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It is important to keep in mind that individuals with coronary stents in place are at risk for st ent t hrombosis in the perioperat ive period cheap plendil american express blood pressure diet chart. Patients with drug-eluting stents in place should receive a minimum of 3 months of dual antiplatelet therapy order generic plendil canada hypertension va compensation. Patients with paclitaxel stents should receive a minimum of 6 mont hs of dual ant iplat elet t herapy buy 2.5mg plendil blood pressure 5080. As a rule purchase plendil pills in toronto pulse pressure 79, one year of d u al an t ip lat elet t h er ap y sh o u ld b e st r on gly con sid er ed for an y in d ivid u al following coronary stent placement. Studies have shown that premature discontinua- tion of antiplatelet therapy can be associated with in-stent thrombosis rates of 25% to 30%; therefore, it is a common practice to extend the antiplatelet therapy beyond the minimal recommended time periods. H is hypertension man- agement should be opt imized and his renal dysfunction should be quantified with measurement of creatinine clearance. Continuation of his dual-antiplatelet therapy is import ant since he h ad coronary st ent placement 8 mont hs ago. A potent ially beneficial pharmacologic protective strategy to consider is a statin, which has proven benefits in the perioperative period. Fr a ilt y is u s ed to describe an individual with diminished physiologic reserve across multiple organ syst ems, usually due t o mult iple cumulat ive comorbid condit ions. The difficult problem in pre- operative cardiac evaluation is that testing does not help identify patients who have significant diastolic dysfunct ion. It is believed t hat a large percent age of periopera- tive cardiac events are related to diastolic dysfunction. T hese include st andard exercise tolerance tests, and pharmacologic stress tests (persanti- nethalium scan and dobutamine stress echocardiography). The negative predictive value of the st ress t est is excellent, since most pat ient s wit h out abnormalit ies do not develop car diac complicat ion s. Becau se of the low pr edict ive valu es of t h ese t est s, the r ole of perioperative testing has significantly reduced over the past decade. An assessment of comorbidities has been found to be especially important for patients undergoing vascular sur- ger y pr oced u r es. Advan ced vascu lar occlu sive d isease is ver y fr equ ent ly associat ed wit h long-st anding diabetes, atherosclerosis, and hypertension, and t hese condi- tions frequently contribute to multiple end-organ damage and a reduction in the patient’s physiologic reserve. The assessment of cardiac risk consists of the eight st eps list ed in Table 1– 2. Several major, int ermediat e, and minor clinical predict ors have been identified to facilitate cardiac-risk assessment (Table 1– 3). Some of the most valuable predictors can be easily gathered from the patient’s history, current sympt oms, and level of act ivit y. Ste p 8 (a ) Th e re su lt s o f n o n in va sive t e st in g o ft e n id e n t ify the n e e d fo r p re o p e ra t ive coronary intervention or cardiac surgery. One of the important factors to not overlook is the type of operation planned and the ant icipated physiologic st ress that t he operat ion produces. For example, body surface area operations such as breast biopsies, groin hernia repairs, and thyroidectomies are generally associated with minimal fluid shifts, blood loss, and hemodynamic fluctuations. O n the other hand, vascular operations in the supra-inguinal region and lengt hy open abdominal operat ions have t he pot ent ial of causing large fluctuations in hemodynamic st atuses and volume shift s. Echocardiography is noninvasive and may pro- vid e som e in for m at ion r egar d in g the syst olic fu n ct ion s of the h ear t ; h owever, it is import ant t o remember t hat a major limit at ion of echocardiography is t hat it does not provide information regarding function. Ve nt ri cul ar di as t o l i c dys funct i o n can be an important cause of perioperative cardiac morbidity, especially when significant fluctuations in intravascular volume and pressures are anticipated (eg, aortic surgery with cross-clamping). In general, patients with moderate cardiac risk factors who are undergoing moderate- to high-risk operat ions may benefit from addit ional car- diac assessment, whereas, high-risk patients undergoing low risk operations gener- ally would do well wit hout addit ional t est ing. One of the most important take-home messages in preoperative assessment is t hat the preoperat ive assessment should not lead t o coronary revascularizat ion just to get the patient through the operation. The results showed that prophylactic coronary revascularization did not lead to reductions in periop- erat ive cardiac-relat ed morbidit ies and mort alit y. In fact, pat ient s who under went preoperative coronary revascularization had significant delays in care. This st u dy d em on st r at ed increase in stroke-related deaths and complications in patients randomized to perioperative beta-block treatment. T h e use of perioperative statins is potentially beneficial for high-risk patients, but this practice has not been examined by high-quality randomized controlled clinical trials. S om e will b e life-savin g em er gen cy or elect ive op er at ion s, wh ile the m ajor it y of the operations will be elective procedures to improve individuals’ quality of life. The preoperative assessment of geriatric patients needs to include assessments that have already been described for patients with cardiovascular disease and/ or cardiac risk factors. In addit ion, these patient s need assessments of some geriatric-specific syndromes such as frailty, mobility-disability, malnutrit ion, mood/ depression, and cogn it ive d eficit s. Some invest igat or s h ave d escr ibed frailty a s the p r e s e n c e o f t h r e e o r more of the following items: ( 1 ) u n i n t e n t i o n a l w e i gh t l o s s o f ≥ 1 0 l b s i n the p a s t ye a r ; (2) self-reported exhaustion; (3) weakness in grip strength; (4) slow walking speed; and (5) low physical act ivit y. The modified index has a total of 11 items and scores represent the degrees of frailt y (see Table 1– 4). The ability to ident ify t hese risk factors is import ant in making decisions regarding whet her or not to proceed with elective nonlife-saving operations. Nutritional status, cognitive function, and mood disorders/ depression are also import ant fact ors t o assess/ ident ify preoperat ively in geriat ric pat ient s. Malnu- trition has been estimated to occur in approximately 23% of the elderly popula- tion, and the presence of malnutrition can have significant impact on perioperative morbidity and mortality. The preoperat ive fu n ct ion al st at u ses of ger iat r ic patient s are imp or t an t t o con sid er, sin ce p r eop - erat ive funct ional st at us can be helpful in ident ifying pat ient s who may require long-t erm recover y and ph ysical t h erapy in in-pat ient set t ings. D ement ia and/ or depression are common problems in the geriatric patient population, and both of these problems can contribute significantly to post-operative complications. Identi- fying t h ese deficit s in the preoperat ive set t ing will also h elp facilit at e post operat ive car e for t h ese in dividu als. In gen er al, eld er ly in d ividu als wit h d ement ia/ cogn it ive defects will often demonstrate additional impairments in cognition following gen- eral anest hesia, and t h ere is evidence t o suggest t hat neuraxial anest hesia (epidural or spinal) is associated with less cognitive dysfunction than general anesthesia. P lace patient o n a b et a- b lo ck er o n e week b efo r e su r ger y an d t h en sch ed u le patient for surgery under local anesthesia C. Discuss with patient about blood pressure control and long-term cardiac- risk reduction benefits and coordinate with his primary care physician to optimize his status D. Place patient on a beta-blocker and statin one week before his operation then proceed with surgery under local anesthesia E. A major benefit of preoperative assessment is to identify patients with silent cardiac disease so t hat percut aneous or operat ive int ervent ions can be implemented B. Coronary angiography is an evaluation tool that should be applied liber- ally t o provide int ervent ions prior t o elect ive surgery in high-risk pat ient s D. Preoperative cardiac risk assessment leads to unnecessary testing and intervent ions and is not beneficial E. Preoperative risk assessment is intended to lead to risk modification strat- egies in t he perioperat ive sett ing and beyond 1. H e has intermittent chest pain, and because of a chronic ankle injury, he is not able to complete an exercise treadmill test. W hich of t he following st at ement s is most accurat e regarding dobut amine echocardiography?
With some infections generic plendil 2.5mg online arteria rectal inferior, such as syphilis buy plendil paypal arrhythmia recognition, the staging depends on the duration and ext ent of t he infect ion discount 2.5mg plendil overnight delivery arrhythmia heart, and follows along t he nat ural h ist ory of t he infect ion (ie buy plendil arrhythmia kidney function, primary syphilis, secondary, latent period, and tertiary/ neurosyphilis). If neither the prognosis nor the treatment was influenced by the st age of the disease process, there would not be a reason to sub- cat egor ize a disease as m ild or sever e. As an example, a pr egn ant woman at 34 weeks’ gest at ion wit h m ild pr eeclamp sia is at less r isk from the d isease t h an if sh e d evel- oped severe preeclampsia (particularly if the severe preeclampsia were pulmonary edema or eclampsia). Accordingly, wit h mild preeclampsia, t he management may be expectant, letting the pregnancy continue while watching for any danger signs (severe disease). In contrast, if preeclampsia with severe features complicated this same 34-week pregnancy, t he t reat ment would be magnesium sulfate to prevent seizures (eclampsia) and, most import ant ly, delivery. In this disease, severe preeclampsia means both maternal and fet al risks are increased. As anot her example, urinary t ract infect ions may be subdivided int o lower t ract infect ions (cyst it is) t hat are t reat ed by oral ant ibiot ics on an outpatient basis, versus upper tract infections (pyelonephritis) that generally require hospitalization and intravenous antibiotics. Hence, the student should approach a new disease by learning the mechanism, clin ical pr esent at ion, st agin g, an d the t r eat ment based on st age. Some responses are clinical such as improvement (or lack of improvement) in a patient’s abdominal pain, t emperat ure, or pulmonary examinat ion. O bviously, t he st udent must work on being more skilled in eliciting the data in an unbiased and stan- dardized manner. The student must be prepared to know what to do if the measured marker does not respond according to what is expected. Is the next step to retreat, or to reconsider the diagnosis, or to repeat the metastatic work-up, or t o follow up wit h anot h er more specific t est? Ap p r o a c h t o Re a d in g The clinical problem-oriented approach to reading is different from the classic “s y s t e m a t i c ” r e s e a r c h o f a d i s e a s e. P a t i e n t s r a r e l y p r e s e n t w i t h a c l e a r d i a g n o s i s ; hence, the student must become skilled in applying the textbook information to the clinical setting. In ot her words, t he student should read with t he goal of answering specific quest ions. Likewise, t he st udent should have a plan for t he acquisit ion and use of the information; the process is similar to having a mental “flowchart” and each st ep sift ing t hrough diagnost ic possibilit ies, t h erapy, complicat ions, and risk fact ors. T h ere are several fundament al quest ions that facilit at e clinical t h in king. The method of establishing the diagnosis has been covered in the previous section. One way of attacking this problem is to develop standard “approaches”to common clin ical sit u at ion s. It is h elpfu l t o u n d er st an d the most com mon cau ses of var iou s presentations such as “the most common cause of postpartum hemorrhage is uter- ine atony. With no other information to go on, the student would note that this patient has postpartum hemorrhage (blood loss of > 500 mL with a vaginal delivery). Using the “most common cause”information, the student would make an educated guess that the patient has uterine atony. Now the most likely diagnosis is a genital tract laceration, usually involving the cer vix. Th u s, the f i r s t s t e p i n p a t i e n t a s s e s s m e n t a n d m a n a g e m e n t i s u t e r i n e massage to check if the uterus is boggy. This question is difficult because the next step has many possibilities; the answer may be to obt ain more diagnostic information, st age the illness, or introduce ther- apy. It is often a more challenging quest ion than “W hat is the most likeyly diag- nosis? Another possibility is that there is enough information for a probable diagnosis, and the next step is to st age t he disease. Hence,from clinicaldata,a judgment needs to be rendered regardinghow far along one is on the road of: Make a diagnosis → St age t he disease → Treat based on stage → Follow response Frequent ly, the st udent is t aught t o “regurgit at e” the informat ion that someone has written about a particular disease, but is not skilled at giving the next step. Make a diagnosis: “Based on the in for m at ion I h ave, I b elieve that this patient has a pelvic inflammatory disease because she is not pregnant and has lower abdominal t enderness, cervical mot ion t enderness, and adnexal t enderness. Stage the disease:“ I d o n o t b e l i e ve t h a t t h i s i s a s e ve r e d i s e a s e b e c a u s e s h e d o e s not have high fever, evidence of sepsis, or peritoneal signs. An ultrasound has already been done showing no abscess (tubo-ovarian abscess would put her in a severe category). Treat based on stage:“ T h e r e f o r e, m y n e x t s t e p i s t o t r e a the r w i t h i n t r a m u s c u l a r ceft r iaxon e an d or al d oxycyclin e. Fo l lo w res po ns e : “ I w a n t t o f o l l o w the t r e a t m e n t b y a s s e s s i n g h e r p a i n ( I w i l l a s k her to rate the pain on a scale of 1-10 every day), her temperature, and abdomi- nal examination, and reassess her in 48 hours. This information is sometimes tested by the dictum, “the gold standard for the diagnosis of acute salpingitis is laparoscopy to visualize the tubes, and particularly seeing purulent material drain from t he tubes. This question goes further than making the diagnosis, but also requires the student to understand the underlying mechanism for the process. For example, a clinical scenario may describe an 18-year-old adolescent female at 24 weeks’gest at ion, who develops dyspnea 2 days after being treated for pyelonephritis. The student must fir st d iagn ose the acu t e r esp ir at or y d ist r ess syn d r om e, wh ich oft en occu r s 1 t o 2 days after antibiotics are instituted. Then, the student must understand that the endot oxins t hat arise from Gram-negat ive organisms cause pulmonary injury, lead- ing t o capillary leakage of fluid int o t he pulmonary int erst it ial space. The student is advised to learn the mechanisms for each disease process, and not merely memorize a constellation of symptoms. From the bladder, the bacteria would ascend further to the kidneys and cau se an in fect ion in the r en al par en ch yma. T h e involvement of the kid n ey n ow cau ses fever ( vs an in fect ion of on ly the blad d er, wh ich u su ally d oes n ot in du ce a fever) an d flan k t en dern ess— a syst emic respon se n ot seen wit h lower urinar y t ract infect ion (ie, bact eriuria or cyst it is). Furt h ermore, t he body’s react ion t o t he bact e- ria brings about leukocytes in the urine (pyuria). Understanding the risk factors helps the practitioner to establish a diagnosis and to determine how to interpret tests. For example, understanding the risk factor analysis may help to manage a 55-year-old woman with post menopausal bleeding aft er an endomet rial biopsy shows no pat hologic changes. If the woman does not have any risk factors for endometrial cancer, the patient may be observed because the likelihood for uterine malignancy is not so great. On the other hand, if the same 55-year-old woman were diabet ic, had a long history of anovulat ion (irregu- lar menses), was nulliparous, and was hypert en sive, a pract it ioner sh ould pursue the postmenopausal bleeding further, even after a normal endomet rial biopsy. The physician may want to perform a hysteroscopy to visualize the endometrial cavity directly and biopsy the abnormal-appearing areas. Thus, the presence of risk fac- tors helps to categorize the likelihood of a disease process. Clinicians must be cognizant of the complications of a disease, so that they will understand how to follow and monitor the patient.
The nerve diverges in variable patterns to form five major branches that supply the muscles of facial expression: the temporal 5mg plendil blood pressure ear, zygomatic order plendil 10 mg without prescription heart attack jeff x ben, buccal purchase plendil 5 mg line blood pressure medication iv, mandibular cheap plendil 5 mg blood pressure chart 5 year old, and cervical branches. There is also a smaller pos- terior auricular branch that supplies the extra-auricular muscles. Sensory nerves may innervate a small patch of skin on the posterior surface of the auricle. The greater petrosal nerve emerges from the geniculate ganglion and courses anteriorly through a small canal. It emerges through a small hiatus into the mid- dle cranial fossa and continues anteriorly in a groove directed toward the fora- men lacerum. The nerve then passes through a tunnel in the cartilage filling the foramen or through a canal in nearby bone. After exiting the basal surface of the skull posterior to the medial pterygoid plate of the sphenoid bone, the nerve heads anteriorly through the pterygoid (Vidian) canal. The pterygoid canal courses through the sphenoid bone at the base of the medial pterygoid plate. The newly formed nerve of the pterygoid canal (Vidian nerve) exits anteriorly into the pterygopalatine fossa. Sensory and sympathetic fibers pass through the ganglion and follow the branches of the maxillary nerve throughout the nasal and oral cavities. Postsynaptic fibers project through the same nerves to innervate glands of the oral and nasal mucosa. Visceral motor fibers innervating the lacrimal gland also originate in the pterygopalatine ganglion. The lacrimal nerve itself is primarily sensory and innervates the periorbital skin. As the facial nerve descends posteriorly to the tympanic cavity, two small but important branches emerge. Its tendon emerges through the apex of the pyramid to attach to the body of the stapes. Contraction of the stapedius dampens the vibration of the ossicles, thus protect- ing against loud sounds. It branches from the motor trunk before it exits the stylomastoid foramen and enters the tympanic cavity through a small canal in the posterior wall. As it does so, it runs between the vertical processes of the incus and the malleus. The nerve then courses through the infratemporal fossa along the superficial surface of the medial pterygoid muscle before joining with the lingual nerve. Sensory fibers in the chorda tympani course with branches of the lingual nerve to supply taste receptors in the anterior two-thirds of the tongue. In addition to its complex branching pattern, the facial nerve has many func- tional components. To summarize, the facial nerve is primarily a motor nerve that supplies branchiomeric muscles. These are primarily the muscles of facial expres- sion but also include the stapedius, stylohyoid, and posterior belly of the digastric muscle. Another important function of the facial nerve is to supply visceral motor fibers that supply the lacrimal gland, the submandibular and sublingual salivary glands, and mucus-secreting glands of the nasal and oral cavities. The special sensory component that supports taste in the anterior two-thirds of the tongue is ultimately carried by the lingual nerve. There is a minor component of general sensation from innervation of a small patch of skin on the posterior surface of the auricle. A schwan- noma involving the cerebellopontine angle can affect both cranial nerves. Forehead wrinkling results from contraction of the frontalis muscle, which is innervated by the facial nerve. The facial nerve is responsible for taste in the anterior two-thirds of the tongue, but the chorda tympani emerges before the main trunk exits through the stylomastoid foramen. Sensation of the cornea and sensation to the cheek are supplied by the trigeminal nerve. The basilar fracture involving the mastoid region of the temporal bone may impinge on the facial nerve as it exits the stylomastoid foramen. She is not taking medica- tions currently, although she previously received intravenous corticosteroid ther- apy. Her physician says that her problem is related to the nerve that innervates the skin of the cheek area. This young woman complains of several seconds of intense spasmodic pain of the right cheek and chin. Her history of multiple sclerosis is important because trigemi- nal neuralgia is relatively common in this group of patients. The character of the pain excludes some of the other common etiologies of head or facial pain such as migraine headache (usually throbbing unilateral pain with orbital involvement) or tension headache (bandlike constricting pain from the temples to the occiput bilat- erally). Treatment includes carbamazepine or baclofen and, in severe cases, trigeminal nerve ablation. Sclerosis in general refers to hardening of the tissue, as in atherosclerosis, or hardening of the arteries. Motor fibers to the muscles of mastication usually arise as a separate smaller root. The nerve courses on the lateral surface of the sphe- noid bone deep to the cavernous sinus. The cell bodies of the sensory nerves form the trigeminal ganglion along the medial wall of the middle cranial fossa. Three large nerves emerge from the ganglion: the ophthalmic, maxillary, and mandibular divisions of the trigeminal nerve (Figure 41-1). The ophthalmic nerve sup- plies the dermatome that courses superiorly to the horizontal midline of the orbit. The maxillary nerve supplies the region over the maxilla, inferior to the orbit, including the lateral surface of the nose and the upper lip. The mandibular division supplies a band of skin running superiorly over the temporalis muscle. The major branches of the ophthalmic nerve that supply skin are the supraorbital and supratrochlear nerves, which supply skin of the forehead and anterior scalp. The nasociliary nerve supplies skin over the medial nose through the external nasal branch of the anterior ethmoidal nerve. Supraorbital nerve Frontal branch of frontal nerve Mesencephalic nucleus of V Supratrochlear nerve Anterior ethmoidal nerve Main sensory Posterior ethmoidal nerve nucleus of V Nasociliary nerve Main motor Infratrochlear nerve Frontal nerve nucleus of V Ophthalmic nerve Ciliary ganglion Semilunar Nucleus of Internal nasal ganglion spinal tract of V rami Infraorbital nerve Lacrimal a Mandibular nerve External nasal rami Anterior and posterior deep temporal nerves Nasal and labial Pterygopalatine (to temporal muscle) rami of infraorbital ganglion Otic ganglion nerve Auriculotemporal nerve Anterior superior External pterygoid muscle alveolar nerves Chorda tympani nerve Submaxillary Internal pterygoid muscle ganglion Masseter muscle Submaxillary and Mylohyoid nerve sublingual glands Mylohyoid muscle Mental nerve Anterior belly of digastric muscle figure 41-1. More laterally, the zygomaticofacial and zygomaticotemporal nerves also contribute. The branches of the mandibular nerve that innervate the skin are the auriculotemporal superiorly and the mental nerve (a branch of the inferior alveolar) inferiorly.
The resultant accumulation of fluid will cause severe cardiac 10mg plendil sale heart attack left or right, pulmonary plendil 10mg otc arrhythmia nodosum, and peripheral edema—and order cheap plendil on line blood pressure is low, ultimately buy genuine plendil online heart attack enrique iglesias, death. As discussed in Chapter 34, these hormones promote dilation of arterioles and veins and also promote loss of sodium and water through the kidneys. If cardiac output becomes too low to maintain sufficient production of urine, the resultant accumulation of water will eventually be fatal. The actual cause of death is complete cardiac failure secondary to excessive cardiac dilation and cardiac edema. Decreased tissue perfusion results in reduced exercise tolerance, fatigue, and shortness of breath; shortness of breath may also reflect pulmonary edema. Increased ventricular filling, reduced systolic ejection, and myocardial hypertrophy result in cardiomegaly (increased heart size). The combination of increased venous tone plus increased blood volume helps cause pulmonary edema, peripheral edema, hepatomegaly (increased liver size), and distention of the jugular veins. Executive Summary: A Report of the American College of Cardiology Foundation/American Heart Association Task Force on Practice Guidelines—is discussed later under “Management of Heart Failure. Diuretics Diuretics are first-line drugs for all patients with signs of volume overload or with a history of volume overload. By reducing blood volume, these drugs can decrease venous pressure, arterial pressure (afterload), pulmonary edema, peripheral edema, and cardiac dilation. However, excessive diuresis must be avoided: if blood volume drops too low, cardiac output and blood pressure may fall precipitously, thereby further compromising tissue perfusion. The principal adverse effect of the thiazides is hypokalemia, which increases the risk for digoxin-induced dysrhythmias (see later). Therefore loop diuretics are preferred to thiazides when cardiac output is greatly reduced. Like the thiazides, these drugs can cause hypokalemia, thereby increasing the risk for digoxin toxicity. In addition, loop diuretics can cause severe hypotension secondary to excessive volume reduction. Potassium-Sparing Diuretics In contrast to the thiazides and loop diuretics, the potassium-sparing diuretics (e. Not surprisingly, the principal adverse effect of the potassium-sparing drugs is hyperkalemia. This drug and a related agent—eplerenone—are discussed later under “Aldosterone Antagonists. In one trial, the 2-year mortality rate for patients taking enalapril was 47% lower than the rate for patients taking placebo. This statement is based in part on the observation that, in experimental models, giving a kinin receptor blocker decreases beneficial effects on remodeling. In addition, these drugs can cause renal failure in patients with bilateral renal artery stenosis. Dosage Adequate dosage is still debated in the literature: higher dosages may be associated with increased survival, but conflicting evidence remains. In fact, the study was terminated early because of the overwhelmingly positive results. Aldosterone antagonists work primarily by blocking aldosterone receptors in the heart and blood vessels. In the past, researchers believed that all aldosterone did was promote renal retention of sodium (and water) in exchange for excretion of potassium. As aldosterone levels grow higher, harmful effects increase, and prognosis becomes progressively worse. Drugs can reduce the effects of aldosterone by either decreasing aldosterone production or blocking aldosterone receptors. However, when an aldosterone antagonist is added to the regimen, any residual effects are eliminated. To minimize risk, potassium levels and renal function should be measured at baseline and periodically thereafter. Spironolactone—but not eplerenone—poses a significant risk for gynecomastia (breast enlargement) in men, a condition that can be both cosmetically troublesome and painful. B l a c k B o x Wa r n i n g : S p i ro n o l a c t o n e Spironolactone is associated with tumorigenesis in studies completed on rats. After all, blockade of cardiac beta -adrenergic receptors 1 reduces contractility—an effect that is clearly detrimental, given that contractility is already compromised in the failing heart. However, it is now clear that, with careful control of dosage, beta blockers can improve patient status. Accordingly, beta blockers are now recommended as first-line therapy for most patients. Although the mechanism underlying benefits is uncertain, likely possibilities include protecting the heart from excessive sympathetic stimulation and protecting against dysrhythmias. Because excessive beta blockade can reduce contractility, doses must be very low initially and then gradually increased. Because it is new and not included in the current treatment guidelines, we will only discuss ivabradine briefly. Ivabradine causes a dose-dependent reduction in heart rate by blocking channels responsible for cardiac pacemaker current. When used in recommended doses, heart rate reduction is approximately 10 beats/minutes. Digoxin Digoxin belongs to a class of drugs known as cardiac glycosides, agents best known for their positive inotropic actions, that is, their ability to increase myocardial contractile force. In addition, it can alter the electrical activity of the heart and can favorably affect neurohormonal systems. Principal adverse effects are hypotension, tachycardia, and a syndrome that resembles systemic lupus erythematosus. Probably, but data are lacking: the manufacturer only tested the product in black patients. Of course, now that BiDil is approved, clinicians may prescribe it for anyone they see fit. Digoxin, a Cardiac Glycoside Digoxin [Lanoxin] belongs to a family of drugs known as cardiac glycosides. These drugs are prepared by extraction from Digitalis purpurea (purple foxglove) and Digitalis lanata (Grecian foxglove) and hence are also known as digitalis glycosides. Digoxin has profound effects on the mechanical and electrical properties of the heart. Digitalis is a dangerous drug because, at doses close to therapeutic, it can cause severe dysrhythmias. Owing to its prodysrhythmic actions, digoxin must be used with respect, caution, and skill.