====== Heart rates ======

===== BRADYCARDIA =====

Marked bradycardia suggests a number of cardiac toxins, and in the presence of hypotension may lead to coma. [[:wikitox:3.4.3.4.2_beta_blockers|Propranolol]] and [[:wikitox:3.4.3.4.2_beta_blockers|oxprenolol]] can also directly cause coma (without hypotension).

[[:wikitox:2.1.1.3_opioids|Opioids]], [[:wikitox:2.2.7.4.5_organophosphates|organophosphates]], [[:wikitox:barbiturates|]], and [[:wikitox:2.1.11.9.1_miscellaneous_anxiolytics_and_sedative_hypnotics|chloral hydrate]] are more likely also in this setting.

Bradycardias suggest propranolol or severe [[:wikitox:2.1.11.9.2.1_tricyclic_antidepressants|TCA]] poisoning.


===== TACHYCARDIA =====

Tachycardia may be commonly due to [[:wikitox:3.2.1.3_toxidromes|anticholinergic effects]] (TCAs, neuroleptics), tissue hypoxia ([[:wikitox:2.2.9.1.1_carbon_monoxide|CO]], [[:wikitox:2.2.7.4.4_organochlorines|organochlorines]]), hypoglycaemia ( [[:wikitox:2.1.7.1.1_insulin|insulin]]), acidosis (toxic [[:wikitox:2.2.5.2.5_methanol|alcohols]] and [[:wikitox:2.2.5.2.2_ethylene_glycol|glycols]]), nicotinic effects (organophosphates) and arrhythmias (TCAs, [[:wikitox:2.1.11.9.3_antipsychotics|thioridazine]], etc.).

Most other proconvulsant poisonings will lead to tachycardia due to anticholinergic effects or sympathetic stimulation.


===== HEART RATE and HALLUCINATIONS =====

Tachycardia may occur with most of these syndromes and is of little diagnostic value. The absence of tachycardia makes LSD, mescaline or hallucinogenic mushrooms more likely.

===== HEART RATE and SEIZURES =====

Bradycardias suggest propranolol or severe TCA poisoning.

Most other proconvulsant poisonings will lead to tachycardia due to [[:wikitox:3.2.1.3_toxidromes|anticholinergic]] effects or [[:wikitox:3.2.1.3_toxidromes|sympathetic]] stimulation.

===== HEART RATE and ANTICHOLINERGICS =====

All of these drugs will lead to a mild tachycardia initially. Severe poisoning with TCAs may lead to bradycardia (with an abnormal ECG) and bradycardia also occurs in [[:wikitox:3.4.2.3_carbamazepine|carbamazepine]] poisoning.

===== HEART RATE and ACIDOSIS =====

Tachycardia is likely with all drugs that cause tissue hypoxia, shock, or seizures:

  * [[:wikitox:3.2.1.3_toxidromes|Sympathomimetic drugs]]
  * [[:wikitox:2.2.9.1.1_carbon_monoxide|Carbon monoxide]]
  * Tricyclic antidepressants
  * Cellular poisons (e.g. [[:wikitox:2.2.9.1.2_cyanide|cyanide]])

===== HEART RATE and TACHYARRHYTHMIAS =====

Bradycardia prior to the tachyarrhythmia suggests torsade de pointes and a lack of adrenergic or anticholinergic effects making propranolol, [[:wikitox:2.1.6.1.2_cardiac_glycosides|digoxin]], [[:wikitox:3.4.3.4_antiarrhythmics|antiarrhythmic drugs]], and [[:wikitox:2.1.11.4.2_antihistamines|non-sedating antihistamines]] more likely.

Most other tachyarrhythmias will be preceded by sinus tachycardia.