Bedside Ultrasound to Guide the Diagnosis and Treatment of Fulminant Right Heart Failure: A Case Report

Background

Right ventricular (RV) failure often results from acute or chronic cardiac or pulmonary disease, or a combination of both, which can lead to increased afterload, decreased contractility, impair preload, ventricular interdependence, or dysrhythmias [1]. Under normal circumstances, RV function relies on the interaction between preload, contractility, afterload, ventricular interdependence, and heart rate. Increased afterload, primarily caused by pulmonary and cardiac diseases, is the main cause of RV failure. In adults, atrial septal defects (ASD) are a common chronic cause of pulmonary hypertension, with a prevalence of 0.88 per 1000 patients [2]. The size of the defect and the distensibility of the left and right ventricles determine disease progression, potentially leading to pulmonary over-circulation, pulmonary hypertension, and premature mortality without treatment [2,3]. In previously healthy individuals, RV failure is often caused by massive pulmonary thromboembolism (PTE), resulting in obstructive shock and acute RV failure. Following acute PTE, pulmonary hypertension (PHT) frequently manifests when more than half of the pulmonary vasculature becomes obstructed. This is attributed to the distension and recruitment of additional pulmonary capillaries, potentially lowering vascular resistance to compensate for flow obstruction. The sudden increase in afterload can trigger acute RV failure and obstructive shock. While cases typically show slightly elevated pulmonary artery pressures, chronic exposed RVs due to pulmonary hypertension, as in ASD, can lead to higher pulmonary pressures during acute pulmonary embolism due to RV adaptation and hypertrophy [1]. However, if the thrombotic burden exceeds the RV’s capacity to adapt to elevated afterloads, it can lead to cardiac arrest [4].

This article presents a case of a 72-year-old patient with no known past medical history, who experienced profound shock progressing to cardiac arrest. The article highlights how bedside ultrasound (US) was used to identify the cause of circulatory collapse, specifically identifying a significant chronic RV overload attributable to an extensive ASD, exacerbated by acute pulmonary thromboembolism.

Case Report

This is a case report of a 72-year-old male patient with no known chronic diagnoses but a history of dyspnea and edema in declining areas for the past 5 years. He was admitted to the hospital with acute severe dyspnea and epigastric pain, along with signs of severe respiratory distress and bilateral edema of the lower limbs. His vital signs upon arrival were blood pressure 59/47 mmHg, heart rate 112 bpm, respiratory rate 25 rpm, and oxygen saturation 95%. An electrocardiogram (ECG) revealed atrial fibrillation with rapid ventricular response and right bundle branch block. Due to the urgency of the situation and the looming threat of cardiac arrest, electrical cardioversion was promptly performed. The intervention led to ventricular fibrillation, so advanced cardiopulmonary resuscitation (CPR) was started. The patient was successfully resuscitated after 1 shock. However, he subsequently developed sustained ventricular tachycardia (VT), which did not respond to synchronous shocks (Figure 1). The patient remained in profound shock and required dual vasopressor and inotropic support along with invasive ventilatory support.

Chest X-ray showed severe cardiomegaly, generalized cottony infiltrates, and a possible left pleural effusion (Figure 2). During observation, the patient suffered another cardiac arrest due to monomorphic VT rhythm, and advanced CPR was restarted, with return of spontaneous circulation (ROSC) after 25 min. A bedside US revealed marked right chambers dilatation, severe mitral and tricuspid insufficiency, and an image suggestive of a large ASD (Figure 3). Additionally, there was mild pericardial effusion and global hypokinesia of the left ventricle. Due to asymmetric edema of the lower limbs, predominantly on the right side, a bedside compression ultrasound (CUS) was performed, which suggested proximal deep vein thrombosis in the right lower limb.

The patient’s severe hemodynamic instability led to a suspicion of pulmonary thromboembolism (PTE) as a contributing cause. Thrombolysis with alteplase was administered and following a partial restoration of hemodynamic stability 20 minutes after the thrombolytic infusion, a chest CT angiography was performed. This image confirmed the presence of acute PTE in the right upper lobe and chronic PTE in the left pulmonary artery and right lower lobe. The patient also exhibited signs of pulmonary hypertension, global cardiomegaly, and a large ASD measuring 7 cm (Figure 4). Subsequently, the patient suffered another cardiac arrest with pulseless electrical activity rhythm (PEA) and echocardiography revealed an absence of cardiac or valvular movement. The clinical condition was considered irreversible, and the patient was declared dead.

Discussion

The right ventricle (RV) and left ventricle (LV) exhibit distinct physiological characteristics. The RV is thinner and more compliant than the LV due to lower pulmonary circulation pressure compared to the systemic circulation [5]. It primarily contracts longitudinally, while the LV contracts circumferentially [6]. RV perfusion occurs in both systole and diastole, but it is more vulnerable to enlargement due to increased intramural pressure and systemic hypotension due to thinner walls and sensitivity to changes in coronary perfusion pressure [7].

The RV is also more sensitive to changes in afterload, contributing to RV dilatation and excessive RV volume restricted by the pericardium, which can lead to LV compression and D-shaping. This results in a decrease in LV systolic volume, a phenomenon known as ventricular interdependence [6]. Up to 40% of RV systolic function relies on septal contraction [8]. Therefore, assessing preload, contractility, afterload, ventricular interdependence, and heart rate is crucial for treating RV dysfunction.

This case illustrates how multiple mechanisms of RV dysfunction can lead to fulminant failure and cardiac arrest, caused by factors like excessive afterload, decreased contractility, dysrhythmias, and ventricular interdependence. Bedside US proved to be useful in identifying the origin of circulatory collapse by revealing chronic RV overload due to an extensive ASD, ventricular interdependence impact on the LV, and acute conditions like pulmonary thromboembolism.

While conventional qualitative ventricular size assessment is common, it has limitations such as high interobserver variability and low sensitivity. Furthermore, this measurement ignores the contribution of the RV outflow tract to the overall systolic function [9]. Instead, measures like tricuspid annular plane systolic excursion (TAPSE) and systolic excursion velocity (S’) provide valuable insights into RV function. TAPSE, for instance, is a readily obtainable measure of RV longitudinal function. While TAPSE predominantly reflects longitudinal RV function, it correlates well with parameters estimating global RV systolic function. However, it may overestimate or underestimate RV function due to cardiac translation. In general, a TAPSE <17 mm is highly suggestive of RV systolic dysfunction [9].

On the other hand, S’ is measured by pulsed tissue Doppler; a value <11.5 cm/s is associated with an ejection fraction <45%, but it is limited by angle and load dependence as well as the “tethering” phenomenon, which can produce falsely normal values [9]. Other echocardiographic tools for assessing RV function, such as fractional area change, RV myocardial performance index (RIMP), and myocardial acceleration during isovolumetric contraction, require expertise and may be challenging to obtain. These measures are somewhat dependent on loading conditions and physiological variations [9].

Acute RV failure treatment involves optimizing volume, restoring perfusion pressure, enhancing myocardial contractility, regaining sinus rhythm, reducing afterload, and considering advanced interventions (Figure 4). In this case, the primary focus was on restoring systemic perfusion, improving myocardial contractility, reducing afterload, and restoring sinus rhythm.

To address systemic perfusion, a dual approach involving the administration of noradrenaline and vasopressin was employed. Noradrenaline plays a role in restoring systemic hemodynamics, although it can increase pulmonary resistances and RV workload without causing significant changes in RV ejection fraction (EF) [10]. On the other hand, vasopressin appears to decrease pulmonary pressures without a significant reduction in pulmonary resistances under normal conditions. Myocardial contractility was enhanced through administration of milrinone.

As increased afterload is the primary determinant of acute RV dysfunction, efforts should be made to decrease its impact through specific interventions. In this case of massive pulmonary thromboembolism accompanied by hemodynamic instability, thrombolytic therapy was chosen since evidence has shown it can reduce in-hospital mortality [11,12]. After thrombolysis, the patient’s condition improved rapidly, suggesting that the thrombotic burden had a significant impact on hemodynamics.

In this patient it was crucial to acknowledge the effect of mechanical ventilation, which can disrupt RV function by decreasing preload and increasing afterload. Therefore, we aimed to reduce tidal volume and positive end-expiratory pressure (PEEP) to achieve plateau pressures below 27 cmH2O and distension pressures below 16 mmHg. Additionally, efforts were made to avoid hypercapnia (>60 mmHg) and acidosis and to prevent or reverse hypoxic pulmonary vasoconstriction [13].

Dysrhythmias played a significant role in the decline of hemo-dynamic stability. Efforts were made to restore sinus rhythm through attempted electrical cardioversion, without success. Cardiac pacing plays a substantial and often underestimated role in RV function. The compromised RV is highly dependent on a regular heart rate to function optimally, especially when facing increased afterload, given its limited contractile reserve [14]. Furthermore, RV pressure overload is often associated with supraventricular dysrhythmias, which adversely affects RV filling. Dysrhythmias contribute to the vicious cycle of deteriorating RV function, ultimately culminating in cardiogenic shock. Therefore, rapid rate control of supraventricular tachydysrhythmias is essential. It is noteworthy that the diastolic filling of the failing RV depends on atrial contraction (“atrial kick”) and atrioventricular synchrony [14]. Hence, rate control alone is often insufficient to restore hemodynamic stability [15].

Another fundamental aspect of RV failure treatment is pre-load optimization. While there is a common misconception that RV failure should be managed with volume replacement, it is essential to recognize that many RV failure cases are either caused or exacerbated by RV volume overload. In these cases, volume loading can potentially overdistended the RV, increase wall stress, reduce contractility, impair LV filling due to increased ventricular interdependence, and ultimately reduce systemic cardiac output [16,17].

Therefore, accurately assessing volume status is not always straightforward, and dynamic predictors of volume response are limited in cases of RV failure. In patients with RV failure and signs of systemic venous congestion, diuretics are usually the first choice for volume optimization [18]. In this context, early evaluation of diuretic response (by monitoring diuresis or urinary sodium levels after diuretic administration) holds great importance in identifying patients with an inadequate response. If decongestion is insufficient, timely dose escalation of loop diuretics, combination of diuretics with different modes of action, or use of renal replacement therapy with ultrafiltration should be considered [1].

A recent study suggests that diuretic therapy is well tolerated and safe in the acute treatment of intermediate-high risk PTE. Although changes in troponin kinetics and echocardio-graphic parameters of RV dysfunction did not differ between groups (with and without diuretic), normalization of BNP was achieved more rapidly in the diuretic group. This finding, which needs to be confirmed in controlled clinical trials, may reflect a rapid improvement in RV function with a 40-mg dose of intravenous furosemide [19]. In the absence of high RV filling pressures, cautious volume loading guided by central venous pressure monitoring may be appropriate [17].

A final step in the management of cardiogenic shock includes mechanical circulatory support. However, veno-arterial extra-corporeal membrane oxygenation (VA ECMO) was dismissed in this case for several reasons. First, the poor short-term prognosis due to the clinical severity at admission, comorbid burden given chronic severe PHT, a complex anatomical defect, coupled with advanced age, substantially diminished the patient’s survival chances even if VA ECMO were employed [20,21]. Additionally, the Extracorporeal Life Support Organization (ELSO) guidelines recommend exercising caution with the use of VA ECMO in patients over the age of 70 and advocate for selective application in cases of post-cardiac arrest, reflecting a more conservative approach in these patient groups [22]. Figure 5 shows a summary of the treatment principles of acute RV failure.

Given our patient´s critical condition, the irreversible structural cardiac alterations, and limited life expectancy, advanced treatments such as extracorporeal circulatory support were deemed inappropriate and excluded. Subsequently, the patient was declared dead.

Conclusions

Acute dysfunction of the RV is generated by an interaction between preload, contractility, afterload, ventricular interdependence, and heart rhythm, making it essential to evaluate these 5 components to guide treatment. This case underscores the importance of recognizing RV dysfunction, even in patients with no prior medical history, when presented with profound shock and rapidly deteriorating cardiac function. It also demonstrates how various mechanisms of RV dysfunction can converge, leading to fulminant RV failure and cardiac arrest.

Furthermore, the article highlights the utility of bedside US in determining the underlying cause of circulatory collapse. In this specific case, US played an important role aiding in the identification of 3 factors contributing to RV failure: chronic RV overload resulting from an extensive atrial septal defect, the impact on the left ventricle due to ventricular interdependence, and acute pulmonary thromboembolism. Awareness of these multifaceted factors and proficiency in employing bedside US empower emergency physicians with the necessary tools to achieve timely diagnoses and effectively manage RV failure-related emergencies.