This means people with both hyperkalemic periodic paralysis and paramyotonia congenita can have attacks with fluctuations of potassium up or down. Andersen-Tawil syndrome (Online Mendelian Inheritance in Man (OMIM): 170390), a form of periodic paralysis that includes significant heart rhythm problems, fainting and risk of sudden death. Potassium levels may be low, high, or normal during attacks of ATS. Patients with ATS may also have skeletal abnormalities like scoliosis (curvature of the spine), webbing between the second and third toes or fingers (syndactyly), crooked fingers (clinodactyly), a small jaw (micrognathia) and low-set ears. Patients need to have another form of periodic paralysis to have the Andersen-Tawil. If a patient has hypo or hyper periodic paralysis they have a 50% chance of getting Andersen-Tawil. They just have to have the gene that causes it. This is a rare occurrence of having this. Only around 100 people in the world are recorded to have it. Cause
One of the most common descriptions of periodic paralysis are episodic attacks of muscle weakness, which are commonly associated with serum potassium levels. Physical activity and diet content (carbohydrates) have been identified as PP triggers. Unlike non-dystrophic myotonias, the periodic paralysis phenotype is triggered after resting following exercise. Voltage-gated sodium channel (Nav1.4) mutations are among the key causes behind periodic paralysis.Hyper-kalemic PP (hyperPP) is identified with high extracellular potassium levels which are typically greater than 5 mM during attacks; however, HyperPP attacks can also take place without rise in potassium concentrations. HyperPP has a prevalence rate of 1/100,000.
Supine hypotensive syndrome

Causes
the causes for this condition are the following:
Obstruction by deep vein thrombosis or tumors (most commonly renal cell carcinoma)
Compression through external pressure by neighbouring structures or tumors, either by significantly compressing the vein or by promoting thrombosis by causing turbulence by disturbing the blood flow. This is quite common during the third trimester of pregnancy when the uterus compresses the vein in the right side position. Iatrogenic causes may be suspected in patients with a medical history of liver transplantion, vascular catheters, dialysis and other invasive procedures in the vicinity
Budd-Chiari syndrome

Diagnosis
The diagnosis can be made clinically by observing the patient when in the right sided position where you can see multiple dilated veins over abdomen due to collaterals. Ultrasound with Doppler flow measurement may be used to assess the IVC and circulatory system. Treatment
Treatment will vary depending on the cause of the vena cava compression or interruption. Often, treatment includes positional changes, avoidance of supine positioning, especially on the right side. In pregnancy, definitive management of the IVCS is to deliver the baby. In other conditions, medical or surgical treatment to remove or relieve the offending structure will relieve symptoms. Frequency
Epidemiological data is elusive owing to the wide variety of clinical presentation. In the U.S., incidence is estimated to be at 5–10 cases per 100,000 per year. Minor compression of the inferior vena cava during pregnancy is a relatively common occurrence. It is seen most commonly when women lie on their back or right side.