Non-cardiac causes are usually secondary, and can involve recreational drug use or abuse, metabolic or endocrine issues, especially hypothyroidism, an electrolyte imbalance, neurological factors, autonomic reflexes, situational factors, such as prolonged bed rest, and autoimmunity.Cardiac causes include acute or chronic ischemic heart disease, vascular heart disease, valvular heart disease, or degenerative primary electrical disease. Ultimately, the causes act by three mechanisms: depressed automaticity of the heart, conduction block, or escape pacemakers and rhythms.In general, two types of problems result in bradycardias: disorders of the SA node, and disorders of the AV node.With SA node dysfunction (sometimes called sick sinus syndrome), there may be disordered automaticity or impaired conduction of the impulse from the SA node into the surrounding atrial tissue (an "exit block"). Second-degree sinoatrial blocks can be detected only by use of a 12-lead ECG. It is difficult and sometimes impossible to assign a mechanism to any particular bradycardia, but the underlying mechanism is not clinically relevant to treatment, which is the same in both cases of sick sinus syndrome: a permanent pacemaker.AV conduction disturbances (AV block; primary AV block, secondary type I AV block, secondary type II AV block, tertiary AV block) may result from impaired conduction in the AV node, or anywhere below it, such as in the bundle of His. The clinical relevance pertaining to AV blocks is greater than that of SA blocks.Beta blocker medicines also can slow the heart rate and decrease how forcefully the heart contracts.
Meacham syndrome is a rare genetic disorder which is characterized by lung, diaphragmatic and genitourinary anomalies. Signs and symptoms
Often people with this condition are born with both underdeveloped lungs and a herniated diaphragm. Urinary symptoms include a horseshoe kidney
Genital symptoms are different according to the biological sex of the baby, genetic males (46,XX) usually have pseudohermaphroditism, ambiguous genitalia, and perineal hypospadias. Genetic females (46,XX) often have septate uterus and duplication of the vagina. In some cases, karyotype is needed to know the biological sex of the baby.Additional symptoms include neoplasm, cryptorchidism, ventricular septal defect, atrial septal defect, hernia, patent ductus arteriosus, Tetralogy of Fallot, and penile hypoplasia. Causes
This condition is caused by an autosomal dominant missense mutation in the WT1 gene, in chromosome 11. This was found through two half-siblings reported by Suri et al. Epidemiology
According to OMIM, only 12 cases have been described in medical literature. == References ==