Medication Summary
Patients with significant left-to-right shunts may benefit from digoxin. Those with severe common atrioventricular valve regurgitation may benefit from vasodilator therapy.
In patients with impaired splenic function, immunization with Haemophilus influenzae vaccine, pneumococcal vaccine, and meningococcal vaccine, as well as antibiotics for subacute bacterial endocarditis (SBE) prophylaxis are necessary. [48, 49] In a systematic review specifically assessing the risk of infection in heterotaxy syndrome (English language only), investigators noted 42 cases of bacteremia in 32 patients, with more than three quarters (79%) of these involving asplenia. [49] Moreover, patients with heterotaxy syndrome had an increased risk of bacteremia leading to mortality, regardless of the anatomic splenic type. [49] Thus, antibiotic prophylaxis is administered to patients before procedures that may cause bacteremia are performed. For more information, see Antibiotic Prophylactic Regimens for Endocarditis and Infectious Endocarditis.
In addition, because ciliary dysfunction is so common in heterotaxy and primary ciliary dyskinesia, [30] antibiotic therapy should be considered for all patients with respiratory symptoms.
Seasonal flu vaccine and H1N1 vaccine are recommended, especially for those who have undergone Fontan operation.
Diuretic agents
Class Summary
These agents promote excretion of water and electrolytes by the kidneys. They are used to treat heart failure or hepatic, renal, or pulmonary disease when sodium and water retention has resulted in edema or ascites. They may be used as monotherapy or in combination to treat hypertension.
Furosemide (Lasix)
Used to treat edema. Increases excretion of water by interfering with chloride-binding cotransport system, which, in turn, inhibits sodium and chloride reabsorption in ascending loop of Henle and distal renal tubule. Dose must be individualized to patient. Depending on response, administer at increments of 20-40 mg, no sooner than 6-8 h after previous dose, until desired diuresis occurs. When treating infants, titrate with 1-mg/kg/dose increments until satisfactory effect achieved.
Spironolactone (Aldactone)
For management of edema resulting from excessive aldosterone excretion. Competes with aldosterone for receptor sites in distal renal tubules, increasing water excretion while retaining potassium and hydrogen ions.
Inotropic agents
Class Summary
Positive inotropes increase the force of contraction of the myocardium and are used to treat acute and chronic congestive heart failure. Some may also increase or decrease the heart rate (eg, positive or negative chronotropic agents), provide vasodilatation, or improve myocardial relaxation. These additional properties influence the choice of drug for specific circumstances. Those used predominantly for their inotropic effects include cardiac glycosides and phosphodiesterase inhibitors.
Digoxin (Lanoxin)
Used to treat congestive heart failure. Cardiac glycoside with direct inotropic effects in addition to indirect effects on the cardiovascular system. Acts directly on cardiac muscle, increasing myocardial systolic contractions. Its indirect actions result in increased carotid sinus nerve activity and enhanced sympathetic withdrawal for any given increase in mean arterial pressure.
Angiotensin-converting enzyme (ACE) inhibitors
Class Summary
ACE inhibitors are beneficial in all stages of congestive heart failure. Pharmacologic effects result in a decrease in systemic vascular resistance, reducing blood pressure, preload, and afterload. Dyspnea and exercise tolerance are improved. Unlike diuretics, studies demonstrate improvement of survival and reduced progression of mild or moderate heart failure to more severe stages. Benefits asymptomatic left ventricular dysfunction.
Enalapril (Vasotec)
Used to treat congestive heart failure. Competitive inhibitor of ACE. Reduces angiotensin II levels, decreasing aldosterone secretion.
Vaccines
Class Summary
Active immunization increases resistance to infection. Vaccines consist of microorganisms or cellular components, which act as antigens. Administration of the vaccine stimulates the production of antibodies with specific protective properties.
Pneumococcal vaccine polyvalent (Pneumovax-23, Pnu-Imune 23)
Polyvalent vaccine used for prophylaxis against infection from Streptococcus pneumoniae. Used in populations at increased risk of pneumococcal pneumonia (ie, age >55 y, chronic infection, asplenia, immunocompromise).
Antibiotics, prophylactic
Class Summary
Antibiotic prophylaxis is administered to patients before performing procedures that may cause bacteremia.
Amoxicillin (Amoxil, Trimox)
Interferes with synthesis of cell wall mucopeptides during active multiplication, resulting in bactericidal activity against susceptible bacteria. Used as prophylaxis in minor procedures.
Ampicillin (Marcillin, Omnipen)
For prophylaxis in patients undergoing dental, PO, or respiratory tract procedures.
Coadministered with gentamicin for prophylaxis in GI or genitourinary procedures.
Clindamycin (Cleocin)
Used in penicillin-allergic patients undergoing dental, PO, or respiratory tract procedures. Useful for treatment against streptococcal and most staphylococcal infections.
Gentamicin (Garamycin)
Aminoglycoside antibiotic for gram-negative coverage. Used in combination with an agent against gram-positive organisms and one that covers anaerobes.
Used in conjunction with ampicillin or vancomycin for prophylaxis in GI or genitourinary procedures.
Vancomycin (Vancocin)
Potent antibiotic directed against gram-positive organisms and active against Enterococcus species. Useful in the treatment of septicemia and skin structure infections. Indicated for patients who cannot receive or have not responded to penicillins and cephalosporins or have infections with resistant staphylococci.
Use CrCl to adjust dose in renal impairment.
Used in conjunction with gentamicin for prophylaxis in penicillin-allergic patients undergoing GI or genitourinary procedures.
Cefazolin (Ancef)
First-generation semisynthetic cephalosporin that arrests bacterial cell wall synthesis, inhibiting bacterial growth. Primarily active against skin flora, including Staphylococcus aureus.
Cephalexin (Keflex)
First-generation cephalosporin that arrests bacterial growth by inhibiting bacterial cell wall synthesis. Bactericidal activity against rapidly growing organisms. Primary activity against skin flora and used for skin infections or prophylaxis in minor procedures.
Cefadroxil (Duricef)
First-generation cephalosporin that arrests bacterial growth by inhibiting bacterial cell wall synthesis. Bactericidal activity against rapidly growing organisms. Primary activity against skin flora and used for skin infections or prophylaxis in minor procedures.
Azithromycin (Zithromax)
Inhibits bacterial growth, possibly by blocking dissociation of peptidyl tRNA from ribosomes, causing RNA-dependent protein synthesis to arrest.
Clarithromycin (Biaxin)
Inhibits bacterial growth, possibly by blocking dissociation of peptidyl tRNA from ribosomes, causing RNA-dependent protein synthesis to arrest.
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The structure and function of cilia is shown here. (A) Most motile cilia are organized with 9 microtubule doublets surrounding a core pair of doublets (9+2 configuration). Outer dynein arms (green) and inner dynein arms (blue) are shown. Cilia on the cells of the ventral node in the normal mouse embryo have no core doublet (a 9+0 configuration) and were initially thought to be nonmotile; however, upon closer scrutiny, node cilia were seen to have a rotatory motion (600 rpm). [Figure A is from Hirokawa N, Tanaka Y, Okada Y. Left-right determination: involvement of molecular motor KIF3, cilia, and nodal flow. Cold Spring Harb Perspect Biol. Jul 2009;1(1):a000802 and is reprinted with permission of Cold Spring Harbor Press.] (B) lrd (left-right dynein), the protein (green) mutated by the iv mutation, is also known as DNAH11, DNAHC11, and DLP11. [Figure B is from the United States Department of Energy Genomes to Life Program.] (C) The rotatory cone of each cilium is tilted posteriorly. Hence, the cilia make a leftward swing at the fluid surface and a rightward swing at the cellular surface. Because more viscous drag is present at the cellular surface, the rightward sweep is less effective at generating fluid movement than is the leftward sweep. [Figure C is from Hirokawa N, Tanaka Y, Okada Y, Takeda S. Nodal flow and the generation of left-right asymmetry. Cell 2006; 125:33-45 and is reproduced with permission from Cell Press.] A = anterior; L = left; P = posterior; r = Right.
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Three phases of elaboration of left-right (LR) asymmetry are shown. The first step consists of differentiating the left and right sides on the cellular level. This probably takes place by means of a chiral molecule. (A) A subset of the cells (yellow) of the fairly early embryo undergo this process. (B) Localized cellular asymmetry is propagated between cells to cause LR determinants to accumulate on one side of the embryonic midline, possibly by a process involving transport through gap junctions. These determinants would then induce cascades of factors in multicellular fields of the embryo. (C) Finally, the asymmetric presence of these factors induces or suppresses asymmetrically located organs such as the spleen and regulates asymmetric morphogenesis of other organs such as the heart tube. Courtesy of Levin M, Mercola M. The compulsion of chirality: toward an understanding of left-right asymmetry. Genes Dev. Mar 15 1998;12(6):763-9.
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Genes required for proper left-right asymmetry are shown. Genes are presented in five columns, according to the developmental phase in which they are currently thought to function. The leftmost column has the earliest functioning genes. The second column has genes required for the development of the node (or its equivalent). The third and fourth column have genes that are required for normal node cilia function. Genes in white, green, or blue denote those in which the proof came from studies of fruit fly (Drosophila melanogaster), zebrafish (Danio rerio), or frog (Xenopus laevis), respectively. Genes in brown are those studied in mice (Mus musculus), whereas those discovered in humans (Homo sapiens) are shown in red.
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Axial magnetic resonance image (MRI) of a case of heterotaxy with polysplenia. (A) The abdominal aorta (abd ao) is on the left side of the spine (S), as is the left-sided azygos (L Azy). Two right-sided spleens (spl) are visible. LHV = left hepatic vein; RHV = right hepatic vein. (B) A common atrioventricular valve (black unlabelled arrows) is markedly malaligned to the right ventricle (RV). A diminutive left atrium (LA) is represented by only an appendage. The patient had an extracardiac conduit (EC) type of Fontan operation. No fenestration is noted between the EC and the neo-left atrium (neoLA). (C) Because this patient had subaortic stenosis, a proximal pulmonary artery-to-ascending aortic anastomosis was performed early in life, along with augmentation of the aortic arch. The L Azy connects to the left superior vena cava (LSVC). LU DAo = left upper descending aorta; Prox = proximal. (D) The LSVC connected originally to the coronary sinus (CS) and then to the right atrium. Despite the fact that the LSVC has been disconnected from the heart and anastomosed end-to-side to the left pulmonary artery, the CS remains large. The narrowed left ventricular outflow tract (LVOT) is seen. Ao = aorta; PA = pulmonary root; RLL PV = right lower lobe pulmonary vein. (E) Because this patient had absence of the hepatic segment of the inferior vena cava, the left-sided SVC-to-left pulmonary artery (LPA) anastomosis is referred to a left-sided Kawashima (LK). The anastomosis of the right superior vena cava to the right pulmonary artery is a right-sided bidirectional Glenn (R BDG) shunt. (F) The left lower lobe pulmonary vein (LLL PV), as part of this patient's totally anomalous pulmonary venous connection, connects to the original right atrium, which is now the neoLA.
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Coronal magnetic resonance image (MRI) of the same patient as shown in the previous image. (A) Both superior vena cava (SVC)–to–pulmonary artery (PA) anastomoses can be seen. LCCA = left common carotid artery. (B) Three-dimensional surface rendering. RIA = right innominate artery. (C) Three-dimensional reconstruction of only the systemic venous pathway.
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Malrotation of the gut. This upper gastrointestinal (GI) barium study of the same heterotaxy patient as shown in the previous two images shows a right-sided stomach (St), opposite of the normal site. The duodenum heads to the left, the duodenal-jejunal junction is to the left of the spine (opposite to what would be expected for situs inversus totalis), and the jejunum (J) stays left-sided.
