nitrendipine were studied in 12 patients with mild established essential hypertension. According to the response to mean arterial pressure, patients were classified into responders (decrease greater than 10 mm Hg, 7 patients) and nonresponders (less than or equal to 10 mm Hg, 5 patients). The decrease in arterial pressure in responders was associated with a significant (p less than 0.01) decrease in total peripheral resistance and a significant (p less than 0.05) increase in heart rate, cardiac index, and left ventricular ejection rate. The plasma norepinephrine level was significantly (p less than 0.05) increased in the responders. The response to upright tilt was qualitatively similar to pretreatment values. Thus, nitrendipine lowered arterial pressure as a result of arteriolar dilatation associated with a reflexive increase in heart rate and cardiac index. These hemodynamic properties make the drug particularly apt for use in combination with beta-adrenergic blockade for the treatment of arterial hypertension.

Hemodynamic effects of a new antiarrhythmic agent, flecainide (R-818), in coronary heart disease

The hemodynamic effects of flecainide acetate, a new class I antiarrhythmic agent, were studied in 10 patients with coronary heart disease. The drug was injected intravenously at a dose of 2 mg/kg over 30 minutes. The mean drug plasma level achieved was 394 ng/ml (range 329 to 470). The heart rate did not change, but a significant increase (p less than 0.001) in P-R (+17%), QRS (+15%), and Q-T (+7%) duration occurred after drug administration. Negative inotropic effects also were observed and consisted of an increase (p less than 0.01) in pulmonary wedge pressure (+27%) and a decrease (p less than 0.01) in stroke index (-10%), left ventricular stroke work index (-12%), and left ventricular ejection rate (-11%). No significant change in mean aortic pressure or systemic and pulmonary vascular resistance occurred. Left ventriculography performed after drug infusion revealed a significant increase (p less than 0.01) in systolic volume (+9%) and a decrease in ejection fraction (-9%) and mean velocity of circumferential fiber shortening (Vcf) (-13%). A progressive and significant decrease of dP/dt was observed during drug infusion, but 15 minutes after the injection, dP/dt had returned to near basal values. Thus, flecainide acetate has slight, but significant negative inotropic effects, particularly conspicuous during drug infusion. The drug should be administered with caution in patients with poorly compensated heart.

The Influence of Cycle Length on the Radionuclide Left Ventricular Volume Curve Acquired with a Scintillation Camera and ECG-Triggered Data Processor

This study was designed to evaluate the effect of cycle length on the parameters of left ventricular function such as left ventricular ejection fraction (LVEF), ejection rates and ejection times. Radionuclide (in vivo 99mTc-labelled red blood cells) volume curves were obtained from ten chacma baboons. Transoesophageal atrial pacing of the baboon hearts was controlled by a microcomputer. A sequence of four beats was generated during arrhythmic pacing, consisting of two beats of equal cycle lengths, followed by a beat 15% shorter and a subsequent beat after a compensatory pause. Triggering impulses were sent to the data processor coincident with one of these beats until sufficient counts were obtained, before advancing to the next beat. Global LVEFs were found to be influenced by the preceding cycle length, increasing on a previous long cycle and decreasing on a previous short cycle and were even found to be influenced one normal beat on from the unrepresentative cycle. Similar trends were found for ejection times and rates. Discarding specific unrepresentative cycle lengths in order to correct for arrhythmia without attention to the previous cycle and even to the following cycle is therefore inappropriate.

Effect of habitual exercise on left ventricular response to exercise.

To evaluate the effects of chronic physical exercise on left ventricular ejection fraction (LVEF) and ejection rate (LVER), radionuclide angiography was performed at rest and during upright-bicycle exercise in 45 healthy men. The subjects varied widely in exercise habits and working capacity. They were divided into three subgroups on the basis of habitual physical activity. Aerobic training was done more than 7, 2-4, and less than 1 h/wk by subgroups of athletes, trained, and untrained men, respectively. The results indicate marked differences in work capacity (298, 233, and 181 W in the athletes, trained, and untrained groups, respectively). Resting LVEF (72, 69, and 68%) and LVER (4.1, 3.4, and 3.6 s-1) were not significantly different among the groups. With maximal exercise, however, small but statistically significant differences in LVEF (75, 69, and 68%; P less than 0.05 athletes vs. trained and athletes vs. untrained) and in LVER (7.5, 6.3, and 5.2 s-1; P less than 0.05 among all groups) were observed. Work capacity was, however, poorly correlated with exercise LVEF (r = 0.18) and LVER (r = 0.47). The results of this study indicate that the enhanced working capacity observed secondary to increases in habitual physical activity can be attributed to differences in LVEF and LVER only in the most general terms. Accordingly the results agree with previous suggestions based primarily on echocardiographic data that the primary cardiac adaptation to exercise is dimensional rather than functional in character.

Left ventricular function at rest, peak exercise and postexercise.

To determine whether the temporal sequence of imaging could influence the results of exercise radionuclide angiography, 15 healthy volunteers were studied at rest, during peak bicycle exercise and immediately postexercise using first pass radionuclide angiography. Responses at rest, peak and postexercise included: heart rate (67 to 174 to 170 bpm), double product (7.4 to 31.5 to 27.5 mm Hg X bpm X 10(3)), left ventricular ejection fraction (68 to 69 to 80%) and mean normalized left ventricular ejection rate (3.63 to 6.56 to 8.56 s-1). The results indicate that left ventricular ejection fraction and mean normalized ejection rate were different during exercise and immediately postexercise although heart rate and double product were not. The results indicate that the temporal sequence of imaging is a significant procedural variable in the conduct of exercise radionuclide angiography.

Left ventricular function during sudden strenuous exercise.

Strenuous exercise without warm-up has been shown to produce ischemia-like electrocardiographic (ECG) abnormalities in 60-70% of healthy subjects. These abnormalities appeared to be related to the development of an unfavorable myocardial supply/demand balance and, in chronically instrumented dogs, to transient decreases in coronary blood flow. A mechanism involving subendocardial ischemia has been proposed to explain the response to sudden strenuous exercise (SSE). To determine whether the response to SSE included the development of changes in myocardial pump performance typical of ischemia, left ventricular (LV) function at rest, during graded exercise and during SSE was evaluated in nine young (26.6 +/- 3.4 years), well-trained male volunteers using first-pass radionuclide angiography. During graded exercise, the LV ejection fraction increased from 66.9 +/- 9.4% at rest to 73.0 +/- 7.1% during peak exercise, and the LV ejection rate increased from 3.36 +/- 0.67 sec-1 at rest to 6.58 +/- 1.10 sec-1 during peak exercise. Segmental wall motion was normal in all studies. During SSE, the LV ejection fraction decreased in very subject, from an average 72.2 +/- 8.6% at rst to 57.3 +/- 8.1% during exercise. The LV ejection rate remained relatively constant (3.98 +/- 0.92 sec-1 at rest vs 4.33 +/- 0.74 sec-1 during SSE). No segmental wall motion abnormalities were observed during SSE; however, LV wall motion appeared to be diffusely hypokinetic during SSE. In contrast to previous reports, few ECG abnormalities were observed during SSE. These results support the hypothesis that subendocardial ischemia is an important mechanism in the response to SSE. However, the lack of ECG changes and segmental wall motion abnormalities and the relatively high absolute value of the LV ejection fraction suggest that if subendocardial ischemia occurs during SSE, it is attributable to physiologic rather than pathologic mechanisms.

Left ventricular ejection rate during the first third of systole in patients with aortic insufficiency

Left ventricular ejection rate during the first third of systole in patients with aortic insufficiency

Hemodynamic correlates of autonomic reflexes in patients with labile and fixed hypertension.

the autonomic sympathetic reflexes to sustained handgrip, upright tilt and the Valsalva maneuver, were tested in 26 patients with labile and 26 with fixed essential hypertension. Sustained handgrip increased systolic (SAP), diastolic (DAP) and mean arterial (MAP) pressure, heart rate (HR), cardiac index (CI), tension time index (TTI) (p less than .01), and had no effect on total peripheral resistance index (TPRI) and left ventricular ejection rate index (LVERI) in both groups of patients. However, the response to upright tilt and the Valsalva maneuver was different in the two groups. Upright tilt in labile hypertensives increased DAP, MAP, HR, and TPRI (p less than .001); decreased CI, stroke index (SI) and LVERI (p less than .01) and had no effect on SAP. In fixed hypertensives, it decreased SAP, MAP, CI, SI and LVERI (p less than .001); increased HR (p less than .01) and had no effect on DAP, and TPRI. The diastolic pressure overshoot of the Valsalva maneuver was attenuated in fixed hypertensives compared to labile (p less then .001). Additionally, when the percent changes from control in DAP, MAP, HR and TPRI to sustained handgrip and upright tilt between the two groups were compared, only differences to upright tilt between the two groups were observed. The results of this investigation suggest that upright tilt and the Valsalva maneuver might serve as better predictors of autonomic reflexes in hypertensive patients than the grip test.

Abnormal left ventricular relaxation in hypertensive patients.

1. The maximum rates of left ventricular ejection and filling were derived (Fourier analysis) from the left ventricular volume curve (99m technetium-human serum albumin gated blood pool studies) in 12 normotensive subjects and 15 hypertensive patients of matched age groups. 2. Average values of cardiac output, ejection fraction, heart rate and left ventricular ejection rate were not significantly different in the two groups. 3. Hypertensive patients had a slower rate of left ventricular filling (P < 0.05), suggesting diminished left ventricular compliance in hypertension.

Comparison of multigated radionuclide angiography with ultrasonic sonomicrometry over a wide range of ventricular function in the conscious dog

This study compared the noninvasive assessment of left ventricular function with radionuclide angiography with that obtained with ultrasonic sonomicrometry. Left ventricular ejection fraction and rate of ventricular ejection (dV/dt) were measured with both techniques over a wide range of ventricular function. Six dogs were prepared with epicardlal crystals across the major and minor axes of the left ventricle, paired transmural wall thickness crystals and a left ventricular catheter. The animals were studied while awake after they had recovered from operation. Left ventricular volume was calculated from the ultrasonic sonomicrometric dimension measurements and the equation for a prolate ellipsoid; dV/dt was calculated from the stroke volume and ejection time. Radionuclide angiograms were performed using technetium-99m-labeled red blood cells and an Anger camera with a converging collimator interfaced to a computer programmed for multigated acquisition. A wide range of ventricular function was produced with sequential infusion of isoproterenol, propranolol, phenylepnrine and sodium thiamylal. Ejection fraction and dV/dt were measured simultaneously during each intervention using the time-activity curves of the multigated radionuclide anglogram and ultrasonic sonomicrometric dimensions. Regression analyses demonstrated a close correlation between the simultaneous measurements of ejection fraction (r values ranged from 0.95 to 0.99) and dV/dt (r values ranged from 0.87 to 0.99). these data indicate that noninvasive multigated radionuclide angiography accurately assesses changes in ejection fraction and dV/dt over a wide range of ventricular function.

Inter-observer variation in estimates by nuclear angiography of left ventricular ejection fraction and ejection rate

The recent decline in the cost of computing has led to the introduction of data processing of gammacamera images in many medical centres, allowing the development and widespread use of radionuclide techniques for assessing left ventricular performance. Methods such as ECG-gated blood-pool imaging have the advantage of being much less invasive than contrast ventriculography and do not rely on geometrical assumptions about the shape of the ventricle. However, Walton et al. (1978) suggested that the analysis of these images is prone to considerable variability. This paper presents a study of the interobserver variation in estimates of ejection fraction (EF) and average and maximum systolic contraction rates using a micro-computer* to analyse gated blood-pool images of the left ventricle. Following an intravenous injection of 740 MBq (20 mCi) of technetium-labelled human serum albumin, patients were positioned under a gamma camera† in the 30° left anterior oblique position with a 10° caudal tilt. The patient'...

Nucleid-angiographic calculations of left ventricular end-diastolic pressure, pulmonary capillary pressure and diastolic pulmonary pressure (author's transl)

Proper of cardiac nucleid-angiography provides parameters which are comparable to those obtained by invasive procedures. Although various methods have been devised for determining left ventricular ejection rate and the geometric analysis of the left ventricle by isotope techniques (Adam 2-5), Ashburn (6, 7), Breuel (11, 12), Strauss/Bill, Strauss/Pitt (65, 66, 67), only a few comparative intra-cavitary pressure measurements are available. Of these, the method developed by de Vernejoul (73 to 76) is of particular importance for measurements during the bolus phase because of the large number of cases studied by simultaneous catheterisation (670 patients). The value of de Vernejoul's formula was confirmed by a study of 350 of our own cases. The disadvantage of the method lies in its susceptibility to variations in the bolus front. We have therefore attempted for some time to obtain pressure measurements by a pooling procedure.

A comparison of simultaneous measurements of systolic function in the baboon by electromagnetic flowmeter and high frame rate ECG-gated blood pool scintigraphy.

Left ventricular (LV) systolic timing and relative volume variations were simultaneously measured by electromagnetic flowmeter (EMF) and high frame rate ECG-gated blood pool scintigraphy in five baboons. No significant differences (p greater than 0.1, paired t test) were observed in the time (from R wave) to peak aortic flow (maximum LV ejection rate), time to cessation of aortic flow (end-systole) or in the duration of aortic flow (LV ejection time). A small (approximately 15 msec) but significant systematic difference (p less than 0.02) was noted in the time to onset of aortic flow. The shape of each scintigraphic time-activity curve during systole was compared to an equivalent curve synthesized from 10 EMF flow profiles obtained in the same baboon. Comparison of these paired curves over systolic ejection yielded an average correlation or r = 0.95 (range 0.90--0.99). The ratio of peak flow to stroke volume determined from these data did not differ significantly (p greater than 0.05). In the baboon, quantitative high temporal resolution ECG-gated scintigraphy appears to reflect closely the detailed timing and relative magnitude variation of LV volume during the entire period of systolic ejection. We conclude that the assumptions underlying the scintigraphic method are valid in the baboon during the ejection interval.

Pre- and postoperative hemodynamic and cineangiocardiographic assessment of left ventricular function in patients with aortic regurgitation

Hemodynamic and angiocardiographic analysis was performed prior to and 14 months on the average following valve replacement in 11 patients with severe, isolated, pure, chronic aortic regurgitation. The aortic diastolic pressure, reduced prior to surgery, reverted to normal as did the cardiac index. Left ventricular filling pressure, elevated prior to surgery, returned to normal while aortic systolic pressure did not vary substantially. The markedly increased stroke volume returned to normal as did the net left ventricular stroke work. Left ventricular end-diastolic and end-systolic volumes, also markedly elevated, decreased but did not return to normal levels. The shape of the left ventricle, which was more spherical than normal during end-systole prior to surgery, as evidenced by the decrease in the systolic axis ratio, reverted to normal. The ejection fraction, severely reduced before surgery, increased moderately (46 ± 13 vs 51 ± 19 per cent) as did the extent of circumferential fiber shortening (δD) (21 ± 8 vs 27 ± 12 per cent). The mean velocity of fiber shortening ( VCF ) increased significantly (0.68 ± 0.2 vs 1.03 ± 0.47 circ./sec.), as did the mean left ventricular ejection rate (1.32 ± 0.48 vs 1.91 ± 0.76). Comparative analysis of the evolution of left ventricular function indices and of extramyocardial factors (end-diastolic fiber stretching and impedance to ejection) showed that whereas in some cases myocardial damage appeared to be irreversible, in others dramatic improvement sometimes occurred following surgery. It was not possible, however, to determine the threshold below which the damage was irreversible. It may therefore be concluded that in some patients with severe regurgitation attended by profound myocardial insufficiency, correction of the valvular defect could produce not only clinical and hemodynamic improvement, but also improvement in myocardial contractile status.

Global and regional left ventricular response to bicycle exercise in coronary artery disease: Assessment by quantitative radionuclide angiocardiography

The left ventricular response to bicycle exercise was evaluated in 60 patients with coronary artery disease and in 13 normal control subjects. Left ventricular ejection fraction, mean normalized ejection rate and regional wall motion were determined using first-pass radionuclide angiocardiograms obtained at rest and again during peak graded bicycle exercise. All normal subjects demonstrated improved left ventricular function with exercise. Left ventricular ejection fraction increased significantly from 67 ± 3 per cent (mean ± SE) at rest to 82 ± 4 per cent with exercise (p < 0.001). Similarly, the left ventricular ejection rate increased significantly from 3.47 ± 0.31 sec −1 to 6.53 ± 0.42 sec −1(p < 0.001). In contrast, in 44 of 60 patients with coronary artery disease, the ejection fraction or ejection rate either decreased or remained the same with exercise. New or exaggerated regional wall motion abnormalities were detected in 28 of 60 patients with coronary artery disease. Over-all, global or regional evidence of compromised left ventricular reserve was found in 48 of 60 patients with coronary artery disease. The major determinant of an abnormal left ventricular response to exercise was the presence or absence of electrocardiographic evidence of myocardial ischemia. Left ventricular ejection fraction decreased or remained the same with exercise in all patients with coronary artery disease and electrocardiographic ischemia. New regional wall motion abnormalities were detected in 20 of these patients. In this group, the left ventricular ejection fraction decreased from 66 ± 2 per cent at rest to 58 ± 2 per cent with exercise (p < 0.001), whereas the ejection rate was unchanged by exercise (rest 3.33 ± 0.21 sec −1; exercise 3.34 ± 0.22 sec −1, p > 0.05). Of the 30 patients with coronary artery disease who exercised to symptom-limiting fatigue without electrocardiographic ischemia, 18 demonstrated compromised left ventricular reserve with exercise. Twelve of the remaining patients with coronary artery disease had normal left ventricular reserve, in eight of whom ventricular function was completely normal both at rest and during exercise. In this group exercised to fatigue, the left ventricular ejection fraction increased from 53 ± 4 per cent at rest to 58 ± 2 per cent with exercise (p < 0.001). The ejection rate also increased from 2.48 ± 0.24 sec −1 to 3.67 ± 0.39 sec −1 (p < 0.001). The direction and magnitude of the left ventricular responses to exercise were not affected by long-term oral propranolol administration in 22 patients. Based upon either abnormal exercise left ventricular reserve or abnormal global and regional left ventricular function at rest, the over-all sensitivity of this radionuclide technic for the detection of coronary artery disease was 87 per cent (52 of 60 patients). These data demonstrate that exercise ventricular performance studies provide important physiologic insights into left ventricular functional reserve as well as a sensitive noninvasive approach for the detection of coronary artery disease.

Effects of aminophylline upon right and left ventricular performance in chronic obstructive pulmonary disease: Noninvasive assessment by radionuclide angiocardiography

Although aminophylline is a widely used bronchodilator in chronic obstructive pulmonary disease (COPD), its effects upon cardiac performance have not been fully established. The effect of aminophylline upon right ventricular and left ventricular ejection fraction and the left ventricular ejection rate was evaluated by first-pass quantitative radionuclide angiocardiography in 15 patients with COPD, including four with cor pulmonale, and in five control subjects without cardiopulmonary disease. Aminophylline infusion (9 mg/kg) significantly increased the right ventricular ejection fraction (45 to 52 per cent), left ventricular ejection fraction (60 to 67 per cent) and left ventricular ejection rate (3.4 to 4.1 sec −1) in patients with COPD (all parameters, p < 0.001). In six of eight patients with depressed control right ventricular performance, right ventricular ejection fraction normalized and in two of five patients with depressed control left ventricular performance, the left ventricular ejection fraction and left ventricular ejection rate normalized. In control subjects, comparable increases were noted in the right ventricular ejection fraction (50 to 56 per cent), left ventricular ejection fraction (62 to 71 per cent) and left ventricular ejection rate (3.2 to 4.6 sec −1) (p < 0.001). One-second forced expiratory volume (FEV 1) and forced vital capacity (FVC) increased significantly in patients with COPD but not in control subjects. Arterial carbon dioxide tension decreased significantly in both groups (p < 0.05), whereas arterial oxygen tension did not change. Theophylline blood levels did not correlate with absolute increases in right ventricular or left ventricular ejection fraction. These data indicate that aminophylline acutely enhances biventricular performance in COPD. Since comparable cardiovascular changes are induced in normal subjects in whom ventilatory function was not altered, the beneficial effects of aminophylline upon global ventricular performance appear to be independent of the degree of pulmonary compromise.