Postoperative right ventricular dysfunction-Integrating right heart profiles beyond long-axis function

Left and right ventricular longitudinal systolic function following aortic valve replacement in the PARTNER 2 trial and registry

AIMS

Evaluation of left and right ventricular (RV) longitudinal systolic function may enhance risk stratification following aortic valve replacement (AVR). The study objective was to evaluate the changes in left and RV longitudinal systolic function and RV-pulmonary artery (RV-PA) coupling from baseline to 30 days and 1 year after AVR.

METHODS AND RESULTS

Left ventricular (LV) longitudinal strain (LS), tricuspid annulus plane systolic excursion (TAPSE), and RV-PA coupling were evaluated in patients from the PARTNER 2A surgical AVR (SAVR) arm (n = 985) and from the PARTNER 2 SAPIEN 3 registry (n = 719). TAPSE and RV-PA coupling decreased significantly following SAVR, but remained stable following TAVR. Lower LV LS, TAPSE, or RV-PA coupling at baseline was associated with increased risk of the composite of death, hospitalization, and stroke at 5 years [adjusted hazard ratios (HRs) for LV LS < 15%: 1.24, 95% confidence interval (CI) 1.05-1.45, P = 0.001; TAPSE < 14 mm: 1.44, 95% CI 1.21-1.73, P < 0.001; RV-PA coupling < 0.55 mm/mmHg: 1.32, 95% CI 1.07-1.63, P = 0.011]. Reduced TAPSE at baseline was the most powerful predictor of the composite endpoint at 5 years. Patients with LV ejection fraction <50% at baseline had increased risk of the primary endpoint with SAVR (HR: 1.34, 95% CI 1.08-1.68, P = 0.009) but not with TAVR (HR: 1.12, 95% CI 0.88-1.42). Lower RV-PA coupling at 30 days showed the strongest association with cardiac mortality.

CONCLUSION

SAVR but not TAVR was associated with a marked deterioration in RV longitudinal systolic function and RV-PA coupling. Lower TAPSE and RV-PA coupling at 30 days were associated with inferior clinical outcomes at 5 years. In patients with LVEF < 50%, TAVR was associated with superior 5-year outcomes.

Management of Post-cardiotomy Shock

Patients undergoing cardiac surgery experience significant physiologic derangements that place them at risk for multiple shock phenotypes. Any combination of cardiogenic, obstructive, hemorrhagic, or vasoplegic shock occurs commonly in post-cardiotomy patients. The approach to the diagnosis and management of these shock states has many facets that are distinct compared to non-surgical cardiac intensive care unit patients. Additionally, the approach to and associated outcomes of cardiac arrest in the post-cardiotomy population are uniquely characterized by emergent bedside resternotomy if the circulation is not immediately restored. This review focuses on the unique aspects of the diagnosis and management of post-cardiotomy shock.

Instantaneous Right Ventricular to Pulmonary Artery Systolic Pressure Difference in Cardiac Surgery: A Retrospective and Prospective Cohort Study

BACKGROUND

During cardiac surgery, right ventricular outflow tract obstruction (RVOTO) is defined as an instantaneous pressure difference ≥ 6 mm Hg between right ventricular systolic pressure (RVSP) and pulmonary artery systolic pressure (PASP), for ≥ 5 minutes. Risk factors for RVOTO remain poorly understood. This cohort study was designed to evaluate the incidence, characteristics, and outcomes of the patients who experienced RVOTO.

METHODS

Instantaneous pressure difference between RVSP and PASP was measured by means of a pulmonary artery catheter with a right ventricular port during cardiac surgery from a retrospective (n = 295) and a prospective (n = 105) cohort.

RESULTS

From the retrospective and prospective cohorts, respectively, incidence of RVOTO was 30.2% and 36.2% before cardiopulmonary bypass (CPB) initiation and 43.7% and 47.6% after CPB separation. Before CPB initiation, patients with RVOTO had higher cardiac output (4.2 ± 1.5 vs 3.8 ± 1.1 L/min; P = 0.033) and received more inhaled epoprostenol (79% vs 61%; P = 0.005) and inotropes (66% vs 51%; P = 0.016) compared with those without RVOTO. After CPB separation, patients with RVOTO had higher heart rate (62 ± 15 vs 58 ± 13 beats/min; P = 0.011), cardiac output (4.1 ± 1.4 vs 3.7 ± 1.1 L/min; P = 0.003), and CPB duration (90 ± 45 vs 77 ± 30 min, P = 0.014), had lower fluid balance (758 ± 1123 vs 1063 ± 1089 mL; P = 0.021), and were more exposed to intratracheal milrinone (12% vs 4%; P = 0.015) compared with those without RVOTO. The time with persistent organ dysfunction (TPOD) at 28 days after surgery was similar among patients who had an RVOTO event, before CPB initiation or after CPB separation, compared with those who did not.

CONCLUSIONS

RVOTO is common in cardiac surgery. However, it is not associated with longer TPOD.

Continuous Right Ventricular Pressure Monitoring in Cardiac Surgery

OBJECTIVE

Right ventricular (RV) dysfunction in cardiac surgery can lead to RV failure, which is associated with increased morbidity and mortality. Abnormal RV function can be identified using RV pressure monitoring. The primary objective of the study is to determine the proportion of patients with abnormal RV early to end-diastole diastolic pressure gradient (RVDPG) and abnormal RV end-diastolic pressure (RVEDP) before initiation and after cardiopulmonary bypass (CPB) separation. The secondary objective is to evaluate if RVDPG before CPB initiation is associated with difficult and complex separation from CPB, RV dysfunction, and failure at the end of cardiac surgery.

DESIGN

Prospective study.

SETTING

Tertiary care cardiac institute.

PARTICIPANTS

Cardiac surgical patients.

INTERVENTION

Cardiac surgery.

MEASUREMENTS AND MAIN RESULTS

Automated electronic quantification of RVDPG and RVEDP were obtained. Hemodynamic measurements were correlated with cardiac and extracardiac parameters from transesophageal echocardiography and postoperative complications. Abnormal RVDPG was present in 80% of the patients (n = 105) at baseline, with a mean RVEDP of 14.2 ± 3.9 mmHg. Patients experienced an RVDPG > 4 mmHg for a median duration of 50.2% of the intraoperative period before CPB initiation and 60.6% after CPB separation. A total of 46 (43.8%) patients had difficult/complex separation from CPB, 18 (38.3%) patients had RV dysfunction, and 8 (17%) had RV failure. Abnormal RVDPG before CPB was not associated with postoperative outcome.

CONCLUSION

Elevated RVDPG and RVEDP are common in cardiac surgery. RVDPG and RVEDP before CPB initiation are not associated with RV dysfunction and failure but can be used to diagnose them.

Clinical relevance of transcranial Doppler in a cardiac surgery setting: embolic load predicts difficult separation from cardiopulmonary bypass

BACKGROUND

During cardiac surgery, transcranial Doppler (TCD) represents a non-invasive modality that allows measurement of red blood cell flow velocities in the cerebral arteries. TCD can also be used to detect and monitor embolic material in the cerebral circulation. Detection of microemboli is reported as a high intensity transient signal (HITS). The importance of cerebral microemboli during cardiac surgery has been linked to the increased incidence of postoperative renal failure, right ventricular dysfunction, and hemodynamic instability. The objective of this study is to determine whether the embolic load is associated with hemodynamic instability during cardiopulmonary bypass (CPB) separation and postoperative complications.

METHODS

A retrospective single-centre cohort study of 354 patients undergoing cardiac surgery between December 2015 and March 2020 was conducted. Patients were divided in tertiles, where 117 patients had a low quantity of embolic material (LEM), 119 patients have a medium quantity of microemboli (MEM) and 118 patients who have a high quantity of embolic material (HEM). The primary endpoint was a difficult CPB separation. Multivariate logistic regression was used to determine the potential association between a difficult CPB separation and the number of embolic materials.

RESULTS

Patients who had a difficult CPB separation had more HITS compared to patients who had a successful CPB separation (p < 0.001). In the multivariate analysis, patients with MEM decreased their odds of having a difficult CPB weaning compared to patients in the HEM group (OR = 0.253, CI 0.111-0.593; p = 0.001). In the postoperative period patients in the HEM group have a higher Time of Persistent Organ Dysfunction (TPOD), a longer stay in the ICU, a longer duration under vasopressor drugs and a higher mortality rate compared to those in the MEM and LEM groups.

CONCLUSION

The result of this study suggests that a high quantity of cerebral embolic material increases the odds of having a difficult CPB separation. Also, it seems to be associated to more complex surgery, a longer CPB time, a higher TPOD and a longer stay in the ICU. Six out of eight patients who died in this cohort were in the HEM group.

Inhaled milrinone in cardiac surgical patients: pharmacokinetic and pharmacodynamic exploration

Mean arterial pressure to mean pulmonary arterial pressure ratio (mAP/mPAP) has been identified as a strong predictor of perioperative complications in cardiac surgery. We therefore investigated the pharmacokinetic/pharmacodynamic (PK/PD) relationship of inhaled milrinone in these patients using this ratio (R) as a PD marker. Following approval by the ethics and research committee and informed consent, we performed the following experiment. Before initiation of cardiopulmonary bypass in 28 pulmonary hypertensive patients scheduled for cardiac surgery, milrinone (5 mg) was nebulized, plasma concentrations measured (up to 10 h) and compartmental PK analysis carried out. Baseline (R₀) and peak (R_max) ratios as well as magnitude of peak response (∆_Rmax-R0) were measured. During inhalation, individual area under effect-time (AUEC) and plasma concentration-time (AUC) curves were correlated. Potential relationships between PD markers and difficult separation from bypass (DSB) were explored. In this study, we observed that milrinone peak concentrations (41-189 ng ml^-1) and Δ_Rmax-R0 (- 0.12-1.5) were obtained at the end of inhalation (10-30 min). Mean PK parameters agreed with intravenous milrinone published data after correction for the estimated inhaled dose. Paired comparisons yielded a statistically significant increase between R₀ and R_max (mean difference, 0.58: 95% CI 0.43-0.73; P < 0.001). Individual AUEC correlated with AUC (r = 0.3890, r² = 0.1513; P = 0.045); significance increased after exclusion of non-responders (r = 4787, r² = 0.2292; P = 0.024). Individual AUEC correlated with ∆R_max-R0 (r = 5973, r² = 0.3568; P = 0.001). Both ∆R_max-R0 (P = 0.009) and CPB duration (P < 0.001) were identified as predictors of DSB. In conclusion, both magnitude of peak response of the mAP/mPAP ratio and CPB duration were associated with DSB.

Longitudinal Validation of Right Ventricular Pressure Monitoring for the Assessment of Right Ventricular Systolic Dysfunction in a Large Animal Ischemic Model

Right ventricular (RV) dysfunction is a major cause of morbidity and mortality in intensive care and cardiac surgery. Early detection of RV dysfunction may be facilitated by continuous monitoring of RV waveform obtained from a pulmonary artery catheter. The objective is to evaluate the extent to which RV pressure monitoring can detect changes in RV systolic performance assess by RV end-systolic elastance (E_es) following the development of an acute RV ischemic in a porcine model.

HYPOTHESIS

RV pressure monitoring can detect changes in RV systolic performance assess by RV E_es following the development of an acute RV ischemic model.

METHODS AND MODELS

Acute ischemic RV dysfunction was induced by progressive embolization of microsphere in the right coronary artery to mimic RV dysfunction clinically experienced during cardiopulmonary bypass separation caused by air microemboli. RV hemodynamic performance was assessed using RV pressure waveform-derived parameters and RV E_es obtained using a conductance catheter during inferior vena cava occlusions.

RESULTS

Acute ischemia resulted in a significant reduction in RV E_es from 0.26 mm Hg/mL (interquartile range, 0.16-0.32 mm Hg/mL) to 0.14 mm Hg/mL (0.11-0.19 mm Hg/mL; p < 0.010), cardiac output from 6.3 L/min (5.7-7 L/min) to 4.5 (3.9-5.2 L/min; p = 0.007), mean systemic arterial pressure from 72 mm Hg (66-74 mm Hg) to 51 mm Hg (46-56 mm Hg; p < 0.001), and mixed venous oxygen saturation from 65% (57-72%) to 41% (35-45%; p < 0.001). Linear mixed-effect model analysis was used to assess the relationship between E_es and RV pressure-derived parameters. The reduction in RV E_es best correlated with a reduction in RV maximum first derivative of pressure during isovolumetric contraction (dP/dt_max) and single-beat RV E_es. Adjusting RV dP/dt_max for heart rate resulted in an improved surrogate of RV E_es.

INTERPRETATION AND CONCLUSIONS

Stepwise decreases in RV E_es during acute ischemic RV dysfunction were accurately tracked by RV dP/dt_max derived from the RV pressure waveform.

Inhaled Epoprostenol and Milrinone Effect on Right Ventricular Pressure Waveform Monitoring

BACKGROUND

Pulmonary hypertension (PH) and right ventricular (RV) dysfunction are major complications in cardiac surgery. This study aimed to evaluate the change in RV pressure waveform in patients receiving a combination of inhaled epoprostenol and inhaled milrinone (iE&iM) before cardiopulmonary bypass (CPB) and to assess the safety of this approach with a matched case-control group.

METHODS

A prospective single-centre cohort study of adult patients undergoing cardiac surgery administered iE&iM through an ultrasonic mesh nebulizer. RV pressure waveform monitoring was obtained by continuously transducing the RV port of the pulmonary artery (PA) catheter.

RESULTS

The final analysis included 26 patients receiving iE&iM. There was a significant drop in mean PA pressure (MPAP) (-4.8 ± 8.7, P = 0.010), systolic PA pressure (SPAP) (-8.2 ± 12.8, P = 0.003), RV end-diastolic pressure (RVEDP) (-2.1 ± 2.8, P < 0.001) and RV diastolic pressure gradient (RVDPG) (-1.7 ± 1.4, P < 0.001) after 17 ± 9 minutes of iE&iM administration. Patients also had a significant increase in RV outflow tract (RVOT) gradient (3.7 ± 4.7, P < 0.001), RV maximal rate of pressure rise during early systole (dP/dt max) (68.3 ± 144.7, P = 0.024), and left ventricular (LV) dP/dt max (66.4 ± 90.1, P < 0.001). Change in RVOT gradient was only observed in those with a positive pulmonary vasodilator response to treatment. Treatment with iE&iM did not present adverse effects when compared with a matched case-control group.

CONCLUSIONS

Coadministration of iE&iM in cardiac surgery patients presenting with PH or signs of RV dysfunction is a safe and effective treatment approach in improving RV function. Appearance of a transient increase in RVOT gradient after iE&iM could be useful to predict response to treatment.

Behavior of echocardiographic parameters of right ventricular function after tricuspid surgery

Evaluation of right ventricular (RV) function after tricuspid valve surgery is complex. The objective was to identify the most appropriate RV function parameters for this purpose. This prospective study included 70 patients undergoing cardiac and tricuspid valve (TV) surgery. RV size and function parameters were determined at 3 months and 1-year post-surgery. Categorical variables were analyzed with the McNemar test and numerical variables with the Student's t-test for related samples or, when non-normally distributed, the Wilcoxon test. Spearman's rho was used to determine correlations between variables at 3 months and 1 year. RV diameters were reduced at 3 months post-surgery and were then unchanged at 1 year. Tricuspid annular plane systolic excursion (TAPSE) and S' wave values were worse at 3 months and then improved at 1 year (t-score-2.35, p 0.023; t-score-2.68; p 0.010). There was no significant reduction in free wall longitudinal strain (LS) or shortening fraction (SF) at 3 months (t-score 1.421 and - 1.251; p 0.218 and 0.172), and they were only slightly below pre-surgical values at 1 year. No relationship was found between RV function parameters and mortality or major complications. During the first few months after TV surgery, LS may be a more appropriate parameter to evaluate global ventricular function in comparison to TAPSE. At 1 year, good correlations are observed between TAPSE, S' wave, and LS values.

Indicators of the Right Ventricle Systolic and Diastolic Function 18 Months after Coronary Bypass Surgery

Objective. Right ventricular (RV) dysfunction after coronary artery bypass grafting (CABG) is associated with increased mortality and morbidity. In previous studies, the parameters of RV systolic function were mainly assessed, while the dynamics of RV diastolic function after surgery was practically not studied. The aim of this study was to study the dynamics of indicators of systolic and diastolic RV function after CABG as well as to identify factors associated with their presence. Methods. The study included 160 patients who underwent CABG and 36 volunteers with no history of coronary artery disease (CAD) as a control group. Echocardiographic examination of patients was performed to assess systolic and diastolic RV dysfunction before surgery and 18 months after CABG. A level of s’t < 10 cm/sec or TAPSE < 16 mm was considered as a sign of existing RV systolic dysfunction. RV diastolic dysfunction was defined as an Et/At ratio < 0.8 or >2.1 and/or an Et/et’ ratio > 6. Results. In CAD patients 18 months after CABG, there was an increase in the frequency of the right ventricular systolic (from 7.5% to 30%, p < 0.001) and diastolic (from 41.8% to 57.5%, p < 0.001) dysfunction. An increase in TAPSE (p = 0.007), a decrease in e’t (p = 0.005), and the presence of RV systolic dysfunction before surgery (p = 0.023) was associated with a significant increase in the likelihood of detecting RV systolic dysfunction 18 months after CABG (χ2(3) = 17.4, p = 0.001). High values of At before surgery (p = 0.021) and old myocardial infarction (p = 0.023) were significantly associated with an increased likelihood of detection of RV diastolic dysfunction 18 months after CABG (χ2(2) = 10.78, p = 0.005). Conclusions. This study demonstrated that in CAD patients 18 months after CABG, there was an increase in the frequency of right ventricular systolic and diastolic dysfunction. We also established the initial clinical, echocardiographic parameters, and perioperative complications associated with the presence of these changes in the postoperative period. The clinical and prognostic significance of the presence of systolic and/or diastolic RV dysfunction in patients 18 months after CABG remains to be explored.

A proposed algorithm for combining transcranial Doppler ultrasound monitoring with cerebral and somatic oximetry: a case report

PURPOSE

Transcranial Doppler (TCD) ultrasound is a non-invasive monitor of cerebral blood velocity that can be used intraoperatively. The purpose of this report is to describe how different patterns seen on TCD can help identify the cause of cerebral desaturation when near-infrared spectroscopy (NIRS) oximetry is used concomitantly.

CLINICAL FEATURES

A 69-yr-old male patient undergoing coronary revascularisation and aortic valve replacement developed perioperative complications that were detected using a combination of transtemporal TCD of the middle cerebral artery along with cerebral and somatic NIRS. Initial brain desaturation was secondary to hypocapnia during which TCD-derived blood velocity and somatic NIRS values remained unchanged. After the procedure, a second episode of brain desaturation occurred secondary to a technical issue with the aortic valve prosthesis requiring a return to cardiopulmonary bypass (CPB); there were no high-intensity transient signals (HITS) on TCD. Brain desaturation occurred a third time following the second attempt to separate from CPB at which time TCD detected a significant amount of HITS suggesting air emboli that were associated with acute right ventricular dysfunction; there was also a reduction in somatic NIRS.

CONCLUSIONS

Combining TCD with cerebral NIRS allows for the rapid identification of three different mechanisms of brain desaturation. An algorithm is proposed to help identify the origin of NIRS cerebral desaturation. Prospective clinical trials are needed to investigate potential benefits of multimodal brain monitoring and its impact on short and/or long-term clinical outcomes.

Point-of-care echocardiography for the evaluation of right-to-left cardiopulmonary shunts: a narrative review

Right-to-left pulmonary and cardiac shunts (RLS) are important causes of refractory hypoxia in the critically-ill perioperative patient. Using a point-of-care ultrasound (POCUS) agitated saline bubble study for an early diagnosis allows patients with clinically significant RLSs to receive expedited therapy. This narrative review discusses the principles of agitated saline ultrasonography as well as the role of POCUS in detecting the most common RLS types seen in the intensive care unit, including patent foramen ovale, atrial septal defects, and pulmonary arterio-venous malformations. An illustrated discussion of the procedure, as well as shunt-enhancing maneuvers (Valsalva or lung recruitment maneuver with subsequent rapid release) is provided. With the wide dissemination of bedside ultrasound within the perioperative and critical care arena, POCUS practitioners should be knowledgeable of the potential pitfalls leading to both false-positive and false-negative studies. False-positive studies may be due to congenital abnormalities, mischaracterization of intrapulmonary shunts as intracardiac shunts (and vice versa), or evidence of the Valsalva effect. False negatives are typically due to respiratory-phasic variation, performing an inadequate shunt-enhancing maneuver, inadequate injection of agitated saline, or pathophysiologic states of elevated left atrial pressure. Finally, alternative POCUS methods for determining presence of an RLS in patients with poor echocardiographic windows are discussed, with a focus on pulsed-wave Doppler interrogation of arterial signals.