Cardiology
Question 92 of 148
A 79 year old man presents to the Emergency Department after collapsing in a bus stop. He recalls standing up to board the bus before feeling lightheaded and experiencing tunnel vision. He tells you he has had several similar episodes over the last 6 months, mostly occurring in the morning while getting out of bed. He has a past medical history of hypertension for which he takes ramipril and amlodipine. Which of the following investigations would be most useful?
Answer:
Orthostatic hypotension is suggested by a typical history — lightheadedness, dizziness, weakness, tunnel vision. Symptoms should not occur while supine, should get worse on standing, and should be relieved by sitting or lying down. Some people may present with recurrent or unexplained falls. Symptoms are often worse early in the morning, in hot environments, after meals, after standing motionless, and after exercise. Potential underlying causes for orthostatic hypotension include treatment with alpha-blockers, diuretics, tricyclic antidepressants, antihypertensives (particularly diuretics), levodopa or dopaminergic agonists, volume depletion, physical deconditioning due to prolonged bed rest, diseases causing peripheral neuropathy (such as diabetes mellitus), Parkinson's disease, or Lewy body dementia. Polypharmacy with antihypertensive and antidepressant medicines is often the cause of orthostatic hypotension in older people. If orthostatic hypotension is suspected, measure lying and standing blood pressure (with repeated measurements while standing for 3 minutes). A fall in systolic blood pressure of at least 20 mmHg (at least 30 mmHg in people with hypertension) and/or a fall in diastolic blood pressure of at least 10 mmHg within 3 minutes of standing confirms the diagnosis.Syncope
Cardiology
Last Updated: 12th February 2021
A blackout is a transient, spontaneous loss of consciousness followed by complete recovery. Syncope is an alternative term for 'blackout'.
Causes
Causes of blackouts include:
- Neurally-mediated reflex syncope — this term encompasses vasovagal syncope (fainting), carotid sinus syndrome (where hypersensitivity of the carotid sinus baroreceptor causes bradycardia and/or vasodilation), and situational syncope (faint with an identifiable trigger).
- Orthostatic hypotension — a fall in systolic blood pressure of at least 20 mmHg (at least 30 mmHg in people with hypertension) and/or a fall in diastolic blood pressure of at least 10 mmHg within 3 minutes of standing.
- Cardiac abnormalities including bradycardia, tachycardia, low cardiac output, blood flow obstruction, vasodilatation, or acute vascular dissection. In all of these scenarios, the mechanism leading to transient loss of consciousness is temporary inadequacy of cerebral nutrient flow, most often triggered by a fall in systemic arterial pressure below the minimum needed to sustain cerebral blood flow.
- Epileptic seizures can also cause blackouts.
Investigations
If considered appropriate, carry out an examination and any relevant investigations, such as:
- Assessment of vital signs
- Lying and standing blood pressure
- Assessment of other cardiovascular and neurological signs such as cardiac auscultation to detect heart murmurs and assessment for the presence of sensory, motor, speech, and vision deficits
- A 12-lead electrocardiogram (ECG)
- Measurement of blood glucose levels
- Full blood count to check haemoglobin levels
Assessment
Assess for the presence of a life-threatening cause for blackout, such as:
- Myocardial infarction and ischaemia
- Cardiac arrhythmia
- Pulmonary embolism
- Occult haemorrhage e.g. ectopic pregnancy, ruptured AAA
- Aortic dissection
- Cardiac tamponade
- Severe hypoglycaemia
- Addisonian crisis
Otherwise:
- Suspect a possible underlying cardiac cause if there is:
- An ECG abnormality such as conduction abnormality (for example, complete right or left bundle branch block or any degree of heart block), evidence of a long (corrected QT > 450 ms) or short (corrected QT < 350 ms) QT interval, any ST segment or T wave abnormalities, inappropriate persistent bradycardia, ventricular arrhythmia (including ventricular ectopic beats), Brugada syndrome, ventricular pre-excitation (part of Wolff-Parkinson-White syndrome), left or right ventricular hypertrophy, pathological Q waves, atrial arrhythmia (sustained), paced rhythm.
- Suspected/confirmed heart failure (suggested by breathlessness, fluid retention, and fatigue).
- Blackout occurring during exertion.
- Palpitations before loss of consciousness.
- A family history of sudden cardiac death in people aged younger than 40 years and/or an inherited cardiac condition.
- New or unexplained breathlessness.
- A heart murmur.
- Blackout without prodromal symptoms in people aged older than 65 years.
- Suspect epilepsy as an underlying cause if there is:
- Prodromal déjà vu, or jamais vu.
- A bitten tongue.
- Head-turning to one side during the blackout.
- Loss of bowel and bladder control.
- Unusual posturing.
- Prolonged limb-jerking.
- Confusion following the event.
- Suspect an uncomplicated faint (uncomplicated vasovagal syncope) if there is:
- An absence of features to suggest an alternative diagnosis (note: brief seizure activity can occur during uncomplicated faints and is not necessarily diagnostic of epilepsy) and
- The presence of features suggestive of uncomplicated faint (the 3 'P's):
- Posture — blackout occurred after prolonged standing. Similar episodes may have been prevented by lying down.
- Provoking factors — such as pain or a medical procedure.
- Prodromal symptoms — such as sweating or feeling warm/hot before the blackout occurred.
- Suspect situational syncope if:
- There are no features to suggest an alternative diagnosis and
- Syncope is clearly and consistently provoked by straining during micturition (usually while standing), defecation, or by coughing or swallowing.
- Suspect carotid sinus syndrome if:
- The blackout(s) occurred while turning the head to one side, particularly in men aged 50 years or older.
- Suspect orthostatic hypotension if there is:
- An absence of features suggesting an alternative diagnosis and
- A typical history — lightheadedness, dizziness, weakness, tunnel vision. Symptoms should not occur while supine, should get worse on standing, and should be relieved by sitting or lying down. Some people may present with recurrent or unexplained falls. Symptoms are often worse early in the morning, in hot environments, after meals, after standing motionless, and after exercise.
- Consider differential diagnoses whose symptoms mimic blackout but which may not involve loss of consciousness, such as falls, psychogenic pseudosyncope or psychogenic non-epileptic seizures (suggested by frequent, recurrent episodes often with a long duration of apparent loss of consciousness, the nature of the events changing over time, and multiple unexplained physical symptoms in a person who may have generalised anxiety disorder, panic disorder, somatisation disorder, or major depression), or transient ischaemic attacks. Migraine is uncommonly associated with syncope. However, note that if there is uncertainty after initial assessment whether or not a true blackout has occurred, the event should be assumed to be a blackout until proven otherwise.
Management
- If there are clinical features suggestive of an underlying cardiovascular cause (that does not require immediate hospitalisation) refer urgently for cardiovascular assessment, with the referral reviewed and prioritised by an appropriate specialist within 24 hours. Also consider referring for cardiovascular assessment, as above, anyone aged older than 65 years who has experienced a blackout without prodromal symptoms. For people with suspected carotid sinus syndrome and for people with unexplained syncope who are aged 60 years or older, offer cardiology referral for carotid sinus massage as a first-line investigation.
- If there are clinical features suggestive of epilepsy as an underlying cause for blackout, refer the person for neurological assessment by an epilepsy specialist within 2 weeks. Advise the person with suspected epilepsy to avoid potentially dangerous work or leisure activities while waiting to see the specialist for confirmation of the diagnosis. In particular, they should avoid swimming and driving, and take care when bathing to avoid the risk of drowning.
- If uncomplicated vasovagal syncope or situational syncope are suspected as the underlying cause for blackout, and there are no features to raise clinical or social concerns, explain the mechanisms causing the syncope, and advise on possible trigger events, and strategies for avoiding them. If the trigger events are unclear, advise the person to keep a record of their symptoms, when they occur and what they were doing at the time, in order to understand what causes them to faint. Reassure them that their prognosis is good.
- A fall in systolic blood pressure of at least 20 mmHg (at least 30 mmHg in people with hypertension) and/or a fall in diastolic blood pressure of at least 10 mmHg within 3 minutes of standing confirms the diagnosis of orthostatic hypotension. For people in whom orthostatic hypotension is confirmed:
- Consider likely causes, review any drug therapy, and eliminate any potentially causative drugs where possible. Potential underlying causes for orthostatic hypotension include treatment with alpha-blockers, diuretics, tricyclic antidepressants, antihypertensives (particularly diuretics), levodopa or dopaminergic agonists, volume depletion, physical deconditioning due to prolonged bed rest, diseases causing peripheral neuropathy (such as diabetes mellitus), Parkinson's disease, or Lewy body dementia.
- Explain the mechanisms causing the blackouts.
- Advise the person of simple lifestyle changes that can lessen symptoms of orthostatic hypotension, including:
- First sitting when going from a supine to a standing position.
- Eating frequent, small meals to lessen postprandial blood pressure falls.
- Liberalising dietary salt intake (unless they have been diagnosed with hypertension).
- Drinking strong tea or coffee.
- Drinking at least 2 litres of water a day.
- Avoiding alcohol.
- Tilting the head of the bed up during the night, by inserting blocks 15 to 22 cm high under the headposts.
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- Biochemistry
- Blood Gases
- Haematology
| Biochemistry | Normal Value |
|---|---|
| Sodium | 135 – 145 mmol/l |
| Potassium | 3.0 – 4.5 mmol/l |
| Urea | 2.5 – 7.5 mmol/l |
| Glucose | 3.5 – 5.0 mmol/l |
| Creatinine | 35 – 135 μmol/l |
| Alanine Aminotransferase (ALT) | 5 – 35 U/l |
| Gamma-glutamyl Transferase (GGT) | < 65 U/l |
| Alkaline Phosphatase (ALP) | 30 – 135 U/l |
| Aspartate Aminotransferase (AST) | < 40 U/l |
| Total Protein | 60 – 80 g/l |
| Albumin | 35 – 50 g/l |
| Globulin | 2.4 – 3.5 g/dl |
| Amylase | < 70 U/l |
| Total Bilirubin | 3 – 17 μmol/l |
| Calcium | 2.1 – 2.5 mmol/l |
| Chloride | 95 – 105 mmol/l |
| Phosphate | 0.8 – 1.4 mmol/l |
| Haematology | Normal Value |
|---|---|
| Haemoglobin | 11.5 – 16.6 g/dl |
| White Blood Cells | 4.0 – 11.0 x 109/l |
| Platelets | 150 – 450 x 109/l |
| MCV | 80 – 96 fl |
| MCHC | 32 – 36 g/dl |
| Neutrophils | 2.0 – 7.5 x 109/l |
| Lymphocytes | 1.5 – 4.0 x 109/l |
| Monocytes | 0.3 – 1.0 x 109/l |
| Eosinophils | 0.1 – 0.5 x 109/l |
| Basophils | < 0.2 x 109/l |
| Reticulocytes | < 2% |
| Haematocrit | 0.35 – 0.49 |
| Red Cell Distribution Width | 11 – 15% |
| Blood Gases | Normal Value |
|---|---|
| pH | 7.35 – 7.45 |
| pO2 | 11 – 14 kPa |
| pCO2 | 4.5 – 6.0 kPa |
| Base Excess | -2 – +2 mmol/l |
| Bicarbonate | 24 – 30 mmol/l |
| Lactate | < 2 mmol/l |
