Pediatric Cardiology

·         Intravenous rapid push adenosine is the drug treatment of choice for all cases of SVT, in infants and in patients of all ages. Verapamil was once used in older patients, but in infants in heart failure, verapamil has serious adverse effects (cardiac arrest) owing to its negative inotropic effects on an already failing myocardium.

In infants, the vagal maneuver of choice is placing a plastic bag containing iced saline completely over the nose and mouth. If this is unsuccessful, intravenous adenosine is the next step. Vagotonic maneuvers in older children include doing a Valsalva maneuver, straining, breath holding, squatting, drinking iced water, coughing, vomiting, and gagging.

·         Pulmonary valve lesions (PS) in rheumatic fever are very unusual. This lesion is common as a dysplastic valve in Noonan syndrome and in Alagille syndrome, which is due to mutations in Jagged 1. Isolated PS is also noted to have an increased frequency of Jagged 1 mutations without Alagille syndrome.

·         Primary pulmonary hypertension is an idiopathic disorder. Some familial cases have mutations in the gene for bone morphogenetic protein receptor II (BMP II).

·         There are rarely any extracardiac problems in patients with WPW. The ECG features of the delta wave (slow upstroke of the QRS complex, also known as preexcitation) are not seen during the SVT and are visible only in sinus rhythm.

·         Many believe that all infants with cardiomyopathy should receive a trial of carnitine after being evaluated for metabolic inborn errors of metabolism associated with cardiomyopathy.

·         Pleconaril is a potent antiviral agent that is very effective against enteroviruses. It is the agent of choice for treatment of severe enteroviral infections.

·         Pulmonary atresia is manifested by a small right ventricle, decreased pulmonary vascular markings, early and marked cyanosis without heart failure, and ductal dependence to maintain some pulmonary blood flow.

·         Poor pulses, reduced left ventricular forces on ECG, cardiogenic shock, and severe cyanosis are typical of hypoplastic left heart syndrome.

·         The most likely cause of sudden death in an athlete immediately after forceful blunt trauma to the chest is Commotio cordis.This unusual event places the heart in asystole, which is unfortunately refractory to almost all resuscitative efforts. At the scene, defibrillation may improve the outcome if done within minutes of the episode.

·         The pulmonary vascular resistance begins to fall after birth and reaches a nadir by 6-8 weeks of age.

·         Oxygen is a potent vasodilator and contributes to the fall in the pulmonary vascular resistance after birth.

·         Shortening fraction (SF) is a measure of the percentage of change in diameter of the left ventricle that occurs during the cardiac cycle. Preload, contractility, and afterload all influence shortening fraction.

SF% = (LV Diastolic Volume-LV Systolic volume)/LV Diastolic X100

The normal range is 28-44%.

·         A hyperoxia test attempts to differentiate between pulmonary disease with V/Q mismatch and cyanotic congenital heart disease.

Common mixing lesions may not be excluded. Examples are total anomalous pulmonary venous return, tetralogy of Fallot with a predominant left-to-right shunt, and hypoplastic left heart syndrome.

·         Dopamine is more effective than dobutamine in the treatment of systemic hypotension in a preterm neonate because the most frequent cause of hypotension in this patient population is abnormal regulation of the peripheral vascular tone with or without associated myocardial dysfunction.

·         The different presentations of TAPVC depend on whether the pulmonary veins are obstructed.

With obstructed veins, infants present with cyanosis and respiratory distress.

With unobstructed veins, tachypnea develops gradually.

·         Scimitar syndrome has the following components: right lung hypoplasia, anomalous connection of the right pulmonary veins to the inferior vena cava, right pulmonary artery hypoplasia, anomalous systemic arterial supply to the right lung, bronchial anomalies, and dextroposition of the heart reflecting the hypoplastic right lung. The term scimitar syndrome derives from a feature on the chest x-ray: the right pulmonary veins cast a shadow like the handle of a scimitar in the right lower zone as they drain anomalously into the inferior vena cava.

·         DiGeorge syndrome with hypocalcemia is present in approximately one third of cases with truncus arteriosus. Also a/w Interrupted Aortic Arch.

·         Different types of interrupted aortic arch:

Type A: Interruption is distal to the left subclavian artery.

Type B: Interruption is between the left carotid artery and the left subclavian artery. An aberrant right subclavian artery can also be seen in this condition (most common, occurring in approximately 40% of all cases).

Type C: Interruption is between the innominate artery and the left carotid artery.

·         An interrupted inferior vena cava prevents access to the right heart from the femoral veins. This interruption, however, is usually below the level of the hepatic veins. Therefore, the umbilical vein remains an alternate way to access the right heart.

·         ECGS IN THE NEWBORN PERIOD:

Left axis deviation in a newborn ECG is abnormal

T waves should be inverted in V1 by 3 days of age

·         Hypomagnesemia mimics hypokalemia

·         Waterston shunt (anastomosis from the ascending aorta to the right pulmonary artery) and the Potts shunt (anastomosis from the descending aorta to the left pulmonary artery). The modified Blalock-Taussig shunt is a Gore-Tex interposition shunt placed between the subclavian artery (right or left) and the right or left pulmonary artery.

·         A bidirectional Glenn anastomosis is a connection from the right superior vena cava to the right pulmonary artery, or the left superior vena cava to the left pulmonary artery, or both (i.e., bicaval bidirectional Glenn anastomosis). The pulmonary arteries are in continuity, so a right bidirectional Glenn anastomosis connection will send blood flow into the right and the left pulmonary arteries. This anastomosis is usually the intermediate step to a Fontan procedure. Lesions for which a bidirectional Glenn procedure is used include those with single ventricle anatomy (e.g., hypoplastic left heart syndrome, hypoplastic right heart syndrome, tricuspid atresia, and pulmonary atresia).

 ·         The Mustard or Senning (atrial switch) procedure is used in d-transposition of the great arteries to baffle systemic and pulmonary venous drainage. In this procedure, the systemic venous drainage returning to the right atrium is baffled through the mitral valve, where it enters the left ventricle, and then the pulmonary artery. The pulmonary venous drainage returning to the left atrium is baffled through the tricuspid valve, into the right ventricle, and then out the aorta. This procedure is not as commonly performed today, and the Jatene Procedure is more commonly used in d-transposition of the great vessels.