Karen Ama-Serwa Chachu

• Assistant Professor of Medicine

https://medicine.duke.edu/faculty/karen-ama-serwa-chachu

Wick between muscle fibers Slit catheter technique Tip of slit catheter protrudes from needle during filling with saline medicine for the people buy cheap isoniazid 300mg line. All air bubbles expressed treatment anemia buy isoniazid 300 mg without a prescription, and catheter tip withdrawn into needle before insertion into muscle medicine 377 cheap isoniazid 300 mg without prescription. Complete lysis of the containing compartmental fascia is mandatory to allow for adequate expansion of the involved soft tissues medicine in balance order isoniazid online from canada. Direct visualization of the fascial envelope is required medicine 93 2264 purchase isoniazid 300mg, and the fasciotomy must extend the entire length of the compartment medications breastfeeding isoniazid 300 mg fast delivery. Partial lysis of the compartment may provide incomplete decompression and contribute to further morbidity. Surgical Anatomy and Technique Fasciotomy in the leg can be achieved with a single lateral incision. The medial incision is used to decompress the posterior compartments, and the lateral incision addresses the anterior and lateral compartments. The medial incision is made approximately 1 to 2 cm posterior to the medial margin of the tibia. The posterior deep and superficial compartments are incised along the length of the leg, essentially from the proximal tibia to the medial malleolus. The long saphenous vein and its tributary branches may be encountered in the surgical field, and care should be taken to avoid injury to these vessels. The venous tributaries can be ligated and divided as needed, allowing the saphenous vein to be reflected either anteriorly or posteriorly to facilitate adequate fascial lysis. Posteromedial incision Transverse intermuscular septum Superficial posterior compartment Superficial flexor muscles Soleus Gastrocnemius Plantaris tendon Anterior compartment Extensor muscles Tibialis anterior Extensor digitorum longus Extensor hallucis longus Anterior tibial a. Anterolateral incision Anterior intermuscular septum Lateral compartment Peroneal muscles Peroneus longus Peroneus brevis Superficial peroneal n. Posterior intermuscular septum Fibula Crural (encircling) fascia Fascial incision into superficial posterior compartment Fascial incision into lateral compartment Fascial incision into deep posterior compartment Tibia Fascial incision into deep anterior compartment Anterior intermuscular septum Junction of transverse intermuscular septum with crural fascia Superficial peroneal n. In addition to entering the posterior deep compartment in the middle and distal leg, the soleus must be detached from the tibia for adequate lysis of the proximal portion of the posterior deep compartment. The lateral incision is placed approximately 1 cm anterior to the border of the fibula. Care should be taken to avoid injury to the superficial fibular nerve as it emanates from beneath the fibularis (peroneus) longus muscle. Proximally, the common fibular (peroneal) nerve can also be inadvertently injured. The anterior intermuscular septum is then identified and the anterior compartment crural fascia incised in a longitudinal direction. There are typically two to three subcompartments arranged in a volar-to-dorsal direction. The most superficial of these contains the flexor carpi radialis, palmaris longus, flexor carpi ulnaris, and superficial portion of the pronator teres. The next division contains the flexor digitorum superficialis, and the flexor digitorum profundus and flexor pollicis longus make up the final section. The main dorsal compartments are divided into the extrinsic finger extensors, thumb extensors with the index proprius, and the wrist extensors with the brachioradialis muscle. These anatomic divisions are important to consider during fasciotomy of the forearm. The resting position of the hand and wrist is slight wrist flexion, with metacarpophalangeal and proximal interphalangeal joint flexion and forearm pronation. The presence of a compartment syndrome is usually associated with swelling in the flexor compartment, because this is the most frequently involved compartment. The classic findings of forearm compartment syndrome are disproportionate pain in view of the physical exam, pain with passive stretch of the finger extensors, restricted finger and wrist motion, and paresthesias in the hand along the distribution of the median, the ulnar, and less often the radial nerve. There may be pallor in the terminal digits with prolonged capillary refill and decreased skin temperature. As this condition progresses, complete anesthesia occurs, and the radial and ulnar pulses can be diminished in severe cases. Ancillary studies should include radiographs because the fracture location can help pinpoint the site of severely injured muscle. In the obtunded or sedated patient, direct compartment pressure measurements should be obtained. A compartment pressure 30 mm Hg above the mean diastolic pressure, or an absolute pressure between 30 and 45 mm Hg, is abnormal. This treatment includes elevation of the limb to the heart level, application of an elbowto-finger splint, and avoidance of excess intravenous fluids. Surgical Anatomy and Technique the mainstay of treatment for confirmed compartment syndrome is decompressive fasciotomy. The volar compartment is most often involved and is approached initially through an extensile anterior or Henry-type approach. A carpal tunnel release is included if the swelling is significant in the distal forearm or palmar aspect of the wrist. Decompression should be extended proximal to the elbow flexion crease if there is swelling in that area. The septae between the muscle groups is also incised to ensure full decompression. The relationship of the median and ulnar nerves within the compartments is such that the ulnar nerve lies adjacent to the flexor digitorum profundus muscle, and the median nerve is generally between the flexor digitorum superficialis and flexor digitorum profundus muscles in the midforearm. The necessity for further surgical intervention is determined by the extent of muscle necrosis. Closure A clean and healthy muscle bed is necessary before closure can be considered. Skin staples with intervening vessel loops can be used to approximate the skin sequentially. The distal and proximal extents are primarily approximated, and the central defect is covered with a split-thickness skin graft. Complications and nonclosure rates of fasciotomy for trauma and related risk factors. In the urgent situation the patient has unstable physiologic parameters and requires immediate chest tube placement. In the semiurgent situation the mandatory chest tube is needed "sooner rather than later," and has an acute problem or indication but appears hemodynamically stable. However, delay in placing the chest tube could result in the patient becoming unstable and the need for an urgent procedure because of clinical deterioration. The nonurgent situation is typically elective and occurs in patients with stable hemodynamics and a chronic or recurrent physiologic problem. In other elective situations a chest tube is needed as part of a scheduled procedure, such as diaphragm repair or thoracotomy. Cross-sectional anatomy to visualize layers of the chest wall the first important concept of placing a chest tube or accessing the pleural space involves the ability to identify superficial anatomic landmarks. The key landmarks for accessing the pleural space are identification of the clavicular head; midclavicular line; the anterior, middle, and posterior axillary lines; and intercostal spaces with corresponding ribs. The ability to count ribs accurately will facilitate the placement of chest tubes. Instead, the inframammary fold should be used to identify the 5th rib at the anterior axillary line. In a male patient the lower border of the pectoralis major muscle is a good approximation for the site of tube insertion. The second key concept when accessing the pleural space is to recognize that the intercostal neurovascular bundles lie just below the inferior portion of the ribs. Thus it is important to place the chest tube over the most superior portion of the rib to avoid injuring the intercostal neurovascular bundle. Surface anatomy of the thorax Sternocleidomastoid muscle Sternal head Clavicular head Clavicle Jugular notch Deltoid muscle Body of sternum Nipple Cephalic vein Biceps brachii muscle Triceps brachii muscle Axilla Anterior axillary fold Posterior axillary fold Pectoralis major muscle Clavicular head Sternal head Latissimus dorsi muscle Xiphoid process of sternum Serratus anterior muscle Chest tube insertion site Linea alba Rectus abdominis muscle External oblique muscle Serratus anterior muscle Tendinous intersection Manubrium of sternum Common carotid artery Brachiocephalic trunk Subclavian artery and vein Brachiocephalic vein Internal thoracic artery and vein Anterior intercostal arteries and veins and intercostal nerve Internal intercostal muscles Innermost intercostal muscles B. Failure to recognize these boundaries can result in misadventures in chest tube placement such as placing a tube into or below the diaphragm, which can cause bleeding or injury to intraabdominal or major vascular structures. The fourth critical anatomic concept is to understand the difference between the left and right chest. The key differences between the left and right chest must be appreciated when accessing the pleural space. The location of the horizontal fissure on the right and oblique fissure on the left is at approximately the 4th rib at the anterior axillary line. The fifth and final important anatomic detail is to understand the cross-sectional anatomy of the chest wall and the layers that must be traversed to access the chest. These layers include the skin, subcutaneous tissue, intercostal muscles, and parietal pleura. It is still recommended to prepare the area with an antiseptic solution, usually chlorhexidine or povidone-iodine. Identify the anterior axillary line and the inframammary or subpectoral fold, and identify the rib at this location. In a thin patient, retracting the skin cranially before making the incision will create more soft tissue for tunneling. After the incision is made, tunnel through the intercostal muscles and the parietal pleura, and enter the pleural space. The classic description is to use a medium or large Kelly clamp with combined pushing and spreading, but in an urgent situation, this procedure should be done quickly with one or two passes. Once the chest cavity is entered, be sure to spread enough to allow a finger to be placed into the chest. The chest tube can be inserted through this tunnel with the assistance of the large Kelly clamp. Either close the Kelly clamp over the tube, or place the clamp tip through one of the side holes and slide it out the end of the tube. The Kelly clamp can assist in directing the tube posteriorly to evacuate fluid or anteriorly to evacuate a pneumothorax. All the holes in the chest tube must be within the pleural space for the tube to work properly. Semiurgent Placement the semiurgent technique is similar to the placement of an urgent chest tube. However, the practitioner will have time to infuse local anesthetic and more completely towel and drape the patient. Local anesthetic can be infused in two steps: infiltration of anesthetic in the skin and soft tissue over the incision site, followed by infiltration over the rib into the intercostal muscles and pleura. The needle should follow the direction of the planned tunnel, aspirating the entire way until the pleura space is entered. If the procedure is performed for pneumothorax or effusion, air or fluid will be aspirated in the syringe; at this point, stop advancing and start withdrawing the needle tip slowly. Infiltrate a large bolus of local anesthetic while slowly withdrawing the needle through the parietal pleura and intercostal muscles. However, this procedure can be done more slowly in the semiurgent situation than with an urgently placed chest tube. Nonurgent (Elective) Placement There are no major changes in technique with nonurgent compared with semiurgent tube placement. With an elective situation, however, there is time to review all imaging and select a more precise location for chest tube placement. Emergency thoracotomy is a lifesaving procedure only used in select circumstances. Knowledge of the appropriate indications for thoracotomy and thoracic anatomy are paramount. This incision can be performed easily with a scalpel and then Mayo scissors, if available. A right anterolateral thoracotomy incision does not provide adequate exposure for control of most cardiac injuries but is useful for penetrating injuries to the right chest cavity. If time allows, a wedge should be placed under the left side of the chest, creating an approximately 15-degree tilt for better exposure. The 4th or 5th intercostal space is located just below the nipple in men and, with the breast retracted, at the inframammary fold in women. The inferior portion of the pectoralis major and minor, serratus anterior, and intercostal muscles are divided. If necessary, the incision can be extended across the sternum to the right midaxillary line as a "clamshell" thoracotomy. Dividing the sternum transversely also will divide the internal mammary arteries, which can lead to troublesome bleeding if they are not ligated. Placement of a rib retractor with the handle toward the left axilla allows for easier extension of the incision into the right side of the chest. Assisted ventilation should be stopped during incision of the pleura to minimize iatrogenic injury to the lung. The incision in the pericardium is performed anterior and parallel to the phrenic nerve, which courses along the posterior third of the pericardium. The incision should be long enough to allow delivery of the heart into the left side of the chest for inspection and temporary control of cardiac wounds. Control of Cardiac Injury Definitive control of cardiac injury is best managed in the operating room.

The mesorectum is retracted medially and the dissection is continued on the right and left 4 medications walgreens buy 300mg isoniazid fast delivery, and the nervi erigentes are allowed to fall laterally as the dissection ensues medications multiple sclerosis purchase isoniazid cheap online. This procedure is continued until the pelvic floor and levator muscles are reached medicine 360 discount 300mg isoniazid free shipping. Completion of posterior dissection to the pelvic floor medicine cat herbs generic isoniazid 300 mg without a prescription, showing pelvic floor/levators F treatment lung cancer buy isoniazid 300 mg with mastercard. The peritoneum in the cul-de-sac is scored just anterior to the fold at the peritoneal reflection treatment whooping cough buy isoniazid 300mg line. The surgeon must keep in mind the location of the pelvic plexus of nerves that overlies the seminal vesicles anteriorly in the male. Also to avoid injury, the proximity of the ureters to the apex of the seminal vesicles must be considered. In women with a bulky, anteriorly based tumor, en bloc posterior vaginectomy is typically performed. The uterus and ovaries can be mobilized en bloc with the rectum if a hysterectomy has not been performed. The gonadal vessels are taken distal to the pelvic brim after identification and preservation of the ureters. The uterine vessels are serially clamped and suture-ligated directly adjacent to the cervix, to avoid the ureters. The anterior vagina is then opened, and the lateral borders of the vagina are divided with the cautery, leaving the posterior vagina en bloc with the rectum. It should be emphasized that the common error of creating a narrow waist of tissue just proximal to the pelvic floor should be avoided. Because the mesorectum naturally tapers above the levator muscles, the surgeon must avoid "coning in" on the specimen and compromising the circumferential margin. This error must be consciously avoided throughout the distal pelvic dissection to complete an oncologic extra-levator dissection, more recently called a "cylindrical resection" by some authors. The pelvic plexus of nerves is immediately overlying the seminal vesicles and the prostate. The stoma can be created, the abdomen closed, and the stoma matured, followed by subsequent turning of the patient to the prone jackknife position. Some surgeons believe that this approach greatly facilitates the perineal dissection. Regardless of positioning, the margins of dissection are determined by tumor location. In general, the posterior margin is determined by palpation of the coccyx, the lateral margins by palpation of the ischial tuberosities, and the anterior margin by the urethra in the male and the posterior vaginal wall in the female. As noted, posterior vaginectomy is typically performed for any bulky, anteriorly based lesion. The amount of skin that needs to be taken is not great, and usually the anal verge suffices, except with a larger squamous lesion. The dissection is continued until the ischiorectal fossa is entered circumferentially. Usually, the posterior dissection is performed first because it has the clearest landmarks. The surgeon continues the lateral dissection up to the lateral origin of the levator muscles, staying in an extra-levator plane. In the male patient, the urethra is noted by palpation of the Foley catheter, and great care is taken to avoid injury. In the female patient, a finger in the vagina can help to define the anterior plane. After the dissection is completed circumferentially, the specimen is delivered through the perineum and carefully examined for adequacy of margins. The vagina, although somewhat narrowed, can usually be closed in a tubular fashion. The perineum is then closed with interrupted vertical mattress sutures, beginning at the introitus. Perineal dissection and entrance into ischiorectal fossa, taking posterior vagina en bloc B. Abdomen is entered posteriorly anterior to coccyx; the levators are hooked with the index finger and divided. Note the intact mesorectum, en bloc vagina, uterus, and ovaries and absence of narrowing just proximal to the levators in the specimen. Randomized clinical trial of conventional versus cylindrical abdominoperineal resection for locally advanced lower rectal cancer. The vast majority of hemorrhoidal presentations can be managed with nonsurgical treatments, although procedural intervention is required in some circumstances. A firm grasp of anorectal anatomy is essential for choosing the appropriate method of treatment. They are typically organized into three anatomically distinct cushions located in the left lateral, right anterolateral, and right posterolateral anal canal. Hemorrhoids are found in the submucosal layer and are considered sinusoids because they typically have no muscular wall. They are suspended in the anal canal by the muscle of Treitz, which is a submucosal extension of the conjoined longitudinal ligament. Internal hemorrhoids are located proximal to the dentate line and have visceral innervation; therefore the most common presentation is painless bleeding. External hemorrhoids are located in the distal third of the anal canal and are covered by anoderm (squamous epithelium). Because of the somatic innervation of external hemorrhoids, patients who have these are more likely to be seen with pain. Hemorrhoids are thought to enhance anal continence and may contribute 15% to 20% of resting anal canal pressure. In addition to making important contributions to the maintenance of continence through pressure phenomena, hemorrhoids also relay important sensory data regarding the composition (gas, liquid, stool) of intrarectal contents. The central causative pathway for the development of hemorrhoidal pathology is an associated increase in intraabdominal pressure. Aging is also associated with dysfunction of the supporting smooth muscle tissue, resulting in prolapse of hemorrhoidal tissues. Hemorrhoids are normal structures and thus are treated only if they become symptomatic. After nonoperative measures have failed, treatment is largely applied on the basis of size and symptomatology. Hemorrhoids classically are categorized into grade 1, with enlargement, but no prolapse outside the anal canal; grade 2, with prolapse through the anal canal on straining, but with spontaneous reduction; grade 3, manual reduction required; and grade 4, hemorrhoids cannot be reduced into the anal canal. First-degree hemorrhoidal disease can usually be treated with nonsurgical measures. The primary goal is to decrease straining with bowel movements and thus reduce the intraabdominal pressure transmitted to the hemorrhoidal vessels. The mainstay of nonoperative hemorrhoidal treatment is increased fiber and water consumption. Patients with 2nd-degree hemorrhoids can be offered a trial of nonsurgical management, although a number of these measures will fail and require procedural intervention. Anatomy of hemorrhoids Left lateral Right posterior Rectosigmoid junction Fibers of taenia spread out to form longitudinal muscle layer of rectum Right anterior Usual position of internal hemorrhoids, or anal cushions Sigmoid colon Free taenia (taenia libera) Fibers from longitudinal muscle join circular muscle layer External hemorrhoidal plexus Dentate line Circular muscle layer Window cut in longitudinal muscle layer to expose underlying vasculature Levator ani muscle Parts* of Deep external anal Superficial Subcutaneous sphincter muscle Fibrous septum Corrugator cutis ani muscle Perianal skin *Parts variable and often indistinct Internal hemorrhoidal plexus Anterior view B. All these techniques rely on some form of tissue destruction, which then results in fixation of the remaining hemorrhoidal tissues. Rubber band ligation is the most frequently used procedure used in the United States. This technique is most often used to address 1st- and 2nd-degree hemorrhoids, although 3rd-degree hemorrhoids can occasionally be treated with this technique as well. The most common of the many implements available for application of the rubber bands is a suction ligator, which allows the surgeon to draw in the hemorrhoidal tissue and apply the rubber band with one hand. Other devices require that the operator grasp the hemorrhoidal pile with a long forceps and apply the rubber band with the other hand. Complications are rare but include vasovagal response, pain, bleeding, and pelvic sepsis. Most complications can be avoided by ensuring that the rubber band is placed well above the dentate line, close to the base of the hemorrhoidal pile. Pelvic sepsis may result from incorporation of the distal rectal wall into the band. The combination of pain, urinary retention, and fever after banding should raise suspicion of pelvic sepsis. Ligature of internal hemorrhoids Loading elastic ligatures over special conical loading device Two ligatures in place, ready for use Hemorrhoid grasped by Allis clamp, drawn into drum of instrument; trigger about to be pulled, to push ligature around base of hemorrhoid C. Both techniques involve elliptical excision of the internal and external hemorrhoidal complex. The layer of connective tissue that is present can be left on the sphincters, although some surgeons directly expose the sphincters. During this dissection it is important to separate the hemorrhoidal tissue from the internal sphincter without damaging the latter. After completion, the procedure is repeated on any further hemorrhoid columns that require removal. After removal of the hemorrhoidal tissues, the base of the hemorrhoid is suture-ligated, and the anal mucosa/anoderm are reapproximated using a running absorbable stitch. The procedure involves placement of a mucosal purse-string suture 2 to 3 cm above the dentate line. A specially designed surgical hemorrhoidal stapler is used to resect the mucosa and submucosa associated with the hemorrhoid and to close the resultant defect. This technique is associated with less pain and analgesic use and higher rates of recurrence and residual prolapse. The most common complication of stapled hemorrhoidopexy is bleeding from the staple line. Other, rare complications include rectal perforation, pelvic sepsis, and chronic pain syndrome. Physical examination typically reveals thrombosis of the internal and external hemorrhoids, with or without evidence of necrosis. If there is evidence of tissue necrosis, all nonviable tissue should be excised and the incision left open. In poor candidates for surgical intervention, the anoderm can be infiltrated with local anesthesia. The anesthesia causes the internal sphincter to relax, and the internal hemorrhoids can be reduced with gentle massage. External thrombectomies and multiple rubber band ligations of the internal hemorrhoids can be performed as an alternative to excisional hemorrhoidectomy. Surgical management of internal hemorrhoids: Excision technique for mixed hemorrhoids Hemorrhoid grasped and pulled down External sphincter External hemorrhoid dissected free; dissection carried cephalad to free internal portion External sphincter Deep suture ligation of vascular pedicle Internal sphincter B. Located in the intersphincteric space, the anal glands drain into the anal canal at the level of the anal crypts located at the dentate line; thus, strictly speaking, all these conditions start as intersphincteric abscesses. Abscesses that remain localized to the body of the gland in the potential intersphincteric space, between internal and external sphincters, are termed intersphincteric abscesses. Abscesses that perforate laterally through the external sphincter into the lower extrarectal space are called ischiorectal abscesses. The ischiorectal space is a pyramidal area bordered by the rectum and anus medially and pelvic side wall laterally. The apex of the ischiorectal space is formed by the levator ani muscle, and posteriorly the sacrotuberous ligament and gluteus maximus muscle form its borders. Importantly, the pudendal and internal pudendal vessels run through the superolateral wall of the ischiorectal space. Most often, the infection will track through the intersphincteric space into the base of the ischiorectal space and into perianal soft tissue. This space contains both the external hemorrhoidal plexus and the subcutaneous part of the external anal sphincter. More frequently, infections in the supralevator space originate in the pelvis, usually as a result of a diverticular abscess eroding through the pelvic floor. This space is bordered inferiorly by the muscles of the levator ani, laterally by the obturator fascia, and medially by the rectum. Surgical management requires not only adequate drainage but also effective anesthesia, for perioperative management as well as early postoperative pain control. An appropriate perianal block must be administered at surgery and relies on blocking nociceptive impulses from the pudendal nerve bilaterally. This approach allows for maximal relaxation and also sphincter relaxation, which augments exposure. The tubercle is easily palpated through the skin, and the needle is introduced medial to this, as deeply as possible. Additional local anesthetic is fanned out in a diamond shape adjacent to the sphincters, to infiltrate the ramifying branches of the nerve. Another option is to perform a ring block, in which local anesthetic is introduced into the perianal skin and the underlying sphincter muscle. For all these methods, a small-bore needle (25 gauge) should be used because rapid infiltration through a large-bore needle can cause pain. Further, the acidic milieu that results from a purulent environment leads to less effective anesthesia if directly infiltrated; therefore the nonerythematous skin in the area should be targeted. Specific Abscesses Superficial anorectal abscesses are drained directly; the incision should be large enough to provide adequate drainage. Incisions should be made radially to avoid disruption of sensory and motor nerves.

To obtain a true cross section of the thorax medications with acetaminophen discount 300 mg isoniazid fast delivery, rotate the transducer until only one rib is seen on each side medicine 4h2 isoniazid 300 mg visa. Tipping caudad from this image shows the coronary sinus and tipping cephalad shows the left ventricular outflow tract and aortic valve brazilian keratin treatment buy generic isoniazid 300mg. Continuing to sweep cranially from the left ventricular outflow tract in the transverse plane 714x treatment purchase isoniazid on line amex, the right ventricular outflow tract and pulmonary valve are seen medications borderline personality disorder cheap isoniazid 300mg overnight delivery. In the normal heart medications similar to gabapentin cheap isoniazid online mastercard, the pulmonary valve is leftward and anterior to the aortic valve and gives rise to the pulmonary artery that crosses over the aorta at a right angle. Continuing the axial sweep, the transverse aortic arch will be seen cranial to the ductus arteriosus. The great arteries are distinguished from each other by their morphological features rather than their connections to the heart. The main pulmonary artery branches shortly after the valve into the right and left pulmonary arteries as well as the ductus arteriosus, whereas the aorta gives rise to head and neck vessels (going superiorly toward the head) some distance from the valve apparatus. The ability to obtain all of these views is the first step in the evaluation of the fetal heart. The second, and maybe more important, step is the ability to recognize the structures and to determine whether they are normal. The axial views obtained from sweeps cranially and caudally from the 4-chamber view are sufficient to identify almost all normal features of the fetal heart, as well as many of the abnormalities. If both are on the right, one needs to consider complete situs inversus, which has a good prognosis. If, however, the heart and stomach are located on opposite sides, heterotaxy or situs ambiguous is present. If the axis is abnormal, one needs to determine if the heart is being "pushed" or "pulled" to one side. Conditions that may "push" or displace the heart are congenital diaphragmatic hernia and congenital pulmonary airway malformations. The heart occupies about 1/2 of the circumference of the chest with a normal range being 0. An increased ratio usually indicates that the heart is dilated (cardiomegaly), but it may also occur when the chest is small due to thoracic dysplasia. Enlargement of multiple chambers is seen with intrinsic cardiomyopathy or secondary to arrhythmia. Isolated right atrial dilation secondary to leakage of the tricuspid valve from Ebstein anomaly can drastically increase the total cardiac 374 radiologyebook. Right ventricular enlargement is seen with coarctation of the aorta and premature ductal constriction. Noncardiac causes of cardiomegaly are typically from volume overload and come in 2 main categories: Twin-related heart failure and vascular shunting. In a multiple pregnancy, one needs to evaluate chorionicity as twin-twin transfusion and twin reversed arterial perfusion only occur with monochorionic placentation. Heart dilation can also be seen with volume overload from an absent ductus venosus or sources of vascular shunting, including sacrococcygeal teratoma, chorioangioma, and vein of Galen malformation. Finally, anemia can cause cardiomegaly due to the creation of a high-output state. This is typically estimated visually, but they can be measured and compared to normative values. The right atrium may be very large in the setting of severe tricuspid regurgitation, as noted above. In cases of asymmetry, you must determine if one is enlarged or the other is hypoplastic; surprisingly, such a distinction can often be challenging. Rarely, two atrioventricular valves may drain into a single left ventricle, a condition called double inlet left ventricle. The degree to which they are unbalanced determines whether the heart will function as a single ventricle or the normal two ventricles after repair. Detailed assessment of the great arteries is critical as many complex cardiac diseases may have a normal 4-chamber view. First, determine if there are one or two great vessels and where they are located in relation to the ventricular septum. Only one great vessel suggests the fetus has either truncus arteriosus or atresia of a semilunar valve (pulmonary or aortic atresia). Semilunar valve atresia with an intact ventricular septum should cause recognizable pathology to the respective ventricle, namely a small or hypoplastic chamber. The valve annulus may also appear normal in plate-like atresia or critical stenosis, so color Doppler is required to determine direction of and restriction to blood flow. If they exit in a side-by-side fashion, this is always abnormal and is most commonly due to transposition. In the sagittal plane, seeing the head and neck vessels come off the anterior great vessel is also abnormal and concerning for transposition. If the aortic valve is patent but the ascending aorta seems small, look for coarctation or an interrupted aortic arch. An interrupted arch will have a ventricular septal defect and a small ascending aorta giving rise to one or more head and neck vessels. The descending aorta is wholly supplied by the ductus arteriosus with no flow connecting the ascending to descending aorta. The physics of Doppler is such that the best images are obtained when the ultrasound beam is as close to parallel to the flow of blood as possible. If the beam is perpendicular to the direction of blood flow, there will be an inadequate Doppler signal despite normal flow. Ideally, color Doppler evaluation should take place in a sequential fashion from venous to arterial flow. Documentation of flow from right to left at the foramen ovale is very important because reversal of flow suggests left-sided outflow tract obstruction. Interrogation of the ventricular septum by color Doppler also helps to identify ventricular septal defects, which may be too small to see by 2D imaging alone. The pulmonary veins should be shown by color Doppler and be interrogated by pulsed Doppler to confirm entrance into the left atrium. Forward flow should be shown across the pulmonary and aortic valves and one should look for regurgitation. Normal flow in the ductus arteriosus is right to left; however, in the setting of pulmonary atresia, the flow will be retrograde from the aorta into the pulmonary artery. In the setting of aortic atresia, flow to the head and heart will be retrograde around the aortic arch from the ductus arteriosus. Pulsed Doppler is helpful as an adjunct to color Doppler because it confirms direction of flow, pattern of flow (venous or arterial), and velocity of flow that varies according to the site being interrogated. This can be helpful when an assessment of cardiac output is needed in the setting of poor ventricular function or when tracking cardiac function in twin-twin transfusion syndrome. Rhythm disturbances are fairly frequent findings on routine scans but most are benign and self-limiting. The ability to identify a benign rhythm disturbance is critical to those who perform routine obstetric ultrasounds. Sometimes, arrhythmias are observed on grayscale evaluation of the 4chamber view, but M-mode and pulsed Doppler techniques will help you identify the exact nature of the arrhythmia. Detailed analysis of the cardiac rhythm requires accurate measurement of the heart rate, the relationship between atrial and ventricular contractions, and measurement of the time intervals between specific events in the cardiac cycle. In M-mode, a single static line is placed through the atrium and ventricle simultaneously; movement is plotted against time to allow measurement of the heart rate and comparison of timing. Using pulsed Doppler, the sample volume can be placed in the left ventricular inflow (flow across the mitral valve) adjacent to the outflow (across the aortic valve) such that both tracings can be obtained at the same time. This allows identification of the normal beats, but it also allows one to see an early atrial beat (and whether or not it is conducted) as well as early ventricular beats. Clinical Implications Congenital heart disease is strongly associated with aneuploidy, and even when chromosomes are normal, it may be the index finding leading to diagnosis of a specific syndrome. Prenatal diagnosis with planned delivery in a facility with appropriate expertise maximizes the potential for a good outcome in operable cases. In this position, the fetal right side is closest to the maternal abdominal wall, while the fetal cardiac apex and stomach should be toward the maternal spine. The path of blood flow is from the left atrium to the left ventricle to the ascending aorta. In the fetus, the "bifurcation" seen around the aortic root is between the ductus arteriosus and the right pulmonary artery. Note the main pulmonary artery with early branching into the ductus arteriosus and right pulmonary artery as well as a widely patent right ventricular outflow tract. One can see flow in all 3 head and neck vessels directed superiorly toward the head. This is part of the transverse sweep from the 4chamber view showing the superior vena cava, aorta, and ductus arteriosus. Mitral regurgitation due to poor ventricular functions cause a jet of flow swirling back into the left atrium. One can see the inferior vena cava and superior vena cava as they drain into the right atrium. This is a coronal section through the heart and allows for side by side comparison of ventricular size and "squeeze. The Mmode allows one to clearly see ventricular contractions and atrial contractions in a fetus with complete heart block and a ventricular rate of 63. These findings are consistent with an interrupted inferior vena cava in a fetus with left atrial isomerism. Gottschalk I et al: Extracardiac anomalies in prenatally diagnosed heterotaxy syndromes. Normally, the direction of flow in the ductal and aortic arches should be the same. The pulmonary artery (recognized by early branching) is posterior to the aorta as in transposition. This is a double outlet right ventricle, which is a common finding in right atrial isomerism. This finding does not mean that all pulmonary veins drain normally, so the right-sided veins must be looked for as well to exclude partial anomalous venous return. On further inspection, an amniotic band stretched from the chest wall defect across the fetal face and anchored the heart in its external location. Note massive pleural effusions and ascites as well as the excavated contour of the liver. Zeidler S et al: Early prenatal disruption; a foetus with features of severe limb body wall sequence, body stalk anomaly and amniotic bands. Amniotic bands may not be immediately apparent but can be demonstrated (as in this case) by rolling the patient to float the fetus away from the uterine wall. The distortion of the great vessels was such that repair failed and the infant died. Surgical repair is often staged and has to address not only the ectopia cordis but also any associated structural anomalies, which are common and often complex. Mixing of blood in the heart results in similar saturations in the aorta and main pulmonary artery. The crux of the heart is missing and there is complete mixing of oxygenated and deoxygenated blood. Ginde S et al: Long-term outcomes after surgical repair of complete atrioventricular septal defect. The plane of section mimics a short-axis view and shows a single common atrioventricular valve. On occasion the covering flap can be redundant and balloon into the left atrium, creating an atrial septal aneurysm. Although definitions vary, an abnormally redundant flap is considered to extend at least halfway across the left atrium. A very redundant flap may even herniate through the mitral valve and cause obstruction of left ventricular inflow. Channing A et al: Maternal hyperoxygenation improves left heart filling in fetuses with atrial septal aneurysm causing impediment to left ventricular inflow. The left ventricular outflow tract is visible in this plane because the heart is rotated. Note the prominent hepatic vein; abnormal right atrial pressure causes back pressure into the liver. The atrium is so large, it is not possible to image the superior and inferior vena cava in the same plane. She was placed on prostaglandins for known retrograde filling of the pulmonary artery via the ductus but failed to oxygenate even with high-flow nasal cannula. There is only a remnant of the septal leaflet of the tricuspid valve, resulting in a large coaptation defect causing severe regurgitation. The pericardium has been removed, revealing a massively enlarged right atrium, which fills the majority of the thoracic cavity. The tricuspid valve is in the normal position but the leaflet tips are thick and dysplastic. The normal position of the leaflets distinguishes it from Ebstein anomaly where there is apical displacement and a small right ventricle. Severe regurgitation leading to right atrial enlargement and hydrops has a poor prognosis. There is a ventricular septal defect, which allows blood to enter the hypoplastic right ventricle.

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Diseases

• Marie type ataxia
• Coronary artery aneurysm
• Syngnathia multiple anomalies
• Mycosis fungoides, familial
• Fanconi Bickel syndrome
• Short syndrome