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Atrial Fibrillation (AF)

prof. Usman Jafferprof. Usman Jaffer

Introduction

Atrial Fibrillation (AF) is the most common heart rhythm disturbance and is increasingly common with increasing age. It often affects hearts that otherwise quite normal. 

It generally exists in one of two forms:

1. Recurrent episodes that stop on their own (Paroxysmal)

2. Episodes that will continue incessantly once they have started (Persistent)

Subclinical atrial fibrillation

Subclinical AF refers to episodes in a patient has without symptoms and without a prior history of AF, which are detected only by monitoring techniques. 

Aetiology / causes

AF is caused by extra beats arising from the mouths of the 4 veins that connect into the left atrium – the heart chamber from which the fibrillation arises. These 4 pulmonary veins have sleeves of electrical tissue that are the sources of the triggers of atrial fibrillation which once started continues as rapid, random electrical activity (fibrillation) around the whole atrium.

Significant structural heart disease is associated with AF, in particular affecting the heart valves. Hearts affected by 'Ischaemic Heart Disease' and hypertension can also be prone to AF.

Diseases which affect conduction in the Atria (chambers of the heart) or the size of the atria also predispose to AF.

Temporary or reversible causes of AF include cardiac surgery, hypertension, alcohol, theophylline or other stimulant toxicity, pericarditis, MI and hormonal problems (hypothyroidism, hyperthyroidism, pheochromocytoma.

AF which has occurred in the absence of any structural heart problems is called 'Lone AF'.


Differential diagnosis

Other forms of irregular heart rate should be considered and excluded with tests and monitoring.

Diagnostic approach

The basic diagnosis is made on the basis of an ECG (EKG). The hallmark of AF is an irregular, fluctuating baseline to the ECG. The ventricles (main pumping chambers of the heart) may well also be beating irregularly and fast (>100 beats per minute).

Hormonal (endocrine) issues can diagnosed on blood tests and structural heart disease is investigated by echocardiogram/ CT or MRI.

Epidemiology

Age

AF is uncommon in children. Healthy young adults are also at low risk (1). The prevalence of AF increases with age (2-5). The ATRIA study in America showed the overall prevalence of AF was 1 percent; 70 percent were at least 65 years old and 45 percent were ≥75 years old (5). The STROKESTOP study in Sweden showed the prevalence of AF in a 75- to 76-year-old population to be 12 percent (6). Another European study of 6808 people ≥ 55 years of age showed an overall prevalence of 5.5 percent, ranging from 0.7 percent in those aged 55 to 59 years and 17.8 percent for those ≥85 years of age (4).

Sex

The prevalence was higher in men than women (1.1 versus 0.8 percent). This difference was seen in every age group. Another study, reported the rates were 6 versus 5.1 percent, respectively (5).

Race

In one study, AF was more frequent in whites than blacks over the age of 50 years (2.2 versus 1.5 percent) (6). 

Geography

The age-adjusted prevalence rate (per 100,000 population) was reported highest in North America (700 to 775) and lowest in Japan and South Korea (250 to 325) (7). The rate in China was also relatively low (325 to 400).

Time period

The prevalence of AF in the population is increasing. In a community-based study of 1.4 million patients in England and Wales, the age-standardized prevalence of AF between 1994 and 1998 increased by 22 and 14 percent in men and women, respectively (2). 

Treatment

Overall, atrial fibrillation can be treated by either trying to restore and maintain normal rhythm (rhythm control) or by leaving the heart in atrial fibrillation but controlling the rate (rate control). Rhythm control, if it can be achieved, is generally preferable unless the atrial fibrillation is particularly longstanding, causing no symptoms or has proved impossible to control by other means.

Blood thinning with medicines (anticoagulation) is also important for patients in AF. The risk versus benefits of anticoagulation are weighed up by a number of factors which are often combined into a score. Rhythm control is achieved by: 1. antiarrhythmic medication (such as Flecainide, Amiodarone, Sotalol) with or without: 2. DC cardioversion (an electrical shock under anaesthetic which abruptly terminates atrial fibrillation) 3. Ablation therapy

This is currently considered appropriate in patients who have a significant burden of atrial fibrillation from which they have symptoms not controlled by antiarrhythmic tablets. Ablation can cure AF in many patients but is a challenging procedure that usually needs repeating, with moderately good success rates and small but significant and important risks.



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Anal Fistula

Treatment of anal fistula: A fistula without symptoms found on regular check up usually requires no therapy . [3,4] In case of anorectal abscess surgery for fistula repair should not be performed (unless the fistula is superficial and the tract is obvious). In the acute phase, simple incision and drainage of the abscess are sufficient. [5] Only 7-40% of patients will develop a fistula. Recurrent anal sepsis and fistula formation are twofold higher after an abscess in patients younger than 40 years and are almost threefold higher in non diabetics. Preoperative considerations include the following: • Rectal irrigation with enemas should be performed on the morning of the operation • Anesthesia can be general, local with intravenous sedation, or a regional block • Administer preoperative antibiotics Intraoperative considerations include the following: • Examine the patient under anesthesia to confirm the extent of the fistula • Identifying the internal opening (inside the anus) to prevent recurrence is imperative • A local anesthetic block at the end of the procedure provides postoperative analgesia Fistulotomy: The laying-open technique (fistulotomy) is useful for 85-95% of primary fistulas (ie, submucosal, intersphincteric, and low transsphincteric). [6, 7, 8, 9] The most common type of surgery for anal fistulas is a fistulotomy. This involves cutting along the whole length of the fistula to open it up so it heals as a flat scar.A fistulotomy is the most effective treatment for many anal fistulas, although it's usually only suitable for fistulas that don't pass through much of the sphincter muscles, as the risk of incontinence is lowest in these cases. If your surgeon has to cut a small portion of anal sphincter muscle during the procedure, they will make every attempt to reduce the risk of incontinence.In cases where the risk of incontinence is considered too high, one of the procedures below may be recommended instead. Seton techniques: If your fistula passes through a significant portion of anal sphincter muscle, your surgeon may initially recommend inserting a seton. A seton is a piece of surgical thread that is left in the fistula for several weeks to keep it open. This allows it to drain and helps it heal, while avoiding the need to cut the sphincter muscles. Loose setons allow fistulas to drain, but don't cure them. To cure a fistula, tighter setons may be used to cut through the fistula slowly. This may require several procedures that your surgeon can discuss with you. Seton Placement: A seton can be placed alone, combined with fistulotomy, or in a staged fashion. This technique is useful in patients with the following conditions [10, 11, 12] : • Complex fistulas (ie, high transsphincteric, suprasphincteric, extrasphincteric) or multiple fistulas • Recurrent fistulas after previous fistulotomy • Anterior fistulas in female patients • Poor preoperative sphincter pressures • Patients with Crohn disease or patients who are immunosuppressed Single-stage seton (cutting): Pass the seton through the fistula tract around the deep external sphincter after opening the skin, subcutaneous tissue, internal sphincter muscle, and subcutaneous external sphincter muscle. The seton is tightened down and secured with a separate silk tie. With time, fibrosis occurs above the seton as it gradually cuts through the sphincter muscles and essentially exteriorizes the tract. The seton is tightened on subsequent office visits until it is pulled through over 6-8 weeks. A cutting seton can also be used without associated fistulotomy. Recurrence and incontinence are important factors to consider when this technique is employed. The success rates for cutting setons range from 82-100%; however, long-term incontinence rates can exceed 30%. [13,14, 15] Two-stage seton (draining/fibrosing): Pass the seton around the deep portion of the external sphincter after opening the skin, subcutaneous tissue, internal sphincter muscle, and subcutaneous external sphincter muscle. Unlike the cutting seton, the seton is left loose to drain the intersphincteric space and to promote fibrosis in the deep sphincter muscle. Once the superficial wound is healed completely (2-3 months later), the seton-bound sphincter muscle is divided. Two studies (74 patients combined) supported the two-stage approach with a 0-nylon seton. Once wound healing is complete, the seton is removed without division of the remaining encircled deep external sphincter muscle. The researchers reported eradication of the fistula tract in 60-78% of cases. Mucosal Advancement Flap: A mucosal advancement flap is reserved for use in patients with chronic high fistula but is indicated for the same disease process as seton use. [1,16, 17] Advantages include a one-stage procedure with no additional sphincter damage. A disadvantage is poor success in patients with Crohn disease or acute infection. This procedure involves total fistulectomy, with removal of the primary and secondary tracts and completes excision of the internal opening. A rectal mucomuscular flap with a wide proximal base (two times the apex width) is raised. The internal muscle defect is closed with an absorbable suture, and the flap is sewn down over the internal opening so that its suture line does not overlap the muscular repair. Plugs and Adhesives: Advances in biotechnology have led to the development of many new tissue adhesives and biomaterials formed as fistula plugs. By their less-invasive nature, these therapies lead to decreased postoperative morbidity and risk of incontinence, but long-term data are lacking for eradication of disease, especially in complex fistulas, which carry high recurrence rates. [18, 19, 17] Reported series exist of fibrin glue treatment of fistula-in-ano, with 1-year follow-up showing recurrence rates approaching 40-80%. [20, 21,22] The Surgisis fistula plug has also had mixed long-term results in direct clinical trials. [23, 24, 25] Early success rates have been reported for newer materials, such as acellular dermal matrix and the bioabsorbable Gore Bio-A fistula plug, in low fistulas and good animal model data. [26] Assessment of long-term success rates with plug techniques for complex disease will be based on further data from randomized trials. In a randomized, controlled study designed to evaluate the efficacy and safety of the anal fistula plug in patients with fistulizing anoperineal Crohn disease, Senéjoux et al did not find the plug to be superior to seton removal for achieving fistual closure, regardless of whether the fistula was simple or complex. [27] A combined sphincter-sparing repair that includes both an anal fistula plug and a rectal advancement flap has been proposed for the treatment of transsphincteric fistula-in-ano. [28] LIFT Procedure: Ligation of the intersphincteric fistula tract (LIFT) is a sphincter-sparing procedure for complex transsphincteric fistulas first described in 2007. It is performed by accessing the intersphincteric plane with the goal of performing a secure closure of the internal opening and by removing the infected cryptoglandular tissue. [29] The intersphincteric tract is identified and isolated by performing meticulous dissection through the intersphincteric plane after making a small incision overlying the probe connecting the external and internal openings. Once isolated, the intersphincteric tract is hooked with a small right-angle clamp, and the tract is ligated close to the internal sphincter and then divided distal to the point of ligation. Hydrogen peroxide is injected through the external opening to confirm the division of the correct tract. The external opening and the remnant fistulous tract are curetted to the level of the proximity of the external sphincter complex. Finally, the intersphincteric incision is loosely reapproximated with an absorbable suture. The curettaged wound is left opened for dressing.[29,30,31] Because of its relative novelty, LIFT has not been extensively researched. In a randomized trial of 39 patients with complex fistula-in-ano who had failed previous procedures and were treated with LIFT technique, success rates were comparable to those seen with the anorectal advancement flap technique. [32] The probability of recurrence at 19 months was 8% for the LIFT technique versus 7% for the anorectal advancement flap. Time to return to work was shorter in the LIFT group (1 vs 2 wk), but there was no difference in incontinence scores. [32] Further randomized surgical trials are needed to determine whether this technique is a viable—or, possibly, a better—alternative to the other previously mentioned procedures for the treatment of fistula-in-ano. Diversion: In rare cases, the creation of a diverting stoma may be indicated to facilitate the treatment of a complex persistent fistula-in-ano. The most common indications include, but are not limited to, patients with perineal necrotizing fasciitis, severe anorectal Crohn disease, reoperative rectovaginal fistulas, and radiation-induced fistulas. Fecal diversion alone is effective in these select patients to control sepsis and symptoms; however, long-term success rates after reanastomosis are low because of recurrence from the underlying disease. Thus, this approach should be avoided unless the underlying fistula-in-ano disease process is repaired or has healed completely, which is unlikely. Postoperative Care: After the operation, most patients can be treated in an ambulatory setting with discharge instructions and close follow-up care. Sitz baths, analgesics, and stool-bulking agents (eg, bran and psyllium products) are used in follow-up care. Complications: Early postoperative complications may include the following: • Urinary retention • Bleeding • Fecal impaction • Thrombosed hemorrhoids Delayed postoperative complications may include the following: • Recurrence • Incontinence (stool) • Anal stenosis - The healing process causes fibrosis of the anal canal; bulking agents for stool help to prevent narrowing • Delayed wound healing - Complete healing occurs by 12 weeks unless an underlying disease process is present (ie, recurrence, Crohn disease) Postoperative rates of recurrence and incontinence vary according to the procedure performed, as follows: • Standard fistulotomy - The reported rate of recurrence is 0-18%, and the rate of any stool incontinence is 3-7% • Seton use - The reported rate of recurrence is 0-17%, and the rate of any incontinence of stool is 0-17% • Mucosal advancement flap - The reported rate of recurrence is 1-17%, and the rate of any incontinence of stool is 6-8% [16] Long-Term Monitoring: Frequent office visits within the first few weeks help to ensure proper healing and wound care. It is important to ensure that the internal wound does not close prematurely, causing a recurrent fistula. Digital examination findings can help distinguish early fibrosis. Wound healing usually occurs within 6 weeks.

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