SummariZation of long-tErm prognostic siGnificance of coronary flow rEserve in special Disorders (SZEGED Study)

Előnézet	PDF (disszertáció) Download (617kB)
Előnézet	PDF (tézisfüzet) Download (183kB)
Előnézet	PDF (tézisfüzet) Download (3MB) | Előnézet

Absztrakt (kivonat) idegen nyelven

1. Introduction The coronary arterial tree consists of four basic segments: large epicardial coronary arteries, medium-sized and small arteries, arterioles and capillary vessels, directly supplying myocardial cells. Each of these coronary segments creates different level and degree of resistance to coronary blood flow. Normal (non-stenosed) large epicardial coronary arteries play a minor role in the regulation of coronary vascular resistance and act mainly as conductance vessels. Normally, coronary blood flow can increase approximately three- to sixfold to meet increasing myocardial oxygen demands. This effect is mediated by vasodilation at the arteriolar bed, which reduces vascular resistance, thereby augmenting flow. The coronary flow velocity reserve (CFR) represents the capacity of coronary circulation to dilate following an increase in myocardial metabolic demands and can be expressed by the ratio between the hyperaemic and resting peak flow velocities. CFR is an important functional parameter in order that we can understand the pathophysiology of coronary circulation and it can be used to examine the integrity of microvascular circulation. CFR could be evaluated invasively in the catheterisation laboratory and in nuclear medicine through perfusion imaging. Besides these both the transoesophageal and transthorasic methods of the vasodilator stress Doppler echocardiography are reliable for the evaluation of coronary flow velocity changes in the left anterior descending coronary artery (LAD). The flow velocity variations are proportional to the blood flow if the vessel lumen is kept constant, so the velocity ratio is used as surrogate of flow reserve. Coronary flow velocity by Doppler assessment appears to be biphasic, with a lower peak during systole and a higher peak during diastole. Myocardial extravascular resistance is higher in systole and lower in diastole due to the effect of myocardial contraction. Coronary flow velocity reserve assessment on the LAD by echocardiography is an excellent option for the evaluation of coronary microcirculation conditions in the absence of significant LAD stenosis. Microcirculatory abnormalities may occur in several diseases including hypertension, diabetes mellitus (DM), hypercholesterolaemia, aortic valve stenosis (AS), dilated and hypertrophic cardiomyopathy (HCM) etc. Recently, the independent prognostic significance of CFR has been demonstrated in a number of diseases, however its prognostic role remained questioned in some special disorders. 2. Methods Patient population (general considerations). Hundreds of patients with suspected coronary artery disease, valvular heart disease or cardiomyopathies were selected prospectively starting from 1997 to evaluate the clinical usefulness and prognostic significance of CFR measurements at the 2nd Department of Medicine and Cardiology Center, University of Szeged, Hungary. All patients underwent a standard transthoracic echo-Doppler study to evaluate left ventricular function and a stress vasodilator TEE study to evaluate CFR. Follow-up data. During the follow-up, all patients were controlled by phone, mail or other available way. The primary outcome was cardiovascular-related mortality including sudden cardiac death, cardiovascular mortality due to heart failure, cerebro- or cardiovascular thrombosis and hospitalization due to invasive procedures (coronary angiography, percutaneous transluminal myocardial septal alcohol ablation or implantable cardioverter defibrillator implantation). Data on primary outcome were gained from hospital recordings or autopsy reports. Transthoracic echocardiography. Transthoracic echo-Doppler study was performed in all patients with commercially available echocardiography systems (ATL Ultramark 9 HDI, Seattle, Washington, USA, and Toshiba Powervision 8000, Tokyo, Japan). Left ventricular internal dimensions and wall thickness were measured by M-mode echocardiography and ejection fraction was calculated using the biplane Simpson’s or Teichholz’s methods, in accordance with guidelines. Transoesophageal echocardiography. A complete TEE examination was carried out in all patients with an ATL® Ultramark 9 HDI echocardiograph (Seattle, Washington, USA), using a biplane transducer or a Toshiba Powervision 8000 echocardiograph (Tokyo, Japan) with a multiplane transducer. Blood pressure and heart rate were monitored continuously during the examinations. Dipyridamole stress TEE examinations were performed according to the standard protocol proposed by Iliceto et al. (3). β-Blockers, nitrates and calcium-antagonists were discontinued two days before the TEE examination. In all patients, the aortic root and the proximal portion of the LAD were visualized in the transversal plane (0 to 120 degrees). Coronary blood flow was visualized by color Doppler flow imaging and the phasic flow velocity waveform in the LAD was recorded by pulsed-wave Doppler. Care was taken to measure coronary flow velociti

Tétel nézet