Low pulse pressure as a poor-manʼs indicator of a low cardiac index in patients with severe cardiac dysfunction

A multimodal stacked ensemble model for cardiac output prediction utilizing cardiorespiratory interactions during general anesthesia

This study examined the possibility of estimating cardiac output (CO) using a multimodal stacking model that utilizes cardiopulmonary interactions during general anesthesia and outlined a retrospective application of machine learning regression model to a pre-collected dataset. The data of 469 adult patients (obtained from VitalDB) with normal pulmonary function tests who underwent general anesthesia were analyzed. The hemodynamic data in this study included non-invasive blood pressure, plethysmographic heart rate, and SpO2. CO was recorded using Vigileo and EV1000 (pulse contour technique devices). Respiratory data included mechanical ventilation parameters and end-tidal CO2 levels. A generalized linear regression model was used as the metalearner for the multimodal stacking ensemble method. Random forest, generalized linear regression, gradient boosting machine, and XGBoost were used as base learners. A Bland-Altman plot revealed that the multimodal stacked ensemble model for CO prediction from 327 patients had a bias of - 0.001 L/min and - 0.271% when calculating the percentage of difference using the EV1000 device. Agreement of model CO prediction and measured Vigileo CO in 142 patients reported a bias of - 0.01 and - 0.333%. Overall, this model predicts CO compared to data obtained by the pulse contour technique CO monitors with good agreement.

Effects of chronic secondhand smoke exposure on cardiovascular regulation and the role of soluble epoxide hydrolase in mice

Background: Secondhand smoke (SHS) is a significant risk factor for cardiovascular morbidity and mortality with an estimated 80% of SHS-related deaths attributed to cardiovascular causes. Public health measures and smoking bans have been successful both in reducing SHS exposure and improving cardiovascular outcomes in non-smokers. Soluble epoxide hydrolase (sEH) inhibitors have been shown to attenuate tobacco exposure-induced lung inflammatory responses, making them a promising target for mitigating SHS exposure-induced cardiovascular outcomes. Objectives: The objectives of this study were to determine 1) effects of environmentally relevant SHS exposure on cardiac autonomic function and blood pressure (BP) regulation and 2) whether prophylactic administration of an sEH inhibitor (TPPU) can reduce the adverse cardiovascular effects of SHS exposure. Methods: Male C57BL/6J mice (11 weeks old) implanted with BP/electrocardiogram (ECG) telemetry devices were exposed to filtered air or 3 mg/m3 of SHS (6 hr/d, 5 d/wk) for 12 weeks, followed by 4 weeks of recovery in filtered air. Some mice received TPPU in drinking water (15 mg/L) throughout SHS exposure. BP, heart rate (HR), HR variability (HRV), baroreflex sensitivity (BRS), and BP variability were determined monthly. Results: SHS exposure significantly decreased 1) short-term HRV by ∼20% (p < 0.05) within 4 weeks; 2) overall HRV with maximum effect at 12 weeks (-15%, p < 0.05); 3) pulse pressure (-8%, p < 0.05) as early as week 4; and 4) BRS with maximum effect at 12 weeks (-11%, p < 0.05). Four weeks of recovery following 12 weeks of SHS ameliorated all SHS-induced cardiovascular detriments. Importantly, mice exposed to TPPU in drinking water during SHS-related exposure were protected from SHS cardiovascular consequences. Discussion: The data suggest that 1) environmental relevant SHS exposure significantly alters cardiac autonomic function and BP regulation; 2) cardiovascular consequences from SHS can be reversed by discontinuing SHS exposure; and 3) inhibiting sEH can prevent SHS-induced cardiovascular consequences.

A systemic congestive index (systemic pulse pressure to central venous pressure ratio) predicts adverse outcomes in patients undergoing valvular heart surgery

Background and Aims

Invasive hemodynamics may provide a more nuanced assessment of cardiac function and risk phenotyping in patients undergoing cardiac surgery. The systemic pulse pressure (SPP) to central venous pressure (CVP) ratio represents an integrated index of right and left ventricular function and thus may demonstrate an association with valvular heart surgery outcomes. This study hypothesized that a low SPP/CVP ratio would be associated with mortality in valvular surgery patients.

Methods

This retrospective cohort study examined adult valvular surgery patients with preoperative right heart catheterization from 2007 through 2016 at a single tertiary medical center (n = 215). Associations between the SPP/CVP ratio and mortality were investigated with univariate and multivariate analyses.

Results

Among 215 patients (age 69.7 ± 12.4 years; 55.8% male), 61 died (28.4%) over a median follow‐up of 5.9 years. A SPP/CVP ratio <7.6 was associated with increased mortality (relative risk 1.70, 95% confidence interval [CI] 1.08–2.67, p = .019) and increased length of stay (11.56 ± 13.73 days vs. 7.93 ± 4.92 days, p = .016). It remained an independent predictor of mortality (adjusted odds ratio 3.99, 95% CI 1.47–11.45, p = .008) after adjusting for CVP, mean pulmonary artery pressure, aortic stenosis, tricuspid regurgitation, smoking status, diabetes mellitus, dialysis, and cross‐clamp time.

Conclusions

A low SPP/CVP ratio was associated with worse outcomes in patients undergoing valvular heart surgery. This metric has potential utility in preoperative risk stratification to guide patient selection, prognosis, and surgical outcomes.

Systemic arterial pulsatility index (SAPi) predicts adverse outcomes in advanced heart failure patients

Ventriculo-arterial (VA) coupling has been shown to have physiologic importance in heart failure (HF). We hypothesized that the systemic arterial pulsatility index (SAPi), a measure that integrates pulse pressure and a proxy for left ventricular end-diastolic pressure, would be associated with adverse outcomes in advanced HF. We evaluated the SAPi ([systemic systolic blood pressure-systemic diastolic blood pressure]/pulmonary artery wedge pressure) obtained from the final hemodynamic measurement in patients randomized to therapy guided by a pulmonary arterial catheter (PAC) and with complete data in the Evaluation Study of Congestive Heart Failure and Pulmonary Artery Catheterization Effectiveness (ESCAPE) trial. Cox proportional hazards regression was performed for the outcomes of (a) death, transplant, left ventricular assist device (DTxLVAD) or hospitalization, (DTxLVADHF) and (b) DTxLVAD. Among 142 patients (mean age 56.8 ± 13.3 years, 30.3% female), the median SAPi was 2.57 (IQR 1.63-3.45). Increasing SAPi was associated with significant reductions in DTxLVAD (HR 0.60 per unit increase in SAPi, 95% CI 0.44-0.84) and DTxLVADHF (HR 0.81 per unit increase, 95% CI 0.70-0.95). Patients with a SAPi ≤ 2.57 had a marked increase in both outcomes, including more than twice the risk of DTxLVAD (HR 2.19, 95% CI 1.11-4.30) over 6 months. Among advanced heart failure patients with invasive hemodynamic monitoring in the ESCAPE trial, SAPi was strongly associated with adverse clinical outcomes. These findings support further investigation of the SAPi to guide treatment and prognosis in HF undergoing invasive hemodynamic monitoring.

Pulse Pressure, Prognosis, and Influence of Sacubitril/Valsartan in Heart Failure With Preserved Ejection Fraction

Arterial stiffness is increased with increasing age, and pulse pressure (PP), a marker of arterial stiffness, is a predictor of incident cardiovascular disease and mortality. However, the prognostic relevance of PP in heart failure (HF) with preserved ejection fraction has not been fully understood. We studied 4796 patients with HF with preserved ejection fraction from the PARAGON-HF trial. All patients underwent sequential run-in phases of valsartan and sacubitril/valsartan before randomization. We categorized patients by PP quartile and evaluated the influence of baseline PP on the PARAGON-HF primary end point (total HF hospitalizations and cardiovascular death). At screening, the median PP was 58 mm Hg (interquartile range, 50-69 mm Hg). There was a nonlinear, J-shaped association between PP and outcomes. Multivariable Cox proportional hazards models showed that patients in the highest PP quartile had a higher risk of the primary end point (adjusted hazard ratio, 1.39 [95% CI, 1.14-1.69]; P=0.001), total HF hospitalizations (adjusted hazard ratio, 1.43 [95% CI, 1.15-1.79]; P=0.001), and myocardial infarction (adjusted hazard ratio, 1.54 [95% CI, 1.06-2.23]; P=0.022) compared with those in the second (lowest risk) PP quartile. Reductions in PP during sacubitril/valsartan run-in were associated with a decreased risk of the primary end point and total HF hospitalizations. One year after randomization, PP was significantly lower in the sacubitril/valsartan group compared with the valsartan group (3.0 mm Hg decrease [95% CI, 2.4-3.5]; P<0.001). In conclusion, PP was an independent predictor of cardiovascular events in patients with HF with preserved ejection fraction enrolled in PARAGON-HF. Sacubitril/valsartan lowered PP compared with valsartan.

Evaluation of pulse pressure and proportional pulse pressure as predictors of severity among patients having heart failure with reduced ejection fraction

Introduction:

Proportional Pulse Pressure (PPP) is a significant risk indicator in heart failure. PPP is a simple, inexpensive and easily measurable clinical index. This non-invasive test provides useful prognostic information for patients with heart failure with reduced ejection fraction (EF) particularly in those with an EF < 30% where lower proportional pulse pressure independently predicts mortality.

Methods:

A prospective observational study involving 150 patients with reduced ejection fraction was done. Detailed history, clinical examination and parameters like pulse pressure, proportional pulse pressure were evaluated and correlated with ejection fraction.

Results:

The mean age of the patients was 58.99 ± 11.03 years and the majority of the study participants (57.33 %) were between 45 and 65 years of age. The most common etiology of heart failure (HF) was coronary heart disease in this study (76%). Proportional Pulse pressure showed significant association with ejection fraction. The specificity for detecting heart failure was more for proportional pulse pressure and systolic blood pressure (95 % each).

Conclusion:

Proportional Pulse Pressure may help to identify HF patients who present with low cardiac output, low ejection fraction, and worse prognosis. Our current observations reinforce the importance of clinically based skills that must not be forgotten when managing HF.

Increased Pulmonary-Systemic Pulse Pressure Ratio Is Associated With Increased Mortality in Group 1 Pulmonary Hypertension

BACKGROUND

Pulmonary arterial hypertension (PAH) is characterised by remodelling of the pulmonary vasculature leading to right ventricular (RV) failure. The failing RV, through interventricular uncoupling, deleteriously impacts the left ventricle and overall cardiac efficiency. We hypothesised that the ratio of the pulmonary artery pulse pressure to the systemic pulse pressure ("pulmonary-systemic pulse pressure ratio", or PS-PPR) would be associated with mortality in PAH.

METHODS

We conducted a retrospective analysis of 262 patients in the National Institute of Health Primary Pulmonary Hypertension Registry (NIH-PPH). We evaluated the association between the PS-PPR and mortality after adjustment for the Pulmonary Hypertension Connection (PHC) risk equation.

RESULTS

Among 262 patients (mean age 37.5±15.8years, 62.2% female), median PS-PPR was 1.04 (IQR 0.79-1.30). In the Cox proportional hazards regression model, each one unit increase in the PS-PPR was associated with more than a two-fold increase in mortality during follow-up (HR 2.06, 95% CI 1.40-3.02, p=0.0002), and this association of PS-PPR with mortality remained significant in the multivariable Cox model adjusted for the PHC risk equation, mean pulmonary artery pressure, and body mass index (BMI) (adjusted HR 1.81, 95% CI 1.13-2.88, p=0.01). Furthermore, PS-PPR in the upper quartile (>1.30) versus quartiles 1-3 was associated with a 68% increase in mortality after adjustment for these same covariates (adjusted HR 1.68, 95% CI 1.13-2.50, p=0.01).

CONCLUSIONS

Pulmonary-systemic pulse pressure ratio, a marker of biventricular efficiency, is associated with survival in PAH even after adjustment for the PHC risk equation. Further studies are needed on the wider applications of PS-PPR in PAH patients.

Arterial pulse pressure and postoperative morbidity in high-risk surgical patients

BACKGROUND

Systemic arterial pulse pressure (systolic minus diastolic pressure) ≤53 mm Hg in patients with cardiac failure is correlated with reduced stroke volume and is independently associated with accelerated morbidity and mortality. Given that deconditioned surgical and heart failure patients share similar cardiopulmonary physiology, we examined whether lower pulse pressure is associated with excess morbidity after major surgery.

METHODS

This was a prospective observational cohort study of patients deemed by their preoperative assessors to be at higher risk of postoperative morbidity. Preoperative pulse pressure was calculated before cardiopulmonary exercise testing. The primary outcome was any morbidity (PostOperative Morbidity Survey) occurring within 5 days of surgery, stratified by pulse pressure threshold ≤53 mm Hg. The relationship between pulse pressure, postoperative morbidity, and oxygen pulse (a robust surrogate for left ventricular stroke volume) was examined using logistic regression analysis (accounting for age, sex, BMI, cardiometabolic co-morbidity, and operation type).

RESULTS

The primary outcome occurred in 578/660 (87.6%) patients, but postoperative morbidity was more common in 243/ 660 patients with preoperative pulse pressure ≤53 mm Hg{odds ratio (OR): 2.24 [95% confidence interval (CI): 1.29-3.38]; P<0.001). Pulse pressure ≤53 mm Hg [OR:1.23 (95% CI: 1.03-1.46); P=0.02] and type of surgery were independently associated with all-cause postoperative morbidity (multivariate analysis). Oxygen pulse <90% of population-predicted normal values was associated with pulse pressure ≤ 53 mm Hg [OR: 1.93 (95% CI: 1.32-2.84); P=0.007].

CONCLUSIONS

In deconditioned surgical patients, lower preoperative systemic arterial pulse pressure is associated with excess morbidity. These data are strikingly similar to meta-analyses identifying low pulse pressure as an independent risk factor for adverse outcomes in cardiac failure. Low preoperative pulse pressure is a readily available measure, indicating that detailed physiological assessment may be warranted.

CLINICAL TRIAL REGISTRATION

ISRCT registry, ISRCTN88456378.

Proportional pulse pressure relates to cardiac index in stabilized acute heart failure patients

AIMS

In chronic heart failure, proportional pulse pressure (PPP) is suggested as an estimate of cardiac index (CI). The association between CI and PPP in acute heart failure (AHF) has not been described.

METHODS

This was examined using hemodynamic measurements (from a trial using serelaxin) in 63 stabilized AHF patients.

RESULTS

Mean (SD) age was 68 (11), 74% male, mean (SD) ejection fraction (EF) was 33.4% (13.7), mean (SD) CI (L/min/m²) was 2.3 (0.6). CI correlated with PPP (Pearson R = 0.42; p < 0.0001) based on a linear mixed-effects model analysis of 171 pairs of measurements from 47 patients (out of 63) where CI and PPP were measured within 3 min of each other during. Serelaxin treatment did not modify the established correlation between CI and PPP. Time-weighted average CI correlated with time-weighted average PPP (Spearman Rank R = 0.35; p = 0.0051) over the -4 h to 24 h time interval. In a multivariable regression analysis, low PPP was an independent predictor of low CI (p < 0.0001).

CONCLUSIONS

In patients with AHF after initial clinical stabilization, both baseline and post-baseline CI measurements are positively related to PPP. This was the most closely related non-invasive blood pressure variable to CI.