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CADIOLOGISTS IN VIDHYARANYAPURA Coronary angiography (cardiac catheterisation) This procedure enables the cardiologist to visualise the coronary arteries It is the standard against which other less-invasive investigations are assessed. Selective catheterisation of the right and left coronary ostia is performed. Contrast is then injected into the vessels and digital tape or disc storage of the images obtained. In most hospitals the patient is admitted on the morning of the test and allowed to go home that afternoon. The procedure is most often performed through the femoral artery (Judkins technique) This artery can be punctured through the skin under local anaesthetic. A fine softtipped guide wire is then advanced into the artery and the needle withdrawn (Seldinger method). A short guiding sheath can then be placed over the wire and long cardiac catheters advanced through this sheath along a long guide wire into the femoral artery and up via the aorta to the aortic arch. The catheter and wire are advanced under X-ray control. Usually one catheter with a curved tip (pig-tail catheter; is advanced across the aortic valve into the left ventricle where left ventricular pressures are measured via a pressure transducer connected to the other end of the catheter. Measurement of the left ventricular end-diastolic pressure gives an indication of left ventricular function. Raised end-diastolic pressure (over 15 mmHg) suggests left ventricular dysfunction The catheter is then connected to a pressure injector. This enables injection of a large volume of contrast over a few seconds; for example, 35 mL at 15 mL/second. X-ray recording during injection produces a left ventriculogram . Here left ventricular contraction can be assessed and the ejection fraction (percentage of end-diastolic volume ejected with each systole) estimated. The normal is 60% or more. The figure obtained by this method tends to be higher than that produced by the nuclear imaging method—gated blood pool scanning. The guide wire is reintroduced and the catheter withdrawn to be replaced by one shaped to fit into the right or left coronary orifice. Hand injections of 5–10 mL of contrast are then made. Modern equipment enables numerous views of the coronaries to be obtained in both right and 4• THE PATIENT WITH CHEST PAIN 129 left oblique and caudal and cranial angulated views. The left system (left main, left anterior descending and circumflex arteries) is more complicated than the right, and more views are obtained ) It is also possible to catheterise the heart by direct puncture of the radial artery at the wrist, using a long sheath and a technique similar to the Judkins. Problems may be encountered advancing the catheters around the shoulder or if spasm of the radial or brachial artery occurs.
CARDIOLOGISTS IN HEBBALA Risk stratification using myocardial perfusion scans A normal perfusion scan is associated with a good prognosis. The annual rate of myocardial infarction of cardiac death is < 1%, at least for some years. Stress echocardiography Ischaemic areas of myocardium are known to have reduced contraction compared with normal areas. This can be demonstrated by high-quality echocardiograms. A number of standard views of the heart are obtained and the wall is divided into regions that are assessed for reduced motion. The echo equipment must be designed to store rest images and to present them next to stress images on a split screen so that direct comparison can be made. The stress can be provided by exercise or dobutamine infusion. Exercise echocardiography is difficult to perform because of movement problems and there is quite high inter-reporter variability, but both techniques can approach the accuracy of sestamibi testing in experienced hands. It is not possible to obtain images of adequate quality in all patients. Coronary angiography (cardiac catheterisation) This procedure enables the cardiologist to visualise the coronary arteries It is the standard against which other less-invasive investigations are assessed. Selective catheterisation of the right and left coronary ostia is performed. Contrast is then injected into the vessels and digital tape or disc storage of the images obtained. In most hospitals the patient is admitted on the morning of the test and allowed to go home that afternoon. The procedure is most often performed through the femoral artery (Judkins technique) . This artery can be punctured through the skin under local anaesthetic. A fine softtipped guide wire is then advanced into the artery and the needle withdrawn (Seldinger method). A short guiding sheath can then be placed over the wire and long cardiac catheters advanced through this sheath along a long guide wire into the femoral artery and up via the aorta to the aortic arch. The catheter and wire are advanced under X-ray control. Usually one catheter with a curved tip (pig-tail catheter;is advanced across the aortic valve into the left ventricle where left ventricular pressures are measured via a pressure transducer connected to the other end of the catheter. Measurement of the left ventricular end-diastolic pressure gives an indication of left ventricular function. Raised end-diastolic pressure (over 15 mmHg) suggests left ventricular dysfunction . The catheter is then connected to a pressure injector. This enables injection of a large volume of contrast over a few seconds; for example, 35 mL at 15 mL/second. X-ray recording during injection produces a left ventriculogram Here left ventricular contraction can be assessed and the ejection fraction (percentage of end-diastolic volume ejected with each systole) estimated. The normal is 60% or more. The figure obtained by this method tends to be higher than that produced by the nuclear imaging method—gated blood pool scanning. The guide wire is reintroduced and the catheter withdrawn to be replaced by one shaped to
HEART SPEACIALISTS IN BANGALORE Stress echocardiography Ischaemic areas of myocardium are known to have reduced contraction compared with normal areas. This can be demonstrated by high-quality echocardiograms. A number of standard views of the heart are obtained and the wall is divided into regions that are assessed for reduced motion. The echo equipment must be designed to store rest images and to present them next to stress images on a split screen so that direct comparison can be made. The stress can be provided by exercise or dobutamine infusion. Exercise echocardiography is difficult to perform because of movement problems and there is quite high inter-reporter variability, but both techniques can approach the accuracy of sestamibi testing in experienced hands. It is not possible to obtain images of adequate quality in all patients.
HEART DOCTORS IN YELAHANKA NEWTOWN, BANGALORE Management of ACS (NSTEACS) Patients with this diagnosis represent a rather heterogeneous group. Some have had the recent onset of angina at the extremes of exercise, others have angina at rest associated with ECG changes. This variation has made attempts to study the effects of different treatment rather difficult. Although the majority of patients with myocardial infarction have a preceding period of unstable angina, only about 5% of all patients admitted to hospital with a diagnosis of an ACS go on to infarct during that admission. The in-hospital mortality for these patients is low. Mortality rates of less than 2% are usual. Nevertheless, there is a real short-term and longerterm risk of infarction, recurrent admission with unstable symptoms and death which is higher than that of patients with stable angina. The diagnosis should therefore lead to admission to a CCU. The cardiac enzymes are, by definition, not elevated in these patients but the newer, more sensitive tests for troponin T and troponin I may be abnormal and indicate a worse prognosis . In the CCU, bed rest, oxygen and ECG monitoring are routinely enforced and any mobile phones taken away (allegedly to protect the monitoring equipment). Recurrence of chest pain can be assessed quickly and ECGs performed to look for changes suggesting infarction. The cardiac biomarkers can be checked regularly. All patients should receive aspirin (300 mg) unless there is a contraindication. Patients with an intermediate or a higher risk should also be given clopidogrel (usually a 300–600 mg loading dose). The use of intravenous heparin has become standard treatment. A typical starting dose is 5000 units as a bolus followed by 24, 000 units over 24 hours. The activated partial thromboplastin time (APPT) should be measured after about six hours of treatment and the infusion rate of heparin adjusted to maintain this at about twice normal. Heparin is generally safe when used in this way. Bleeding problems may sometimes occur and the platelet count should be checked every few days so that heparin-induced thrombocytopenia (HITS), a rare but serious complication, can be detected early. Low molecular weight heparins are at least as effective as unfractionated heparin. These drugs have some advantages over heparin. Their dose response effect is more predictable and they cause less thrombocytopenia. They are effective given subcutaneously without APPT monitoring and are now cheaper than IV heparin when savings on APPT monitoring and the use of infusion sets are considered. A standard twice-daily dose is given according to the patient’s weight—1 mg/kg for enoxaparin (Clexane). The dose is reduced by half for those with moderate or severe renal impairment and for those over the age of 75. Additional treatment should include beta-blockers unless these are contraindicated. These drugs reduce the number of ischaemic episodes and probably the risk of myocardial infarction. Nitrates can be a useful adjunctive treatment. They may be given orally, topically or intravenously. The IV dose can be titrated up or down depending on the amount of pain the patient is experiencing and the severity of side effects such as hypotension and headache. The problem of tachyphylaxis with nitrates can be overcome by steady increases in the IV dose if necessary. Calcium antagonists are appropriate treatment for patients intolerant of beta-blockers and may sometimes be added to beta-blockers. Nifedipine, especially in its short-acting form, should not be used for patients with acute coronary syndromes unless they are already taking beta-blockers. Thrombolytic drugs have been disappointing when used for NSTEACS. In trials where they have been used for patients with ischaemic chest pain but without ST elevation there has been a trend towards an adverse outcome. This may be related to the rebound hypercoagulable state that can occur after their use. In general they should not be used for the treatment of NSTEACS. Glycoprotein IIb/IIIa inhibitors (p. 198) should be given for high-risk patients,
HEART SPECIALISTS IN H S R LAYOUT BANGALORE A systematic description of ECGs The following eight short steps will enable most ECGs to be described correctly: 1 Check the paper speed and calibration markers. 2 Measure or estimate the heart rate. 3 Estimate the rhythm. 4 Look for P waves. 5 Measure the PR interval. 6 Examine the QRS complex. 7 Check the ST segment. 8 Measure the T wave. ECG interpretation should always be as restrained as practicable, taking into account the clinical context where known and comparison with previous tracings where possible. The possibility of Prinzmetal’s electrocardiographic heart disease must always be borne in mind—that is, do not assume that an abnormal ECG always means heart disease.2 Paper speed and calibration markers The standard paper speed is 25 mm/second. This means that 1 mm (small square) = 0.04 seconds and 5 mm (large square) = 0.20 seconds. Provided that the grid is shown, this gives the time scale regardless of the actual image magnification used. Voltage is measured on the vertical axis: 10 mm = 1 mV, as shown in the calibration artefact Leads are often described in groups that correspond approximately to the area of the heart they represent. n Leads 1 and aVL are (high) lateral leads. n Leads 2, 3 and aVF are inferior leads. n Leads 1, 2, 3, aVL, aVF and aVR are collectively called limb or frontal plane leads. Leads 1, 2 and 3 are standard limb leads, while leads aVL, aVF and aVR are augmented limb leads. n Leads V1 and V2 are anteroseptal leads. n Leads V3 and V4 are anterior leads. n Leads V5 and V6 are anterolateral leads. n Leads V1–V6 are collectively called chest, precordial or horizontal plane leads. 3• AN OVERVIEW OF CLINICAL ELECTROCARDIOGRAPHY 49 Heart rate By definition, sinus tachycardia is a heart rate ≥ 100/minute and sinus bradycardia is a heart rate ≤ 50/minute.3 To calculate the heart rate from the ECG, the R-R interval in mm can be divided into 1500. For example, an R-R interval of 20 mm gives a rate of 75/minute and an R-R interval of 15 mm gives a rate of 100. Similarly, large 5 mm squares can be divided into 300; thus three squares give a rate of 100/minute. In regular rhythms, any two congruous points of the P-QRS-T sequence can be used to estimate the rate. An ECG ruler has a scale that enables rapid rate measurement and calculation of other intervals. With practice, the rate can be estimated at a glance. Rhythm Begin by looking for P waves. They are best seen in lead 2 (L2) (which is calculated electrocardiographically as the arithmetic sum of leads 1 and 3), aVR (where everything including the P waves
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