Effects of pericardiocentesis on renal function and cardiac hemodynamics.

BACKGROUND: Previous case studies have reported reversal of acute renal failure after pericardiocentesis in pericardial effusion. This study examines the effects of pericardiocentesis on preprocedural low cardiac output and acute renal dysfunction in patients with pericardial effusion. METHODS: This is a retrospective study of 95 patients undergoing pericardiocentesis between 2015 and 2020. Pre- and post-procedure transthoracic echocardiograms (TTE) were reviewed for evidence of cardiac tamponade, resolution of pericardial effusion, and for estimation of right atrial (RA) pressure and cardiac output. Laboratory values were compared at presentation and post-procedure. Patients on active renal replacement therapy were excluded. RESULTS: Ninety-five patients were included for analysis (mean age 62.2 ± 17.8 years, 58% male). There was a significant increase in glomerular filtration rate pre- and post-procedure. Fifty-six patients (58.9%) had an improvement in glomerular filtration rate after pericardiocentesis (termed "responders"), and these patients had a lower pre-procedure glomerular filtration rate than "non-responders." There was a significant improvement in estimated cardiac output and right atrial pressure for patients in both groups. Patients who had an improvement in renal function had significantly lower pre-procedural diastolic blood pressure and mean arterial pressure. CONCLUSIONS: Pericardial drainage may improve effusion-mediated acute renal dysfunction by reducing right atrial pressure and thus systemic venous congestion, and by increasing forward stroke volume and perfusion pressure.

Post-COVID-19 Peripartum Cardiomyopathy: Experience from a Large Tertiary Referral Center.

BACKGROUND: Peripartum cardiomyopathy (PPCM) is a rare but potentially devastating complication of pregnancy. Although the pathophysiology of PPCM is not fully understood, there are known risk factors for developing PPCM, which are maternal and gestation related. In the first wave of the coronavirus disease 2019 (COVID-19) pandemic, we witnessed an elevated incidence of PPCM among COVID-19 survivors. OBJECTIVES: To present a single-center case series of three patients diagnosed with peripartum cardiomyopathy after recovered from COVID-19 during the index pregnancy. METHODS: In this single center case study, all patients diagnosed with PPCM at our institute during the examined time frame were included. Electronic medical records were studied. RESULTS: Three patients previously diagnosed with asymptomatic or mildly symptomatic COVID-19 disease during pregnancy presented with PPCM before or shortly after delivery. Patients underwent testing to rule out residual COVID-19 myocarditis, were treated pharmacologically and with wearable defibrillators as needed, and were examined in follow-up 1-9 months after delivery. CONCLUSIONS: Residual endothelial damage due to COVID-19 disease, even if originally mild in presentation, could predispose pregnant patients to PPCM and should be considered as a risk factor when assessing patients with new onset symptoms of heart failure. Further research is needed to confirm this hypothesis and fully determine the underlying pathophysiology. These preliminary findings warrant a high index of suspicion for PPCM in COVID-19 recoverers.

Predictors of Adverse Outcome in High-Risk Percutaneous Coronary Interventions Patients.

BACKGROUND: Identifying high-risk percutaneous coronary intervention (PCI) patients is challenging. We aimed to evaluate which high-risk patients are prone to adverse events. METHODS: We performed a retrospective study including consecutive high-risk PCIs from 2005 to 2018 in a large tertiary medical centre. Patients with unprotected left main (LM) disease, last patent coronary vessel, or 3-vessel coronary artery disease with left ventricular ejection fraction < 35% were included. A predictive 30-day major adverse cardiac events (MACE) score consisting of any myocardial infarction, all-cause death, or target-vessel revascularisation was constructed. RESULTS: From 2005 to 2018, a total of 1890 patients who underwent PCI met the predefined high-risk PCI criteria. Mortality rate was 8.8% at 30 days and 20.7% at 1 year, and 30-day MACE rate was 14.2% and 33.5% at 1 year. Predictors of short-term MACE were New York Heart Association functional class (NYHA) 4 (hazard ratio [HR] 6.65; P < 0.001), systolic blood pressure (SBP) < 90 mm Hg (HR 4.93; P < 0.001), creatinine > 1.3 mg/dL (HR 3.57; P < 0.001), hemoglobin < 11.0 g/dL (HR 3.07; P < 0.001), pulmonary artery systolic pressure > 50 mm Hg (HR 2.06; P < 0.001), atrial fibrillation (HR 1.74; P < 0.001), and LM disease (HR 2.04; P < 0.001) or last patent vessel (HR 1.70; P = 0.002). A score constructed from these parameters reached a sensitivity of 90% and a specificity of 81% with areas under the receiver operating characteristic curve of 0.92 for MACE and 0.94 with 89% sensitivity and 87% specificity for all-cause mortality. CONCLUSIONS: Specific features such as LM lesion or last patent conduit, pulmonary hypertension, atrial fibrillation, anemia, and renal failure, along with low SBP and NYHA 4, aid risk stratification and consideration of further treatment measures.

Soft tissue displacement for detection of left ventricle apical dyskinesis with transthoracic echocardiography.

We tested the hypothesis that the use of outward displacement of the soft tissue between the apex and the chest wall as seen in TTE, is a sign of apical displacement and would allow for more accurate diagnosis of apical dyskinesis. This is a retrospective study of 123 patients who underwent TTE and cardiac magnetic resonance imaging (MRI) within a time frame of 6 months between 2008 and 2019. 110 subjects were deemed to have good quality studies and included in the final analysis. An observer blinded to the study objectives evaluated the echocardiograms and recorded the presence or absence of apical dyskinesis. Two independent observers evaluated the echocardiograms based on the presence or absence of outward displacement of the overlying tissue at the LV apex. Cardiac MRI was used to validate the presence of apical dyskinesis. The proportion of studies which were identified as having apical dyskinesis with conventional criteria defined as outward movement of the left ventricular apex during systole were compared to those deemed to have dyskinesis based on tissue displacement. By cardiac MRI, 90 patients had apical dyskinesis. Using conventional criteria on TTE interpretation, 21 were diagnosed with apical dyskinesis (23.3%). However, when soft tissue displacement was used as the diagnostic marker of dyskinesis, 78 patients (86.7%) were diagnosed with dyskinesis, p < 0.01. Detection of displacement of soft tissue overlying the LV apex facilitates better recognition of LV apical dyskinesis.

Nonobstructive coronary atherosclerosis is associated with adverse prognosis among patients diagnosed with myocardial infarction without obstructive coronary arteries.

BACKGROUND AND AIMS: The prognostic impact of nonobstructive coronary artery disease (CAD), as opposed to normal coronary arteries, on long-term outcomes of patients with myocardial infarction with no obstructive coronary arteries (MINOCA) is unclear. We aimed to address the association between nonobstructive-CAD and major adverse events (MAE) following MINOCA. METHODS: We conducted a retrospective cohort study of consecutive MINOCA patients admitted to a large referral medical center between 2005 and 2018. Patients were classified according to coronary angiography as having either normal-coronaries or nonobstructive-CAD. The primary outcome was MAE, defined as the composite of all-cause mortality and recurrent acute coronary syndrome (ACS). RESULTS: Of the 1544 MINOCA patients, 651 (42%) had normal coronaries, and 893 (58%) had CAD. The mean age was 61.2 ± 12.6 years, and 710 (46%) were females. Nonobstructive-CAD patients were older and less likely to be females, with higher rates of diabetes, hypertension, dyslipidemia, atrial fibrillation, and chronic renal-failure (p < 0.05). At a median follow-up of 7 years, MAE occurred in 203 (23%) patients and 67 (10%) patients in the nonobstructive-CAD and normal-coronaries groups, respectively (p < 0.01). In multivariable models, nonobstructive -CAD was significantly associated with long-term MAE [adjusted-hazard-ratio (aHR):1.67, 95% confidence-interval (95%CI):1.25-2.23; p < 0.001]. Other factors associated with a higher MAE-risk were older-age (aHR:1.05,95%CI:1.03-1.06; p < 0.001) and left ventricular ejection-fraction<40% (aHR:3.04,95%CI:2.03-4.57; p < 0.001), while female-sex (aHR:0.72, 95%CI: 0.56-0.94; p=0.014) and sinus rhythm at presentation (aHR:0.66, 95%CI: 0.44-0.98; p=0.041) were associated with lower MAE-risk. CONCLUSIONS: In MINOCA, nonobstructive-CAD is independently associated with a higher MAE-risk than normal-coronaries. This finding may promote risk-stratification of patients with nonobstructive-CAD-MINOCA who require tighter medical follow-up and treatment optimization.

Outcomes among patients admitted for non-ST-segment myocardial infarction in the pre-pandemic and pandemic COVID-19 era: Israel Nationwide study.

BACKGROUND: Since the beginning of the coronavirus disease 2019 (COVID-19) pandemic in 2019, several countries have reported a substantial drop in the number of patients admitted with non-ST-segment myocardial infarction (NSTEMI). OBJECTIVE: We aimed to evaluate the changes in admissions, in-hospital management and outcomes of patients with NSTEMI in the COVID-19 era in a nationwide survey. METHOD: A prospective, multicenter, observational, nationwide study involving 13 medical centers across Israel aimed to evaluate consecutive patients with NSTEMI admitted to intensive cardiac care units over an 8-week period during the COVID-19 outbreak and to compare them with NSTEMI patients admitted at the same period 2 years earlier (control period). RESULTS: There were 624 (43%) NSTEMI patients, of whom 349 (56%) were hospitalized during the COVID-19 era and 275 (44%) during the control period. There were no significant differences in age, gender and other baseline characteristics between the two study periods. During the COVID-19 era, more patients arrived at the hospital via an emergency medical system compared with the control period (P = 0.05). Time from symptom onset to hospital admission was longer in the COVID-19 era as compared with the control period [11.5 h (interquartile range, IQR, 2.5-46.7) vs. 2.9 h (IQR 1.7-6.8), respectively, P < 0.001]. Nevertheless, the time from hospital admission to reperfusion was similar in both groups. The rate of coronary angiography was also similar in both groups. The in-hospital mortality rate was similar in both the COVID-19 era and the control period groups (2.3% vs. 4.7%, respectively, P = 0.149) as was the 30-day mortality rate (3.7% vs. 5.1%, respectively, P = 0.238). CONCLUSION: In contrast to previous reports, admission rates of NSTEMI were similar in this nationwide survey during the COVID-19 era. With longer time from symptoms to admission, but with the same time from hospital admission to reperfusion therapy and with similar in-hospital and 30-day mortality rates. Even in times of crisis, adherence of medical systems to clinical practice guidelines ensures the preservation of good clinical outcomes.

Immediate and early percutaneous coronary intervention in very high-risk and high-risk non-ST segment elevation myocardial infarction patients.

BACKGROUND: The European Society of Cardiology (ESC) guidelines for the management of acute coronary syndromes in patients presenting without persistent ST-segment elevation (non-ST-segment elevation myocardial infarction [NSTEMI]) has recommended immediate (<2 h) percutaneous coronary intervention (PCI) in very-high risk patients and early (<24 h) PCI in high-risk patients. HYPOTHESIS: To examine the ESC NSTEMI guidelines adherence in a nationwide survey in Israel using the Acute Coronary Syndrome Israeli Survey (ACSIS). We hypothesized that adherence to the guidlines' recommnded PCI timing in NSTEMI pateints will be inadequate, partly due to the inconsistent evidence regarding its effect on clinical outcomes. METHODS: All NSTEMI patients who underwent PCI during the ACSIS surveys in 2016 and 2018 were included in the analysis. RESULTS: Out of 1793 NSTEMI patients, 1643 (92%) patients underwent PCI, and door to balloon time was documented in 1078 of them. One hundred and fifty-six (14.5%) patients and 922 (85.5%) patients were defined as very high-risk and high-risk NSTEMI patients, respectively. Of the very high-risk NSTEMI patients, only 10 (6.4%) underwent immediate coronary angiography, and 50 (32.1%) underwent early coronary angiography. Acute heart failure 139 (89.1%) was the main reason for including NSTEMI patients in the very high-risk category. Of the high-risk patients, early coronary angiography was performed in only 405 (43.9%) patients. Patients in whom coronary angiography was postponed were older and had more comorbidities. CONCLUSIONS: Despite guidelines recommendations for immediate and early PCI in very high-risk and high-risk NSTEMI patients, respectively, most patients do not undergo immediate or early PCI according to contemporary guidelines. Further studies are needed to better understand the reasons for guidelines' nonadherence in those high-risk patients.

The Use of Colchicine in Cardiovascular Diseases: A Systematic Review.

The medicinal properties of colchicine have been recognized for centuries. Although previously used for gout and familial Mediterranean fever, its immune-modulating, anti-inflammatory, and antifibrotic effects are increasingly recognized as beneficial in the treatment of cardiovascular disorders. In this systematic review, we summarize the current evidence on colchicine's effectiveness in 1) pericarditis, 2) coronary artery disease, and 3) atrial fibrillation. We also discuss the safety, potential adverse effects, and common drug interactions that should be considered during use.

Left ventricular global longitudinal strain in identifying subclinical myocardial dysfunction among patients hospitalized with COVID-19.

BACKGROUND: The incidence of acute cardiac injury in COVID-19 patients is very often subclinical and can be detected by cardiac magnetic resonance imaging. The aim of this study was to assess if subclinical myocardial dysfunction could be identified using left ventricular global longitudinal strain (LV-GLS) in patients hospitalized with COVID-19. METHODS: We performed a search of COVID-19 patients admitted to our institution from January 1st, 2020 to June 8th, 2020, which revealed 589 patients (mean age = 66 ± 18, male = 56%). All available 60 transthoracic echocardiograms (TTE) were reviewed and off-line assessment of LV-GLS was performed in 40 studies that had sufficient quality images and the views required to calculate LV-GLS. We also analyzed electrocardiograms and laboratory findings including inflammatory markers, Troponin-I, and B-type natriuretic peptide (BNP). RESULTS: Of 589 patients admitted with COVID-19 during our study period, 60 (10.1%) underwent TTE during hospitalization. Findings consistent with overt myocardial involvement included reduced ejection fraction (23%), wall motion abnormalities (22%), low stroke volume (82%) and increased LV wall thickness (45%). LV-GLS analysis was available for 40 patients and was abnormal in 32 patients (80%). All patients with LV dysfunction had elevated cardiac enzymes and positive inflammatory biomarkers. CONCLUSIONS: Subclinical myocardial dysfunction as measured via reduced LV-GLS is frequent, occurring in 80% of patients hospitalized with COVID-19, while prevalent LV function parameters such as reduced EF and wall motion abnormalities were less frequent findings. The mechanism of cardiac injury in COVID-19 infection is the subject of ongoing research.

Re-Appraisal of Echocardiographic Assessment in Patients with Pulmonary Embolism: Prospective Blinded Long-Term Follow-Up.

BACKGROUND: Acute pulmonary embolism (PE) is considered to be one of the most common cardiovascular diseases with considerable mortality. Conflicting data imply possible role for echocardiography in assessing this disease. OBJECTIVES: To determine which of the echo parameters best predicts short-term and long-term mortality in patients with PE. METHODS: We prospectively enrolled 235 patients who underwent computed tomography of pulmonary arteries (CTPA) and transthoracic Echocardiography (TTE) within < 24 hours. TTE included a prospectively designed detailed evaluation of the right heart including right ventricular (RV) myocardial performance index (RIMP), RV end diastolic and end systolic area, RV fractional area change, acceleration time (AT) of pulmonary flow and visual estimation. Interpretation and performance of TTE were blinded to the CTPA results. RESULTS: Although multiple TTE parameters were associated with PE, all had low discriminative capacity (AUC < 0.7). Parameters associated with 30-day mortality in univariate analysis were acceleration time (AT) < 81 msec (P = 0.04), stroke volume < 44 cc (P = 0.005), and RIMP > 0.42 (P = 0.05). The only RV independent echo parameter associated with poor long-term prognosis (adjusted for significant clinical, and routine echo associates of mortality) was RIMP (hazard ratio 3.0, P = 0.04). The only independent RV echo parameters associated with mortality in PE patients were RIMP (P = 0.05) and AT (P = 0.05). Addition of RIMP to nested models eliminated the significance of all other parameters assessing RV function. CONCLUSIONS: Doppler-based parameters like pulmonary flow AT, RIMP, and stroke volume, have additive value in addition to visual RV estimation to assess prognosis in patients with PE.

Right-Sided Infective Endocarditis 2020: Challenges and Updates in Diagnosis and Treatment.

Compared with the extensive data on left-sided infective endocarditis (IE), there is much less published information on the features and management of right-sided IE. Right-sided IE accounts for 5% to 10% of all IE cases, and compared with left-sided IE, it is more often associated with intravenous drug use, intracardiac devices, and central venous catheters, all of which has become more prevalent over the past 20 years. In this manuscript on right-sided IE we provide an up-to-date overview on the epidemiology, etiology, microbiology, potential locations of infection in the right heart, diagnosis, imaging, common complications, management, and prognosis. We present updated information on the treatment of pacemaker and device infections, infected fibrin sheaths that appear to be an easily missed source of infection after central line as well as pacemaker removal. We review current data on the AngioVac percutaneous aspiration device, which can obviate the need for surgery in patients with infected pacemaker leads and fibrin sheaths. We also focused on advanced diagnostic modalities, such as positron emission tomography/computed tomography. All of these are supported by specific case examples with detailed echocardiographic imaging from our experience.

Left ventricular cavity obliteration: Mechanism of the intracavitary gradient and differentiation from hypertrophic obstructive cardiomyopathy.

BACKGROUND: Controversy surrounds the cause of the pressure gradient in patients with hypertrophic obstructive cardiomyopathy (HOCM). Left ventricular cavity obliteration (LVCO) was first described as the cause of the gradient but subsequently systolic anterior motion (SAM) of the mitral valve has been established as the cause. Nevertheless, the two gradients, though different in origin and significance, share similar characteristics. They both have a similar "dagger" profile, are obtained from the cardiac apex, are associated with a hyperdynamic left ventricle, and the gradients are worsened by Valsalva. The distinction has clinical relevance, because treating the intracavitary gradient (ICG) of LVCO as if it were a SAM-associated gradient associated with HOCM would be inappropriate and possibly harmful. MATERIALS AND METHODS: To clarify the cause and characteristics of the ICG in patients with LVCO in patients without HOCM, we assessed the extent and duration of cavity obliteration, and for differentiation, we compared the spectral profiles with patients with HOCM and severe aortic stenosis (AS). RESULTS: Higher ICG is associated with a greater extent and more prolonged apposition of LV walls, and smaller left ventricular cavity size. The spectral profile of patients with AS, HOCM, and LVCO is differentiated by the peak/mean gradient ratios of 2 or less, 2-3, and 3 or greater, respectively, in >90% of patients. Most patients with LVCO without HOCM or severe LVH have an ICG < 36 mm Hg. CONCLUSION: The magnitude of ICG is quantitatively associated with the extent and duration of LVCO. Spectral profiles of severe AS, HOCM, and LVCO can be differentiated by the peak/mean gradient ratio.

Asymptomatic Degenerative Mitral Regurgitation: A Review.

Importance: Most patients with severe degenerative mitral regurgitation (DMR) are likely to require surgery, but years can pass until there is a clear indication for it. The timing of mitral valve surgery for asymptomatic patients with severe DMR is controversial, and current guidelines are limited because they are based on nonrandomized studies and expert opinion. Observations: In this narrative review, a decrease in left ventricular ejection fraction and an increase in left ventricular end-systolic diameter are adverse signs in the context of mitral regurgitation. Consequently, serial echocardiography is essential. However, measurements may be imprecise, and the evidence regarding the association with outcome in asymptomatic patients is inconsistent. Mitral valve repair is the preferred surgical approach; however, repair rate, durability, and outcomes vary between centers, rendering decision-making in an asymptomatic patient with DMR even more challenging. The use of natriuretic peptides, stress testing, cardiac magnetic resonance imaging, and myocardial strain imaging can aid in risk stratification and optimization of the timing of mitral valve surgery in an asymptomatic patient. Conclusions and Relevance: Management of asymptomatic patients with DMR requires a comprehensive approach that goes beyond the guidelines. Close follow-up and the use of multiple modalities are recommended. Knowledge of surgical options, experience, and outcomes is important when an intervention is considered.

Coronary Artery Fistula: An Unexpected Cause of Heart Failure in a 58-Year-Old Woman.

Coronary artery fistula (CAF) is an abnormal connection between a coronary artery and a heart chamber resulting in left-to-right shunt. A large CAF was an unexpected cause of heart failure in a 58-year-old woman who underwent transcatheter closure of the CAF with improvement in symptoms but complicated by myocardial infarction. (Level of Difficulty: Beginner.).

Aortic Regurgitation.

PURPOSE OF REVIEW: Aortic regurgitation (AR) is a common form of valvular disease which is characterized by reflux of blood from the aorta into the left ventricle (LV) during diastole. AR results from various etiologies, affecting the aortic valve cusps or the aortic root. The clinical presentation of patients with AR depends on the severity of the regurgitation and differs whether AR develops acutely or if it progresses over a prolonged period, allowing the cardiac chambers to adapt. Echocardiography is the primary method to determine the etiology of AR and to define its severity. We review the current data regarding the diagnosis and treatment of AR. RECENT FINDINGS: No single parameter is sufficient to determine AR severity; thus, an integrative, multi-parametric approach is required. Echocardiography is key for imaging the aortic valve morphology and flow as well as aortic root and ascending aorta. Determining LV ejection fraction and dimensions is essential for patient management and optimizing timing for intervention. Three-dimensional (3D) echocardiography is useful in the evaluation of AR etiology and severity. The use of Trasncatheter aortic valve replacement (TAVR) has emerged as an alternative to surgery in patients at high operative risk. The diagnosis and management of AR requires a comprehensive approach and routine clinical and echocardiographic follow-up. Surgical or percutaneous therapy is indicated when symptoms develop and in those who have LV dysfunction or LV dilation.

Differentiating the QRS Morphology of Posterior Fascicular Ventricular Tachycardia From Right Bundle Branch Block and Left Anterior Hemiblock Aberrancy.

BACKGROUND: Left posterior fascicular ventricular tachycardia (LPF-VT) is frequently misdiagnosed as supraventricular tachycardia with aberrant right bundle branch block (RBBB) and left anterior hemiblock (LAHB). The purpose of the present study was to define the morphological ECG characteristics of LPF-VT and attempt to differentiate it from RBBB and LAHB aberrancy. METHODS AND RESULTS: A systematic Medline search was used to identify or locate ECG tracings from patients with LPF-VTs. ECGs with LPF-VT were also collected from patients who underwent ablation of this arrhythmia at the Tel Aviv and Sheba Medical Centers. These ECGs were compared with ECGs of consecutive patients with RBBB and LAHB and no obvious cardiac pathology by echocardiography. Overall, 183 ECGs of LPF-VT were compared with 61 ECGs showing RBBB and LAHB. Univariate analysis demonstrated differences in QRS axis, limb (I, aVr), and precordial (V1, V2, V6) ECG leads. On multivariate logistic regression analysis, LPF-VT was more often associated with atypical RBBB-like V1 morphology (odds ratio, 5.1; P=0.004), positive QRS in aVr (odds ratio, 19.2; P<0.001), V6 R/S ratio ≤1 (odds ratio, 6.7; P=0.01), and QRS ≤140 ms (odds ratio, 7.7; P<0.001). Using these 4 variables, a prediction model was developed that predicted LPF-VT with sensitivity and specificity of 82.1% and 78.3%, respectively. Patients with 3 of 4 positive variables had high probability of having LPF-VT, whereas patients with ≤1 positive variable always had RBBB plus LAHB. CONCLUSIONS: The morphological ECG characteristics of LPF-VT were defined, and a high accurate tool for correctly differentiating LPF-VT from RBBB and LAHB aberrancy was developed.

Automatic assessment of cardiac load due to acute pulmonary embolism: Saddle vs. central and peripheral emboli distribution.

BACKGROUND: Changes in cardiac chambers' volumes in relations to different distributions of pulmonary embolism (PE) have not been investigated. OBJECTIVES: To compare cardiac chambers' volumes of patients with saddle, central or peripheral PE. METHODS: Consecutive patients with PE on computed tomography pulmonary angiography (CTPA), 1/2007-12/2010, divided according to emboli distribution. Software automatically provided the volumes of each cardiac compartment. We measured the ability of each chamber's volume and ratios between the right and left ventricles (RV/LV) and right and left atria (RA/LA) to discriminate between emboli locations. RESULTS: Among the 636 patients, 325 (51%) had peripheral, 278 (44%) central and 33 (5%) had saddle emboli. The RV/LV and RA/LA volume ratios discriminated well between saddle and central PE (AUC ≥0.74) and saddle and peripheral PE (AUC ≥0.83), but not between central and peripheral PE (AUC ≤0.6). CONCLUSION: Automatic volumetric analysis of diagnostic CTPAs provides rapid tool which can discriminate between cardiac responses in saddle, central or peripheral PE.