Search PubMedSearch

SEARCH · Search PubMed

Results for “ventricular dysfunction”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 307 records · Page 17Linked to original sources

Exercise training in patients with severe left ventricular dysfunction. Hemodynamic and metabolic effects.

We studied the effects of exercise training in patients with chronic heart failure attributed to left ventricular dysfunction (ejection fraction, 24 +/- 10%). Twelve ambulatory patients with stable symptoms underwent 4-6 months of conditioning by exercising 4.1 +/- 0.6 hr/wk at a heart rate corresponding to 75% of peak oxygen consumption. Before and after training, patients underwent maximal bicycle exercise testing with direct measurement of central hemodynamic, leg blood flow, and metabolic responses. Exercise training resulted in a decrease in heart rate at rest and submaximal exercise and a 23% increase in peak oxygen consumption from 16.8 +/- 3.8 to 20.6 +/- 4.7 ml/kg/min (p less than 0.01). Heart rate, arterial lactate, and respiratory exchange ratio were unchanged at peak exercise after training. Maximal cardiac output tended to increase from 8.9 +/- 2.7 to 9.9 +/- 3.2 1/min and contributed to improved peak oxygen consumption in some patients, although this change did not reach statistical significance (p = 0.13). Rest and exercise measurements of left ventricular ejection fraction, left ventricular end-diastolic volume, and left ventricular end-systolic volume were unchanged. Right atrial, pulmonary arterial, pulmonary capillary wedge, and systemic arterial pressures were not different after training. Training induced several important peripheral adaptations that contributed to improved exercise performance. At peak exercise, systemic arteriovenous oxygen difference increased from 13.1 +/- 1.4 to 14.6 +/- 2.3 ml/dl (p less than 0.05). This increase was associated with an increase in peak-exercise leg blood flow from 2.5 +/- 0.7 to 3.0 +/- 0.8 l/min (p less than 0.01) and an increase in leg arteriovenous oxygen difference from 14.5 +/- 1.3 to 16.1 +/- 1.9 ml/dl (p = 0.07). Arterial and femoral venous lactate levels were markedly reduced during submaximal exercise after training, even though cardiac output and leg blood flow were unchanged at these workloads. Thus, ambulatory patients with chronic heart failure can achieve a significant training effect from long-term exercise. Peripheral adaptations, including an increase in peak blood flow to the exercising leg, played an important role in improving exercise tolerance.(ABSTRACT TRUNCATED AT 400 WORDS)

Adult

Left ventricular filling pattern and pulmonary wedge pressure are closely related in patients with recent anterior myocardial infarction and left ventricular dysfunction.

To determine whether mitral flow velocity can be used to estimate mean pulmonary wedge pressure (PWP) in patients with left ventricular dysfunction, 50 patients with recent Q-wave anterior infarction and a reduced ejection fraction (less than 40%) underwent simultaneous pulsed-wave Doppler measurements of mitral flow and right heart catheterization. Doppler tracings and PWP were recorded at rest, after passive leg lifting (45 degrees) and (in 15 patients with increased PWP) after 5 mg sublingual ISDN. Significant correlations were found between the ratio of peak early to peak late diastolic velocity (E/A) and PWP (r = 0.83). Early diastolic deceleration and the ratio of the time velocity integral of atrial contribution to the total time velocity integral were also correlated to PWP (r = 0.80 and r = 0.79 (respectively). The E/A ratio was less than 1 in 25 patients and more than 1 in the remaining 25. An E/A ratio of at least 1 predicted a PWP of more than 20 mmHg with a sensitivity of 100% and a specificity of 86%. In all five patients, in whom the PWP was less than 20 mmHg at baseline and became greater with leg lifting, the E/A ratio changed from less than 1 to more than 1. After ISDN, changes in E/A ratio from more than 1 to less than 1 identified all 12 patients with a PWP falling below 20 mmHg. In conclusion, patients with recent Q-wave anterior infarction and a reduced ejection fraction mitral flow velocity-derived variables correlate with PWP representing a reliable index for the diagnosis of markedly increased PWP.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult

Comparison of rest-redistribution thallium-201 imaging and reinjection after stress-redistribution for the assessment of myocardial viability in patients with left ventricular dysfunction secondary to coronary artery disease.

Thallium (Tl)-201 reinjection after stress-redistribution (RI) imaging has been proven to accurately identify ischemic and viable myocardium. Quantitative Tl-201 analysis after stress has also shown viable myocardium in most mild to moderate (51% to 85% of normal uptake) irreversible Tl-201 defects. However, if the main clinical question is whether a region is viable, and not whether there is inducible ischemia, a resting protocol may be more appropriate. The aim of this study was to determine whether rest-redistribution (RD) quantitative Tl-201 single-photon emission tomographic imaging provides the same information on viable myocardium as Tl-201 RI. Thus, 15 patients (mean age 58 +/- 9 years) with chronic coronary artery disease and left ventricular dysfunction (ejection fraction 35 +/- 8%) were studied by both RI and RD Tl-201 single-photon emission tomography. Regional Tl-201 uptake was assessed quantitatively using a 16-segment model. When Tl-201 images were classified as normal/reversible (viable) or irreversible (nonviable), RI showed viable myocardium in 145 of 240 myocardial regions (60%), whereas RD showed it in 103 of 240 myocardial regions (43%). The 2 imaging protocols provided concordant information in 176 of 240 myocardial regions (73%). Among the 64 (27%) discordant regions, 53 (22%) were viable by RI and nonviable by RD, whereas 11 (5%) were viable by RD and nonviable by RI (p < 0.001).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult

Effects of lisinopril on cardiorespiratory, neuroendocrine, and renal function in patients with asymptomatic left ventricular dysfunction.

OBJECTIVE: To determine the cardiac, renal, and neuroendocrine effects of lisinopril in men with untreated, symptom free left ventricular systolic dysfunction. DESIGN: A randomised, double blind cross over trial with six week treatment periods to compare lisinopril (10 mg/day) and matching placebo. SETTING: Hospital outpatient department. PATIENTS: Patients with pronounced systolic dysfunction on cross sectional echocardiography due to myocardial infarction at least six months previously, without angina and with no or minimal breathlessness. Eighteen men were identified of whom 15 completed the study. INTERVENTIONS: Lisinopril (10 mg) or placebo given once daily by mouth. MAIN OUTCOME MEASURES: Primary: oxygen consumption at peak exercise. Secondary: resting cardiac function as measured by radionuclide ventriculography and echocardiography, renal function estimated radioisotopically, and plasma indices of neuroendocrine activity. RESULTS: Compared with placebo, lisinopril increased (mean (SD)) peak oxygen consumption during exercise (19.8(3.1) ml/kg/min v 21.4(3.2) ml/kg/min; p < 0.003). Lisinopril did not improve indices of cardiac function at rest. It reduced plasma concentrations of angiotensin II (median values 7 pg/ml to 5 pg/ml; p < 0.02), aldosterone (median values 113 pg/ml to 66 pg/ml; p < 0.05) and atrial natriuretic peptide (median values 69 pg/ml to 40 pg/ml; p < 0.04), but noradrenaline and antidiuretic hormone concentrations did not change. Renal blood flow increased and glomerular filtration rate declined. CONCLUSIONS: Even before the onset of heart failure lisinopril improves the cardiopulmonary response to exercise in patients with systolic ventricular dysfunction.

Angiotensin-Converting Enzyme Inhibitors

Scintigraphically detected predominant right ventricular dysfunction in acute myocardial infarction: clinical and hemodynamic correlates and implications for therapy and prognosis.

To determine the clinical and hemodynamic correlates as well as therapeutic and prognostic implications of predominant right ventricular dysfunction complicating acute myocardial infarction, 43 consecutive patients with scintigraphic evidence of right ventricular dyssynergy and a depressed right ventricular ejection fraction (less than 0.39) in association with normal or near normal left ventricular ejection fraction (greater than or equal to 0.45) were prospectively evaluated. All 43 patients had acute inferior infarction, forming 40% of patients with acute inferior infarction, and only eight (24%) had elevated jugular venous pressure on admission. On hemodynamic monitoring, 74% of patients had a depressed cardiac index (less than or equal to 2.5 liters/min per m2), averaging 2.0 +/- 0.05 for the group. Of these, 30% did not demonstrate previously described hemodynamic criteria of predominant right ventricular infarction (right atrial pressure greater than or equal to 10 mm Hg or right atrial to pulmonary capillary wedge pressure ratio greater than or equal to 0.8, or both). The left ventricular end-diastolic volume was reduced to 49 +/- 11 ml/m2 (n = 22) and correlated significantly with the stroke volume index (r = 0.82; p less than 0.0001) and cardiac index (r = 0.57; p = 0.005). The follow-up right ventricular ejection fraction, determined in 33 patients, showed an increase of 10% or greater in 26 (79%), increasing from a mean value of 0.30 +/- 0.06 to 0.40 +/- 0.09 (p less than 0.0001) without a significant overall change in the mean left ventricular ejection fraction (0.56 +/- 0.10 to 0.56 +/- 0.11, p = NS).(ABSTRACT TRUNCATED AT 250 WORDS)

Acute Disease

[Identification of viable myocardium in patients with chronic ischemic disease and left ventricular dysfunction: correlations between blood flow, metabolic activity and regional function].

To identify the presence of viable myocardium in areas of severe systolic dysfunction, we studied 22 patients (age 45 to 78 years) with chronic coronary artery disease and left ventricular dysfunction (mean ejection fraction 29 +/- 9%). All subjects underwent thallium-201 single photon emission computed tomography (SPECT), using the reinjection technique, positron emission tomography (PET) with H2(15)O and 18-fluorodeoxyglucose (FDG) to measure regional blood flow and exogenous glucose uptake, respectively, and nuclear magnetic resonance imaging (MRI). From matched transaxial PET, SPECT and MRI tomograms, a total of 290 left ventricular myocardial regions were analyzed. According to the regional wall thickening, measured from MRI, 3 groups of myocardial regions were identified: akinetic-dyskinetic (n = 60), showing either absence of systolic thickening or systolic thinning; hypokinetic (n = 97), showing an absolute wall thickening less than or equal to 2 mm; normal (n = 133), showing an absolute wall thickening greater than 2 mm. Of the 60 akinetic or dyskinetic regions, 3 were normal by SPECT and 37 corresponded to either a total or partially reversible thallium defect: 34 of these 40 regions also showed presence of FDG uptake by PET. The remaining 20 akinetic or dyskinetic regions showed a thallium defect that remained irreversible after reinjection: in 7 of these 20 regions, however, there was evidence of metabolic activity, as expressed by FDG uptake. Thus, 47 (78%) of the myocardial akinetic or dyskinetic regions showed presence of viable tissue.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged

Prevalence and prognostic value of left ventricular dysfunction in non-Q-wave myocardial infarction.

Forty-two consecutive patients with non-Q-wave acute myocardial infarction (AMI) and 40 consecutive patients with transmural AMI were comparatively examined by equilibrium gated radionuclide angiography (ERNA) to assess prevalence and prognostic value of left ventricular dysfunction in non-Q-wave AMI. Left ventricular ejection (LVEF) was generally preserved both in anterior and inferior non-Q-wave infarctions and sharply reduced only in anterior transmural infarctions. ERNA cannot assist in identifying any subgroup of patients with non-Q-wave AMI at risk of major complications other than left ventricular failure because they may develop such complications in spite of a normal LVEF.

Adult

Current and ongoing randomized trials in heart failure and left ventricular dysfunction.

Several large randomized trials have been completed recently and provided valuable information on the effects of various interventions in heart failure and left ventricular dysfunction. A review of ongoing randomized trials showed that there were 19 major trials addressing the effect of treatments on exercise tolerance, morbidity or mortality. Although it is hoped that these trials will answer many questions, they will also raise additional questions. Therefore, these remaining questions will need to be answered by future clinical trials.

Adrenergic beta-Antagonists

Serial evaluation of right ventricular dysfunction associated with acute inferior myocardial infarction.

Right ventricular (RV) function was evaluated serially by multigated blood pool imaging in 18 patients with RV dysfunction associated with acute inferior myocardial infarction. Radionuclide ventriculograms were performed on all patients within 18 hours of chest pain and again at 10 days. In addition, 15 of 18 patients had rest and exercise radionuclide ventriculograms at 3 months. The mean resting right ventricular ejection fractions (RVEF) at admission, 10 days, and 3 months in these patients was 31.8 +/- 12.6% (SD), 46.9 +/- 11.2% (p less than 0.05), and 44.5 +/- 10.2% (p less than 0.05), while the left ventricular ejection fractions were 55.9 +/- 10.6%, 57.9 +/- 13.3%, and 53.1 +/- 11.2% (p = ns). The 3-month exercise radionuclide ventriculogram demonstrated an increase in RVEF greater than 5% in 6 of 15 patients. In eight catheterized patients, neither the location nor the severity of coronary artery narrowing nor the presence of collaterals correlated with the RV exercise response. Improvement in RV function over a 10-day interval following acute inferior myocardial infarction suggests the presence of significant reversible right ventricular dysfunction during the acute phase.

Cardiac Catheterization

Cardiovascular and neurohormonal effects of atrial natriuretic peptide in conscious dogs with and without chronic left ventricular dysfunction.

Atrial natriuretic peptide (hANP 4-28) was infused for 1 h (0.3 microgram/kg/min) in 11 normal awake dogs and seven awake dogs with chronic left ventricular dysfunction, induced 16 weeks earlier by repetitive DC shock. The responses were similar in the two groups and included decreases in arterial pressure (107-99 mm Hg), heart rate (83-72 beats/min), and cardiac output (3.6-2.8 L/min), without changes in right or left ventricular filling pressures. Systemic vascular resistance (SVR) tended to rise during the infusion and was significantly increased (2,847-3,442 dyn s cm-5, p less than .05) during the postinfusion recovery period. Regional blood flows (microspheres) during infusion revealed a decrease in skin and splanchnic flow. Despite the apparent vasoconstrictor effect, plasma norepinephrine (PNE), renin activity (PRA), and arginine vasopressin (AVP) levels all fell during ANP infusion. These data suggest that ANP exerts a cardioinhibitory effect, possibly similar to that of arginine vasopressin (AVP), and that the net systemic vasoconstrictor effect of ANP in these dogs is mediated by a complex interrelationship between direct vascular effects, neurohormonal inhibition, and central reflex activation.

Animals

Effect of indecainide in patients with left ventricular dysfunction.

Indecainide, a new antiarrhythmic agent classified as type Ic was evaluated in 11 patients with heart disease who had greater than or equal to 30 ventricular premature complexes/hour, moderate-to-marked left ventricular dysfunction, and mean ejection fraction 34% +/- 8%. Patients received indecainide, 50 mg by mouth, every 6 hours and the dose was increased until greater than or equal to 80% suppression was noted, adverse effects occurred, or a maximum dose of 100 mg indecainide was given every 6 hours. Ventricular premature complexes were suppressed greater than or equal to 80% in nine patients (p less than 0.05) and ventricular tachycardia episodes were completely suppressed in five of eight patients. The effective or maximal mean daily indecainide dose was 191 +/- 32 mg; half of the responders achieved achieved efficacy at serum drug concentration greater than or equal to 600 ng/ml. Serum drug concentration was directly related to gender (r = 0.78, p less than 0.04) and inversely related to creatinine clearance (r = 0.74, p less than 0.05) and ejection fraction (r = 0.71, p less than 0.02). Indecainide prolonged mean PR and QRS intervals (p less than 0.05) but not QT or QTc. There was a linear relation between percent change in PR (r = 0.80, p less than 0.001) and QRS (r = 0.66, p less than 0.001) intervals and serum drug concentration. After starting or increasing the dose, careful observation of patients with decreased renal function or reduced ejection fraction should be exercised because they attain higher drug concentration than normal subjects.

Adult

"Escape" of aldosterone production in patients with left ventricular dysfunction treated with an angiotensin converting enzyme inhibitor: implications for therapy.

Despite the findings in randomized trials of a significant effect of angiotensin-converting enzyme (ACE) inhibitors in reducing morbidity and mortality of patients with symptomatic left ventricular dysfunction, the morbidity and mortality of these patients remains relatively high. One potential strategy to further improve morbidity and mortality in these patients is blockade of a aldosterone. Many clinicians have assumed that ACE inhibitors would block both angiotensin II and aldosterone. However, there are data to suggest that aldosterone production may "escape" despite the use of an ACE inhibitor. An escape of aldosterone production has several important consequences, including: sodium retention, potassium and magnesium loss, myocardial collagen production, ventricular hypertrophy, myocardial norepinephrine release, endothelial dysfunction, and a decrease in serum high density lipoprotein cholesterol. Due to the potential importance of these mechanisms, the finding that there is a significant correlation between aldosterone production and mortality in patients with heart failure, as well as evidence that an aldosterone antagonist, spironolactone, when administered to patients with heart failure treated with conventional therapy including an ACE inhibitor results in increased diuresis and symptomatic improvement, an international prospective multicenter study has been organized, the Randomized Aldactone Evaluation Study (RALES Pilot Study), to evaluate the safety of blocking the effects of aldosterone in patients with heart failure treated with an ACE inhibitor.

Aldosterone

Acute haemodynamic effects of the beta 1-adrenoceptor partial agonist xamoterol at rest and during supine exercise in patients with left ventricular dysfunction due to ischaemic heart disease: a double-blind randomized trial.

The effects of xamoterol 0.2 mg kg-1 i.v. and placebo on left ventricular function at rest and on exercise were compared in patients with left ventricular dysfunction due to ischaemic heart disease. Improvements were seen in systolic and diastolic function at rest, and at up to 50% of maximal exercise, without evidence of worsening myocardial ischaemia.

Adrenergic beta-Agonists

Left ventricular dysfunction after acute myocardial infarction: results of a prospective multicenter study.

In a multicenter prospective study of 866 patients who survived the coronary care unit phase of an acute myocardial infarction, variables reflecting left ventricular function were examined to assess their impact on 2 year survival. Single variables that reflected left ventricular dysfunction before infarction and in the acute and recovery phases were, respectively, history of prior myocardial infarction, rales in the coronary care unit dichotomized at greater than bibasilar and predischarge radionuclide ejection fraction dichotomized at less than 0.40. When combined in a stepwise fashion, patients lacking these three risk characteristics had a 2 year 4.2% mortality rate, whereas patients possessing all three characteristics had a 45% mortality rate. Rales in the coronary care unit and predischarge ejection fraction act independently, and each contributes to mortality. Fifty-two patients with advanced rales but an ejection fraction of 0.40 or greater had a 21% mortality rate. Similarly, 208 patients with few rales but an ejection fraction of less than 0.40 had a 15% mortality rate. These data suggest that the mortality risk imposed by those factors that assess permanent left ventricular damage is independent of and additive to the mortality risk contributed by dynamic, acute phase dysfunction. These data fit the hypothesis that acute phase dysfunction is, in part, due to transient ischemia that, on reversal, can restore function toward normal. The results suggest 1) that assessment of left ventricular function during the acute and recovery phases of myocardial infarction is necessary to define prognostic characteristics of an individual patient, and 2) that of particular importance is the identification of patients whose postinfarction course is consistent with reversible ischemia.

Cardiac Output

Comparative neurohormonal responses in patients with preserved and impaired left ventricular ejection fraction: results of the Studies of Left Ventricular Dysfunction (SOLVD) Registry. The SOLVD Investigators.

OBJECTIVES: The aim of this study was to determine the differences in neurohumoral responses between patients with pulmonary congestion with and without impaired left ventricular ejection fraction. BACKGROUND: Previous studies have established the presence of neurohumoral activation in patients with congestive heart failure. It is not known whether the activation of these neurohumoral mechanisms is related to the impairment in systolic contractility. METHODS: The 898 patients recruited into the Studies of Left Ventricular Dysfunction (SOLVD) Registry substudy were examined to identify those patients with pulmonary congestion on chest X-ray film who had either impaired (< or = 45%, group I) or preserved (> 45%, group II) left ventricular ejection fraction. Plasma norepinephrine, plasma renin activity, arginine vasopressin and atrial natriuretic peptide levels were measured in these two groups of patients and compared with values in matched control subjects. RESULTS: Distribution of the New York Heart Association symptom classification was the same in the two groups of patients. Compared with control subjects, patients in group II with pulmonary congestion and preserved ejection fraction had no activation of the neurohumoral mechanisms, except for a small but statistically significant increase in arginine vasopressin and plasma renin activity. Compared with patients in group II, those in group I with pulmonary congestion and impaired ejection fraction had significant increases in plasma norepinephrine (p < 0.002), plasma renin activity (p < 0.02) and atrial natriuretic peptide levels (p < 0.0007). When we controlled for baseline differences between groups I and II, the between-group differences in plasma norepinephrine (p < 0.02) and atrial natriuretic peptide (p < 0.002) remained significant. However, plasma renin activity was not significantly different between groups I and II. When the effects of diuretic agents and angiotensin-converting enzyme inhibitors were adjusted, patients with lower ejection fraction were found to have significantly higher plasma norepinephrine and atrial natriuretic peptide levels. CONCLUSIONS: The results point to the importance of the decrease in left ventricular ejection fraction as one of the mechanisms for activation of neurohormones in patients with heart failure.

Adult

Comparative hemodynamic effects of mexiletine and quinidine in patients with severe left ventricular dysfunction.

Mexiletine and quinidine are often administered to patients with severe congestive heart failure, but their hemodynamic effects have not been adequately studied in these individuals. In a randomized, crossover study, the hemodynamic responses to single oral doses of quinidine (600 mg) and mexiletine (400 mg) were compared in 20 patients with marked left ventricular dysfunction. Quinidine predominantly caused vasodilation, with mean arterial, left ventricular filling, and right atrial pressures all decreasing (-7 +/- 2, -2.3 +/- 1.0, and -1.1 +/- 0.5 mm Hg, respectively) and the systemic vascular resistance also declining (-308 +/- 84 dynes.sec.cm5). In contrast, the systemic vascular resistance increased (314 +/- 84 dynes.sec.cm-5) and the mean arterial, left ventricular filling, and right atrial pressures also increased (+2 +/- 2, +6.1 +/- 1.8, and +1.8 +/- 0.6 mm Hg, respectively) after mexiletine. Cardiac performance declined with mexiletine (cardiac and stroke work indexes decreasing -0.3 +/- 0.1 L/min/m2 and -5 +/- 1 gm.m/m2, respectively), but there was no significant change in cardiac or stroke work indexes with quinidine (+0.1 L/min/m2 and -0.3 +/- 0.9 gm.m/m2, respectively). The response to the two agents significantly differed for all parameters measured (p less than 0.005). These hemodynamic changes were accompanied by clinical effects. Mexiletine induced increased dyspnea in five patients and quinidine led to symptomatic hypotension in two patients. Plasma concentrations of mexiletine and serum concentrations of quinidine were within or below the therapeutic range in all patients. In conclusion, mexiletine and quinidine exert different hemodynamic effects when given to patients with severe congestive heart failure.(ABSTRACT TRUNCATED AT 250 WORDS)

Administration, Oral

Detection of regional left ventricular dysfunction in early pacing-induced heart failure using ultrasonic integrated backscatter.

BACKGROUND: It has been demonstrated that cyclic variation of ultrasonic integrated backscatter (CVIBS) may be useful in detecting altered physical conditions in the heart. However, no previous study has examined serial changes of CVIBS in the myocardium during the development of left ventricular dysfunction. METHODS AND RESULTS: We examined alterations of CVIBS in pacing-induced cardiac dysfunction. Eight pigs (36 +/- 2 kg) were studied before and sequentially during sustained rapid ventricular pacing (225 +/- 9 beats per minute). CVIBS was measured in the IVS and left ventricular PLW before pacing and daily for 4 days after onset of pacing. Five additional pigs (35 +/- 10 kg) were examined after 14 days of pacing. Regional function and CVIBS were assessed with pacemakers inactivated. A quantitative integrated backscatter imaging system (two-dimensional format) was used. Over 4 days of pacing, the magnitude of CVIBS progressively decreased in the PLW but was unchanged in the IVS, findings that persisted at 14 days. Percent wall thickening in the PLW progressively decreased to a greater degree than percent wall thickening in the IVS. A linear relation between the magnitude of CVIBS and percent wall thickening was found. At 14 days, blood flow to the two regions was similar but regional differences in CVIBS persisted. CONCLUSIONS: Rapid left ventricular pacing produces abnormalities of regional myocardial function within 48 hours of pacing. Regional myocardial dysfunction is accompanied by a reduction in CVIBS in the same region.

Animals