Robert Olszewski

Three-dimensional echocardiographic evaluation of left ventricular volume: Comparison of Doppler myocardial imaging and standard gray-scale imaging with cineventriculography—an in vitro and in vivo study☆☆☆★

BACKGROUND Standard gray-scale imaging (GSI), three-dimensional (3D) echocardiography has been shown to be superior to two-dimensional echocardiography in measuring left ventricular volume. However, the often relatively poor quality of transthoracic gray-scale data can limit the potential application of this technique. Doppler myocardial imaging (DMI) is a new ultrasound technique that potentially offers higher-quality 3D images with a transthoracic approach than the 3D GSI technique. This study was designed to compare the accuracy of standard GSI and DMI 3D left ventricular volume measurements in vitro and in vivo. METHODS AND RESULTS In vitro, the minimum and maximum volume of the contracting single-chamber, tissue-mimicking phantom was calculated by using both techniques. In vivo, GSI and DMI 3D left ventricular volume measurements were performed in 16 patients. End-diastolic and end-systolic left ventricular volumes were computed for both techniques and compared with those calculated by cineventriculography. In vitro, both methods tended to underestimate the true phantom volume, but the systematic error was smaller for DMI than for GSI (-1.2% +/- 1.5% vs. -4.3% +/- 3%; p < 0.01) and was more constant in the case of DMI over the range of different sizes of true volume. In vivo, for GSI the end-diastolic volume mean difference was -12.6 ml and the limits of agreement were +/-18 ml, and for DMI the corresponding values were -4.2 and +/- 10.6 ml, respectively. The difference for end-systole was -6.5 +/- 10.6 ml and -1.5 +/- 10 ml for GSI and DMI, respectively. The magnitude of the difference in volume measurement between 3D echocardiography and cineventriculography was significantly smaller when using the Doppler technique. CONCLUSIONS The results of this in vitro and in vivo study indicate that DMI is superior to GSI as a transthoracic acquisition technique for 3 D volume computation.

Assessment of wall velocity gradient imaging using a test phantom

A new phantom has been designed to gain a better understanding of tissue Doppler imaging (TDI). Specifically, the phantom can easily be used to determine myocardial velocity gradients. The phantom mimics the left ventricle and is made of fine-grade sponge material whose ultrasound image closely resembles the gray scale image obtained from heart walls. Theoretical analysis of phantom wall movements offers a plausible explanation for the velocity gradients developing across the heart walls. The results of computer analysis were found to be in very good agreement with TDI M-mode recordings of phantom wall displacement.

Heart function disturbances in chronic kidney disease - echocardiographic indices

Introduction In chronic kidney disease (CKD) patients left ventricular (LV) diastolic dysfunction occurs frequently and is associated with heart failure (HF) and higher mortality. Left ventricular systolic dysfunction is associated with coronary artery disease (CAD) and is a major determinant of prognosis. The aim of this study was to assess indices of LV diastolic dysfunction in CKD patients. Material and methods Study included 118 CKD patients. All patients underwent transthoracic echocardiography. Diastolic function based on E and A, E/A ratio and pulmonary vein flow velocities as well as EF%, deceleration time, RA, LA volume were assessed. In dialysis patients examination was carried out before and after dialysis. Results In CKD patients the stage of renal failure was associated with the significant increase in LV mass (268.0 ±47.6 CKD I/II vs. 432.7 ±122.4 CKD V/dialysis, p < 0.0001), systolic LV (37.3 ±4.5 vs. 51.2 ±8.9, p < 0.0001) and diastolic LV (CKD I–II 44.7 ±4.1 vs. CKD III 48.5 ±6.7 vs. CKD IV 47.1 ±5.6; p = 0.004) dimensions and in the size of the LA (40.4 ±2.0 vs. 41.9 ±2.7 vs. 42.3 ±3.2 vs. 44.8 ±3.1; p < 0.0001). The increase the E/E’ ratio between groups of patients (6.7 ±1.5 vs. 8.9 ±2.4 vs. 11.5 ±4.0 vs. 13.5 ±5.0; p < 0.0001) was seen in this study. The reduction in deceleration time (247.2 ±34.5 in CKD I/II vs. 197.4 ±61.0 in CKD IV, p = 0.0005) along with the decrease in estimated glomerular filtration rate was also observed in this study. Conclusions Early identification of factors involved is necessary to prevent this devastating process. Many indexes of contractility are used and each of them has imperfections. It seems that TVI, E, E/A and E/E’ are good instruments for the early detection of left ventricular hypertrophy and diastolic dysfunction.

Sudden cardiac death in CKD patients

The risk of sudden cardiac death (SCD) is high in chronic kidney disease patients, and it increases with the progression of kidney function deterioration. The most common causes of SDC are the following: ventricular tachycardia, ventricular tachyarrhythmia, tachycardia torsade de pointes, sustained ventricular fibrillation and bradyarrhythmia. Dialysis influences cardiovascular system and results in hemodynamic disturbances as well as electrolyte shifts altering myocardial electrophysiology. Studies suggest that this procedure exerts both detrimental (poor volume control can exacerbate hypertension and left ventricle hypertrophy) and beneficial effects (associated with fluid removal and subsequent decrease in left ventricle stretch). Dialysis-related vulnerability to serious arrhythmias is the result of sudden shifts in fluid status and electrolytes, particularly potassium, which alter the physiological milieu. Also Ca2+ ions, in which concentration alters during dialysis, are of key importance in the contraction of vascular smooth muscle cells and cardiac myocytes, thus exerting significant effects on hemodynamics. Due to the fact that SCD occurs with similar frequency in peritoneal dialysis and in hemodialysis patients, it seems that end-stage renal disease factors are more important than the specific ones associated with dialysis type. The results of randomized trials suggested that hemodialysis patients may not derive the same benefit of cardiovascular disease therapy including beta-blockers, calcium channel blockers and angiotensin-converting enzyme inhibitors as the general population with normal kidney function. Noninvasive tests used to stratify SCD risk in HD patients have poor positive value, and thus, combining tests including HRV, baroreceptor sensitivity and effectiveness index as well as its function indices and heart rate turbulence should be implemented. There are only few large randomized placebo-controlled trials assessing the influence of cardioprotective medications or implantable cardioverter defibrillator (ICD) implantation in dialysis patients on life quality and survival, and their results are sometimes contradictory. The decision concerning treatment and/or ICD implantation in this group of patients should be made on the basis of careful assessment of individual risk factors. Moreover, due to the high hazard of cardiovascular mortality including SCD in dialysis patients, physicians should concentrate on the early selection of high-risk patients, monitoring them and introduction of preventive measures.

MULTIGATE DOPPLER MEASUREMENTS OF ULTRASONIC ATTENUATION AND BLOOD HEMATOCRIT IN HUMAN ARTERIES

A clinically applicable method for noninvasive measurement of hematocrit based on 20 MHz multigate Doppler ultrasound was developed. The ultrasound attenuation coefficient in blood is obtained by measuring the power of the signal coming from gates at different depths. A robust averaging method is introduced, which provides stable and repeatable results by using the echo signals from all depths inside the vessel. In vitro measurements have been done on porcine blood with hematocrit ranging from 3.0% to 65.0%. Steady and pulsatile flow conditions have been simulated using a peristaltic pump. The attenuation coefficient indicated the linear relation to hematocrit. The resulting correlation coefficient was R = 0.999 for the continuous blood flow and R = 0.992 for pulsatile flow. In vivo measurements have been performed in the brachial artery in 43 patients with hematocrit in the range of 32.0% to 49.3%. The mean absolute error has been 3.24% with a standard deviation of 3.72%.

Trans-Fatty Acids and Cardiovascular Disease: Urgent Need for Legislation

Hydrogenated oils containing trans-fatty acids (TFA) are used to produce margarine and various processed foods. TFA affect serum lipid levels, fatty acid metabolism, and endothelial function. High TFA intake is linked to increased all-cause mortality, coronary heart disease mortality, and cardiovascular disease (CVD) incidence. Denmark was the first country to introduce a law that limited TFA content in food; this action led to lower CVD mortality. So far 7 European countries have followed this practice, in a few others the food industry voluntarily reduced TFA use. The issue remains mostly unaddressed in the rest of the world. Legal TFA limits should be commonly established as they are the optimal solution considering both CVD prevention and the associated cost savings in public healthcare.

Revisional bariatric surgery after failed laparoscopic adjustable gastric banding – a single-center, long-term retrospective study

Introduction Laparoscopic adjustable gastric banding (LAGB) used to be one of the most popular bariatric procedures. Aim To present our institution’s experience with LAGB, its complications, causes of failure and revisional bariatric procedures, in a long-term follow-up. Material and methods Records of patients who underwent pars flaccida LAGB from 2003 to 2006 were gathered. We selected data on patients with a history of additional bariatric procedures. Their initial demographic data, body mass index and causes of revision were gathered. We analyzed length of stay and early perioperative complications. Results 60% of patients (n = 57) who underwent LAGB in our institution between 2003 and 2006 had their band removed (out of 107, 11% lost to follow-up). Median time to revisional surgery was 50 months. The main reasons for removal were: weight regain (n = 23; 40%), band slippage (n = 14; 25%), and pouch dilatation (n = 9; 16%). Thirty (53%) patients required additional bariatric surgery, 10 (33%) of which were simultaneous with band removal. The most popular procedures were: laparoscopic Roux-en-Y gastric bypass (LRYGB) (n = 15; 50%), open gastric bypass (n = 8; 27%), and laparoscopic sleeve gastrectomy (LSG) – (n = 3; 10%). Mean length of stay (LOS) was 5.4 ±2.0. One (3%) perioperative complication was reported. Conclusions The results show that LAGB is not an effective bariatric procedure in long-term follow-up due to the high rate of complications causing band removal and the high rate of obesity recurrence. Revisional bariatric surgery after failed LAGB may be performed in a one-stage approach with band removal.

The Use of Plant Sterols and Stanols as Lipid-Lowering Agents in Cardiovascular Disease

BACKGROUND The prevalence of premature atherosclerosis and cardiovascular disease (CVD) is constantly increasing worldwide. It has been proved that LDL-cholesterol (LDL-C) plays causal role in the development of coronary atherosclerosis. The fact that atherosclerosis is a chronic and progressive disease which onsets during the first three decades of life bores questions what to do to maintain LDL-C at low levels throughout life and thus to delay and/or prevent the progress this disease. Currently, most of public health expenses are spared on treatment, but not on prophylaxis. METHODS This is a review article summarizing novel reports concerning the efficacy of sterols/stanols as lipidlowering agents, assessing their influence on cardiovascular risk and safety. RESULTS It has been suggested that sterols and stanols are effective in the lowering of low-density cholesterol levels and diminishing cardiovascular risk. However, the results of other studies suggest that phytosterols may not exert positive effects during atherogenesis. Firstly, patients with phytosterolaemia (genetic disease in which high plant sterol plasma concentrations are observed) develop malignant premature atherosclerosis. Moreover, several epidemiological studies demonstrated the association between upper normal plasma concentrations of plant sterols and increased risk of cardiovascular events. Finally, the supplementation with plant stanols and plant sterols may be not beneficial due to their incorporation in various tissues and potentially resulting in adverse effects. CONCLUSION Despite the worldwide promotion of sterols as health improving supplements, it seems that in some people responding with relatively high phytosterol serum levels after its consumption such additives may turn out to be as good as it has been believed.

Doppler multigate measurements of ultrasonic scattering, attenuation and hematocrit of blood in the human artery

The goal of this work was to develop a clinically applicable method for noninvasive measurement of hematocrit based on Doppler ultrasound. The method uses of a 20 MHz unfocused transducer (2 mm diameter) in a multigate Doppler system. The ultrasound attenuation coefficient in blood is obtained by measuring the power of the signal coming from gates at different depths. A robust averaging method is introduced, which provides stable and repeatable results by using the echo- signals from all depths inside the vessel. A large amount of in vitro and in vivo data has been collected. In vitro measurements have been done on porcine blood, with samples of whole blood and separated plasma with hematocrit ranging from 3.0% to 65.0%. Steady and pulsatile flow conditions, similar to those existing in the human brachial artery, have been simulated using a peristaltic pump. The attenuation coefficient, determined from the reduction of Doppler amplitude with increasing depth, indicated the linear relation to hematocrit. The resulting correlation coefficient was R = 0.999 for the continuous blood flow and R = 0.992 for pulsatile flow. In vivo measurements have been performed in the brachial artery in 33 patients with hematocrit in the range 32.0% - 46.1%. The mean absolute error has been 3.5% with a SD of 2.7%.

20-MHz Ultrasound for Measurements of Flow-Mediated Dilation and Shear Rate in the Radial Artery

A high-frequency scanning system consisting of a 20-MHz linear array transducer combined with a 20-MHz pulsed Doppler probe was introduced to evaluate the degree of radial artery flow-mediated dilation (FMD [%]) in two groups of patients after 5 min of controlled forearm ischemia followed by reactive hyperemia. In group I, comprising 27 healthy volunteers, FMD (mean ± standard deviation) was 15.26 ± 4.90% (95% confidence interval [CI]: 13.32%-17.20%); in group II, comprising 17 patients with chronic coronary artery disease, FMD was significantly less at 4.53 ± 4.11% (95% CI: 2.42%-6.64%). Specifically, the ratio FMD/SR (mean ± standard deviation), was equal to 5.36 × 10-4 ± 4.64 × 10-4 (95% CI: 3.54 × 10-4 to 7.18 × 10-4) in group I and 1.38 × 10-4 ± 0.89 × 10-4 (95% CI: 0.70 × 10-4 to 2.06 × 10-4) in group II. Statistically significant differences between the two groups were confirmed by a Wilcoxon-Mann-Whitney test for both FMD and FMD/SR (p <0.01). Areas under receiver operating characteristic curves for FMD and FMD/SR were greater than 0.9. The results confirm the usefulness of the proposed measurements of radial artery FMD and SR in differentiation of normal patients from those with chronic coronary artery disease.