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| | Critical Care Full text Increasing afterload induces myocardial diastolic dysfunction |
 | | This is an interesting paper that suggests that changes in afterload produce significant changes in diastolic performance and the authors comment that this may be further exacerbated in diseased heart. | | | Afterload induced changes in myocardial relaxation: a mechanism for diastolic dysfunction | | | In this experiment, only one heart beat was used as the test, after which the afterload was reduced which should have eliminated any neuro humoral or global haemodynamic changes. |
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http://ccforum.com/paperreport/ccf-1999-2081
(717 words)
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| | need help explaining preload and afterload - allnurses.com Nursing for Nurses |
| | Afterload (PVR/SVR) is what the heart has to work against. | | | So - right-side problems:if the patient has chronically stiff lungs, the right side of the heart has a high afterload - a high resistance to pump into. | | | Thank you for the explanation on preload and afterload. |
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http://allnurses.com/forums/f15/need-help-explaining-preload-afterload-61876.html
(2120 words)
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| | Heart Failure: The Physiologic Basis for Current Therapeutic Concepts |
| | Afterload is determined primarily by arterial tone and the resultant pressure within the arterial system (ie, blood pressure). | | | These responses cause constriction of peripheral blood vessels, thereby increasing afterload; expand intravascular volume, thereby increasing preload; strengthen contractility either directly or via reflex response to the increased afterload and preload; and enlarge cardiac muscle mass, thereby improving myocardial performance, at least for a period (Figure 4). | | | Because the heart functions within a closed system, afterload will also influence the amount of blood discharged into the systemic circulation. |
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http://www.aacn.org/aacn/jrnlccn.nsf/c54ad59fdf5d6228882565a0006a1369/1057ad806431634488256801006f530f?OpenDocument
(4893 words)
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| | Altered cardiac function |
| | This relationship between left ventricular systolic function and afterload forms the basis for afterload reduction therapy used in the treatment of systolic failure and congestive cardiac failure. | | | Treatment of systolic heart failure is fundamentally based on an attempt to meet two goals, stabilising or improving systolic function and reducing ventricular filling pressure. | | | The causes of these changes have not been fully elucidated but clearly knowledge of the patho-physiology of this process will enable a logical approach to the management of these patients. |
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http://www.rcsed.ac.uk/journal/vol46_1/4610005.htm
(4133 words)
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| | THE MERCK MANUAL, Sec. 16, Ch. 203, Heart Failure |
| | Afterload (the force resisting myocardial fiber shortening after stimulation from the relaxed state) is determined by the chamber pressure, volume, and wall thickness at the time of aortic valve opening. | | | The mechanism by which an asymptomatic patient with cardiac dysfunction develops overt CHF is unknown, but it begins with renal retention of Na and water, secondary to decreased renal perfusion. | | | Increased heart rate and myocardial contractility, arteriolar constriction in selected vascular beds, venoconstriction, and Na and water retention compensate in the early stages for reduced ventricular performance. |
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http://www.merck.com/pubs/mmanual/section16/chapter203/203a.htm
(5496 words)
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| | [No title] |
| | Afterload clinically there are many methods of measuring afterload. | | | fixed afterload, contractility increase contractility (use norepinephrine, digoxin, digitalis) fixed preload, afterload reduce afterload (discussed above) Q: “Uh
.what are the units of preload and afterload?” A: The length/tension curve is related to the pressure/volume curve, and clinically, changes in wedge pressure are used to represent changes in the length of the muscle fibers, i.e. | | | Preload, afterload, and contractility determine the extent of shortening of a muscle, which determines stroke volume, which, multiplied by heart rate, gives cardiac output. |
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http://www.uhmc.sunysb.edu/som/students/2003/Lectures/Cardio/cardio02.doc
(2275 words)
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| | Medical Pharmacology Topics |
| | Hydralazine and minoxidil reduce afterload by relaxing arteriolar smooth muscle. | | | Preload is the tension placed on the ventricle at the end of diastole, when it is ready to contract and expel blood into the systemic circulation. | | | Minoxidil may relax arterial smooth muscle by increasing K |
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http://www.angelfire.com/sc3/toxchick/medpharm/medpharm34.html
(1082 words)
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| | CV 32 |
| | The long-term benefit of inotropic therapy is being debated and the present trend is to reduce afterload and inhibit the renin-angiotensin system (and sometimes beta blockade) rather than rely only on an inotrope in the management of chronic heart failure. | | | There is a consistent increase in peripheral resistance which is mainly ascribed to a direct constricting action of the drug on the arterioles. | | | The inotropic effect of digoxin on the heart and the increase in cardiac output results in reflex changes which decrease sympathetic tone. |
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http://www.umanitoba.ca/faculties/medicine/cardiology/cvnotes/cv32.htm
(5790 words)
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| | Acta Cardiologica - Abstract, vol.58 - nr. 4/6 - 2003 |
| | In the current study, we evaluated acute afterload dependence of dP/dtmax in both ventricles in rats. | | | This should be taken into account for its application in the haemodynamic evaluation of cardiac function in experimental and clinical settings. | | | Conclusions — In this study we demonstrated that, in contrast to the left ventricle, right ventricular dP/dtmax and dP/dtmax/EDD relation are significantly afterload sensitive. |
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http://www.actacardiologica.be/abstracts/abs5804200306.htm
(280 words)
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| | Congestive Heart Failure |
| | When the heart begins to fail and the CO is no longer sufficient to meet the metabolic demands of the body, three major compensatory mechanisms are activated: the adrenergic system, the renin-angiotensin-aldosterone system, and ventricular hypertrophy. | | | With increased afterload, the heart muscles must work harder to overcome the constricted vascular bed. | | | In addition to oxygen therapy, vasodilators try to increase oxygenated blood to ischemic areas of the heart, thus improving myocardial action. |
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http://www.csufresno.edu/nursing/n140/studassign/chf.htm
(4582 words)
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| | VM8754: PATHOPHYSIOLOGY AND MEDICAL MANAGEMENT OF CONGESTIVE HEART FAILURE |
| | As afterload increases, more contractile energy must be devoted to generate tension to overcome the afterload rather than myocardial fiber shortening and ejection of adequate volumes of blood. | | | Vasodilation is becoming a common therapeutic procedure for congestive heart failure since the peripheral circulation has become a more important site for treating congestive heart failure. | | | Calcium antagonists have a negative inotropic effect and relax vascular and other smooth muscle. |
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http://education.vetmed.vt.edu/Curriculum/VM8754/xi.html
(5875 words)
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| | Echocardiography |
| | The concept of afterload mismatch with limited preload reserve provides an explanation for the value of ejection phase indices compared to isovolumic phase measures in assessing the basal level of inotropic state: the former may be more reliable because they are sensitive to afterload. | | | The effects and implications of therapeutic afterload reduction as modulated by the preload also are understood within this framework. | | | This finding, and the lack of change in ejection phase measures after the normal heart has adapted to a chronic pressure or volume overload, provides justification for the use of ejection phase indices for detecting depressed inotropic state under basal conditions. |
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http://www2.umdnj.edu/~shindler/mismatch.html
(363 words)
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| | PHYSIOLOGY, BLOCK 2: JANUARY 1995 |
| | This intrinsic ability of cardiac muscle to adapt immediately to a changing load is used physiologically to permit each ventricle to adjust to specific variations of preload or afterload that each may encounter independently of the other. | | | If the afterload is greater than the muscle can lift, the muscle develops tension without shortening externally (isometric contraction). | | | The afterload determines the work that the muscle must do. |
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http://condor.bcm.tmc.edu/MIEC/Syllabi/PhysB2/cardiac02.html
(2862 words)
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| | Heart Physiology : the WorldWide Intensivist |
| | Despite the increased afterload, and the consequent increase in end-diastolic pressure (with normal stroke volume by the Starling effect), there is over subsequent beats a gradual fall in left-ventricular end-diastolic pressure, and stroke volume is nevertheless maintained! | | | Inotropy is the term applied to changes in heart muscle performance independent of alterations in preload and afterload. | | | A further load is then added (the "afterload") and the muscle is allowed to shorten when stimulated. |
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http://www.anaesthetist.com/icu/organs/heart/phys.htm
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| | Right heart failure: its etiology and pathophysiology |
| | In this, as in all instances of fluid infusion, careful monitoring is necessary to avoid a concomitant increase in afterload, impeding flow into the pulmonary circulation. | | | The main therapeutic goals aimed at breaking this circle are restoration of adequate oxygen delivery to the myocardium and diminution of RV afterload (Romand | | | This in turn will cause an increase in diastolic transmural pressure on the left ventricle, thereby reducing its compliance (Doyle |
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http://herkules.oulu.fi/isbn9514264010/html/x604.html
(847 words)
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| | Vasodilators - Clinical Pharmacology |
| | Afterload is only affected by changes between the left ventricle and the capillaries. | | | Reduce afterload for acute decompensation (Blood pressure can be titrated) | | | The choice of a vasodilator should be based on the needs of the individual patient for modification of either of these parameters. |
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http://cpharm.vetmed.vt.edu/vm8784/CARDIOVASCULAR/vasodilators.htm
(440 words)
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| | Vasoactive drugs: |
| | The drug should be used with extreme caution in patients with heart disease. | | | Drugs such as nitric oxide and adenosine, which have extremely short half-lives, can effectively be used to target the pulmonary circulation. | | | As with other afterload reducing agents, it tends to cause a reflex tachycardia which can be counteracted by the concurrent administration of a beta blocking drug. |
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http://www.manbit.com/PAC/chapters/P35.cfm
(1864 words)
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| | Management of Patients With Valvular Heart Disease Guidelines:Specific Valve Lesions |
| | The majority of patients with this degree of dilatation will have already developed systolic dysfunction because of afterload mismatch and will thus be candidates for valve replacement on the basis of the depressed ejection fraction. | | | Thus, AR represents a condition of combined volume overload and pressure overload (156). | | | The depressed ejection fraction in many of the patients in this latter group is caused by excessive afterload (afterload mismatch [52]), and LV function improves after AVR in such patients. |
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http://www.acc.org/clinical/guidelines/valvular/jac5929fla16.htm
(10631 words)
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| | Cardiac Output Answers |
| | Level of consciousness, presence/degree of chest pain, tachycardia | | | Explain how blood pressure can change when considering these components. | | | Afterload reduction is important to maintain, as it reduces her myocardial oxygen consumption. |
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http://www.bakerstuff.com/new_page_36.htm
(248 words)
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| | [No title] |
| | Increased Preload/Afterload Constant: IC Alters stretch of muscle prior to contraction Increased preload means that the muscle is starting off with a greater degree of tension than the control. | | | In Physiological settings, many compensating factors (increased heart rate, Sympathetic stimulation, etc.) act to maintain or increase stroke volume. | | | Endpoint tension is greater in the altered condition because a greater afterload must be overcome. |
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http://www.uhmc.sunysb.edu/som/students/2001/noteservice/h7.doc
(2073 words)
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| | VetGo Cardiology |
| | Go -> How are changes in afterload detected on physical examination? | | | Go -> How do changes in afterload change cardiac performance? | | | Go -> How does afterload affect myocardial performance? |
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http://www.vetgo.com/cardio/concepts/concindx.php
(2548 words)
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| | Antianginals |
| | The goal of drug therapy is to reduce cardiac ischemia by: | | | Decreasing peripheral arteriolar resistance reduces myocardial work and therefore myocardial oxygen consumption | | | Organic nitrates have been used for more than 100 years, and are still widely used in the treatment of angina pectoris |
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http://lysine.pharm.utah.edu/netpharm/netpharm_00/notes/antianginals.html
(2393 words)
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| | Postgraduate Medicine: Congestive Heart Failure Symposium: Acute Congestive Heart Failure |
| | In cardiac muscle, phosphodiesterase inhibitors increase contractility; in the peripheral vasculature, they relax smooth muscle, resulting in vasodilatation (10,11). | | | Immediate treatment of acute CHF consists of reducing myocardial oxygen demand while augmenting forward blood flow. | | | They increase contractility and reduce afterload, and in contrast to beta-receptor agonists, they increase intracellular cyclic adenosine monophosphate by inhibiting the enzyme responsible for its breakdown. |
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http://www.postgradmed.com/issues/1997/01_97/levin.htm
(3304 words)
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| | ONLOAD is there an afterLoad alternative (Iframe problem) |
| | ONLOAD is there an afterLoad alternative (Iframe problem) | | | Is there an alternative to onLoad that will do this? | | | Re: ONLOAD is there an afterLoad alternative (Iframe problem) |
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http://www.forum4designers.com/message73262.html
(467 words)
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| | eMedicine - Heart Failure : Article by Michael E Zevitz, MD |
| | IAPB is used to stabilize patients, which allows time to plan the definitive surgical procedure in patients who are hemodynamically unstable. | | | IABP may be a lifesaving intervention in patients with acute mitral regurgitation secondary to papillary muscle ischemia, infarction, and other causes such as infectious endocarditis or myxomatous degeneration. | | | Topical NTG may be as effective as sublingual NTG in most patients with heart failure, but it should be avoided in patients with severe LV failure because of poor skin perfusion (manifesting as skin pallor or mottling) and resultant poor absorption. |
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http://www.emedicine.com/med/topic3552.htm
(11115 words)
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| | [No title] |
| | Afterload, that load applied after a muscle begins to contract, alters stroke volume (Figure 2.03). | | | Systemic hypertension, aortic stenosis, and atherosclerosis all increase afterload, mean ejection pressure, and end-systolic volume. | | | Afterload - Increased tension on a muscle fiber after contraction begins; usually due to increased aortic/arterial blood pressure and/or decreased compliance; imposed during systole. |
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http://www.coheadquarters.com/PennLibr/MyPhysiology/lect2/pen2.08.htm
(108 words)
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| | APStracts 6:0299H, 1999. |
| | Conclusions (1) Preload and afterload influence torsion through their effects on SV and EF, and (2) there is an additional direct inotropic effect on torsion that is independent of changes in volume, but rather, is force-dependent. | | | Methods In ten isolated, blood -perfused canine hearts, ejection was controlled by a servopump: end -diastolic volume (EDV) was controlled by manipulating preload parameters, and end-systolic volume (ESV) by manipulating afterload using a 3-element Windkessel model. | | | Independent effects of preload, afterload and contractility on left ventricular torsion. |
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http://www.uth.tmc.edu/apstracts/1999/heart/June/299h.html
(335 words)
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| | Association of Veterans Affairs Anesthesiologists |
| | Afterload — Technically, afterload refers to the pressure that the ventricle must overcome in order to eject blood. | | | In the management of valvular heart disease, control of preload not only refers to control of end-diastolic volume, but also refers to the effects of left atrial pressure on the lungs and the effects of right atrial pressure on the body. | | | Decreased SVR tends to limit regurgitation by lowering diastolic pressure but the degree of afterload reduction may be limited by the decline in diastolic pressure. |
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http://www.vaanes.org/FORUMS/ValvesAVAA.html
(7571 words)
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| | [No title] |
| | There is also a relationship between the load (afterload) on a muscle and the velocity of shortening (Figure 10). | | | Preload and afterload have different effects on velocity of muscle contraction. | | | Although varying the afterload and preload alters tension generation, extent of shortening, and velocity of shortening, inotropicity (contractility) is not altered by these maneuvers. |
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http://www.coheadquarters.com/PennLibr/MyPhysiology/myocell/myo.10.htm
(149 words)
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| | Treating with meds vs surgery |
| | Although intuitively the use of vasodilators may appear to be logical for the same reasons that they are effective in acute MR and chronic AR, there are no large long-term studies to indicate that they are beneficial. | | | Furthermore, because MR with normal ejection fraction is a disease in which afterload is not increased (155,405,414,415), drugs that reduce afterload might produce a physiological state of chronic low afterload with which there is very little experience. | | | These data do not appear to be applicable to asymptomatic patients. |
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http://www.medhelp.org/forums/cardio/messages/34274.html
(462 words)
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| | [No title] |
| | Ejection fraction may be estimated from the change in cross-sectional area as viewed by echocardiography, or other imaging techniques. | | | The disadvantage of this index is that it is influenced by both contractility and afterload, and it is not possible to tell which one of these parameters is changing. | | | Inceasing afterload will decrease stroke volume and raise the blood pressure. |
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http://cpmcnet.columbia.edu/student/ssn/heart1.doc
(664 words)
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| | Shock |
| | There are certain factors which affect the stroke volume. | | | There are many etiologies of cardiogenic shock, including congenital heart disease, arrythmias, ischemic heart disease, myocarditis, pericardial effusion and tamponade, myocardial contusion and/or traumatic injury, acute drug toxicities, chronic drug toxicities, late septic shock, infiltrative disease, thyrotoxicosis and pheochromocytoma. | | | The afterload is defined as impedance or resistance to ventricular contraction. |
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http://home.coqui.net/myrna/shock.htm
(2490 words)
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| | 1.4.3 Control of cardiac output |
| | Thus the total stroke volume will increase, but the forward stroke volume will not change (or may even fall in severe cases). | | | This occurs in a number of situations, for example in animals with hypovolaemic or septic shock, or in animals with pericardial effusions which have resulted in cardiac tamponade. | | | Factors which affect afterload are summarised in Table 1.1. |
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http://www.provet.co.uk/equinecardiology/5a583af.htm
(1087 words)
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| | blood pressure |
| | Both can have independent effects on stroke volume, but both rarely change separately. | | | This is known as aortic pressure or afterload (125). | | | Atherosclerotic disease may also disproportionately increase systolic blood pressure over a diastolic rise. |
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http://www.emunix.emich.edu/~bogle/blood_pressure.htm
(13652 words)
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