Pulmonary artery wave reflection and right ventricular function after lung resection

Left ventricular stroke volume decreases due to surgical procedures of anatomical lung resection

OBJECTIVES

The influence of lung resection on cardiac function has been reported, and previous studies have mainly focused on right ventricular (RV) dysfunction. As few studies have analyzed changes in left ventricular hemodynamic variables caused by lung resection, we aimed to investigate the perioperative changes in left ventricular stroke volume (LVSV) caused by anatomical lung resection.

METHODS

We enrolled 61 patients who underwent anatomical lung resection and perioperative LVSV monitoring. The Flo Trac system was used for dynamic monitoring. We investigated changes in LVSV after lung resection and the factors that affected these changes. The operative procedures that contributed to these changes were also investigated.

RESULTS

LVSV decreased after anatomical lung resection in the majority of patients (n = 38, 62.2%). Operative procedures affecting this change were (a) taping the superior pulmonary vein (SPV; right: V1-3) before dorsal part procedure (e.g., major fissure division of right upper lobectomy, A1 + 2c, and A4 + 5 division of left upper lobectomy); (b) division of the SPV (right: V1-3, V4 + 5); (c) division of A6-10 (in lower lobectomy); and (d) finish division of all vessels.

CONCLUSIONS

LVSV decrease was caused by anatomical lung resection in the majority of patients owing to the intraoperative procedures described above.

Risk factors and prognostic analysis of right ventricular dysfunction after lung resection for NSCLC

Objectives

Lung cancer is the leading cause of cancer death, and 80-85% of all lung cancer cases are non-small cell lung cancer (NSCLC). Surgical resection is the standard treatment for early-stage NSCLC. However, lung resection, a surgical procedure, can result in complications and increased mortality. Recent studies have shown a significant correlation between complications after lung resection and right ventricular dysfunction.

Methods

Transthoracic echocardiography-derived right ventricular-pulmonary artery coupling (RV-PAC) was utilized to assess right ventricular function in these patients. Multivariate logistic regression analysis was also conducted to assess risk factors independently associated with RV-PA uncoupling. The 3- and 5-year cumulative survival rates were estimated with Kaplan-Meier curves, and differences between groups were analyzed using the Mantel-Cox log-rank test.

Results

RV-PA uncoupling was defined as a TAPSE/PASP value < 0.67 mm/mm Hg according to spline analysis. The results of multivariable logistic regression analysis indicated that diabetes is an independent risk factor for right ventricular dysfunction after lung resection in patients with NSCLC. Kaplan-Meier analysis revealed a significant decrease in the survival rate of patients with RV-PA uncoupling at both the 3-year follow-up (73% vs 40%, p < 0.001) and 5-year follow-up (64% vs 37%, p < 0.001).

Conclusions

After lung resection for NSCLC, the patient's right ventricular function predicts prognosis. Patients with right ventricular dysfunction, particularly those with diabetes mellitus, have a worse prognosis. It is crucial to actively prevent and correct risk factors to reduce the mortality rate in these patients.

Epidemiology of perioperative RV dysfunction: risk factors, incidence, and clinical implications

In this edition of the journal, the Perioperative Quality Initiative (POQI) present three manuscripts describing the physiology, assessment, and management of right ventricular dysfunction (RVD) as pertains to the perioperative setting. This narrative review seeks to provide context for these manuscripts, discussing the epidemiology of perioperative RVD focussing on definition, risk factors, and clinical implications. Throughout the perioperative period, there are many potential risk factors/insults predisposing to perioperative RVD including pre-existing RVD, fluid overload, myocardial ischaemia, pulmonary embolism, lung injury, mechanical ventilation, hypoxia and hypercarbia, lung resection, medullary reaming and cement implantation, cardiac surgery, cardiopulmonary bypass, heart and lung transplantation, and left ventricular assist device implantation. There has however been little systematic attempt to quantify the incidence of perioperative RVD. What limited data exists has assessed perioperative RVD using echocardiography, cardiovascular magnetic resonance, and pulmonary artery catheterisation but is beset by challenges resulting from the inconsistencies in RVD definitions. Alongside differences in patient and surgical risk profile, this leads to wide variation in the incidence estimate. Data concerning the clinical implications of perioperative RVD is even more scarce, though there is evidence to suggest RVD is associated with atrial arrhythmias and prolonged length of critical care stay following thoracic surgery, increased need for inotropic support in revision orthopaedic surgery, and increased critical care requirement and mortality following cardiac surgery. Acute manifestations of RVD result from low cardiac output or systemic venous congestion, which are non-specific to the diagnosis of RVD. As such, RVD is easily overlooked, and the relative contribution of RV dysfunction to postoperative morbidity is likely to be underestimated.We applaud the POQI group for highlighting this important condition. There is undoubtedly a need for further study of the RV in the perioperative period in addition to solutions for perioperative risk prediction and management strategies. There is much to understand, study, and trial in this area, but importantly for our patients, we are increasingly recognising the importance of these uncertainties.

Characterization of pulmonary arterial stiffness using cardiac MRI

Pulmonary arterial stiffness (PAS) is a pathologic hallmark of all types of pulmonary hypertension (PH). Cardiac MRI (CMR), a gold-standard imaging modality for the evaluation of pulmonary flow, biventricular morphology and function has been historically reserved for the longitudinal clinical follow-up, PH phenotyping purposes, right ventricular evaluation, and research purposes. Over the last two decades, numerous indices combining invasive catheterization and non-invasive CMR have been utilized to phenotype the character and severity of PAS in different types of PH and to assess its clinically prognostic potential with encouraging results. Many recent studies have demonstrated a strong role of CMR derived PAS markers in predicting long-term clinical outcomes and improving currently gold standard risk assessment provided by the REVEAL calculator. With the utilization of a machine learning strategies, strong diagnostic and prognostic performance of CMR reported in multicenter studies, and ability to detect PH at early stages, the non-invasive assessment of PAS is on verge of routine clinical utilization. In this review, we focus on appraising important CMR studies interrogating PAS over the last 20 years, describing the benefits and limitations of different PAS indices, and their pathophysiologic relevance to pulmonary vascular remodeling. We also discuss the role of CMR and PAS in clinical surveillance and phenotyping of PH, and the long-term future goal to utilize PAS as a biomarker to aid with more targeted therapeutic management.

Relationship between pulmonary blood flow and volume following lung resection using dynamic perfusion digital radiography

Background

Surgical intervention for lung resection can cause ventilation-perfusion mismatches and affect gas exchange; however, minimally invasive assessment of blood flow is difficult. This study aimed to evaluate changes in pulmonary blood flow after radical lung cancer surgery using a minimally invasive dynamic digital chest radiography system.

Methods

We evaluated 64 patients who underwent radical lobectomies. Postoperative changes in pulmonary blood flow, assessed using dynamic chest radiography-based blood flow ratios (BFRs), were compared with the temporal evolution of both functional lung volumes (FLVs) and estimated lung weight (ELW) derived from computed tomography (CT) volumetry.

Results

FLVs on the affected side gradually recovered over time from the lowest value observed 3 months after surgery in all procedures. BFRs on the affected side also showed a gradual recovery from the lowest value 1 month after surgery, except for left upper lobectomies (LULs). In LULs, FLVs and ELWs increased proportionally up to 3 months after surgery, with lung volumes continuing to increase thereafter. The recovery of BFRs differed depending on the resected lobe.

Conclusions

A relationship between pulmonary blood flow and FLV was observed in the postoperative period. Despite varying compensatory responses depending on the surgical procedure, FLV recovery coincided with increased pulmonary blood flow.

Study protocol for IMPRoVE: a multicentre prospective observational cohort study of the incidence, impact and mechanisms of perioperative right ventricular dysfunction in non-cardiac surgery

INTRODUCTION

Perioperative myocardial injury evidenced by elevated cardiac biomarkers (both natriuretic peptides and troponin) is common after major non-cardiac surgery. However, it is unclear if the rise in cardiac biomarkers represents global or more localised cardiac injury. We have previously shown isolated right ventricular (RV) dysfunction in patients following lung resection surgery, with no change in left ventricular (LV) function. Given that perioperative RV dysfunction (RVD) can manifest insidiously, we hypothesise there may be a substantial burden of covert yet clinically important perioperative RVD in other major non-cardiac surgical groups. The Incidence, impact and Mechanisms of Perioperative Right VEntricular dysfunction (IMPRoVE) study has been designed to address this knowledge gap.

METHODS AND ANALYSIS

A multicentre prospective observational cohort study across four centres in the West of Scotland and London. One hundred and seventy-five patients will be recruited from five surgical specialties: thoracic, upper gastrointestinal, vascular, colorectal and orthopaedic surgery (35 patients from each group). All patients will undergo preoperative and postoperative (day 2-4) echocardiography, with contemporaneous cardiac biomarker testing. Ten patients from each surgical specialty (50 patients in total) will undergo T1-cardiovascular magnetic resonance (CMR) imaging preoperatively and postoperatively. The coprimary outcomes are the incidence of perioperative RVD (diagnosed by RV speckle tracking echocardiography) and the effect that RVD has on days alive and at home at 30 days postoperatively. Secondary outcomes include LV dysfunction and clinical outcomes informed by Standardised Endpoints in Perioperative Medicine consensus definitions. T1 CMR will be used to investigate for imaging correlates of myocardial inflammation as a possible mechanism driving perioperative RVD.

ETHICS AND DISSEMINATION

Approval was gained from Oxford C Research Ethics Committee (REC reference 22/SC/0442). Findings will be disseminated by various methods including social media, international presentations and publication in peer-reviewed journals.

TRIAL REGISTRATION NUMBER

NCT05827315.

Thoracic anaesthetic research: 90 years of sustained progress

Over the 90 years since the first description of one-lung ventilation, the practice of thoracic surgery and anaesthesia continues to develop. Minimally invasive surgical techniques are increasingly being used to minimise the surgical insult and facilitate improved outcomes. Challenging these outcomes, however, are parallel changes in patient characteristics with more older and sicker patients undergoing surgery. Thoracic anaesthesia as a speciality continues to respond to these challenges with evolution of practice and strong academic performance.