Understanding Vasoplegic Syndrome : Causes, Symptoms, and Treatment Options

Vasoplegic Syndrome is also known as vasoplegia. It is a form of vasodilatory shock characterised by severe and prolonged low blood pressure. It commonly occurs following cardiothoracic surgery. In this syndrome, there is dysfunctioning of vascularity of arteries and arterioles, as a result, they are not able to maintain systemic vascular resistance (SVR). This will lead to dilation of the blood vessel, following that a fall in blood pressure is observed. Due to this, the vital organs may not function well, and potentially life-threatening condition is generated.

Vasoplegia (VS) following cardiovascular surgery only accounts for less than 5% of all circulatory shocks. Despite this, between 5 and 50% of patients undergoing cardiac-related surgery may often experience Vasoplegia with high morbidity and mortality rates in those patients.^[1]

Vasoplegia typically occurs after a cardiopulmonary bypass (CPB), and its underlying mechanism can vary depending on factors like the surgical procedure and the individual patient. The general mechanism is that, in a healthy human being contraction of the smooth muscle occurs due to the rise of intracellular calcium levels. This mechanism is disrupted during the CPB, as the exposure of blood to the foreign surface takes place during CPB, which will result in the release of various inflammatory mediators such as cytokines. These cytokines further stimulate the hypothalamic-pituitary-adrenal axis in the paraventricular axis which leads to a proinflammatory state. These inflammatory mediators further produce nitric oxide (NO) which is vasodilatory in nature, and if produced in excess results in vasoplegic shock.^[1]

Argenziano et al. examined a total of 145 patients gone through the cardiopulmonary bypass surgery and found that left ventricular ejection fraction < 35% was independently associated with the development of post-CPB vasodilatory shock in patients.

There are various types of causes known which are proven to be risk factors for vasoplegia. They may be of two different types one is of cardiac surgery-related causes and the other is non-cardiac surgery-related causes.

• Sepsis: Vasoplegia can occur due to a severe infection and sepsis which can further lead to widespread inflammation and vascular dysfunction.^[3]
• Cardiac surgery: It is the second most common cause of vasoplegia. It mainly occurred due to the production of inflammatory cytokines and nitric oxide.
• Drug: There are some types of drugs such as calcium channel blockers that block the entry of calcium inside the cell and that results in vasodilation and hence produce hypotension. Frequent use of these drugs can lead to regular hypotension and cause vasoplegia.
• Burns, trauma and pancreatitis: These are conditions mainly united by tissue injury, with consequent systemic inflammation and predisposition to developing organ function.^[3] They can lead to Vasoplegia due to the release of inflammatory mediators and systemic response to tissue damage.

• Hypotension: Hypotension is mainly produced due to vascular smooth muscle relaxation. Due to this patient may be dizzy and faint. It is improved by smooth muscle contraction, as the contraction is achieved it will result in increased blood pressure.
• Vasodilation: Vasodilation is mainly produced by the production of nitric oxide, which is a potent vasodilator, due to this the vital organ receives poor water supply. It can be treated by decreasing the production of nitric oxide.

Other than this tachycardia, organ dysfunction and delayed wound healing process also appear as symptoms of vasoplegia. These symptoms are interconnected, meaning that the presence of one symptom can lead to further consequences, resulting in the appearance of additional symptoms.

Generally, the treatment approach for Vasoplegia is multidirectional. During treatment physician has two aims, one is to restore the vascular tone and the other is to address or treat the cause of the syndrome. These aims are achieved using various kinds of techniques or medicine.

• Catecholamines: Among catecholamines specifically norepinephrine is mainly used for the treatment and management of vasoplegic shock. The mechanism behind their working is such that they activate the alpha1 receptor by binding on it and resulting in the entry of calcium inside the cell, which will lead to contraction of the smooth muscle, due to this vascular tone is restored.^[2]
• Vasopressin: It is also known as an antidiuretic hormone, with very selective activity on the V1 receptor located on the vascular smooth muscle. It mainly causes smooth muscle contraction by G protein-coupled receptor or by modulation of the production of nitric oxide (NO). They mainly improve cardiac contractility and raise blood pressure which is very helpful in the management of vasoplegic shock.
  • Hajjar et al. evaluated vasopressin in contrast with norepinephrine as first-line therapy in the treatment of Vasoplegia. The results showed that the mortality or any severe complications were significantly lower in the vasopressin group, which was driven by a lower incidence of atrial fibrillation (AF) and acute renal failure.^[1]
• Ascorbic acid, thiamine, and corticosteroids: The combination of these 3 medications may show a beneficial effect in the treatment of Vasoplegia. They work by several mechanisms such that, ascorbic acid act as a co-factor to produce catecholamine, as a result, norepinephrine synthesis is enhanced, other than this its antioxidative property may counteract the excessive production of reactive oxygen species, which are known to cause reduced vascular tone, by using ascorbic acid vascular tone is enhanced. Thiamine on the other hand prevents the conversion of the ascorbic acid to oxalate, which thus indirectly increases the availability of the ascorbic acid. Glucocorticoids may work synergistically with ascorbic acid, and results in increased catecholamine synthesis and also improves endothelial function.
  • The combination of these 3 drugs regimen was recently evaluated in a study, Marik et al. demonstrated a significant reduction in mortality as well as a rapid reduction in vasopressor requirements in patients receiving these three-drug combinations.^[1]
• Fluid Management: The fluid management technique plays a significant role in the management of the Vasoplegia. The presence of adequate fluid in the circulatory system aims to improve preload and cardiac output that can help counteract vasodilation. In this way, it is a very crucial therapy for the treatment of vasoplegia.

Vasoplegia mainly occurs in those patients who are undergoing cardiothoracic surgery. It has a significant impact on the patient’s life and sometimes life-threatening conditions are also produced due to this syndrome. As it is very dangerous so it become very necessary to provide a rational treatment approach, however till now there is no clinical database is present which supports the use of a particular treatment in the management of vasogenic syndrome. So scientists and researchers must have to find some special treatment methods so that morbidity rates due to this can be decreased and patients’ life quality will be improved.

References: