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Signa Vitae

Journal of Intensive Care and Emergency Medicine

Acute heart failure and cardiogenic shock

Introduction

Cardiovascular disease accounts for one quarter of all deaths, and once cancer mortality is excluded, cardiac disease alone accounts for more deaths than all other causes put together. Heart failure (defined as the inability of the heart to pump enough blood to meet the demands of the body) is common, being the primary cause of hospital admission in >1million patients per year in the USA, with 25% readmitted within 1 month, and a 10-20% mortality at 6 months after discharge. In newly diagnosed patients there is a >20% mortality at one year, rising to 50% at two years and >66% at ten years – proving as malignant as many common cancers. The underlying causes include coronary artery disease, hypertension, valve dysfunction, cardiomyopathies (inherited and acquired), congenital heart disease, arrhythmia, toxins (either ‘recreational’ – cocaine and alcohol, or therapeutic – some chemotherapeutic agents), pulmonary embolism and sepsis. Acute heart failure (AHF) may be a new diagnosis in patients with no history of cardiac disease, or occur as a result of acute decompensation in patients with known heart failure. It is the leading cause of hospital admission in people >65 years in the UK. European-wide, approximately 50% of these patients will be readmitted within 12 months, and 30% deceased at the 1-year follow-up.

Key words: cardiogenic shock, heart failure, mechanical circulatory support

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Percutaneous mechanical support in acute coronary syndromes

Abstract

Despite advances in interventional cardiology, persistently disappointing outcomes in patients with cardiogenic shock complicating myocardial infarction, together with the lack of evidence the that intra-aortic balloon pump improves outcomes in this patient population have led to a re-evaluation of other types of mechanical circulatory support. The increase in extracorporeal membrane oxygenation (ECMO) prompted by the H1N1 pandemic led to an increase in experience in using this technique in critically ill adult patients, and its use is now expanding in both respiratory and cardiac failure. Despite enthusiasm for the technique, high-quality evidence is lacking for its benefit. Nonetheless, ECMO and other types of percutaneous mechanical circulatory support do provide critical care clinicians with new supportive therapies that may prove to benefit patients, both from the high level of support that can be offered, and also minimising the use of potentially toxic inotropic agents.

Key words: cardiogenic shock, heart failure, mechanical circulatory support, extracorporeal membrane oxygenation, ECMO, myocardial infarction, acute coronary syndromes

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Cardiogenic shock and complete heart block as a manifestation of fulminant Wegener’s granulomatosis

Abstract

Wegener’s vasculitis is an autoimmune disease affecting small and medium-sized blood vessels with a high mortality rate. It is a disease of usually subsidious course and nonspecific initial symptoms that are diagnostically misleading. Cardiac involvement is described most frequently in the form of supraventricular tachyarrhytmias, and rarely as a clinically significant myocardial infarction. This case demonstrates another facet of this disease presenting as full blown shock and respiratory insufficiency progressing to ARDS (acute respiratory distress syndrome) and multi-organ failure over the course of two weeks, with an unfortunately fatal outcome.

Key words: Wegener’s granulomatosis, vasculitis, cardiogenic shock

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Measurement of skeletal muscle tissue oxygenation in the critically ill

Abstract

Shock is a state of acutely reduced tissue oxygenation. In cardiogenic shock oxygen delivery (DO2) is reduced, but oxygen extraction is preserved. In septic shock DO2 is preserved, but oxygen extraction is decreased because of microvascular changes and disturbed metabolism. Global assessment of DO2 and oxygen consumption does not tell us enough about adequacy of regional perfusion. The aim of this study was to assess the value of near infrared spectroscopy (NIRS) in detecting skeletal muscle tissue oxygenation (StO2) in critically ill patients.
Patients in cardiogenic shock (n=17), septic shock (n=14), without shock but with localized infection (n=14) and healthy volunteers (n=15) were included. Thenar StO2 was measured with NIRS before (baseline StO2, %), between (downward StO2 slope, %/min) and after 90 seconds of upper arm stagnant ischemia (hyperemic StO2, %). Muscle oxygen extraction (mOER) was calculated as follows: mOER (%) = (1-baselineStO2/hyperemic StO2)*100. Repeatability was assessed using the Bland Altman method (95 % of values within limits of agreement), comparing 55 pairs of measurements performed in 5-minute intervals.
Repeatability of measurements was clinically acceptable. Compared to septic shock patients, cardiogenic shock patients had lower baseline StO2 (68.9 ± 10.0 % vs. 84.3 ± 10.4 %; p < 0.05) and hyperemic StO2 (80.8 ± 7.8 % vs. 91.8 ± 8.3 %; p < 0.05), and a higher downward StO2 slope (-17.4 ± 31.7 %/min vs. -9.1 ± 2.6 %/min; p < 0.05). mOER was higher in healthy volunteers (11.9 ± 3.8 %) and volunteers with cardiogenic shock (14.8 ± 7.3 %) compared to septic shock patients (8.1 ± 7.8 %) and those with localized infection (7.6 ± 5.4 %) (p < 0.05).
Repeatability of baseline StO2 and hyperemic StO2 is clinically acceptable. Results support the hypothesis that skeletal muscle oxygen extraction capability is preserved and extraction is increased in cardiogenic shock compared to septic shock.

Key words: repeatability, NIRS, tissue oxygenation, cardiogenic shock

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