Even though she is at low to intermediate risk buy lady era 100mg cheap, she is highly likely to be admited as an inpatient based on local institution pro- tocol cheap lady era 100 mg on-line. Still, would there be any beneft to obtaining any imaging at this early stage of diagnostic evaluation? A Report of the American College of Cardiology Foundation Appropriate Use Criteria Task Force, the Society of Cardiovascular Computed Tomography, the American College of Radiology, the American Heart Association, the American Society of Echocardiography, the American Society of Nuclear Cardiology, the North American Society for Cardiovascular Imaging, the Society for Cardiovascular Angiography and Interventions, and the Society for Cardiovascular Magnetic Resonance. Model 1 used standard Framingham risk factors: age, sex, race/ethnicity, tobacco use, systolic blood pressure, antihypertensive medication use, and high-density lipoprotein and total cholesterol levels. Net reclassif- cation improvement and distribution of risks were calculated between the two models. Information for traditional cardiovascular risk factors (age, blood pres- sure, tobacco use, cholesterol, triglycerides, plasma glucose) were measured at baseline examination. Follow- Up: Telephone interviews at 9–12 month intervals through May 2008 (patient enrolled 2000–2002). Data were abstracted for 96% of hospitalized cardiovascular events and 95% of outpatient diagnostic encounters to verify patient- reported diagnoses. He has a family history of coronary heart disease, but reports no chest pain symptoms. T is additional information could help fur- ther stratify this intermediate-risk patient to a higher risk classifcation, and make him eligible to receive more intensive therapy as a result of screening. T ese potential preventive interventions may include lifestyle changes, mini dose aspirin, starting a statin, and/or treating hypertension. Coronary artery calcium score and risk classifcation for coronary heart disease prediction. Coronary calcium as a predictor of coronary events in four racial or ethnic groups. A Report of the American College of Cardiology Foundation Appropriate Use Criteria Task Force, the Society of Cardiovascular Computed Tomography, the American College of Radiology, the American Heart Association, the American Society of Echocardiography, the American Society of Nuclear Cardiology, the North American Society for Cardiovascular Imaging, the Society for Cardiovascular Angiography and Interventions, and the Society for Cardiovascular Magnetic Resonance. Who Was Studied: Men aged 65–74 years identifed from Health Authority and family doctor patient lists. Patients were randomly as- signed to either receive an invitation for a screening abdominal ultrasound (in- vited group) or not (control group). Men with normal aortas (<3 cm diameter) and those where the aorta was not visualized were not rescanned. Urgent referral to surgery was recommended for patients with aortas measuring 155 Abdominal Aortic Aneurysm Screening 155 ≥5. Quality of life was as- sessed using four standardized scales among screened and nonscreened study participants. Exposure: Screening ultrasounds were performed by experienced sonog- raphers using a portable ultrasound machine. T e maximum transverse and anterior-posterior diameters of the abdominal aorta were measured and re- corded (Figure 24. While the invited group had fewer emergency operations than the control group (27 vs. Criticisms and Limitations: T e portable ultrasound machine used in this study represents outdated technology. A small proportion of patients’ aortas (about 1%) were not visualized on ultrasound, and these patients were not re- screened. T is trial further found no adverse efects on emotional states of patients who underwent screening or subsequent surgery 1 year afer screening or surgery. She would also like to know if a screening study would be covered by her Medicare insurance. You should inform her that there may be some potential beneft from detecting an aneurysm by ultrasound, but that there is not enough evidence to sug- gest that the risks outweigh the potential benefts. Quantifying the risks of hypertension age, sex and smoking in patients with ab- dominal aortic aneurysm. Screening men for abdominal aortic aneurysm: 10 year mortal- ity and cost efectiveness results from the randomized Multicentre Aneurysm Screening Study. Screening for abdominal aortic an- eurysm: a best-evidence systematic review for the U. T e care of patients with abdominal aortic aneurysm: the Society for vascular Surgery practice guidelines. Year Study Began: 1998 Year Study Published: 1999 Study Location: Single large urban pediatric teaching hospital. Who Was Studied: Children and adolescents aged 3–21 years with equivocal fndings for acute appendicitis. Who Was Excluded: Pregnant patients, patients with previous appendectomy, or contraindication to rectal contrast. All children with suspected ap- pendicitis were evaluated by a senior surgical resident under the supervision of an atending pediatric surgeon. Patients with equivocal fndings were ini- tially evaluated with pelvic ultrasound. Exposure: Pelvic ultrasounds were performed by a pediatric radiology fellow or atending using a 5. Diagnosis of appendicitis was based on detecting a fuid- fled, distended tubular structure measuring at least 6 mm in diameter and/or periappendiceal infammatory changes. Follow- Up: All children who did not undergo surgery were contacted for follow-up at 2 weeks by telephone. Criticisms and Limitations: T is study was performed at a single academic institution; thus, its fndings may not be widely generalizable. Radiologists performing ultrasounds were aware of the surgeon’s estimated likelihood of appendicitis, potentially biasing their in- terpretations of ultrasound examinations. Other Relevant Studies and Information: • Ultrasound may diagnose appendicitis in a substantial proportion of pediatric patients with equivocal clinical fndings without the need for radiation. For the pediatric patient population with a low pretest probability of appendicitis, ultrasound remains the primary diagnostic modality. T e patient has an elevated white blood cell count and the parents report that their son has not had an appetite all day. You order an ultrasound of the right lower quadrant, and the pediatric radiolo- gists reports that the appendix was not visualized and there was no evidence of abscess or fuid collections in the right lower quadrant. T e use of additional oral or rectal con- trast is institution dependent, and, in many cases, intravenous contrast alone should be sufcient for obtaining a very high accuracy for diagnosing pediat- ric acute appendicitis. Ultrasonography and limited com- puted tomography in the diagnosis and management of appendicitis in children. Year Study Began: 2009 Year Study Published: 2012 Study Location: Seoul national University bundang Hospital, South Korea. Who Was Excluded: Patients meeting inclusion criteria but with body mass index <18. Care providers were not blinded to the interven- tion group, but patients and outcomes assessors were blinded to assignments. Routine 5-mm-thick images were augmented with 2-mm thin-slice images and multi- planar sliding-slab averaging techniques. Follow- Up: Pathological examination afer surgery, or review of medical re- cords and telephone interviews 3 months afer patients’ initial presentation if no surgery. Endpoints: Primary endpoint was percentage of negative appendectomies among all nonincidental appendectomies, with a noninferiority margin of 5. Secondary clinical endpoints included rate of perforated appendices, proportion of patients requiring additional imaging (e. Ultrasound with graded compression may also be appropriate (rating 6 out of 9) in this seting. She denies any nausea or vomiting, and has had prior episodes of generalized lower abdom- inal pain that have resolved and that she associates with her menstrual cycle. Radiation dose associated with common computed tomography examinations and the associated lifetime atrib- utable risk of cancer. Follow- Up: Minimum 12-month clinical follow-up via medical records for nonsurgical cohort. Diagnostic performance characteristics included sensitiv- ity, specifcity, and predictive values.
Chapter 3 Radiographic Contrast Agents 19 L3 Rapid contrast flow L4 toward the spinal canal consistent with intra-arterial injection L5 Needle in position for transforaminal injection A B Figure 3-5 discount 100 mg lady era visa. A: Intra-arterial contrast injection is typi- cally not seen on still images because the contrast material is rapidly diluted in the blood- stream cheap lady era 100 mg fast delivery. During real-time or live ﬂuoroscopy, intra-arterial contrast injection appears as in this anterior-posterior digital subtraction radiograph of the lumbar spine taken during lumbar transforaminal injection. The contrast can be seen ﬂowing toward the end organ (in this image, toward the lumbar spinal cord) with the arterial blood. Use of digital subtraction cine- radiography allows for detection of intravascular injection with small doses of radiographic contrast material. Osmotoxic cardiac contractility), neurologic (seizures), and renal toxicity reactions have been dramatically reduced with the advent of (oliguria, impaired creatinine clearance, and reduced glomeru- low-osmolar, nonionic agents such as iohexol and should be lar ﬁltration rate that may progress to acute renal failure). Treatment of these life-threatening reac- damage (capillary leak and edema), vasodilation (ﬂush- tions is urgent, necessitating the immediate availability of ing, warmth, hypotension, cardiovascular collapse), hyper- full resuscitation equipment and trained personnel, along volemia, and direct cardiac depression (reduced cardiac with a practiced routine for responding to these rare events. Epinephrine Recognition and Treatment of Reactions is the drug of choice for the treatment of anaphylaxis; the usual adult starting dose is 0. Reactions can be generally grouped as mild, moderate, Death may ensue following this type of severe adverse reac- or severe. Some authors recommend of particulate steroid directly into critical vessels supplying addition of H2-antagonists (e. Use of Gadolinium as an Alternative to Patients believed to be at greater than usual risk are listed in Iodinated Radiographic Contrast Media Table 3-5. It has been our practice to avoid radiographic con- trast altogether in those at elevated risk for adverse reaction. Gadolinium chelates, for example, gadopentate dimeglu- Most procedures in pain medicine can be carried out safely mine (Magnevist), are commonly used intravenous contrast without use of radiographic contrast. In some instances agents used to enhance vascular structures during diagnostic (e. Gadolinium chelates also have using loss of resistance alone, and ﬁnal needle position can an intrinsic ability to attenuate x-rays and have been used be veriﬁed using anterior-posterior and lateral radiography successfully in place of iodinated contrast media for angiog- without contrast. However, some injections should not be raphy and spinal injections used in image-guided pain treat- attempted without radiographic contrast injection (e. They have also been used as an alternative to iodinated transforaminal injection); in this case, injection of contrast contrast agents in patients with known contrast allergy. The under live or real-time ﬂuoroscopy (with or without digital radiopacity of gadolinium is less than that of iodinated con- subtraction) is the only means to detect intra-arterial needle trast agents, resulting in a less conspicuous appearance on location (see Fig. Utility of digital subtraction ﬂuoroscopy for visualization of the gadolinium-based contrast epidurogram. A nonselective epidural steroid injection performed in a 62-year-old male at L4 to L5 employing an interlaminar approach. A: Right anterior oblique projection of the lumbar spine shows a needle (arrow) inserted into the interlaminar space at L4 to L5. B: Conventional ﬂuoroscopy permits visualization of an epidurogram in the lateral pro- jection (arrows). C: Digital subtraction ﬂuoroscopy in the lateral projection more clearly demonstrates the distribution of the gadolinium chelate in the epidural space. Use of gadolinium chelate to conﬁrm epidural needle placement in patients with an iodinated contrast reaction. Prevention of contrast-induced nephropathy: been used successfully and reliably for identiﬁcation of the an overview. Grainger & through use of digital subtraction in combination with Allison’s Diagnostic Radiology. Use of gadolinium applications, the risk of renal toxicity should be negligible, chelate to conﬁrm epidural needle placement in patients with making gadolinium a viable and readily available alternative an iodinated contrast reaction. Association of gadolinium based determine potential communication between the cerebrospinal magnetic resonance imaging contrast agents and nephrogenic ﬂuid pathways and intracranial arachnoid cysts. Like- wise, direct intra-arterial injection of just a few milligrams of Local Anesthetic Allergy local anesthetic into the vertebral artery can cause immedi- ate generalized seizures because the local anesthetic travels Local anesthetics have low allergic potential. Any practitioner of “allergic reactions” reported by patients are misinterpre- performing injection techniques with local anesthetics must tations of the cause of symptoms following local anesthetic be familiar with these toxicities and their management and injection. A frequent scenario reported by patients as “an work in a facility equipped to handle such adverse events. On close questioning, the symp- toms are usually attributable to intravascular injection of Treatment of Local Anesthetic local anesthetic containing epinephrine as a vasoconstric- Systemic Toxicity tor (e. This group of experts emphasizes the need to seek additional help and insti- Local Anesthetic Toxicity tute basic life support measures immediately upon any suspi- Local anesthetics are associated with life-threatening tox- cion of local anesthetic systemic toxicity. As serum levels of local anesthetic rise, symptoms with 100% oxygen has been established, immediate cessation of excitation of the central nervous system appear, ﬁrst in of seizure activity with a small dose of benzodiazepine should the form of tinnitus and dizziness followed by generalized follow. Recommended maximal doses of local anesthetics are warranted, given the time needed for metabolism and elimi- shown in Table 4-3. Even small doses of local anesthetic placed within the thecal sac (spinal anesthesia) can produce profound sensory and motor block that extends to the upper torso and, at higher doses, to the head and neck (total spinal anesthesia). Based on The pharmacology of the corticosteroids is complex, and the improvement in survival demonstrated in animal studies this group of drugs affects almost all body systems. In phar- and the lack of major adverse effects associated with intrave- macologic doses (e. Finally, a number of case lizing leukocyte lysosomal membranes; preventing release of reports detail successful resuscitation and full recovery when destructive acid hydrolases from leukocytes; inhibiting mac- cardiopulmonary bypass is instituted soon after cardiac arrest rophage accumulation in inﬂamed areas; reducing leukocyte caused by local anesthetic systemic toxicity. Anesthetic Maximum Recommended Patient symptoms with progressive rise in plasma lidocaine lev- Dose (mg/kg) els. This symptom progression—from dizziness and tinnitus to generalized seizures followed by cardiovascular collapse at the Lidocaine 4–5 highest plasma concentrations—occurs reliably with lidocaine. Mepivacaine 5–6 However, cardiovascular instability and collapse may present Bupivacaine, ropivacaine, 2. Pharmacology aLarge doses of local anesthetic are used infrequently during image-guided of local anesthetics. There are several available steroid preparations with pro- injection of steroid preparations commonly used for epi- longed duration of action. The equipotent hol, benzalkonium chloride, and edetate sodium are common doses for commonly used steroids are shown in Table 4-5. The safety of subarachnoid administra- Equivalent doses are approximations and may not apply tion of the steroids themselves, as well as their preservatives to routes of administration other than the oral route. Other adverse events associated with glucocorticoid administration are shown in Table 4-7. The vast majority of these adverse reac- Table 4–5 tions are associated with long-term glucocorticoid adminis- Approximate Equivalent Glucocorticoid tration. The most common adverse reactions after single-dose Oral Dosages Established by Laboratory or short-course epidural administration of glucocorticoids Assays include asymptomatic peripheral edema and increased insu- lin requirements in diabetic patients. Finally, Prednisolone 5 anaphylactoid reactions following glucocorticoid administra- Prednisone 5 tion are rare but have been well described. Methylprednisolone 4 Much attention has been given to the use of particulate Triamcinolone 4 steroid preparations during transforaminal injection. It is clear from experi- All available parenteral suspensions contain a wide and mental animal studies that when particulate steroids are overlapping range of particle sizes; practitioners should not injected into the vertebral artery, massive stroke occurs, and rely on the choice of steroid to eliminate the risk of direct animals do not regain consciousness. The nonparticulate, soluble syn- injection of dexamethasone into the vertebral artery results thetic glucocorticoid dexamethasone sodium phosphate has in no discernable sequelae. Massive posterior circulation stroke resulting from inadvertent injection of particulate ste- roid into the left vertebral artery during C1/C2 intra-articular facet injection. This patient became comatose immediately after the intra-articular cervical facet steroid injection. A: Lateral x-ray shows needle posterior to the C1/C2 joint, with radiographic contrast over the posterior portion of the joint. B: Schematic illustration, with inset highlighting the ana- tomic area of interest, demonstrates proximity of superior cervical portion of the vertebral artery to the injection site. C: Reformatted computed tomography angiography of the left vertebral artery (posterior view), performed 5 hours after the cervical injection, does not reveal evidence of arterial dissection, vasospasm, or occlusion. F: Fixed brain demonstrates gross evi- dence of bithalamic necrosis and microhemorrhages. G: Luxol fast blue with hematoxylin and eosin staining of thalamic section demonstrates small irregular discrete areas of acute infarction. G, Inset: Axonal spheroids are present in the surrounding thalamus adjacent to the lesions, consistent with ischemic injury. The combination of small, distinct regions of infarction with axonal spheroids conﬁrms that the ischemic lesions occurred due to occlu- sion of distal vascular beds, consistent with the hypothesis of microembolization.
Review of Systems Here is another area where the physician can use a unique method to cover the entire body in an organized way effective 100mg lady era, thus saving a lot of time purchase lady era 100mg amex. Because symptoms are organized into five categories, as emphasized subsequently in this book, one simply asks the following questions: Do you have any pain anywhere in your body? Have you had any bleeding from any body orifice (mouth, nose, ear, 34 rectum, vagina, urethra), or have you coughed up blood, vomited up blood, urinated blood, or had bloody diarrhea? Especially, have you had difficulty hearing, seeing, breathing, swallowing, moving your bowels, urinating, walking, talking, or performing your job? Family History No doubt the clinician will ask about diseases that affected the patient’s mother and father. However, it is important to include the grandparents on both sides of the family as well as brothers, sisters, and children. Social and Sexual History The clinician should be sure to ask about multiple partners of the same and 35 opposite sex, even though it may be embarrassing. And it is necessary to ask about arrests, anxiety, depression, and suicidal reaction or attempts. Determine whether he or she is fat or slim; tall or short; pale or ruddy; or depressed, anxious, or happy. Assess whether he or she is positive or negative when interacting with the physician or distant and almost sorry to be in the office. It is necessary to conduct an eye examination, including an examination of the eye grounds. The physician can detect at least 30 diseases with a careful ophthalmoscopic examination. Open the examination room door a crack, turn the lights off, and have the patient focus on his or her outstretched thumb (give the patient something to look at). Now, focus the ophthalmoscope on the cornea and pupil at about 10 in away and then move into the fundus at about 1 to 2 in away. Do not tilt your head; this may block the patient’s other eye from seeing his or her thumb. If need be, practice this examination on a nurse or another person in the office until it is routine. If it is still difficult to see the fundus, dilate the pupil with a short-acting sympathomimetic compound. If the ear drums are blocked with wax or other debris, remove it by irrigation and then reexamine the ears. Alternatively, perform a whisper test of each ear at 3 ft, although this is not as good. However, if there is middle or inner ear pathology, the physician will realize it because of the significant hearing loss. Palpate for a thyroid nodule or enlarged thyroid, enlarged lymph nodes, other masses, and tracheal deviation. Check that the range of motion is full and there is no nuchal rigidity, especially in a child 36 with fever. The physician frequently bypasses percussion these days, but he or she should not. Moving to the heart, the clinician routinely checks for irregular rhythm, cardiomegaly, and murmurs, but it is just as important to listen carefully to the heart sounds. This is the best way to tell if a systolic or diastolic murmur is present and what valve is involved. For example, if there is a systolic murmur and the second heart sound is diminished or absent, it is most likely aortic stenosis. When presented with a patient with abdominal pain, it is important not to forget to check for rebound tenderness and resonance over the liver (indicating air under the diaphragm). Retraction of one or both testicles may indicate peritoneal irritation from a ruptured viscus. The routine physical examination requires an examination of the external genitalia and rectal and vaginal examination. Some women state that they just had their annual Papanicolaou (Pap) smear, but if they have come for a complete physical examination, it is necessary to do at least a manual examination. Besides, the gynecologist may not have completed a thorough manual examination when doing the Pap smear. For an obese woman in whom one cannot palpate the adnexa adequately, it is necessary to order an ultrasonic examination. It is possible to detect many diseases by looking at the nails, such as the clubbing in congenital heart disease, chronic obstructive pulmonary disease, and bronchiectasis; the thickening in hypothyroidism; and the spoon nails in iron deficiency anemia. Most physicians rely on nurses and other health care professionals to take blood pressure. Unless these nurses have received your instructions about the auscultatory gap, this is not a good idea. The author teaches health care professionals in his office to take blood pressure with the radial pulse first before applying the stethoscope. The clinician should not forget to check for axillary and inguinal adenopathy and peripheral pulses. If the dorsal pedis and posterior tibial pulses are absent, he or she needs to check the femoral arteries for absent pulses or bruits. Unless a clinician is a neurologist, he or she is not going to perform a thorough neurologic examination during the routine physical examination unless the patient’s complaints are definitely neurologic. Here is an abbreviated examination that may be useful if there is simply no time to do a thorough examination: Check coordination by having the patient pat the physician’s hand with each of his or her hands and feet in rapid succession. Now, check for weakness or hemiparesis by having the patient grip the physician’s fingers with each hand and dorsiflex and plantar flex his or her feet against resistance. Check sensation in all four extremities with a tuning fork, preferably a 128-cps one. Check for simultaneous stimulation by seeing if the patient can recognize the physician’s fingers on one or both extremities at the same time. Check the cranial nerves, beginning with the funduscopic examination (which you have already done); have the patient follow a light; and check the gross visual field by confrontation, pupillary equality, and response to light. Check facial nerve function by telling the patient to close his or her eyes and whistle and then watch to see if the patient can extend his or her tongue in the midline. The examination is not finished until the physician has checked for the symmetry of the physiologic reflexes on all four extremities and plantar responses on the feet. The author realizes that this still seems like a lot; however, there are no other shortcuts to a good neurologic examination. If the readers have any pearls that they would like to share, they are encouraged to write to the author (care of Wolters Kluwer 38 Health/Lippincott Williams and Wilkins), so that they can be included in the next edition. Additional clinical techniques for evaluation of patients with many common symptoms and signs will be discussed here. They are the result of the author’s many years of experience in clinical practice as well as reviewing a host of textbooks on physical diagnosis. Although some of these techniques will be familiar to the reader, many will not be. Note that these symptoms and signs are organized into the five categories used in the review of systems: pain, lumps and bumps, bloody discharge, nonbloody discharge, and functional changes. The author hopes that the reader enjoys this fresh approach to the physical examination. No matter what portion of the abdomen is involved in the complaint, the physician must look for rebound tenderness. One applies pressure to the abdomen where the pain is located and then suddenly releases it. If the patient winces, there is rebound tenderness and a serious abdominal condition. If the right testicle is retracted, there is a possibility of a ruptured appendix. When both testicles are retracted, peritonitis from a perforated peptic ulcer or pancreatitis is likely. Place your thumb under the right subcostal margin and have the patient take a deep breath.
Tachycardia is narrow complex and characterized by very short V–A interval and an H–A interval of <70 ms cheap 100mg lady era overnight delivery. After comparison with the clinical arrhythmia lady era 100 mg generic, the induced tachycardia can be considered clinically significant unless clear differences exist. If a wide complex tachycardia with a supraventricular mechanism is induced, the recording is compared with a clinical recording. Atrial flutter, a special type of atrial tachycardia that involves a well- defined anatomic circuit, is amenable to curative catheter ablation techniques. In the typical form of atrial flutter, the waveform travels counterclockwise around the tricuspid annulus. The circuit is bounded anteriorly by the tricuspid annulus and posteriorly by the crista terminalis and its inferior medial continuation as the eustachian ridge. The site of functional block appears to be in the isthmus region, which is the narrow corridor between the inferior tricuspid annulus and the inferior vena cava. The site of conduction delay or slowing appears to be caused by transverse conduction block into the crista, forcing the wavefront to enter the crista at its superior end before propagating down the crista into the isthmus region. To induce counterclockwise atrial flutter, progressively more rapid (approximately 250 to 200 ms) burst pacing appears to be most successful and is performed anywhere medial to the isthmus. The impulses block in the isthmus and conduct counterclockwise around the tricuspid ring with sufficient delay to sustain atrial flutter. If burst pacing is used lateral to the isthmus, clockwise atrial flutter may be induced. Less commonly, different types of atrial flutter in which the subeustachian isthmus is not part of the circuit are induced. These atypical flutters have many varieties and locations but share a common reentrant circuit that revolves around an area of conduction block or delay, usually scar tissue. Treatment involves creating an ablation line from the area of scar to an anatomic barrier or ablating critically narrowed reentrant paths within a scarred region. The success rates in ablating these atypical forms of atrial flutter are not as high as isthmus-dependent flutters. The most common locations for accessory pathways in decreasing order of frequency are left free wall, posterior region, posteroseptal region, right free wall, and the anteroseptal region. Right-sided accessory pathways are more likely than left-sided accessory pathways to be associated with congenital heart disease. An unusual type of right- sided accessory pathway is the atriofascicular accessory pathways, which originate in the right atrium, traverse the right anterior region of the tricuspid valve annulus, and insert in the region of the right bundle or the right-sided Purkinje network. These pathways are frequently referred to as Mahaim pathways and typically do not conduct retrogradely. Multiple accessory pathways are more frequently encountered on the right side and in survivors of sudden death. In these patients, the most common combination is posteroseptal and right free wall pathways. In rare instances, antidromic tachycardia can involve one accessory pathway in the antegrade direction and a second pathway in the retrograde direction. The electrophysiologic properties of the accessory pathway are examined, including its antegrade and retrograde conduction and refractory periods. If tachycardia is induced during atrial or ventricular stimulation, its mechanism is defined according to the techniques discussed earlier. Induction is facilitated by the presence of a relatively long antegrade refractory period of the accessory pathway or a long retrograde refractory period of the His-Purkinje system. It almost always involves a free wall accessory pathway as the antegrade limb and is frequently associated with the presence of multiple accessory pathways. This tachycardia was induced with atrial burst pacing in a young patient with two right-sided manifest accessory pathways. Changing antegrade delta waves during sinus rhythm, atrial pacing, atrial fibrillation, and with antiarrhythmic drugs b. An atrial study is considered for all patients undergoing evaluation of ventricular tachycardia. However, isoproterenol should not be given to patients with active ischemic heart disease. It is primarily of value to those with exercise-induced or catecholamine-dependent ventricular tachycardia. If no ventricular tachycardia is induced with any of these techniques, the arrhythmia is deemed noninducible. Pacing terminates as many as 85% of induced ventricular tachycardias in the laboratory. Success is more likely to be achieved with slower tachycardia rates (<200 beats/min) and in hemodynamically tolerated tachycardias. Other factors predictive of successful pacing include the site of stimulation in relation to the tachycardia zone, ventricular conduction properties, and refractoriness. Pacing can also accelerate tachycardia, an important consideration when antitachycardia pacing is being considered. One technique entails the use of one or more progressively earlier premature ventricular stimuli. The other technique uses burst pacing to overdrive the tachycardia, but there is a greater risk of accelerating the tachycardia into a hemodynamically unstable arrhythmia. Techniques that can be used if pacing fails include delivery of ultrarapid train stimulation and synchronized direct current cardioversion. What is important is the correlation between these responses in different populations of patients and future risk of adverse outcome. This is particularly true if the induced tachycardia is similar to the clinical arrhythmia in both rate and structure. It is important to document reproducibility of ventricular tachycardia during programmed stimulation. Slow, sustained tachycardia, particularly in patients with ischemic substrate, is typically more reproducible than more rapid tachycardias and tachycardias in those with nonischemic cardiomyopathies. Sustained tachycardia has clearly worse prognostic implications than nonsustained tachycardia. There is no agreement on what constitutes an abnormal response among patients with nonsustained tachycardia or whether any therapeutic intervention should be pursued for these patients. Induction of sustained monomorphic ventricular tachycardia in any of the above subsets has very high specificity (>90%) for spontaneous clinical ventricular tachycardia and sudden death. The prognosis may be more favorable if inducible tachycardia is suppressed by drugs, but the risk of future events continues to be high. It occurs most often among patients with dilated cardiomyopathy and is frequently symptomatic. Polymorphic ventricular tachycardia frequently occurs with high-output stimulation. For example, inducible polymorphic ventricular tachycardia in a survivor of sudden cardiac death is considered significant. In a patient with ventricular ectopy and normal ventricular function, inducible polymorphic ventricular tachycardia is a nonspecific response. If the patient has never had clinical ventricular tachycardia or ventricular fibrillation and has no underlying heart disease, the induced ventricular fibrillation is considered a nonspecific finding that does not warrant therapy. Induction of sustained monomorphic ventricular tachycardia, induction of ventricular fibrillation without aggressive stimulation protocols, and induction of ventricular arrhythmias with atrial pacing or as a result of atrial fibrillation are generally considered to be poor prognostic signs. Noninducibility in patients with nonischemic cardiomyopathy or survivors of sudden cardiac death may not provide prediction as accurate as that for patients with underlying ischemic substrate and documented nonsustained ventricular tachycardia. Mapping of ventricular tachycardia involves identification of the earliest sites of activationduring tachycardia and detailed outlining of the tachycardia circuit. Because this lengthy process has to take place during tachycardia, it must be hemodynamically tolerable. The earliest activation site should correspond to the exit site of the circuit unless the focus is midmyocardial, epicardial, or in the other ventricle. Entrainment involves transient overdrive pacing and resetting of the tachycardia without terminating the tachycardia.
N. Yespas. Southwestern Assemblies of God University. 2019.
8 of 10 - Review by N. Yespas
Votes: 228 votes
Total customer reviews: 228