Biomedical subjects

A N DeMaria

Publications and source records attributed to A N DeMaria.

At least 91 records · Page 5Linked to original sources

PubMed1992

Age and beta-adrenergic receptor sensitivity to S(-)- and R,S(+/-)-propranolol in humans.

The relationship between age and beta-adrenergic receptor sensitivity to the pharmacologically active S(-) enantiomer and the racemic mixture of propranolol was evaluated in 46 healthy male subjects (age range, 24 to 89 years). The in vivo apparent dissociation constants for S(-)- and R,S(+/-)-propranolol were determined on the basis of the unbound steady-state plasma concentration of each and the dose of isoproterenol needed to increase the heart rate of the subjects by 25 beats/min in the absence (I25) and then in the presence of a continuous propranolol infusion. The I25 was significantly correlated with age (r = 0.700, p less than 0.05). The apparent dissociation constant for S(-)- and R,S(+/-)-propranolol demonstrated a significant, although weak, increase with advancing age (r = 0.403 and r = 0.396, respectively; p less than 0.05). Although these findings confirm those of other studies, beta-receptor sensitivity to propranolol was only modestly decreased with age in this study.

Adult↗

PubMed1992

Stress Doppler echocardiography in the evaluation of ischemic heart disease.

Doppler echocardiography enables convenient, noninvasive evaluation of global, systolic performance at rest and during exercise. Early studies suggested that Doppler parameters of systolic function were sensitive to exercise-induced myocardial ischemia and could identify patients with severe coronary artery disease. Subsequent investigation, however, has identified several factors in addition to myocardial ischemia that can significantly influence exercise Doppler study results. Thus, in order to obtain reliable information, the many factors that can influence Doppler measurements of aortic flow velocity and acceleration must be accounted for. Further work in this area is likely to produce results that encourage greater application of this technique in experimental and clinical research. At present, the role of stress Doppler echocardiography in the evaluation of ischemic heart disease remains uncertain.

Coronary Disease↗

PubMed1991

Midventricular obstruction associated with chronic systemic hypertension and severe left ventricular hypertrophy.

Midventricular obstruction is an uncommon finding previously defined by catheterization and angiographic techniques in patients with hypertrophic cardiomyopathy. This study describes the clinical and echocardiographic findings of 10 consecutive patients (mean age 73 years) with severe concentric left ventricular (LV) hypertrophy and the unusual finding of a dynamic systolic obstruction located in the midportion of the left ventricle. All patients were known to have chronic hypertension, and none had a history or family history of hypertrophic cardiomyopathy. In each case, a well-defined, high velocity, turbulent jet was identified by Doppler color flow imaging and subsequently confirmed with conventional Doppler techniques. Septal and posterior wall thickness averaged 1.67 and 1.57 cm, respectively. Mean LV mass index was 199 g/m2 and ejection fraction averaged 78%. Peak systolic velocity obtained by continuous-wave Doppler averaged 2.7 m/s and appeared as either a "late-peaking" or a "spike and dome" configuration. Seven of 10 patients gave a history of syncope or severe presyncope at the time of echocardiographic examination. At a mean follow-up of 1 year, syncope or presyncope had resolved in 5 patients in whom medication was adjusted based on the ultrasound study, but persisted in 2 patients in whom diuretic therapy was continued. It is concluded that obstruction to systolic flow can occur at the mid-LV level in some patients with severe concentric LV hypertrophy and avoidance of medication known to lower LV volume may relieve symptoms of transient inadequate cardiac output.

Aged↗

PubMed1991

Effect of heart rate on left ventricular diastolic transmitral flow velocity patterns assessed by Doppler echocardiography in normal subjects.

Although a number of factors, including age and ventricular loading, are known to influence the pattern of left ventricular (LV) filling as depicted by Doppler echocardiographic transmitral flow velocities, few and conflicting data are available regarding the influence of heart rate (HR). Therefore, 20 volunteers (mean age 30 years) were evaluated with pulsed-wave Doppler echocardiography, performed with the sample volume placed at the mitral anulus level in the apical 4-chamber projection. Transmitral flow measurements comprised peak and integrated early passive (E) and late atrial (A) filling velocities and the slope of velocity decline from peak E filling. Measurements were recorded during baseline (sinus rhythm, mean 70 beats/min) and during transesophageal atrial pacing (mean 88 beats/min). LV end-diastolic dimension, mean arterial pressure and PR interval (corrected for pacing-induced delay in interatrial conduction time) were unchanged during pacing versus baseline measurements. Peak and integrated E filling velocities averaged 0.59 +/- 0.09 m/s and 6 +/- 1 cm, respectively, at baseline and were not significantly greater at the higher HR. In contrast, baseline peak and integrated A velocities averaged 0.37 +/- 0.06 m/s and 2.3 +/- 0.7 cm, respectively, but were significantly greater at the higher HR (0.5 +/- 0.07 m/s and 3.2 +/- 1.1 cm, respectively [p less than 0.003 vs baseline for each]). Further analysis of a subgroup of 9 subjects for whom Doppler measurements were available at 3 HRs (sinus 70; pacing 80 and 90) yielded strong evidence for a linear relation between HR and peak A velocity (A = 0.008 HR - 0.21, with p less than 0.0001 for significance of the linear trend).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

PubMed1991

Value and limitations of Doppler pressure half-time in quantifying mitral stenosis: a comparison with micromanometer catheter recordings.

The purpose of this study was to compare the Doppler and catheterization pressure half-time methods of estimating mitral valve area with valve areas obtained by the Gorlin equation in a group of patients with clinically significant mitral stenosis. Data were analyzed from 67 consecutive patients who were undergoing continuous-wave Doppler examination and catheterization with micromanometer catheters. Doppler pressure half-time was calculated as the interval between peak transmitral velocity and velocity divided by the square root of 2, as measured from the outer border of the spectral envelope. Doppler mitral valve area (MVA) was obtained with the equation: MVA = 220 divided by pressure half-time. For catheterization data, the pressure half-time was measured directly from simultaneously recorded left ventricular and left atrial pressure (18 patients) or pulmonary capillary wedge pressure (49 patients). The catheterization half-time was taken as the time required for the peak pressure gradient to fall to one half of the initial value. Calculations of the mitral valve area at catheterization were obtained by the Gorlin equation with pressure gradient and cardiac output determinations. Mitral valve area as determined by the Gorlin equation for all cases ranged from 0.4 to 2.0 (mean = 1.03 +/- 0.37) cm2. Linear regression analysis that compared cardiac catheterization and Doppler half-times yielded r = 0.68. For the subgroup of patients with sinus rhythm, the correlation improved to r = 0.76.(ABSTRACT TRUNCATED AT 250 WORDS)

Atrial Fibrillation↗

PubMed1991

Hemodynamic effects of calcium channel and beta-receptor antagonists: evaluation by Doppler echocardiography.

To evaluate the ability of Doppler echocardiography to identify hemodynamic changes due to cardiac medications, 10 volunteers underwent Doppler examination at rest and immediately following vigorous treadmill exercise. Upon completion of the control test, each subject received moderate oral doses of propranolol, verapamil, pindolol, or nifedipine, and the same exercise protocol was repeated. During four control tests, values for peak acceleration and flow velocity integral were similar for each subject at rest and exercise. Following propranolol and pindolol, resting acceleration fell by 4.5 and 2 m/sec2, respectively p less than 0.05. Resting acceleration was unchanged by verapamil and increased following nifedipine by 1.7 m/sec2 (p less than 0.0001), but neither verapamil nor nifedipine altered either Doppler parameter. Flow velocity integral was increased by nifedipine at rest and by each of the beta-blockers during exercise (p less than 0.05). We conclude that (1) rest and exercise Doppler measurements are stable and reproducible, given stable cardiovascular status; (2) pindolol produced less hemodynamic depression as measured by Doppler echocardiography at rest relative to propranolol, but showed similar potency at maximal exertion; (3) nifedipine enhanced global cardiac performance at rest, but neither calcium antagonist affected Doppler measurements during exercise; and (4) Doppler echocardiography is a useful, noninvasive technique for evaluating hemodynamic effects of medication at rest and during vigorous exercise.

Adrenergic beta-Antagonists↗

PubMed1991

Acute effects of parenteral beta-blockade on regional ventricular function of infarct and noninfarct zones after reperfusion therapy in humans.

Although the mechanism is unknown, clinical trials have suggested that intravenous beta-adrenergic blockade may prevent early cardiac rupture after myocardial infarction. Previous studies have examined effects of beta-blockers on global left ventricular function after myocardial infarction; however, few data exist regarding their immediate effects on regional function or in patients after successful reperfusion. Therefore, 65 patients in whom thrombolysis with or without coronary angioplasty achieved reperfusion at 4.6 +/- 1.7 h from symptom onset were studied. Low osmolarity contrast ventriculograms were obtained immediately before and after administration of 15 mg of intravenous metoprolol (n = 54) or placebo (n = 11). Intravenous metoprolol immediately decreased heart rate (from 92 to 76 beats/min, p less than 0.0001), increased left ventricular diastolic volume (from 150 to 163 ml, p less than 0.001) and systolic volume (from 72 to 77 ml, p less than 0.0005) but did not change systolic and diastolic pressures. Although there was no difference in ejection fraction after metoprolol, centerline chord analysis revealed reduced noninfarct zone motion (from 0.41 to 0.12 SD/chord, p less than 0.05), improved infarct zone motion (from -3.1 to -2.9 SD/chord, p less than 0.01) and smaller circumferential extent of hypokinesia (from 30 to 27 chords, p less than 0.05). Patients with dyskinesia of the infarct zone had the most striking improvement in infarct zone wall motion. Because these changes occurred immediately after beta-blockade, they could not be attributed to myocardial salvage. No significant changes in heart rate, left ventricular volumes or regional wall motion were apparent in the control group.(ABSTRACT TRUNCATED AT 250 WORDS)

Adrenergic beta-Antagonists↗

PubMed1991

Regurgitant jet size by transesophageal compared with transthoracic Doppler color flow imaging.

Combined echocardiography and Doppler color flow mapping from transthoracic imaging windows has become the standard method for the noninvasive assessment of valvular regurgitation. This study compared regurgitant jet areas by Doppler color flow imaging derived from the newer transesophageal approach with measurements obtained from conventional transthoracic apical views. Maximal regurgitant jet area determinations and an overall visual estimate of lesion severity were obtained from 42 patients who underwent color flow examination by both techniques. Seventy-three regurgitant lesions were visualized by transesophageal flow imaging: 34 mitral, 22 aortic, and 17 tricuspid jets. Transthoracic studies in the same patients revealed fewer regurgitant lesions for each valve; 20 mitral, 16 aortic, and 12 tricuspid (p = 0.0009). A comparison of maximal jet areas determined by transesophageal and transthoracic studies showed a good overall correlation (r = 0.85, SEE = 2.8 cm2) and a systematic overestimation by the transesophageal technique (TEE = 0.96 TTX + 2.7). For the subgroup with mitral insufficiency, valve lesions visualized by both techniques were larger by the transesophageal approach (n = 18, 6.0 versus 3.6 cm2, p = 0.008). Semiquantitative visual grading of individual valve lesions by two independent observers revealed a higher grade of regurgitation with more jets classified as mild (38 versus 25), moderate (18 versus 13), and severe (17 versus 10) by esophageal imaging than by transthoracic imaging. Thus, transesophageal color flow mapping techniques yield a higher prevalence of valvular regurgitation than do transthoracic techniques in the same patients. Jet area and the overall estimate of regurgitant lesion severity were also greater by transesophageal color Doppler imaging compared with standard transthoracic imaging.(ABSTRACT TRUNCATED AT 250 WORDS)

Echocardiography, Doppler↗

PubMed1991

Quality of life after bypass surgery for unstable angina. 5-year follow-up results of a Veterans Affairs Cooperative Study.

To assess the effect of bypass surgery on outcome from unstable angina, 468 patients were randomized to medical treatment (237 patients) or surgery plus medical treatment (231 patients) and have been followed for comparison of survival, cardiac end points, and quality of life; the latter end point is discussed in the present report. Data were available at 3 and 5 years for 80% and 82% of patients in the medical group, respectively, and 77% and 80% of patients in the surgery group, respectively. At 3 months after randomization to therapy, 79.8% of patients in the surgery group reported subjective improvement, compared with 58% of the medical group, 12.6% of the surgery group reported no change compared with 24.5% of the medical group, and 5.5% of the surgery group reported worsening compared with 24.5% of the medical group (p less than 0.01 by chi 2). Similar data were found for chest pain status, and the benefit to the surgery group remained statistically significant through 5 years of follow-up. Crossover rate to surgery was 43% by 5 years. Treadmill duration was increased in the surgery group compared with the medical group (6.5 +/- 0.25 versus 5.3 +/- 0.25 minutes at 6 months, p less than 0.01), and a significant difference was again demonstrated at 3 and 5 years. A trend toward decreased recurrence of unstable angina was present in the surgery group at 1 year (six of 168 [3.6%] versus 13 of 187 [6.9%] in the medical group, p = 0.158), but the two groups were similar at 3 and 5 years.(ABSTRACT TRUNCATED AT 250 WORDS)

Angina, Unstable↗

PubMed1991

A prospective, randomized trial comparing combination half-dose tissue-type plasminogen activator and streptokinase with full-dose tissue-type plasminogen activator. Kentucky Acute Myocardial Infarction Trial (KAMIT) Group.

BACKGROUND: The potential benefits of combination thrombolytic agents in the treatment of myocardial infarction remain uncertain. In a small pilot study, we demonstrated that combining half-dose tissue-type plasminogen activator (t-PA) with streptokinase (SK) achieved a high rate of infarct vessel patency and a low rate of reocclusion at half the cost of full-dose t-PA. METHODS AND RESULTS: We designed a prospective trial in which 216 patients were randomized within 6 hours of myocardial infarction to receive either the combination of half-dose (50 mg) t-PA with streptokinase (1.5 MU) during 1 hour or to the conventional dose of t-PA (100 mg) during 3 hours. Acute patency was determined by angiography at 90 minutes, and angioplasty was reserved for failed thrombolysis. Heparin and aspirin regimens were maintained until follow-up catheterization at day 7. Acute patency was significantly greater after t-PA/SK (79%) than with t-PA alone (64%, p less than 0.05). After angioplasty for failed thrombolysis, acute patency increased to 96% in both groups. Marked depletion of serum fibrinogen levels occurred after t-PA/SK compared with t-PA alone at 4 hours (37 +/- 36 versus 199 +/- 66 mg/dl, p less than 0.0001) and persisted 24 hours after therapy (153 +/- 66 versus 252 +/- 75 mg/dl, p less than 0.0001). Reocclusion (3% versus 10%, p = 0.06), reinfarction (0% versus 4%, p less than 0.05), and need for emergency bypass surgery (1% versus 6%, p = 0.05) tended to be less in the t-PA/SK group. Greater myocardial salvage was apparent in the t-PA/SK group as assessed by infarct zone function at day 7 (-1.9 SD/chord versus -2.3 SD/chord after t-PA alone, p less than 0.05). In-hospital mortality (6% versus 4%) and serious bleeding (12% versus 11%) were similar between the two groups. CONCLUSIONS: These results suggest that a less expensive regimen of half-dose t-PA with SK yields superior 90-minute patency and left ventricular function and a trend toward reduced reocclusion compared with the conventional dose of t-PA.

Adolescent↗

PubMed1991

Intravascular ultrasound assessment of lumen size and wall morphology in normal subjects and patients with coronary artery disease.

BACKGROUND: Necropsy studies demonstrate that coronary artery disease (CAD) is frequently complex and eccentric. However, angiography provides only a silhouette of the vessel lumen. Intravascular ultrasound is a new tomographic imaging method for evaluation of coronary dimensions and wall morphology. Few data exist regarding intravascular ultrasound in patients with CAD, and no data exist for subjects with normal coronaries. METHODS AND RESULTS: We used a multielement 5.5F, 20-MHz ultrasound catheter to examine eight normal subjects and 43 patients with CAD. We assessed the safety of coronary ultrasound and the effect of vessel eccentricity on comparison of minimum luminal diameter by angiography and ultrasound. Normal and atherosclerotic wall morphology and stenosis severity were also evaluated by intravascular ultrasound. The only untoward effect was transient coronary spasm in five patients. At 33 sites in normal subjects, the lumen was nearly circular, yielding a close correlation between angiographic and ultrasonic minimum diameter (r = 0.92). At 90 sites in patients with CAD, ultrasound demonstrated a concentric cross section; correlation was also close (r = 0.93). However, at 72 eccentric sites, correlation was not as close (r = 0.77). For 41 stenoses, correlation between angiography and ultrasound for area reduction was moderate (r = 0.63). In normal subjects, wall morphology revealed a thin (0.30 mm or less) intimal leading edge and subadjacent sonolucent zone (0.20 mm or less). Patients with CAD exhibited increased thickness and echogenicity of the leading edge, thickened sonolucent zones, and/or attenuation of ultrasound transmission. CONCLUSIONS: These data establish that intravascular ultrasound is feasible and safe and yields luminal measurements that correlate generally with angiography. Differences between angiographic and ultrasound measures of lumen size in eccentric vessels probably reflect the dissimilar perspectives of tomographic and silhouette imaging techniques. Intravascular ultrasound provides detailed images of normal and abnormal wall morphology not previously possible in vivo.

Adult↗

PubMed1991

Stress echocardiology.

Stress echocardiography is a convenient, rapid alternative technique for the assessment of myocardial ischemia. It clearly adds much information to regular stress electrocardiography, and it provides clear alternative to stress thallium. It also provides an estimated ejection fraction and regional wall motion abnormalities. Whether or not echocardiography is preferable to stress thallium tests is presently determined by institutional preferences. There are some institutions with substantial expertise in radionuclide techniques, and there it is probably the best choice. In others with equivalent expertise in ultrasound, it is your best test. If there is expertise in both areas, there is a growing national preference for the convenience of stress echocardiography.

Coronary Disease↗

PubMed1991

Doppler echocardiographic evaluation of diastolic dysfunction.

Recently, considerable effort has been directed toward the application of Doppler methods for detecting diastolic dysfunction. Recordings of transmitral filling velocity as obtained from pulsed-wave Doppler have been extensively investigated as a noninvasive method for determining left ventricular diastolic filling properties. Although Doppler parameters appear to reflect volumetric transmitral flow, close correlations with invasive descriptors of diastolic performance have not been found. Furthermore, Doppler transmitral velocities are sensitive to changes in ventricular preload, afterload, and heart rate. However, at least two distinct Doppler spectral patterns have been identified that are associated with impaired ventricular relaxation and restrictive physiology. Thus, Doppler recordings have proven to be of value in identifying the presence and type of diastolic dysfunction, and in the future they may be helpful in following the response to therapeutic interventions. The purpose of this paper is to review the available information relating Doppler transmitral recordings with catheterization and clinical descriptors of diastolic function. Additionally, the aim is to provide an understanding of the value and limitations of these noninvasive measurements in identifying and treating patients with diastolic abnormalities.

Amyloidosis↗

PubMed1990

Mechanism of acute myocardial infarction in patients with prior coronary artery bypass grafting and therapeutic implications.

Although acute myocardial infarction (AMI) is usually due to thrombotic occlusion when involving a native coronary artery, the mechanism responsible for AMI in patients with previous coronary artery bypass grafting (CABG) is not well understood. Since knowledge of pathophysiology of AMI may alter subsequent management, angiograms obtained between 1 hour and 7 days of AMI (median 1 day) were reviewed in 50 patients greater than 1 year after CABG. The culprit vessel was identified by the presence of residual stenosis and/or thrombus in the vessel supplying the infarct zone or by reviewing previous angiograms. The infarct vessel was identified as a vein graft in 38 (76%) patients, the native vessel in 8 patients (16%) and could not be accurately determined in 4 patients (8%). Among the 38 vein grafts suspected as the infarct vessel, unequivocal angiographic evidence of residual thrombus (filling defect/persistent staining) was present in 31 (82%) and was greater than 2 cm in length in 15 patients. Successful reperfusion occurred in only 2 of 8 (25%) grafts after intravenous thrombolytic therapy. Intragraft thrombolysis with or without additional angioplasty was successful at restoring flow in 8 of 10 (80%) grafts. Data indicate that in patients who have undergone previous CABG, AMI is usually caused by thrombotic occlusion of a saphenous vein graft and that conventional intravenous thrombolytic therapy may be inadequate to restore flow. The large mass of thrombus and absent flow in the graft may require subselective drug infusion, a higher thrombolytic dose or a mechanical means of recanalization.

Angiography↗

PubMed1990

Effect of isometric exercise on mitral and aortic regurgitation as assessed by color Doppler flow imaging.

Isometric exercise produces well-defined hemodynamic changes in normal and diseased states. However, the effect of isometrics on the degree of valvular regurgitation recorded by color Doppler flow imaging (CDFI) has not been reported. CDFI was therefore used to evaluate changes in valvular regurgitation in 34 patients, mean age 53 +/- 16 years. Data were collected for 43 regurgitant lesions including 20 cases of aortic regurgitation and 23 cases of mitral regurgitation. Isometrics produced a significant increase in heart rate (71 to 83 beats/min) and blood pressure (132/64 to 153/70 mm Hg) in all patients (p less than 0.0001). Regurgitant jet area by CDFI increased significantly in both aortic regurgitation (4.5 to 6.2 cm2, p less than 0.0001) and mitral regurgitation (6.2 to 8.2 cm2, p less than 0.001). Patients taking concurrent vasodilator or angiotensin-converting enzyme inhibitor therapy had similar responses to those not receiving long-term therapy. Thus, CDFI detects an increase in aortic and mitral regurgitant jet area induced by isometric exertion. The change in CDFI jet area with handgrip demonstrates the influence of loading conditions on the size of a regurgitant jet area, and suggests that isometric exertion may increase the magnitude of mitral and aortic regurgitation.

Aortic Valve Insufficiency↗

PubMed1990

Influence of beta-adrenergic blockade upon hemodynamic response to exercise assessed by Doppler echocardiography.

Peak aortic blood flow acceleration and velocity measured by Doppler echocardiography have been documented to be accurate descriptors of left ventricular systolic function. Both acceleration and velocity are reduced in the presence of beta-blockade at rest and during exercise. Whether and to what extent the simultaneous alterations in heart rate (HR) due to beta-blockade affect these parameters has received little study. In order to determine the influence of alterations in HR on Doppler measurements of velocity and acceleration, 10 healthy men were studied during upright exercise under control conditions, following propranolol administration, and following propranolol plus transesophageal atrial pacing. In addition, we assessed the response of stroke volume (measured as flow velocity integral) during beta-blocked and control exercise. Propranolol significantly reduced acceleration and velocity during all stages of exercise compared with control values (p less than 0.05). Increasing the HR during exercise via pacing had no effect on acceleration or velocity compared with propranolol administration alone, thus demonstrating that during upright exercise, changes in acceleration and velocity are independent of alterations in HR. At low levels of exercise, propranolol significantly reduced flow velocity integral (FVI) compared with control (-1.14 cm, p less than 0.05.). At high levels of exertion, however, FVI exceeded values obtained during control conditions (1.2 cm at stage 4). Pacing during beta-blockade reduced FVI at high levels of exercise but had no effect at lower levels. Our results suggest that during low levels of exercise stroke volume is increased as a consequence of both increased contractility and augmented left ventricular filling.(ABSTRACT TRUNCATED AT 250 WORDS)

Adrenergic beta-Antagonists↗

PubMed1990

Influence of alterations in loading produced by lower body negative pressure on aortic blood flow acceleration.

The objectives of this study were to evaluate the effects of alterations in loading induced by lower body negative pressure on aortic blood flow velocity and acceleration. Twenty-seven normal men were studied during various levels of lower body negative pressure (0 to -60 mm Hg) during which echocardiographic, Doppler and hormonal measurements were obtained. Lower body negative pressure induced a decrease in left ventricular diastolic diameter from 5.18 +/- 0.08 to 4.41 +/- 0.1 cm (p less than 0.0001) and in left ventricular systolic diameter from 3.33 +/- 0.09 to 2.84 +/- 0.1 cm (p less than 0.0001). Shortening fraction remained unchanged. The decrease in diastolic diameter resulted in a reduction in flow velocity integral from 13.8 +/- 0.8 to 7.5 +/- 0.4 cm (p less than 0.0001) and, therefore, in stroke volume from 89.6 +/- 4.7 to 49.5 +/- 2.8 ml (p less than 0.0001). Heart rate reflexly increased from 62.5 +/- 1.9 to 82.2 +/- 2.3 beats/min (p less than 0.0001) as did systemic vascular resistance from 1,280.8 +/- 69.5 to 1,863.4 +/- 121.4 dyne.s.cm-5 (p less than 0.0001). The increase in heart rate was insufficient to maintain cardiac output, which decreased from 5.53 +/- 0.29 to 3.99 +/- 0.21 liters/min (p less than 0.0001). Systolic, diastolic and mean arterial blood pressure was maintained. The negative pressure resulted in a concomitant significant increase in norepinephrine levels from 1.46 +/- 0.09 to 2.056 +/- 0.2 nmol/liter (p = 0.0019) but no change in plasma epinephrine: 0.845 +/- 0.22 to 0.78 +/- 0.11 nmol/liter (p = NS).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

PubMed1990

Reduction of left ventricular preload by lower body negative pressure alters Doppler transmitral filling patterns.

The objective of this study was to evaluate the effect of alterations in preload induced by lower body negative pressure on Doppler transmitral filling patterns. Echocardiograms and Doppler recordings were performed in 18 normal young men (aged 23 to 32 years) during various levels of lower body negative pressure (0, -20 and -50 mm Hg). Lower body negative pressure induced a reduction in diastolic velocity integral (from 12.17 +/- 0.79 to 8.42 +/- 0.71 cm, p = 0.0067) and consequently left ventricular diastolic diameter (from 5.11 +/- 0.09 to 4.45 +/- 0.1 cm, p less than 0.0001). There was a significant reflex increase in heart rate from 59.9 +/- 1.9 to 77.1 +/- 2.4 beats/min (p less than 0.0001), but blood pressure was unchanged. This reduction in preload altered Doppler transmittral filling patterns as follows: 1) peak early velocity (E) decreased from 59.2 +/- 3.8 to 39.1 +/- 1.7 cm/s (p less than 0.0001); 2) atrial filing velocity (A) was unchanged (35.58 +/- 1.5 to 33.52 +/- 1.4 cm/s, p = 0.517); 3) E/A ratio decreased from 1.7 +/- 0.13 to 1.19 +/- 0.08 (p = 0.0087); 4) mean acceleration (from 482 +/- 37 to 390 +/- 27 cm/s2, p = 0.03) and mean deceleration (from 327 +/- 31 to 169 +/- 21 cm/s2, p less than 0.001) of the early filling wave were significantly reduced; and 5) peak acceleration (from 907 +/- 42 to 829 +/- 29 cm/s2) and peak deceleration (from 771 +/- 94 to 547 +/- 76 cm/s2) also decreased, but not significantly.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗