Validierung der Herzleistung (Cardiac Power Output) in experimentellen Modellen des Herzversagens in Abhängigkeit von der Körpertemperatur

Einleitung: Das Cardiac Power Output (CPO) beschreibt das Produkt des Herzminutenvolumens und des mittleren aortalen Drucks. Bei Patienten im kardiogenen Schock gilt das CPO als bester Prädiktor der Mortalität. Die Fläche der Druck-Volumen- Kurve stellt die linksventrikuläre externe Schlagarbeit (LV SW) dar und entspricht dem Goldstandard zur Bestimmung der kardialen Funktion. Teilt man die LV SW durch den Faktor Zeit, ergibt sich ein Maß (LV SW/min), welches die Einheit des CPO trägt (W). Ziel dieser Arbeit war es, das CPO als Maß der externen Herzarbeit unter verschiedenen inotropen Zuständen zu validieren. Methoden: Experimentelle Daten von 59 anästhesierten Schweinen (68 ± 1 kg) wurden retrospektiv analysiert. Eine akute Instrumentierung der Schweine erfolgte ohne Thorax- Eröffnung (Swan-Ganz-Katheter, Konduktanzkatheter, rechtsatriale Schrittmachersonde, intraaortaler Valvuloplastie-Ballon-Katheter, intravenöser Kühlkatheter). Die Daten wurden bei milder Hypothermie (MH, 33 °C), Normothermie (NT, 38 °C) und Hyperthermie (HT, 40,5 °C) vor und nach Reanimation nach Kammerflimmern (Gruppe 1), Myokardinfarkt (Gruppe 2), Endotoxinämie (Gruppe 3), Sevofluran-induzierter myokardialer Depression (Gruppe 4) und vor oder während Dobutamin-Infusion (Gruppe 5) ermittelt. Mittels linearer Regressionsanalyse wurde das Verhältnis von LV SW und LV SW/min zu folgenden Parametern untersucht: CPO, LV Ejektionsfraktion (LV EF), Rate-Pressure-Product (RPP), Triple Product (TP), LV Spitzendruck (LVDmax) und maximale LV Druckanstiegsgeschwindigkeit (LV dP/dtmax). Ergebnisse: Das CPO korrelierte am besten mit LV SW/min (r2 = 0,89; p < 0,05). Die LV EF zeigte keine Korrelation der LV SW/min auf (r2 = 0,01; p = 0,259). Alle weiteren Parameter korrelierten signifikant, aber moderat mit der LV SW/min (RPP r2 = 0,67; TP r2 = 0,54 und LVPmax r2 = 0,47). LV dP/dtmax korrelierte am schlechtesten mit LV SW und LV SW/min (r2 = 0,23 bzw. r2 = 0,28). Zusammenfassung: Das CPO stellt über eine große Spannweite an inotropen Zuständen einen exzellenten Parameter der externen Herzarbeit dar. Die LV EF reflektiert die Herzarbeit in keiner Weise. Diese Daten untermauern die Verwendung des CPO als Maß der Herzleistung unter intensivmedizinischen Bedingungen.Background: Multiplying cardiac output with mean aortic pressure results in cardiac power output (CPO). CPO is the best indicator of hospital mortality in patients with cardiogenic shock. Left ventricular stroke work (LV SW) is represented by the pressure-volume loop area, which is the gold standard for measuring cardiac work. When LV SW is divided by time (LV SW/min) it has the same physical unit as CPO (W). It is unknown if CPO represents LV SW/min in different inotropic states. Methods: Data from 59 anaesthetized pigs (68 ± 1 kg) was analyzed retrospectively. Animals were instrumented with pulmonary artery catheters, pressure-conductance catheters, right atrial pacing electrodes, valvuloplasty balloon catheters, and intravenous cooling catheters. Data acquisition took place at different body temperatures (mild hypothermia, 33.0°C; normothermia, 38.0°C; hyperthermia, 40.5°C) before and after resuscitation following induced ventricular fibrillation (group 1), myocardial infarction (group 2), endotoxemia (group 3), sevoflurane-induced myocardial depression (group 4), or pre- or post-dobutamine administration (group 5). We investigated the relationships between LV SW or LVSW/min with CPO, LV ejection fraction, rate-pressure product, triple product, LV maximum pressure (LVPmax), and maximal rate of rise of LVP (LV dP/dtmax) as different parameters of cardiac function using linear regression analysis. Results: CPO had the strongest correlation with LV SW/min (r2 = 0,89; p < 0,05), while LV EF had no correlation with LV SW/min (r2=0,01; p=0,259). All other parameters had a statistically significant but modest correlation with LV SW/min (LVPmax r2 = 0,47; rate- pressure product r2 = 0,67 and p < 0,05; triple product r2 = 0,54; LV dP/dtmax r2 = 0,28). Conclusion: Over a large variety of inotropic states, CPO is a strong parameter of external cardiac work. During acute heart failure, LV ejection fraction does not measure external cardiac work in any way. These results encourage further use of CPO to track cardiac function in intensive care units

Thermodilution vs estimated Fick cardiac output measurement in an elderly cohort of patients: A single-centre experience

AIMS: Patients referred to the cath-lab are an increasingly elderly population. Thermodilution (TD, gold standard) and the estimated Fick method (eFM) are interchangeably used in the clinical routine to measure cardiac output (CO). However, their correlation in an elderly cohort of cardiac patients has not been tested so far. METHODS: A single, clinically-indicated right heart catheterization was performed on each patient with CO estimated by eFM and TD in 155 consecutive patients (75.1±6.8 years, 57.7% male) between April 2015 and August 2017. Whole Body Oxygen Consumption (VO2) was assumed by applying the formulas of LaFarge (LaF), Dehmer (De) and Bergstra (Be). CO was indexed to body surface area (Cardiac Index, CI). RESULTS: CI-TD showed an overall moderate correlation to CI-eFM as assessed by LaF, De or Be (r2 = 0.53, r2 = 0.54, r2 = 0.57, all p < .001, respectively) with large limits of agreement (-0.64 to 1.09, -1.07 to 0.77, -1.38 to 0.53 l/m2/min, respectively). The mean difference of CI between methods was 0.22, -0.15 and -0.42 (all p<0.001 for difference to TD), respectively. A rate of error ≥20% occurred with the equations by LaF, De or Be in 40.6%, 26.5% and 36.1% of patients, respectively. A CI <2.2 l/m2min was present in 42.6% of patients according to TD and in 60.0%, 31.0% and in 16.1% of patients according to eFM by the formulas of LaF, De or Be. CONCLUSION: Although CI-eFM shows an overall reasonable correlation with CI-TD, the predictive value in a single patient is low. CI-eFM cannot replace CI-TD in elderly patients

The non-invasive assessment of myocardial work by pressure-strain analysis: clinical applications

Pressure-volume (PV) analysis is the most comprehensive way to describe cardiac function, giving insights into cardiac mechanics and energetics. However, PV analysis still remains a highly invasive and time-consuming method, preventing it from integration into clinical practice. Most of the echocardiographic parameters currently used in the clinical routine to characterize left ventricular (LV) systolic function, such as LV ejection fraction and LV global longitudinal strain, do not take the pressure developed within the LV into account and therefore fall too short in describing LV function as a hydraulic pump. Recently, LV pressure-strain analysis has been introduced as a new technique to assess myocardial work in a non-invasive fashion. This new method showed new insights in comparison to invasive measurements and was validated in different cardiac pathologies, e.g., for the detection of coronary artery disease, cardiac resynchronization therapy (CRT)-response prediction, and different forms of heart failure. Non-invasively assessed myocardial work may play a major role in guiding therapies and estimating prognosis. However, its incremental prognostic validity in comparison to common echocardiographic parameters remains unclear. This review aims to provide an overview of pressure-strain analysis, including its current application in the clinical arena, as well as potential fields of exploitation

The role of non-invasive devices for the telemonitoring of heart failure patients

Heart failure (HF) patients represent one of the most prevalent as well as one of the most fragile population encountered in the cardiology and internal medicine departments nowadays. Estimated to account for around 26 million people worldwide, diagnosed patients present a poor prognosis and quality of life with a clinical history accompanied by repeated hospital admissions caused by an exacerbation of their chronic condition. The frequent hospitalizations and the extended hospital stays mean an extremely high economic burden for healthcare institutions. Meanwhile, the number of chronically diseased and elderly patients is continuously rising, and a lack of specialized physicians is evident. To cope with this health emergency, more efficient strategies for patient management, more accurate diagnostic tools, and more efficient preventive plans are needed. In recent years, telemonitoring has been introduced as the potential answer to solve such needs. Different methodologies and devices have been progressively investigated for effective home monitoring of cardiologic patients. Invasive hemodynamic devices, such as CardioMEMS™, have been demonstrated to be reducing hospitalizations and mortality, but their use is however restricted to limited cases. The role of external non-invasive devices for remote patient monitoring, instead, is yet to be clarified. In this review, we summarized the most relevant studies and devices that, by utilizing non-invasive telemonitoring, demonstrated whether beneficial effects in the management of HF patients were effective

Cardiac power output accurately reflects external cardiac work over a wide range of inotropic states in pigs

BACKGROUND: Cardiac power output (CPO), derived from the product of cardiac output and mean aortic pressure, is an important yet underexploited parameter for hemodynamic monitoring of critically ill patients in the intensive-care unit (ICU). The conductance catheter-derived pressure-volume loop area reflects left ventricular stroke work (LV SW). Dividing LV SW by time, a measure of LV SW min- 1 is obtained sharing the same unit as CPO (W). We aimed to validate CPO as a marker of LV SW min- 1 under various inotropic states. METHODS: We retrospectively analysed data obtained from experimental studies of the hemodynamic impact of mild hypothermia and hyperthermia on acute heart failure. Fifty-nine anaesthetized and mechanically ventilated closed-chest Landrace pigs (68 ± 1 kg) were instrumented with Swan-Ganz and LV pressure-volume catheters. Data were obtained at body temperatures of 33.0 °C, 38.0 °C and 40.5 °C; before and after: resuscitation, myocardial infarction, endotoxemia, sevoflurane-induced myocardial depression and beta-adrenergic stimulation. We plotted LVSW min- 1 against CPO by linear regression analysis, as well as against the following classical indices of LV function and work: LV ejection fraction (LV EF), rate-pressure product (RPP), triple product (TP), LV maximum pressure (LVPmax) and maximal rate of rise of LVP (LV dP/dtmax). RESULTS: CPO showed the best correlation with LV SW min- 1 (r2 = 0.89; p < 0.05) while LV EF did not correlate at all (r2 = 0.01; p = 0.259). Further parameters correlated moderately with LV SW min- 1 (LVPmax r2 = 0.47, RPP r2 = 0.67; and TP r2 = 0.54). LV dP/dtmax correlated worst with LV SW min- 1 (r2 = 0.28). CONCLUSION: CPO reflects external cardiac work over a wide range of inotropic states. These data further support the use of CPO to monitor inotropic interventions in the ICU

In-hospital Heart Rate Reduction With Beta Blockers and Ivabradine Early After Recovery in Patients With Acute Decompensated Heart Failure Reduces Short-Term Mortality and Rehospitalization

Objective: In the past years, heart rate (HR) has emerged as a highly relevant modifiable risk factor for heart failure (HF) patients. However, most of the clinical trials so far evaluated the role of HR in stable chronic HF cohorts. The aim of this multi-center, prospective observational study was to assess the association between HR and therapy with HR modulators (beta blockers, ivabradine, or a combination of ivabradine and beta blockers) at hospital discharge with patients' cardiovascular mortality and re-hospitalization at 6 months in acutely decompensated HF patients. Materials and Methods: We recruited 289 HF patients discharged alive after admission for HF decompensation from 10 centers in northern Italy over 9 months (from April 2017 to January 2018). The primary endpoint was the combination of cardiovascular mortality or re-hospitalizations for HF at 6 months. Results: At 6 months after discharge, 64 patients were readmitted (32%), and 39 patients died (16%). Multivariate analysis showed that HR at discharge >= 90 bpm (OR = 8.47; p = 0.016) independently predicted cardiovascular mortality, while therapy with beta blockers at discharge was found to reduce the risk of the composite endpoint. In patients receiving HR modulators the event rates for the composite endpoint, all-cause mortality, and cardiovascular mortality were lower than in patients not receiving HR modulators. Conclusions: Heart rate at discharge >90 bpm predicts cardiovascular mortality, while therapy with beta blockers is negatively associated with the composite endpoint of cardiovascular mortality and hospitalization at 6 months in acutely decompensated HF patients. Patients receiving a HR modulation therapy at hospital discharge showed the lowest rate of cardiovascular mortality and re-hospitalization