Usefulness of dipyridamole transesophageal echocardiography in the evaluation of myocardial ischemia and coronary artery flow

Current Diagnostic and Therapeutic Strategies in Microvascular Angina

Microvascular angina is common among patients with signs and symptoms of acute coronary syndrome and is associated with an increased risk of cardiovascular and cerebrovascular events. Unfortunately, microvascular is often under-recognized in clinical settings. The diagnosis of microvascular angina relies on assessment of the functional status of the coronary microvasculature. Invasive strategies include acetylcholine provocation, intracoronary Doppler ultrasound, and intracoronary thermodilution; noninvasive strategies include cardiac positron emission tomography (PET), cardiac magnetic resonance, and Doppler echocardiography. Once the diagnosis of microvascular angina is established, treatment is focused on improving symptoms and reducing future risk of cardiovascular and cerebrovascular events. Pharmacologic options and lifestyle modifications for patients with microvascular angina are similar to those for patients with coronary artery disease.

[Tolerance to perioperative anemia. Mechanisms, influencing factors and limits]

The expected cost explosion in transfusion medicine increases the socio-economic significance of specific institutional transfusion programs. In this context the estimated use of the patient's physiologic tolerance represents an integral part of any blood conservation concept. The present article summarizes the mechanisms, influencing factors and limits of this natural tolerance to anemia and deduces the indication for perioperative red blood cell transfusion. The current recommendations coincide to the effect that perioperative transfusion is unnecessary up to a Hb concentration of 10 g/dl (6.21 mmol/l) even in older patients with cardiopulmonary comorbidity and is only recommended in cases of Hb <6 g/dl (<3.72 mmol/l) in otherwise healthy subjects including pregnant women and children. Critically ill patients with multiple trauma and sepsis do not seem to benefit from transfusions up to Hb concentrations >9 g/dl (>5.59 mmol/l). In cases of massive hemorrhaging and diffuse bleeding disorders the maintenance of a Hb concentration of 10 g/dl (6.21 mmol/l) seems to contribute to stabilization of coagulation.

[Tolerance to perioperative anemia. Mechanisms, influencing factors and limits]

The expected cost explosion in transfusion medicine (increasing imbalance between donors and potential recipients, treatment of transfusion-associated complications) increases the socio-economic significance of specific institutional transfusion programs. In this context the estimated use of the patient's physiologic tolerance to anemia enables 1) the tolerance of larger blood losses (loss of "diluted blood"), 2) the onset of transfusion to the time after surgical control of bleeding to be delayed and 3) the perioperative collection of autologous red blood cells. The present review article summarizes the mechanisms, influencing factors and limits of this natural tolerance to anemia and deduces the indication for perioperative red blood cell transfusion. Under strictly controlled conditions (anesthesia, normovolemia, complete muscular relaxation, hyperoxemia, mild hypothermia) extremely low hemoglobin concentrations [Hb <3 g/dl (<1.86 mmol/l)] are tolerated without transfusion by individuals with no cardiopulmonary disease. In the clinical routine these situations are limited to borderline situations e.g. unexpected massive blood losses in Jehovah's Witnesses or unexpected shortcomings in blood supply. The current recommendations coincide to the effect that perioperative red blood cell transfusion 1) is unnecessary up to a Hb concentration of 10 g/dl (6.21 mmol/l) even in older patients with cardiopulmonary comorbidity and 2) is only recommended in cases of Hb <6 g/dl (<3.72 mmol/l) in otherwise healthy subjects including pregnant women and children. Critically ill patients with multiple trauma and sepsis do not seem to benefit from transfusions up to Hb concentrations >9 g/dl (>5.59 mmol/l). In cases of massive hemorrhaging and diffuse bleeding disorders the maintenance of a Hb concentration of 10 g/dl (6.21 mmol/l) seems to contribute to stabilization of coagulation.