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DIABETIC SPECIALIST IN YALAHANKA Syncope and dizziness The history Syncope is a transient loss of consciousness resulting from cerebral anoxia, usually due to inadequate blood flow. Syncope may represent a simple faint or be a symptom of cardiac or neurological disease. Establish whether the patient actually loses consciousness and under what circumstances the syncope occurs—for example, on standing for prolonged periods or standing up suddenly (postural syncope), while passing urine (micturition syncope), on coughing (tussive syncope) or with sudden emotional stress (vasovagal syncope). Find out whether there is any warning such as dizziness or palpitations, and how long the episodes last. Recovery may be spontaneous or require attention from bystanders. Bystanders may also have noticed abnormal movements if the patient has epilepsy, but these can also occur in primary syncope. If the patient’s symptoms appear to be postural, enquire about the use of anti-hypertensive or anti-anginal drugs and other medications that may induce postural hypotension. If the episode is vasovagal, it may be precipitated by something unpleasant like the sight of blood, or it may occur in a hot crowded room; patients often feel nauseated and sweaty before fainting and may have had prior similar episodes, especially during adolescence and young adulthood. The diagnosis of this relatively benign and very common cause of syncope can usually be made from the history. Patients with very typical symptoms rarely require extensive investigations. If syncope is due to an arrhythmia there is often sudden loss of consciousness regardless of the patient’s posture. A history of rapid and irregular palpitations or a diagnosis of atrial fibrillation in the past suggests the possibility of sick sinus syndrome. These patients have intermittent tachycardia, usually due to atrial fibrillation, and episodes of profound bradycardia, often due to complete heart block. Chest pain may also occur if the patient has aortic stenosis or hypertrophic cardiomyopathy. Exertional syncope may occur in these patients because of obstruction to left ventricular outflow by aortic stenosis or septal hypertrophy . Dizziness that occurs even when the patient is lying down or that is made worse by movements of the head is more likely to be of neurological origin (vertigo), although recurrent tachyarrhythmias may occasionally cause dizziness in any position. Try to decide whether the dizziness is really vertiginous (there is a sensation of movement or spinning of the surroundings or the patient’s head), or whether it is a presyncopal feeling. A family history of syncope or sudden death raises the possibility of an ion channel abnormality (long QT syndrome, Brugada syndrome or hypertrophic cardiomyopathy). Attempts should be made to find out what the diagnosis was for the affected relatives. A past history of severe structural heart disease, especially heart failure,
BEST CARDIOLOGY HOSPITALS IN BANGALORE Cardiac failure Cardiac failure is an increasingly common condition affecting about 1% of the population but much higher proportions of older people. It is responsible for an increasing number of hospital admissions. The various aetiologies have been discussed above, but the most common cause is now ischaemic heart disease rather than hypertensive heart disease. This reflects the improved modern management of hypertension in the population. The definition of heart failure has always included reference to the inability of the heart to meet the metabolic needs of the body. The earliest concepts of heart failure were of inadequate cardiac pump function and associated salt and water retention. Treatment was aimed at improving cardiac contractility and removing salt and water from the body. In the 1970s the concept of after-load reduction was introduced. This was based partly on the realisation that vasoconstriction was part of the problem. This has led to the modern neuro-hormonal concept of heart failure. It is clear that many of the features of cardiac failure are a result of stimulation of the renin-angiotensin-aldosterone system and sympathetic stimulation. These responses of the body to the fall in cardiac output temporarily increase cardiac performance and blood pressure by increasing vascular volumes, cardiac contractility and systemic resistance. In the medium and longer term these responses are maladaptive. They increase cardiac work and left ventricular volumes and lead to myocardial fibrosis with further loss of myocytes. Most recently it has become clear that heart failure is also an inflammatory condition, with evidence of cytokine activation. Work is underway to establish a role for treatment of this part of the condition. Current drug treatment has been successful in blocking many of the maladaptive aspects of neuro-hormonal stimulation. Many of these treatments have become established after benefits have been ascertained in large randomised controlled trials. These trials have also led to the abandoning of certain drugs (often those that increase cardiac performance) that were shown to have a detrimental effect on survival (e.g. Milrinone). The principles of treatment of heart failure are as follows: 1 Remove the exacerbating factors. 2 Relieve fluid retention. 3 Improve left ventricular function and reduce cardiac work; improve prognosis. 4 Protect against the adverse effects of drug treatment. 5 Assess for further management (e.g. revascularisation, transplant). 6 Manage complications (e.g. arrhythmias). 7 Protect high-risk patients from sudden death.
A risk factor is a demographic characteristic associated with an increased risk of ischaemic heart disease when other variables have been controlled. The presence of a risk factor in an individual increases his or her relative risk of a coronary event (angina, infarction or death). The absolute risk of a coronary event depends on the individual’s total number of risk factors and theirseverity (total risk). Important coronary risk factors are shown in Table 1.1. Risk assessment charts have been developed to estimate a patient’s cardiac risk over a number of years using easily identified risk factors. There are charts for different populations. The charts can be used to predict cardiovascular events or mortality (as in the NHF chart in Fig 1.1 on p. 4) or cardiac risk (systematic coronary risk evaluation system or SCORE charts). These charts can be very helpful in deciding when intervention to reduce risk is warranted; for example, when anti-hypertensive treatment should be commenced for a patient with mild blood pressure elevation. Risk factor reduction involves assessing the presence, severity and importance of risk factors for a
CARDIOLOGIST IN YELAHANKA SECOND DEGREE AV BLICK There are two basic types of second-degree AV block: AV nodal Möbitz type I (Wenckebach) heart block, and the more distal and more sinister Möbitz type II heart block. Möbitz type I heart block is much more common. In Möbitz type I block the PR interval lengthens progressively with each cardiac cycle, until an atrial wave is not conducted. There is recovery of conduction and the next a wave is conducted with a shorter interval and the cycle begins again. The QRS complex is narrow (Fig 3.10) (unless associated with pre-existing BBB). The increment is largest between the first and second conducted P wave, and the PR interval continues to increase by less and less until a P wave is dropped. Möbitz type II heart block is almost always associated with a BBB (Fig 3.11), since its origin is intraventricular (below the AV node), and it tends to lapse suddenly into extreme bradycardia or asystole. It tends to be over-diagnosed, especially in the setting of 2:1 AV block (Fig 3.12). There is no lengthening of the PR interval before an atrial wave is not conducted. At times, atropine or exercise can demonstrate the site of the block, by increasing the block from 2:1 to a higher grade when the underlying mechanism is Möbitz II. Conversely, Wenckebach conduction may improve to 3:2 or better. For a distinction to be made between Möbitz type I and Möbitz type II, at least two consecutively conducted P waves have to be evaluated. This is impossible in 2:1 conduction (block) and can only be reported as 2:1 AV block (Fig 3.12). Yet this is very commonly reported as
THE BEST CARDIOLOGISTS IN YELAHANKA Second-degree AV block There are two basic types of second-degree AV block: AV nodal Möbitz type I heart block, and the more distal and more sinister Möbitz type II heart block. Möbitz type I heart block is much more common. In Möbitz type I block the PR interval lengthens progressively with each cardiac cycle, until an atrial wave is not conducted. There is recovery of conduction and the next a wave is conducted with a shorter interval and the cycle begins again. The QRS complex is narrow (unless associated with pre-existing BBB). The increment is largest between the first and second conducted P wave, and the PR interval continues to increase by less and less until a P wave is dropped. Möbitz type II heart block is almost always associated with a BBB , since its origin is intraventricular (below the AV node), and it tends to lapse suddenly into extreme bradycardia or asystole. It tends to be over-diagnosed, especially in the setting of 2:1 AV block . There is no lengthening of the PR interval before an atrial wave is not conducted. At times, atropine or exercise can demonstrate the site of the block, by increasing the block from 2:1 to a higher grade when the underlying mechanism is Möbitz II. Conversely, Wenckebach conduction may improve to 3:2 or better. For a distinction to be made between Möbitz type I and Möbitz type II, at least two consecutively conducted P waves have to be evaluated. This is impossible in 2:1 conduction (block) and can only be reported as 2:1 AV block (Fig 3.12). Yet this is very commonly reported as Möbitz type
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