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Lown-Ganong-Levine syndrome.What is Lown-Ganong-Levine syndrome?The Lown-Ganong-Levine (LGL) syndrome is one of the pre-...
31/05/2024

Lown-Ganong-Levine syndrome.

What is Lown-Ganong-Levine syndrome?
The Lown-Ganong-Levine (LGL) syndrome is one of the pre-excitation syndromes of which Wolff-Parkinson-White (WPW) syndrome is the best known. In WPW syndrome there is an accessory pathway for conduction, called the Bundle of Kent, that bypasses the atrioventricular (AV) node. No such pathway has been identified for LGL. Theories to explain the condition have suggested possible accessory fibres that bypass all, or part of, the AV node.1 In some cases there may be a congenitally malfunctioning AV node.2 Whatever the pathophysiology, conduction is passed from the atria to the bundle of His without the delay usually incurred at the AV node.

Diagnostic criteria include PR interval of no more than 120 ms, normal QRS complex duration, a normal or inverted P wave, and paroxysmal supraventricular tachycardia (PSVT) but not atrial fibrillation or flutter.

The condition was first described in 1952 before the advent of electrophysiological testing, and some people dispute its existence as an entity.3 Where there is a short PR interval but no history of supraventricular tachycardia (SVT), it is probably just a variation of normal. Where arrhythmias have been investigated in people with the diagnostic criteria, another cause has often been found.

Sometimes the duration of conduction through the AV node is fast and this is called enhanced atrioventricular nodal conduction (EAVNC).1

Although tachycardia, along with increased stroke volume, enables cardiac output to meet demands in exercise, a very fast tachycardia is inefficient and may cause compromise. The ventricles do not have adequate time to fill in diastole and this may reduce cardiac output. Tachycardia reduces the duration of both systole and diastole but it is diastole that is reduced more. Around 75% of the blood flow to the right ventricle and 100% of the blood flow to the left ventricle occur during diastole. Hence, there is less time to perfuse the myocardium at a time of increased metabolic need.

How common is Lown-Ganong-Levine syndrome? (Epidemiology)
The initial retrospective study by Lown found nearly 200 electrocardiograms (ECGs) of 13,500 had a short PR interval and a normal QRS complex, giving a prevalence of just over 1% in a selected population.4 Further evaluation has determined that the incidence of paroxysmal supraventricular tachycardia in Lown-Ganong-Levine patients is significantly higher, nearing 11%.. In the general population however, it is very rare, with prevalence estimated to be less than one in a million.5

Continue reading below

Symptoms of Lown-Ganong-Levine syndrome (presentation)4
History
The history is of bouts of tachycardia that may present as rapid palpitations. It most often starts in early adulthood but can present in childhood. It tends to get less frequent with passing years. In the otherwise healthy person there is probably no other feature but, where the heart and circulation are already compromised, perhaps from coronary heart disease, this can produce angina pectoris, shortness of breath and heart failure. There may well be light-headedness and dizziness due to hypotension.

Examination
There is usually no abnormality to be found between attacks, although some people have a resting sinus tachycardia. During an attack the pulse rate may be 200 beats per minute or sometimes even higher.

Diagnosing Lown-Ganong-Levine syndrome (investigations)
A 12-lead ECG is required. The PR interval should be less than 120 ms and with no delta wave. A normal QRS is essential for diagnosis and a delta wave suggests an accessory pathway and a diagnosis of WPW syndrome.

If possible, try to encourage the patient to come in during an attack so that an ECG can be recorded when symptomatic.

Check U&E, calcium and magnesium. Check TFTs.

A Holter monitor may be used to record the heart rate. Ask the patient to note the time that an attack starts and stops. A longer recording of a week increases the chances of recording an episode.

Management of Lown-Ganong-Levine syndrome4
Referral to a cardiologist is required to try to obtain a definite diagnosis.

Echocardiogram and electrophysiological studies may be performed in an attempt made to find a cause for the SVT and assess the risk of sudden cardiac death.

There is no aberrant bundle to ablate as in WPW syndrome.

Beta-blockers such as metoprolol or atenolol may be useful and slow AV conduction.

Non-dihydropyridine calcium-channel blockers such as verapamil may slow AV conduction and can be used to treat an acute PSVT. Verapamil plus a beta-blocker may produce complete heart block and so they should not be used together.

Digoxin can also decrease conduction in the AV node. It has been used to control symptoms in pregnancy.6

In cases refractory to medical therapy, as with other supraventricular tachycardias or accessory pathways, radiofrequency catheter ablation has become a preferred treatment.7

Dual AV sequential demand pacemakers have been used for this condition where medication has failed to give control.8

People with LGL syndrome need special care and management during anaesthesia as they are at high risk of peri-operative arrhythmias which may be life-threatening.2 Certain drugs and anaesthetic agents should be avoided, and specialist cardiology input is helpful.

Prognosis
The syndrome can produce ventricular fibrillation and sudden death.9 However, this is unusual, and it is normally far more benign and can be controlled by pharmacological means.

History
LGL is named after three American cardiologists. Bernard Lown was born in 1921, William Ganong was born 1924 and died in 2007, and Samuel Albert Levine was born in 1891 and died in 1966. The occurrence of frequent paroxysms of tachycardia in patients with a short PR interval and normal QRS duration had been described by Clerc et al in 1938 but it was the Americans who achieved the immortality of an eponym. Bernard Lown was a founder of International Physicians for the Prevention of Nuclear War and, in 1985, the group was awarded the Nobel Prize for Peace. He developed the direct current defibrillator.

02/04/2024

Primary Hyperparathyroidism:

Most common cause is parathyroid single adenoma. Less than 15% are due to adenomas in multiple glands or hyperplasia or ectopic PTH production. 1% or less is due to parathyroid carcinoma.

Familial or genetic cases should be considered in patients younger than 30, more than one parathyroid glands involved, or when part of MEN syndrome (MEN 1.2 or 4).

Mostly cases have hypercalcemia which is mild to moderate which is often clinically not symptomatic due to slow onset. However, patient can have renal &/or bone diseases despite being clinically not having symptoms of high calcium. Like the hypercalcemia, these changes of the bone or kidneys are also detected on testing.

Less commonly, primary hyperparathyroidism can have normal serum calcium. Such cases should be differentiated from secondary hyperparathyroidism due to low Vit D or calcium. High PTH level in these cases can compensate for low calcium and the calcium level may become normal. However, such cases don’t have bone or renal involvement which is seen in primary Hyperparathyroidism.

Renal involvement in primary Hyperparathyroidism include:
Calcium excretion >250 mg/24 hour
Renal failure (especially CLD with eGFR0.02 in primary Hyperparathyroidism. However, this ratio may be b/w 0.01-0.02 in both disease. Rarely FHH can have high ratio and Hyperparathyroidism can have low ratio as well. Parathyroid adenoma isn’t there in FHH. Parathyroid Surgery is contraindicated in FHH.

Tertiary hyperparathyroidism develops after long-standing Vit D or calcium deficiency (CKD, chronic malabsorption, chronic malnutrition etc.). This also has high calcium and high PTH. But the disease course is very obvious.

All other cause of hypercalcemia (Dietry intake, vitamin D intoxication, granulomatous disease, malignancies, etc.) have low PTH.

Investigations are:
Serum calcium (total) & albumin. Ionised calcium is also available.
24 hour urinary calcium to exclude FHH. Also to quantify urinary calcium excretion.
PTH level
Renal functions and Renal imaging for stones or nephrocalcinosis.
Bone density at radius, lumbosacral spine and hip.
X-ray hands, radius and spine.
Prolactin and blood glucose, etc. to exclude MEN-1
Genetic studies in selected cases (see above).

Parathyroid imaging :

It’s done if the patient is candidate for surgery or cancer is suspected. It helps plan less invasive surgical approach.

USS is poor if there are thyroid nodules, neck fibrosis due to surgery, ectopic gland, more than one gland is involved. It’s 80% sensitive for single adenoma.

Technetium-sestaMIBI has sensitivity of 88-90% for single adenoma and can also detect ectopic. It’s also poor if multiple glands are involved.

CT with contrast (4-D) or PET with fluorocholine are very useful if available and if not contraindicated.

MRI of the neck is also very useful.

Surgery is indicated for the following cases of primary Hyperparathyroidism after exclusion of FHH;
1): Age 250 mg/24 hour in females (>300 mg/24 hours in males).
5): Bone changes as stated above
6): High risk of malignancy such as those in MEN syndrome, etc.

If patient can’t have surgery, then medical therapy is option.

Bisphosphonates if not contraindicated such as CKD, denture issues, severe GORD, swallowing issues, etc.

Denosumab if bisphosphonates can’t be used for any reason.

Cinacalcet stimulates CaSR on parathyroid cells and reduces PTH. But it does not improve bone density, etc. Also it’s costly and GI upset is common.

Calcium or vitamin D supplements are not usually stopped. Risk of rising calcium level is low but risk of increasing PTH level due to low calcium intake is there.
A.H

21/02/2024

Vitamin D Deficiency in Pregnancy

Background:

The NICE Guideline in 2008 and British Scientific Advisory Committee on Nutrition (SACN) in 2007 provided somewhat contradictory advice reviewed below.

The NICE Guideline2 advises that all women should be informed at the booking appointment about the importance for their own and their baby’s health of maintaining adequate vitamin D stores during pregnancy and whilst breastfeeding. NICE also advises that the safe upper intake for supplementary vitamin D is 25 micrograms/day (1000units/day).

NICE defines a cohort of women who are particularly at risk of Vitamin D deficiency and who would benefit from 400units/day Vitamin D.

‘At risk’ women include:
• Women in low-income households
• Women 19–24 years of age
• Women of South Asian, African, Caribbean or Middle Eastern family origin
• Women who have limited exposure to sunlight, such as women who are predominantly housebound, or usually remain covered when outdoors
• Women who eat a diet particularly low in vitamin D, such as women who consume no oily fish, eggs, meat, vitamin D-fortified margarine or breakfast cereal
• Women with a pre-pregnancy body mass index above 30 Kg/m2

In addition:
• Women with malabsorption (coeliac, small bowel resection etc.).
• Women on bone modifying drugs: steroids, anti-epileptics, anti-retrovirals.
• Women at risk of osteoporosis: inflammatory disease, immobilization, liver or kidney disease.

SACN does not define an at risk group but highlights that all pregnant and breastfeeding women should consider taking a daily supplement of vitamin D in order to ensure their own requirement for vitamin D is met and to build adequate fetal stores for early infancy and recommends 10micrograms a day (400units/day).

Evidence and the subsequent Endocrine Society guideline in 20115 suggests that pregnant and lactating women require at least 600units/day of vitamin D and recognise that at least 1,500–2,000units/day of vitamin D may be needed to maintain a target blood level of 25(OH)D above 75nmol/L.

In April 2013 the Vitamin D guidance from the National Osteoporosis Society highlighted that all pregnant and lactating women are at risk of Vitamin D deficiency and all should receive 400 units/day to ensure mother’s requirements are met and to build adequate fetal stores for early infancy.

A randomised mixed ethnicity UK trial of women recruited at 27/40 gestation and treated with daily 800units Vitamin D or single dose 200,000units Vitamin D showed that the entire cohort remained deficient with median Vitamin D levels of 42nmol/l (daily dose) and 34nmols/l (stat dose) versus 27nmol/l (no supplementation).

A further randomised controlled trial with 350 women of diverse racial and ethnic backgrounds in the US (baseline total Vitamin D ~60nmols/l) showed that doses of up to 4,000units Vitamin D/day starting at 12–16 weeks of gestation are effective in improving the vitamin D status of pregnant women without causing any adverse effects.

The concern about high dose vitamin D is that there are reports in the literature of hypercalcaemia and fetal malformations, but it should be noted that these have been noted with the active metabolites of vitamin D and not when treated with native vitamin D itself. These active metabolites should therefore be avoided. *Data is not available for the use of high dose Vitamin D in the first trimester.

The rationale behind correcting severe Vitamin D deficiency in pregnancy is to optimise both maternal and fetal well-being. The fetus at birth (cord blood) will contain ~50–60% of the maternal circulating concentrations of 25(OH) vitamin D9. This relation appears to be linear. Without correction, Vitamin-D deficiency in the fetus may result in hypocalcaemia with associated risks of rickets and hypocalcaemic seizures. The long-term benefit to bone health in the child/adult remains controversial. The evidence for preventing adverse pregnancy outcomes such as pre-eclampsia, small for gestational age, low birth-weight, gestational diabetes etc remain controversial.

Human breast milk and unfortified cows milk contain very little Vitamin D. Data suggest that only after lactating women were given 4,000-6,000 units/day was enough transferred to breast milk to meet the infant’s requirements.

Therapy:

Essentially many of the national recommendations for low dose Vitamin D are in place in order to supplement normal levels since requirements increase during pregnancy. However, when you have a woman with severe vitamin D deficiency (30
Malabsorption syndromes
Women on bone modifying drugs
Women with high osteoporosis risk

Treatment options could include:
1. Colecalciferol 20,000 units (Dekristol®;see above) once a week for two months
OR
2. Colecalciferol 1,600 units (Fultium-D3®;see above) daily for two months
OR
3. Colecalciferol oily solution 3,000units in 1mL daily for 8 weeks. Derived from wool fat of (slaughtered) sheep and may be unacceptable to some individuals.
4. Ergocalciferol 150,000 units by intramuscular injection. This is a red drug in the formulary and therefore for hospital use only. Suitable for vegetarians and vegans. Ideally only to be used if strictly vegetarian/vegan or significant concordance issues with medication. There is some evidence to suggest that an oral dosage is more likely to achieve target levels but this must be balanced against concordance issues etc.

Total vitamin D levels should ideally be reassessed after 6 months of treatment but an earlier repeat at 3 months may be considered in the context of pregnancy if concerns remain regarding on-going severe deficiency to help guide a further treatment course.

Maintenance therapy should be introduced at the end of the course of treatment (once total Vitamin D >50nmol/l). Appropriate maintenance would typically be 1,000 units per day.

21/02/2024

Vitamin D Deficiency in Primary Hyperparathyroidism (PHPT):

Vitamin D deficiency appears to be more common in patients with PHPT and Vitamin D deficiency appears to make PHPT more severe1. There is a theoretical risk of exacerbating hypercalcaemia with Vitamin D replacement but some studies suggest that it can be done reasonably safely without any impact on the serum calcium when the corrected calcium is 50nmol/L then please continue with maintenance Vitamin D. The frequency of serum calcium monitoring will depend upon the individual case and guidance will be given via the required endocrine out-patient review.

21/02/2024

Risk factors for Vitamin D deficiency:

Aging : Reduced synthesis in the skin

Season : Reduced exposure to UV radiation October-April

Latitude : Reduced exposure to UV radiation

Sunblock use : Reduced exposure to UV radiation

Clothing : Reduced exposure to UV radiation

Institutionalization : Reduced exposure to UV radiation

Skin pigmentation : Absorption of UV radiation by melanin

Malabsorption : e.g. pancreatic insufficiency, inflammatory bowel disease, coeliac disease, bariatric surgery, medications such as cholestyramine and orlistat

Obesity : Sequestration of Vitamin D in fat

Drugs : Induced metabolism of Vitamin D to inactive calcitroic acid e.g. rifampicin, phenytoin, glucocorticoids, HAART for HIV, transplant medications

Severe liver failure : Failure to 25-hydroxylate vitamin D

Nephrotic syndrome : Loss of Vitamin D in urine

Chronic kidney disease : Hyperphosphataemia suppresses 1-hydroxylation

23/01/2024

Role of SGLT-2 inhibitors and GLP-1 Agonists in type II Diabetes:

Type II Diabetes patients with any of the followings should be on SGLT-2 inhibitor &/or GLP-1 agonists (with proven CVS benefits) regardless of Metformin, with or without Metformin, and regardless of HBA1c value.

1): Heart failure (systolic or diastolic)
2): eGFR

17/01/2024

Treating primary hyperparathyroidism

Surgery to remove the parathyroid gland is usually the only way of treating primary hyperparathyroidism.

If your calcium levels are very high, you may need to be admitted to hospital urgently if you have lost a lot of fluids (dehydration). You may need to have fluids through an intravenous drip.

Medicine called bisphosphonates may also be given to lower calcium. These are only used as a short-term treatment. Surgery will be needed once the calcium levels are stabilised.

For people who are unable to have surgery – for example, because of other medical conditions or they're too frail – a tablet called cinacalcet may be used to help control the condition.

Make sure you have a healthy, balanced diet.

You do not need to avoid calcium altogether. A lack of dietary calcium is more likely to lead to a loss of calcium from your skeleton, resulting in brittle bones (osteoporosis).

But you should avoid a high-calcium diet and drink plenty of water to prevent dehydration.

Medicines such as thiazide diuretics (water tablets commonly used to treat high blood pressure) should be avoided because they can cause dehydration and raise calcium levels.

17/01/2024

Diagnosing hyperparathyroidism
It's important that hyperparathyroidism is diagnosed as soon as possible. Without treatment, it can gradually get worse and may lead to complications.

But in most cases, the condition is mild to moderate and remains stable for years.

Hyperparathyroidism is diagnosed after a blood test shows:

high levels of parathyroid hormone
high levels of blood calcium, often with low levels of phosphorus
A DEXA scan (a bone density X-ray) can help detect bone loss, fractures or bone softening, and X-rays, CT scans or ultrasound scans may show calcium deposits or kidney stones.

17/01/2024

Types of hyperparathyroidism
There are 3 types of hyperparathyroidism.

Primary hyperparathyroidism is when there's a problem within the parathyroid gland itself, usually a benign (non-cancerous) tumour of the gland.
Secondary hyperparathyroidism is when the glands are fine but a condition, like kidney failure, lowers calcium levels and causes the body to react by producing extra parathyroid hormone.
Tertiary hyperparathyroidism is when long-standing secondary hyperparathyroidism starts to behave like primary hyperparathyroidism.
Tertiary hyperparathyroidism is often associated with very advanced kidney failure (usually requiring dialysis).

People with tertiary hyperparathyroidism are almost always under the care of kidney specialists.

17/01/2024

Symptoms of hyperparathyroidism
Hyperparathyroidism affects people differently. Some people have mild or no symptoms, while others have many.

The symptoms may not relate to the level of calcium in your blood. For example, some people with a slightly raised calcium level may have symptoms, while others with high calcium levels may have few or no symptoms at all.

A diagnosis may be missed or delayed because there are no symptoms or they are vague, like feeling tired, and thought to be caused by another condition.

Possible signs of hyperparathyroidism include:

depression
tiredness
feeling thirsty and peeing a lot
feeling sick and losing your appetite
muscle weakness
constipation
tummy pain
loss of concentration
mild confusion
Symptoms of hypercalcaemia
If hyperparathyroidism is not treated, it can lead to high blood calcium levels (hypercalcaemia), which may cause:

being sick (vomiting)
drowsiness
dehydration
confusion
muscle spasms
bone pain or tenderness
joint pain
irregular heartbeat
high blood pressure (hypertension)
Hypercalcaemia can also cause other complications, including:

osteoporosis and bone fractures
kidney stones and blockage, and kidney damage or failure
stomach ulcers (gastric or peptic ulcers)
pancreatitis (inflammation of the pancreas)
In very severe cases of hyperparathyroidism, high calcium levels can lead to rapid kidney failure, loss of consciousness, coma, or serious life-threatening heart rhythm abnormalities.

But hyperparathyroidism is usually diagnosed at an early stage in the UK, and these complications are extremely rare.

17/01/2024

In primary hyperparathyroidism, PTH levels are generally elevated, although approximately 10% to 20% of individuals will have normal levels by either assay. With hypercalcemia, an intact PTH level of greater than 25 pg/mL is considered abnormal, assuming a normal range of 10 to 65 pg/mL.

07/01/2024

ANAPHYLAXIS

Anaphylaxis is highly likely when any one of the following three criteria are met:

1. Acute onset of an illness (this means minutes to several hours) with skin and/or mucosal tissue involvement PLUS at least one of:

a. respiratory compromise

b. reduced blood pressure

2. Acute onset (minutes to several hours) after exposure to a known allergen for the patient of two or more of the following:

- skin or mucosal tissue involvement,
- respiratory compromise,
- reduced blood pressure or associated symptoms and
- persistent gastrointestinal symptoms.

3. Reduced blood pressure after exposure to known allergen for patient (minutes to several hours):

a. Infants and children: low systolic blood pressure (age specific) or >30% decrease

b. Adults: systolic blood pressure of 30% decrease from person's baseline.

Patients at risk of anaphylaxis should be prescribed an adrenaline auto-injector (such as an epipen) to carry with them at all times, in case of an emergency.

If in doubt it is best to assume anaphylaxis and to treat as anemergency with IM adrenaline.

30/12/2023

MAS

Macrophage Activation Syndrome (MAS) is a severe potentially life-threatening complication of childhood rheumatic conditions. It is most commonly associated with systemic-onset JIA (alsoknown as Still's disease), SLE, Kawasaki disease and may also be seen in Adult Onset Still's Disease.

MAS is one of thehaemophagocytic syndromes and cancarry a mortality rate of up to 53%. The key clinical features of MAS include fever, hepatosplenomegaly, lymphadenopathy, pancytopenia, deranged ALT, hypertriglyceridaemia, disseminated intravascular coagulation, hypofibrinogenaemia, hyperferritinaemia. ESR may be paradoxically depressed. Bone marrow aspirate commonly shows haemophagocytosis.

Criteria for diagnosis suggested by Ravelli et al are helpful in diagnosing MAS, (https://www.sciencedirect.com/science/article/abs/pii/S0022347604011680)

Treatments include corticosteroids, ciclosporin, and intravenous immunoglobulin. In treatment-refractory cases, etoposide has been used but carries with it a high mortality rate.

Inhibition of IL with anakinra shows promise as an emerging therapy.

MAS can be very difficult to differentiate clinically from TTP, but the presence of schistocytes (helmet cells) on a blood film would strongly suggest a microangiopathic haemolytic anaemia due to TTP. Bone marrow examination of patients with MAS is characterised by the presence of haemophagocytosis.

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