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Title: Dysautonomia: A Forgotten Condition - Part 1.
Author: Rocha EA, Mehta N, Távora-Mehta MZP, Roncari CF, Cidrão AAL, Elias Neto J.
Journal: Arq Bras Cardiol; 2021 Apr; 116(4):814-835. PubMed ID: 33886735.
Abstract:
Dysautonomia covers a range of clinical conditions with different characteristics and prognoses. They are classified as Reflex Syndromes, Postural Orthostatic Tachycardia Syndrome (POTS), Chronic Fatigue Syndrome, Neurogenic Orthostatic Hypotension (nOH) and Carotid Sinus Hypersensitivity Syndrome. Reflex (vasovagal) syndromes will not be discussed in this article. Reflex (vasovagal) syndromes are mostly benign and usually occur in patients without an intrinsic autonomic nervous system (ANS) or heart disease. Therefore, they are usually studied separately. Cardiovascular Autonomic Neuropathy (CAN) is the term most currently used to define dysautonomia with impairment of the sympathetic and/or parasympathetic cardiovascular autonomic nervous system. It can be idiopathic, such as multisystemic atrophy or pure autonomic failure, or secondary to systemic pathologies such as diabetes mellitus, neurodegenerative diseases, Parkinson's disease, dementia syndromes, chronic renal failure, amyloidosis and it may also occur in the elderly. The presence of Cardiovascular Autonomic Neuropathy (CAN) implies greater severity and worse prognosis in various clinical situations. Detection of Orthostatic Hypotension (OH) is a late sign and means greater severity in the context of dysautonomia, defined as Neurogenic Orthostatic Hypotension (nOH). It must be differentiated from hypotension due to hypovolemia or medications, called non-neurogenic orthostatic hypotension (nnOH). OH can result from benign causes, such as acute, chronic hypovolemia or use of various drugs. However, these drugs may only reveal subclinical pictures of Dysautonomia. All drugs of patients with dysautonomic conditions should be reevaluated. Precise diagnosis of CAN and the investigation of the involvement of other organs or systems is extremely important in the clinical suspicion of pandysautonomia. In diabetics, in addition to age and time of disease, other factors are associated with a higher incidence of CAN, such poor glycemic control, hypertension, dyslipidemia and obesity. Among diabetic patients, 38-44% can develop Dysautonomia, with prognostic implications and higher cardiovascular mortality. In the initial stages of DM, autonomic dysfunction involves the parasympathetic system, then the sympathetic system and, later on, it presents as orthostatic hypotension. Valsalva, Respiratory and Orthostatic tests (30:15) are the gold standard methods for the diagnosis of CAN. They can be associated with RR Variability tests in the time domain, and mainly in the frequency domain, to increase the sensitivity (protocol of the 7 tests). These tests can detect initial or subclinical abnormalities and assess severity and prognosis. The Tilt Test should not be the test of choice for investigating CAN at an early stage, as it detects cases at more advanced stages. Tilt response with a dysautonomic pattern (gradual drop in blood pressure without increasing heart rate) may suggest CAN. Treatment of patients at moderate to advanced stages of dysautonomia is quite complex and often refractory, requiring specialized and multidisciplinary evaluation. There is no cure for most types of Dysautonomia at a late stage. NOH patients can progress with supine hypertension in more than 50% of the cases, representing a major therapeutic challenge. The immediate risk and consequences of OH should take precedence over the later risks of supine hypertension and values greater than 160/90 mmHg are tolerable. Sleeping with the head elevated (20-30 cm), not getting up at night, taking short-acting antihypertensive drugs for more severe cases, such as losartan, captopril, clonidine or nitrate patches, may be necessary and effective in some cases. Preventive measures such as postural care; good hydration; higher salt intake; use of compression stockings and abdominal straps; portioned meals; supervised physical activity, mainly sitting, lying down or exercising in the water are important treatment steps. Various drugs can be used for symptomatic nOH, especially fludrocortisone, midodrine and droxidopa, the latter not available in Brazil. The risk of exacerbation or triggering supine hypertension should be considered. Chronic Fatigue Syndrome represents a form of Dysautonomia and has been renamed as a systemic disease of exercise intolerance, with new diagnostic criteria: 1 - Unexplained fatigue, leading to occupational disability for more than 6 months; 2 - Feeling ill after exercising; 3 - Non-restorative sleep; 4 - One of the following findings: cognitive impairment or orthostatic intolerance. Several pathologies today have evolved with chronic fatigue, being called chronic diseases associated with chronic fatigue. Postural orthostatic tachycardia syndrome (POTS), another form of presentation of dysautonomic syndromes, is characterized by sustained elevation of heart rate (HR) ≥30 bpm (≥40 bpm if <20 years) or HR ≥120 bpm, in the first 10 minutes in an orthostatic position or during the tilt test, without classical orthostatic hypotension associated. A slight decrease in blood pressure may occur. Symptoms appear or get worse in an orthostatic position, with dizziness, weakness, pre-syncope, palpitations, and other systemic symptoms being common. O termo disautonomia abrange um conjunto de condições clínicas com características e prognósticos distintos. Classificam-se em síndromes reflexas, síndrome postural ortostática taquicardizante (SPOT), síndrome da fadiga crônica, Hipotensão Ortostática Neurogênica (HON) e a Síndrome da hipersensibilidade do seio carotídeo. As síndromes reflexas (vasovagal) não serão discutidas neste artigo. As síndromes reflexas (vasovagal) são, na maioria das vezes, benignas, e ocorrem usualmente em pacientes sem doença intrínseca do sistema nervoso autônomo (SNA) ou do coração. Por isso, geralmente são estudadas separadamente. O termo neuropatia autonômica cardiovascular (NAC) é o mais utilizado na atualidade para definir as disautonomias com comprometimento do sistema nervoso autônomo cardiovascular simpático e/ou parassimpático. Pode ser idiopática, como a atrofia multissistêmica ou a falência autonômica pura, ou secundária a patologias sistêmicas como diabetes mellitus, doenças neurodegenerativas, doença de Parkinson, síndromes demenciais, insuficiência renal crônica, amiloidose, podendo também acometer idosos. A presença de neuropatia autonômica cardiovascular (NAC) implica em maior gravidade e pior prognóstico em diversas situações clínicas. A detecção de hipotensão ortostática (HO) é um sinal tardio e significa maior gravidade no contexto das disautonomias, definida como hipotensão ortostática neurogênica (HON). Deve ser diferenciada das hipotensões por hipovolemia ou medicamentosas, chamadas de hipotensão ortostática não neurogênica (HONN). A HO pode decorrer de causas benignas, como a hipovolemia aguda, crônica, ou ao uso de diversos fármacos. Esses fármacos podem, entretanto, apenas desmascarar quadros subclínicos de disautonomia. Deve-se reavaliar todos os fármacos de pacientes com quadros disautonômicos. O diagnóstico preciso de NAC e a investigação do envolvimento de outros órgãos ou sistemas é de extrema importância na suspeita clínica de uma pandisautonomia. No diabético, além da idade e do tempo de doença, outros fatores estão associados a maior ocorrência de NAC, como descontrole glicêmico, hipertensão, dislipidemia e obesidade. Entre os pacientes diabéticos, 38–44% podem evoluir com disautonomia, com implicações prognósticas e maior mortalidade cardiovascular. Nas etapas iniciais da DM, a disfunção autonômica envolve o sistema parassimpático, posteriormente o simpático e mais tardiamente manifesta-se com hipotensão ortostática. Os testes de Valsalva, respiratório e ortostático (30:15) são os métodos de padrão ouro para o diagnóstico de NAC. Eles podem ser associados aos testes de variabilidade RR no domínio do tempo, e principalmente da frequência, para aumento da sensibilidade (protocolo dos 7 testes). Esses testes podem detectar alterações iniciais ou subclínicas e avaliar a gravidade e o prognóstico. O teste de inclinação (tilt test) não deve ser o exame de escolha para investigação de NAC em fase inicial, pois detecta casos em fases mais avançadas. A resposta no tilt com padrão disautonômico (queda gradativa da pressão arterial sem aumento da frequência cardíaca) pode sugerir NAC. O tratamento dos pacientes em fases moderadas a avançadas das disautonomias é bastante complexo e muitas vezes refratário, necessitando de avaliação especializada e multidisciplinar. Não há cura para a maioria das disautonomias em fase tardia. Os pacientes com HON podem evoluir com hipertensão supina em mais de 50% dos casos, representando um grande desafio terapêutico. O risco imediato e as consequências da HO devem ter preferência sobre os riscos mais tardios da hipertensão supina e valores maiores que 160/90 mmHg são toleráveis. Medidas como dormir com a cabeceira elevada (20–30 cm), não levantar à noite, uso de anti-hipertensivo de ação curta noturna para casos mais severos, como a losartana, captopril, clonidina ou adesivos de nitratos, podem ser necessários e efetivos em alguns casos. As medidas preventivas como cuidados posturais, boa hidratação, maior ingesta de sal, uso de meias e cintas abdominais compressoras, refeições fracionadas, atividade física supervisionada principalmente sentada, deitada ou exercícios na água são etapas importantes no tratamento. Diversos fármacos podem ser usados para HON sintomática, principalmente a fludrocortisona, a midodrina e a droxidopa. Esses últimas não estão disponíveis no Brasil. O risco de exacerbação ou desencadeamento de hipertensão supina deve ser considerado. A síndrome da fadiga crônica representa uma forma de disautonomia e tem sido renomeada como doença sistêmica de intolerância ao exercício, com novos critérios diagnósticos: 1 - Fadiga inexplicada, levando a incapacidade para o trabalho por mais que 6 meses; 2 - Mal-estar após exercício; 3 - Sono não reparador; 4 - Mais um dos seguintes achados: comprometimento cognitivo ou intolerância ortostática. Várias patologias na atualidade têm evoluído com fadiga crônica, sendo denominadas de doenças crônicas associadas a fadiga crônica. A síndrome postural ortostática taquicardizante (SPOT), outra forma de apresentação das síndromes disautonômicas, é caracterizada por elevação sustentada da frequência cardíaca (FC) ≥30 bpm (≥40 bpm se <20 anos) ou FC ≥120 bpm, nos primeiros 10 minutos em posição ortostática ou durante o tilt test, sem hipotensão ortostática clássica associada. Pode ocorrer leve redução na pressão arterial. Os sintomas manifestam-se ou pioram em posição ortostática, sendo comuns a tontura, fraqueza, pré-síncope, palpitações, além de outros sintomas sistêmicos. Dysautonomia covers a range of clinical conditions with different characteristics and prognoses. They are classified as Reflex Syndromes, Postural Orthostatic Tachycardia Syndrome (POTS), Chronic Fatigue Syndrome, Neurogenic Orthostatic Hypotension (nOH) and Carotid Sinus Hypersensitivity Syndrome. Reflex (vasovagal) syndromes will not be discussed in this article. 1. Reflex (vasovagal) syndromes are mostly benign and usually occur in patients without an intrinsic autonomic nervous system (ANS) or heart disease. Therefore, they are usually studied separately. 2. Cardiovascular Autonomic Neuropathy (CAN) is the term most currently used to define dysautonomia with impairment of the sympathetic and/or parasympathetic cardiovascular autonomic nervous system. It can be idiopathic, such as multisystemic atrophy or pure autonomic failure, or secondary to systemic pathologies such as diabetes mellitus, neurodegenerative diseases, Parkinson's disease, dementia syndromes, chronic renal failure, amyloidosis and it may also occur in the elderly. 3. The presence of Cardiovascular Autonomic Neuropathy (CAN) implies greater severity and worse prognosis in various clinical situations. 4. Detection of Orthostatic Hypotension (OH) is a late sign and means greater severity in the context of dysautonomia, defined as Neurogenic Orthostatic Hypotension (nOH). It must be differentiated from hypotension due to hypovolemia or medications, called non-neurogenic orthostatic hypotension (nnOH). 5. OH can result from benign causes, such as acute, chronic hypovolemia or use of various drugs. However, these drugs may only reveal subclinical pictures of Dysautonomia. All drugs of patients with dysautonomic conditions should be reevaluated. 6. Precise diagnosis of CAN and the investigation of the involvement of other organs or systems is extremely important in the clinical suspicion of pandysautonomia. 7. In diabetics, in addition to age and time of disease, other factors are associated with a higher incidence of CAN, such poor glycemic control, hypertension, dyslipidemia and obesity. Among diabetic patients, 38–44% can develop Dysautonomia, with prognostic implications and higher cardiovascular mortality. In the initial stages of DM, autonomic dysfunction involves the parasympathetic system, then the sympathetic system and, later on, it presents as orthostatic hypotension. 8. Valsalva, Respiratory and Orthostatic tests (30:15) are the gold standard methods for the diagnosis of CAN. They can be associated with RR Variability tests in the time domain, and mainly in the frequency domain, to increase the sensitivity (protocol of the 7 tests). These tests can detect initial or subclinical abnormalities and assess severity and prognosis. 9. The Tilt Test should not be the test of choice for investigating CAN at an early stage, as it detects cases at more advanced stages. Tilt response with a dysautonomic pattern (gradual drop in blood pressure without increasing heart rate) may suggest CAN. 10. Treatment of patients at moderate to advanced stages of dysautonomia is quite complex and often refractory, requiring specialized and multidisciplinary evaluation. There is no cure for most types of Dysautonomia at a late stage. 11. NOH patients can progress with supine hypertension in more than 50% of the cases, representing a major therapeutic challenge. The immediate risk and consequences of OH should take precedence over the later risks of supine hypertension and values greater than 160/90 mmHg are tolerable. Sleeping with the head elevated (20–30 cm), not getting up at night, taking short-acting antihypertensive drugs for more severe cases, such as losartan, captopril, clonidine or nitrate patches, may be necessary and effective in some cases. 12. Preventive measures such as postural care; good hydration; higher salt intake; use of compression stockings and abdominal straps; portioned meals; supervised physical activity, mainly sitting, lying down or exercising in the water are important treatment steps. 13. Various drugs can be used for symptomatic nOH, especially fludrocortisone, midodrine and droxidopa, the latter not available in Brazil. The risk of exacerbation or triggering supine hypertension should be considered. 14. Chronic Fatigue Syndrome represents a form of Dysautonomia and has been renamed as a systemic disease of exercise intolerance, with new diagnostic criteria: 1 - Unexplained fatigue, leading to occupational disability for more than 6 months; 2 - Feeling ill after exercising; 3 - Non-restorative sleep; 4 - One of the following findings: cognitive impairment or orthostatic intolerance. Several pathologies today have evolved with chronic fatigue, being called chronic diseases associated with chronic fatigue. 15. Postural orthostatic tachycardia syndrome (POTS), another form of presentation of dysautonomic syndromes, is characterized by sustained elevation of heart rate (HR) ≥30 bpm (≥40 bpm if <20 years) or HR ≥120 bpm, in the first 10 minutes in an orthostatic position or during the tilt test, without classical orthostatic hypotension associated. A slight decrease in blood pressure may occur. Symptoms appear or get worse in an orthostatic position, with dizziness, weakness, pre-syncope, palpitations, and other systemic symptoms being common.

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