Thrombus formation in the left atrial appendage in the course of atrial fibrillation.

BACKGROUND: Thromboembolism in patients with nonvalvular atrial fibrillation is secondary to emboli arising from atrial cavities, particularly left atrial appendage. Stroke Prevention Atrial Fibrillation (SPAF) III study showed washing flow, left appendage ejection fraction, natural echocontrast, and left appendage volume and morphology, as risk parameters of thromboembolism. METHODS: The authors examined 69 patients by transesophageal echocardiography, subdividing them into 3 groups: 26 patients in sinus rhythm in Group A (Gr.A), 22 patients in atrial fibrillation without thrombi in the left atrial appendage in Group B (Gr.B), 21 patients with tromboembolism and with thrombus in the left atrial appendage (Gr.C). RESULTS: Atrial volume in sinus rhythm (SR) patients (41.9 +/- 23.4 cm3) was lower than the one in Gr.B (86.2 +/- 47.9 cm3, p < 0.001) and Gr.C (78.6 +/- 28.5 cm3, p < 0.01), whereas no difference was found between Gr.B and Gr.C (86.2 vs. 78.6 cm3; p > 0.05). No difference was found between Gr.A and Gr.B left atrial appendage fraction (31.8% versus 29.1%, p > 0.05), whereas it was found related to Gr.C (31.8% versus 15.4% p < 0.01). Flow velocity within left atrial appendage was significantly higher in Gr.A in relation to the other two groups (p < 0.001); flow velocity in Gr.B was lower than in Gr.A but higher than in Gr.C and in all cases such differences were statistically significant (p < 0.001). Gr.A flow duration was approximately twice as much compared to the one in Gr.B (616.8 +/- 94.1 msec vs. 483.3 +/- 172.6 msec, p < 0.01), whereas it was approximately four times higher compared to the one in Gr.C (616.8 +/- 94.1 msec vs. 165.7 +/- 53.7 msec; p < 0.001). Such duration, if related to the corresponding cardiac cycle, indicates the percentage of time during which blood flows through a cycle within the left atrial appendage; this value is about 85% of cardiac cycle in Gr.A, while it is 65% in Gr.B (p < 0.01) and about 21% in Gr.C (p < 0.001). CONCLUSIONS: Such results add a new parameter to the ones suggested in the SPAF III study for the evaluation of TE risk, that is flow duration measurement within the left atrial appendage, and its ratio to the cardiac cycle. The availability to measure this parameter, by recording the transesophageal pulse wave sample volume positioned in the atrial appendage, makes the evaluation of TE risk more reliable.

Diastolic mitral regurgitation: a borderline case in cardiovascular physiology.

BACKGROUND: Mitral regurgitation during diastole in 5 subjects, of whom 4 affected by cardiovascular disease and 1 healthy competitive athlete, was the aim of this work. The 4 patients are respectively affected by: 1st case: arterial hypertension, dyslipidemia and III degree AV block in NYHA class II heart failure (HF); 2nd case: NYHA III HF, prosthetic biologic aortic valve dysfunction; 3th case: NYHA III HF, ischemic dilated cardiomyopathy; 4th case: ischemic dilated cardiomyopathy waiting for heart transplantation. METHODS AND RESULTS: The above 4 patients showed, on transthoracic echocardiogram, mitral diastolic regurgitation. The authors deem as caused, in agreement with the literature, both by an atrio-ventricular pressure gradient inversion during long-lasting diastoles (III degree atrioventricular block, blocked atrial systole, aortic valve regurgitation), and by an inadequate ventricular remodelling/distensibility. The 5th case deals with a healthy highly trained competitive athlete who, at the fitness checkup, showed mitral diastolic regurgitation. The study was also extended to two healthy groups of subjects, in order to rule out mitral regurgitation during the diastolic interval of the cardiac cycle. CONCLUSIONS: Such finding, after an accurate and critical analysis, led the authors to assume it may deal with a borderline physiological condition.

Kidney vasculogenesis and angiogenesis: role of vascular endothelial growth factor.

Vascular Endothelial Growth Factor (VEGF) plays a crucial role in the establishment of the vascular tree pattern. New vessels can be formed by two different ways; in the development of kidney both vasculogenesis and angiogenesis participate to microvessel assembly. VEGF and its receptor (VEGF-R) are co-expressed during kidney organogenesis and stimulate renal blood vessels development, induce and maintain the fenestrated phenotype in endothelium and regulate vascular permeability. VEGF and many other growth factors participate to the development of embryonic glomerular microvasculature. We believe that therapeutical use of VEGF or anti-VEGF antibodies may be performed in the treatment of many disorders.

Pathophysiology, clinical features and management of hepatorenal syndrome.

Hepatorenal syndrome (HRS) is a form of functional renal failure occurring in patients with advanced liver disease. Hypoperfusion of the kidney, due to renal vasoconstriction, is the main feature of HRS. Conversely, the extrarenal circulation is characterized by low systemic resistance, especially occurring in splanchnic vessels, and arterial hypotension. It has been postulated that renal vasoconstriction is induced either by a hepatorenal reflex related to the diseased liver or by arterial vasodilation and the subsequent baroreceptor-mediator activation of systemic vasoconstrictor factors. The diagnosis of HRS requires the exclusion of other causes of renal failure in patients with liver disease. On the basis of clinical and prognostic differences, two types of HRS have been defined. The prognosis of HRS is poor and, to date, the only effective treatment is the liver transplantation.