Exploring the Applicability of Pre-Anesthetic Cardiac POCUS in Unexpected Conditions: Could it be Helpful?

Abstract Formal preoperative echocardiography has traditionally been recommended when there is substantial cardiovascular disease without recent follow up, unexplained dyspnea, a functional class less than 4 METS or a Duke Activity Status Index less than 34. However, it is important to note that certain patients may present with a variety of cardiac abnormalities due to their preexisting condition or multiple treatments, and these individuals warrant consideration. The objective of pre-anesthetic cardiac POCUS is to provide clinical information in a timely manner. Although it does not aim to replace conventional echocardiography, cardiac POCUS can undoubtedly assist anesthesia practitioners in identifying asymptomatic and potentially hazardous conditions, allowing for more accurate risk allocation and individualized patient care.


Evidence supporting preoperative cardiac POCUS
A prospective observational study in which preoperative cardiac POCUS was performed by an anesthesiologist and validated by a cardiologist in 100 patients older than 65 years or with suspected cardiac disease, 54 patients had their anesthetic plan altered; some were referred to a cardiologist, others had their anesthetic or surgical technique altered, and others were referred to highly dependent facilities in the postoperative period [9].In a separate observational study, anesthesiologists performed preoperative cardiac POCUS on 170 patients, obtaining adequate images in 167 (98%) and detecting significant alterations such as mitral valve disease, pulmonary hypertension, and aortic stenosis, pathologies that could alter perioperative management [10].Another prospective observational study involving 99 patients with previous cardiac diagnoses (systolic or diastolic left ventricular failure, vasodilatation, hypovolemia or pericardial effusion) scheduled for non-cardiac emergency surgery, 44% of patients had their treatment modified after preoperative cardiac POCUS [11].An additional prospective cohort study of 100 patients older than 60 years assessed hemodynamics, biventricular function, valvular competence, pericardial effusion, and pulmonary pressures using preoperative cardiac POCUS.They found 26% of patients with LVEF alterations, 18% of patients with valvular lesions, and 40% of patients with diastolic dysfunction.Additionally, the anesthetic behavior of 20% of patients was altered, and 4% of patients were cancelled [12].A separate large database of transthoracic echocardiography (TTE) conducted by the department of anesthesia at the Memorial Sloan Kettering Cancer Center in the United States revealed that cardiac POCUS patterns provided significant responses that guided management in a substantial percentage of patients [13].
Following these observational studies, two randomized controlled trials (RCTs) have recently been conducted.In a pilot RCT led in Australia, anesthesiologists were instructed to perform cardiac POCUS in 100 patients undergoing femoral neck fracture surgery.Cardiac POCUS resulted in a significant decrease in death, acute kidney injury, myocardial infarction, and cerebrovascular accidents [14,15].In contrast, cardiac POCUS did not appear to reduce postoperative hospitalization days or mortality in the PREOPFOCUS RCT, which included 327 high-risk patients over the age of 65 undergoing abdominal or orthopedic surgery and ASA 3 -4 [16].Unfortunately, this trial had to be terminated early due to COVID-19 restrictions.Perioperative evaluation of cardiac morphology and function is clearly plausible [17].However, conducting real-world studies in the field of pre -operative cardiac POCUS can be challenging due to the heterogeneity of the patient population.
Recent studies indicate that practitioners can comprehend cardiac POCUS after receiving 20 to 30 cases of guided cardiac POCUS education [18].However, it is unknown how many are required for accurate interpretation, though this could be overcome through consistent training.The majority of residency programs in anesthesiology do not include a formal curriculum in the use of perioperative cardiac POCUS, which is typically designated for residents who voluntarily choose to expand their knowledge of cardiac anesthetic or critical care [19].

Elderly patients (over 65 years)
The global population is advancing in age and elderly individuals warrant particular attention [20].As a result of aging, geriatric patients experience stiffening of their arterial circulatory system and heart chambers which might result in a variety of illnesses, notably heart failure [21].Valve thickening specifically at mitral or aortic positions (i.e., degenerative, rheumatic, calcific, others) [22], is an additional significant structural change that can occur over time and occasionally lead to stenosis or insufficiencies with potential hemodynamic effects.Arrhythmias are common, especially atrial fibrillation (AF), which worsens with age and may affect 1 in every 5 people by the age of 80, significantly increasing the risk of stroke [23].
Using cardiac POCUS, we can visually determine if the chambers of the heart are enlarged, which indicates the presence of a chronic cardiac condition.Prior to administering anesthesia, a rough estimate of the left ventricle ejection fraction (LVEF) is essential, either qualitatively by eyeballing [24] or quantitatively using Simpson´s biplane method [25].
In addition, certain findings can aid in determining of an increased thromboembolic risk, predominantly in patients with AF.Left atrial enlargement is a significant indicator of chronic remodeling that provides clues to underlying cardiac disease and is a strong predictor of future events.Using 2D imaging during cardiac POCUS, we will be able to roughly estimate the increase in atrial size, as well as the possible deviation of the interatrial septum and the enlargement of the left atrial appendage [26].There is evidence that a volume increase exceeding 34 ml/m 2 is associated with an increased risk of ischemic stroke and mortality [27].
Moreover, spontaneous echo contrast resembling the appearance of smoke within the LA indicates blood stasis and stagnation and appears to be a precursor of intracavitary thrombi [28].Reduced velocity (less than 20cm/s) and the presence of a thrombus in the LA appendage are extremely high-risk characteristics; however, transesophageal echocardiography (TEE) is required for detecting them [29].
Additionally, the assessment of mitral and aortic valves can be performed in order to determine the presence of notable stenosis or regurgitation.However, in these instances, spectral doppler and advanced training are required (Table 1).

Patients with cancer
According to the World Health Organization, cancer is the second leading cause of death worldwide, only behind cardiovascular disease [30].This subgroup of patients frequently necessitates preoperative consultation [31].
Patients with cancer may develop a variety of cardiovascular complications, including effects of mediastinal metastatic disease [32][33][34], less frequently encountered are primary intracardiac tumors such as sarcomas or myxomas.Moreover, while new cancer medicines have made remarkable improvements in terms of quality of life and mortality, short-and long-term direct cardiotoxicity is strongly linked to cancer treatment [35], including anthracyclines (i.e.doxorubicin), alkylating agents (i.e.cyclophosphamide), monoclonal antibodies (i.e.trastuzumab, imatinib, bortezomib), among others routinely used in a wide range of hematological and solids tumors.Cancer related coagulation disorders increase the risk of deep vein thrombosis (DVT) and pulmonary embolism (PE) [36], which remain an additional important factor to take into account prior to surgery.
Cardiac POCUS can play a pivotal role in the necessary preoperative assessment [37].It is crucial to promptly exclude the presence of significant left ventricular (LV) dysfunction (e.g., cardiotoxicity due to chemotherapy).In addition, it is extremely important to look for tumor extension and pericardial effusion, which can go undetected in mild cases and lead to life-threatening tamponade in others.
Although cardiac POCUS does not replace computed tomography in the diagnosis of PE, severe cases can present with acute dilatation and dysfunction of the right ventricle (RV) (low TAPSE and fractional area change [FAC]), and McConnell's sign [38] (Table 2).

Patients in the intensive care unit
Critically ill patients are faced with life-threatening multisystem processes and routinely necessitate central vascular access and multiorgan support (e.g., mechanical ventilation and dialysis) [39], which may result in some adverse effects for which cardiac POCUS may be beneficial.Due to the performance of various surgical procedures during their stay in the intensive care unit, this subgroup of patients often requires anesthesiology consultation as part of their multidisciplinary management, and cardiac POCUS can aid cardiovascular evaluation.
Mechanical ventilation support may cause a decrease in RV preload by decreasing right atrial transmural pressure and cause an increase in RV afterload by increasing pulmonary vasculature resistance (e.g., high PEEP), resulting in RV dysfunction in severe cases [40][41][42].Cardiac POCUS can also be used to identify increased ventricular interdependence [43].

McConnell´s sign
To evaluate the right atrial (RA) pressure of the patient at the bedside, the diameter of the inferior vena cava (IVC) in proximity to the cavo-atrial junction (CAJ) can be measured [44].Simplified, if the IVC measures less than 10 millimeters with collapse on inspiration, the patient is has low RA pressure (often due to hypovolemia).Conversely, if the IVC exceeds 20 millimeters and does not have respiratory variation, RA pressure is elevated, which can be due to hypervolemia; therefore, perioperative fluid restriction or diuretic use may be required.It is also possible to calculate the velocity time integral (VTI) of the left outflow tract and estimate the cardiac output in order to better comprehend the hemodynamic profile at a fixed point [45,46].
Takotsubo syndrome, common but not exclusive to critically ill patients, is a reversible heart failure characterized by apical segment akinesia and basal segment hyperkinesia, resembling the Japanese octopus trap from which it derives its name; however, other atypical patterns can occur.Pre-anesthetic cardiac POCUS can be used to assess left ventricular (LV) function and identify the typical apical-midventricular ballooning pattern, as well as the circumferential pattern of Takotsubo cardiomyopathy [47,48].
Cardiac manifestations of septic cardiomyopathy affect 10% to 80% of septic patients [49], involving a variety of patterns ranging from hyperdynamic profiles to biventricular dysfunction; consequently, cardiac POCUS is useful in recognizing some of these features.Catheterrelated endocarditis is an uncommon but serious complication associated with central venous catheter infections [50], primarily caused by highly prevalent microorganisms in intensive care units such as staphylococcus aureus and candida spp., hence a high level of suspicion must always be maintained.During the preanesthetic phase, cardiac POCUS has the potential to recognize these endocardial changes (Table 3).

Patients with comorbidities
A wide range of diseases, including autoimmune conditions, sickle cell disease, chronic obstructive pulmonary disease, liver cirrhosis, chronic kidney disease, malnutrition, and HIV, among others, may result in latent cardiac conditions.These include pulmonary hypertension with RV compromise (i.e.tricuspid valve regurgitation jet velocity greater 2.8m/s), right atrial and ventricle enlargement, flattened septum caused by volume or pressure overload, cardiomyopathies such as diastolic and systolic biventricular heart failure, pericardial effusions, and other life-threatening complications, many of which are detectable by cardiac POCUS [51][52][53].
Coronary artery disease may be suspected if there is the presence of regional wall motion abnormalities, predominantly hypokinesia or akinesia of segments corresponding to a specific vascular territory [54].Furthermore, cardiac POCUS enables a quick estimation of LV systolic function and identification of secondary complications such as free wall or septal rupture, LV aneurysms, intracavitary thrombi, and chronic myocardial remodeling.

Users of illicit psychoactive substances
Illicit and prohibited substances are widespread in modern society, affecting individuals of all ages, genders, and socioeconomic backgrounds [55].A considerable number of these substances have the potential to directly impair cardiac function.Cocaine is a sympathomimetic substance that can cause long-term myocardial damage due to vasoconstriction, coronary spasm, and platelet aggregation, among other factors.Chronically increased left ventricle mass can result in diastolic heart failure and a significant reduction in LVEF [56].Injection drug-related infective endocarditis can affect individuals who inject drugs [57].It is critical to consider this condition during the pre-anesthetic period.

Conclusion
Cardiac POCUS is a rapidly available tool that may assist us in detecting potentially silent and dangerous preoperative conditions, allowing anesthesiologists to provide timely perioperative management.Cardiac POCUS is not intended to replace a formal echocardiogram, traditionally considered the domain of specialists such as cardiologists and cardiac anesthesiologists.However, there are situations in which perioperative management requires the assessment of patients for specific conditions that may have immediate cardiac implications.

Table 1 .
Preoperative cardiac POCUS for elderly patients.

Table 2 .
Preoperative cardiac POCUS for patients with cancer.

Table 3 .
Preoperative cardiac POCUS for critically ill patients, comorbid patients, and users of illicit psychoactive substances.