Low cardiac output syndrome (LCOS) is a reduction in cardiac output often seen in postoperative situations, especially those of coronary artery bypass grafting (CABG), and cardiopulmonary bypass (CPB) [1] [2]. It happens on account of the oxidative stress caused by reperfusion after surgical manipulations. The oxidative stress, as well as inflammatory reactions, cause a disturbance of function in the myocardium resulting in a necessity of inotropic support [3]. Pulmonary tissues also undergo reperfusion that participates in the development of vascular reactivity and damage to the alveoli causing pulmonary edema; the latter is responsible for poor tissue oxygenation [4].

There are no strict clinical criteria for diagnosing the patient with possible LCOS. Strong indications for LCOS is hemodynamic instability and impaired tissue oxygenation occurring postoperatively. Additionally, one of the essential pointers is the need for administration of afterload reduction agents or inotropic agents e.g. dobutamine, epinephrine, and dopamine in order to maintain sufficient cardiac function [5]. Intra-aortic balloon counterpulsation support and positive pressure oxygenation are also important factors contributing to the diagnosis [3] [2].

On examination, the patient will reveal cold extremities, particularly in the most distal parts like toes, an absence of pedal pulse and a decrease in the systolic pressure measuring under 90 mmHg. Likewise, weakened perception of sensation may be noted [6]. LCOS is considered to be associated with high risk of morbidity and mortality, thus prompt recognition and preservation of adequate circulation are of immense importance [2].

Low cardiac output syndrome can be the cause of decreased tissue oxygenation and disturbance in the cardiovascular system. Parameters evaluating the dynamics of this syndrome are linked with measurements of the arterial blood gas, central venous pressure, blood pressure, and estimates of the cardiac output.

It is possible to assess cardiac output (CO) directly by thermodilution. This technique includes a placement of the pulmonary artery catheter and is considered a gold standard for measuring the CO. It also gives data of right ventricle activity, such as right ventricular ejection fraction and right ventricular end diastolic volume. Although there are some drawbacks to this method, firstly it is an invasive procedure and secondly, it is not meant for continuous measurement of the CO [7]. There are other less invasive techniques for measuring the CO e.g. with transthoracic (TTE) or transesophageal (TEE) echocardiography.

LCOS is considered if the cardiac index (which is calculated with CO as a variable) is less than 2.2 L/min/m2, pulmonary artery occlusion pressure (PAOP) is more than 16 mmHg, and oxygen saturation drops to less than 60% [6] [8].

In the case of poor oxygenation caused by LCOS, serum lactate levels increase to more than 2 mmol/L for at least 2 hours and metabolic acidosis is recognized. Compensatory mechanisms will be exhibited by oliguria with urine output of less than 1.0 mL/kg/h [6].

Arterial blood gas analysis may uncover changes in partial arterial oxygen tension with less than 100 mmHg and partial arterial carbon dioxide tension of value exceeding the normal range of 35–45 mmHg. Central venous pressure is also likely to deviate from the norm of 6–8 mmHg [6] [9].

The treatment of LCOS focuses on improving cardiac output and ensuring adequate oxygen delivery to tissues. This may involve medications such as inotropes, which strengthen heart contractions, and vasodilators, which widen blood vessels to reduce the heart's workload. In some cases, mechanical support devices like intra-aortic balloon pumps or ventricular assist devices may be used. Treating underlying causes, such as heart attack or valve disease, is also crucial.

The prognosis for patients with LCOS varies depending on the underlying cause and the patient's overall health. Early recognition and treatment are critical for improving outcomes. While some patients recover fully with appropriate management, others may experience long-term complications or require ongoing treatment for heart failure.

LCOS can result from various conditions that impair the heart's ability to pump effectively. Common causes include heart attacks, severe heart failure, and complications following cardiac surgery. Other potential causes are valve disorders, arrhythmias (irregular heartbeats), and cardiomyopathies (diseases of the heart muscle).

LCOS is most commonly observed in patients undergoing cardiac surgery, with an estimated incidence of 3-10% in this population. It can also occur in patients with advanced heart failure or those who have suffered a significant heart attack. The condition is more prevalent in older adults and those with pre-existing heart conditions.

The pathophysiology of LCOS involves a decrease in cardiac output, which is the volume of blood the heart pumps per minute. This reduction can be due to weakened heart muscle contractions, increased resistance in blood vessels, or both. As a result, the body's organs receive less oxygen and nutrients, leading to the symptoms and complications associated with LCOS.

Preventing LCOS involves managing risk factors for heart disease and optimizing care for patients undergoing cardiac surgery. This includes controlling high blood pressure, diabetes, and cholesterol levels, as well as encouraging a healthy lifestyle with regular exercise and a balanced diet. In surgical settings, careful monitoring and management of patients can help reduce the risk of developing LCOS.

Low-Cardiac-Output Syndrome is a serious condition where the heart cannot pump enough blood to meet the body's needs. It can occur after cardiac surgery or due to other heart-related issues. Early diagnosis and treatment are essential for improving patient outcomes. Management involves medications, mechanical support, and addressing underlying causes.

If you or a loved one is experiencing symptoms like extreme fatigue, shortness of breath, or low blood pressure, it may be related to the heart's ability to pump blood effectively. Low-Cardiac-Output Syndrome is a condition where the heart struggles to meet the body's demands. Treatment is available and focuses on improving heart function and ensuring the body gets enough oxygen. It's important to work closely with healthcare providers to manage this condition and improve quality of life.

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