Assesment of Markers of Endothelial Dysfunction and Myocardial Stress in Patients with Hypertrophic Cardyomyopathy

Aim. To study the level of serum biomarkers of endothelial dysfunction and myocardial stress in patients with various types of hypertrophic cardiomyopathy (HCM).Material and Methods. 48 patients with hypertrophic cardiomyopathy (27 men and 21 women) were examined, the mean age was 54±13 years. The patients were divided into two groups according to the course options: group 1 - symptomatic stable course (n=14); group 2 - progressive course of symptomatic HCM (n=34). In accordance with the assigned tasks, all patients underwent determination of biological markers of neurohumoral systems in blood serum using immunofluorescence assay analysis: N-terminal fragment of brain natriuretic peptide (NT-proBNP), von Willebrand factor (vWF), endothelin-1, E-selectin with subsequent evaluation and correlation of results with clinical and instrumental characteristics of patients. When performing echocardiography following parameters were assessed: dimensions of the heart chambers, the thickness of the interventricular septum, the thickness of the posterior wall of the left ventricle (LV), LV mass, LV mass index, the ratio between LV filling in diastole (peak E) and atrial systole (peak A)-(E/A), relative myocardial thickness index, left atrial volume index.Results. Both groups showed increased levels of NT-proBNP and endothelin-1. E-selectin and vonWillebrand factor remained within the normal range. There was no statistically significant intergroup difference. There was a correlation between the level of the index of the relative myocardial thickness and the level of NT-proBNP (r=0.30; p=0.04). A correlation was found between the level of the vWF marker and the left atrial volume index (r=0.32; p=0.04). When assessing the association of indicators of intracardiac hemodynamics with other markers (E-selectin and endothelin-1, no statistically significant relationships were found.Conclusion. In the course of the research, it was found that the high activity of endothelin-1 and NT-proBNP reflects endothelial dysfunction and myocardial stress in patients with HCM, especially in patients with a progressive variant of HCM. However, we did not find any changes in the levels of E-selectin and von Willebrand factor, as well as their intergroup differences. These results require additional studies to assess endothelial dysfunction in patients with HCM.

Study on the effect of different blood flow velocities of pulmonary vein on endocardial microwave ablation of atrial fibrillation

OBJECTIVE: To cure atrial fibrillation, the maximum ablation depth (⩾ 50∘C) should exceed the myocardial thickness to achieve the effect of transmural ablation. The blood flow of pulmonary vein in the endocardium can cause the change in the myocardial temperature distribution. Therefore, the study investigated the effect of different pulmonary vein blood flow velocities on the endocardial microwave ablation. METHODS: The finite element model of the endocardial microwave ablation of pulmonary vein was simulated by electromagnetic thermal flow coupling. The ablation power was 30 W and the ablation time was within 30 s. The blood flow in the coupling of fluid mechanics equation and heat transfer equation results in the heat damage. Furthermore, the cause of the different lesion dimensions is the blood flow velocity. The flow velocities were set as 0, 0.02, 0.05, 0.07, 0.12, 0.16, 0.20, 0.25 and 0.30 m/s. RESULTS: When the flow velocities were 0, 0.02, 0.05, 0.07, 0.12, 0.16, 0.20, 0.25 and 0.30 m/s, the maximum ablation depth were 6.0, 5.56, 5.16, 5.12, 5.04, 5.01, 4.98, 4.96 and 4.94 mm, respectively; the maximum ablation width were 12.52, 9.63, 9.23, 9.16, 9.07, 9.05, 8.94, 8.91, 8.90 mm, respectively; the maximum ablation length were 12.00, 11.61, 8.98, 8.59, 8.37, 8.23, 8.16, 8.06 and 8.04 mm respectively. To achieve transmural ablation, the time was 3, 3, 3, 3, 3, 4, 4, 4, 4 s, respectively when the myocardial thickness was 2 mm; the time was 7, 8, 8, 8, 9, 9, 9, 9, 9 s, respectively when 3 mm; the time was 15, 16, 18, 19, 19, 20, 20, 20, 20 s, respectively when 4 mm. CONCLUSIONS: When the velocity increases from 0 m/s to 3 m/s, the microwave lesion depth decreases by 1.06 mm. To achieve transmural ablation, when the myocardial thickness is 2 mm, 3 and 4 s should be taken when the velocity is 0–0.12 and 0.120.30 m/s, respectively; when the myocardial thickness is 3 mm, 7, 8 and 9 s should be taken when 0, 0–0.07 and 0.07–0.30 m/s respectively; when the myocardial thickness is 4 mm, 15, 16, 18, 19, 20 s should be taken when 0, 0–0.02, 0.02–0.05, 0.05–0.12, 0.12 m/s–0.30 m/s.

Cardiovascular magnetic resonance normal values in children for biventricular wall thickness and mass

Background Pediatric patients are becoming increasingly referred for cardiovascular magnetic resonance (CMR). Measurement of ventricular wall thickness is typically part of the assessment and can be of diagnostic importance, e.g. in arterial hypertension. However, normal values for left ventricular (LV) and right ventricular (RV) wall thickness in pediatric patients are lacking. The aim of this study was to establish pediatric centile charts for segmental LV and RV myocardial thickness in a retrospective multicenter CMR study. Methods CMR was performed in 161 healthy children and adolescents with an age range between 6 and 18 years from two centers in the UK and Germany as well as from a previously published CMR project of the German Competence Network for Congenital Heart Defects. LV myocardial thickness of 16 segments was measured on the short axis stack using the American Heart Association segmentation model. In addition, the thickness of the RV inferior and anterior free wall as well as biventricular mass was measured. Results The mean age (standard deviation) of the subjects was 13.6 (2.9) years, 64 (39.7%) were female. Myocardial thickness of the basal septum (basal antero- and inferoseptal wall) was 5.2 (1.1) mm, and the basal lateral wall (basal antero- and inferolateral) measured 5.1 (1.2) mm. Mid-ventricular septum (antero- and inferoseptal wall) measured 5.5 (1.2) mm, and mid-ventricular lateral wall (antero- and inferolateral wall) was 4.7 (1.2) mm. Separate centile charts for boys and girls for all myocardial segments and myocardial mass were created because gender was significantly correlated with LV myocardial thickness (p < 0.001 at basal level, p = 0.001 at midventricular level and p = 0.005 at the apex) and biventricular mass (LV, p < 0.001; RV, p < 0.001). Conclusion We established CMR normal values of segmental myocardial thickness and biventricular mass in children and adolescents. Our data are of use for the detection of abnormal myocardial properties and can serve as a reference in future studies and clinical practice.

Small Animal Review

Summary: In feline hypertrophic cardiomyopathy the increase in myocardial thickness and cardiac weight in some cases is due to diffuse expansion of the interstitium by granulation tissue as a consequence of cardiomyocyte degeneration, probably associated with infarcts, and is not necessarily the result of true myocardial hypertrophy.

P1766Clinical impact of atrial fibrillation and heart failure in a cohort of patients with hypertrophic cardiomyopathy

Background Atrial fibrillation (AF) and heart failure (HF) are common complications in Hypertrophic Cardiomyopathy (HCM) patients, leading to a worsening of their quality of life, need of hospitalization and prognosis. Purpose To analyze clinical variables associated with the presence of AF and HF in HCM patients. Methods HCM patients followed-up in cardiological visits from 2005 to 2017 were included and a descriptive analysis of those with AF and HF was performed. Results Out of 168 patients, 28% had reported AF. They were older than those without arrhythmia (68±15 years (yrs) vs 56±20 yrs, p<0.001) and had more comorbidities such as diabetes (27.7% vs 12.4%, p=0.02) and chronic renal disease (21.3% vs 6.6%, p=0.006). Echocardiographic findings are summarized in Table 1. In our cohort, 27.4% of the patients had HF with a functional class according to the New York Heart Association criteria ≥2. They were older than those without HF (69.3±11.6 yrs vs 55.9±20.6 yrs, p<0.001) and had higher rate of cardiovascular (CV) risk factors such as hypertension (65.2% vs 44.3%, p=0.015). The presence of HF was directly associated with the presence of AF: 52.2% of the patients with HF and 18.9% of the patients without HF developed this arrhythmia (p<0.001). HF patients associated larger left atrial diameter (48±8.1 vs 41.6±7.2mm, p<0.001), myocardial thickness (21.7±3.9 vs 19.2±5.8mm, p=0.002) and higher left ventricular outflow obstruction (LVOO) (55±32 vs 34.3±31.3mmHg, p=0.021), without any differences in the left ventricular ejection fraction. HF patients had a worse prognosis (Picture 1). Multivariate analysis showed that the presence of AF (OR 2.6, CI 95% 1.1–6.3) and LVOO (OR 4.8, CI 95% 1.5–14.8) were independent risk factors of developing HF. Table 1. Echocardiographic findings AF (n=47) Non AF (n=121) p LVOO 27.7 19 0.22 Aortic regurgitation 12.8 3.3 0.02 Mitral regurgitation 27.7 12.4 0.02 Left atrial diameter (mm) 48.8±7.2 40.7±7 <0.001 Myocardial thickness (mm) 20±5.4 19±5.2 0.02 Qualitative variables are expressed as percentages (%) and quantitative variables as mean and standard deviation (M ± SD). Picture 1. Main outcomes of HF patients Conclusions AF and HF were directly associated in our cohort, especially in elderly patients with higher comorbidities, leading to a worse prognosis with a higher hospitalization rate and CV death. This emphasizes the importance of a thorough search of both complications in order to initiate early treatment and improve the prognosis of HCM patients.

The way to control the interventricular septum thickness during septal myectomy. An experimental study

Background: At present, there are no methods for intraoperative monitoring of the interventricular septum (IVS) thickness in a stopped and empty heart. This might be an obvious reason for unsatisfactory results after a number of septal myectomies.Aim: To provide an experimental background for the method to control the IVS thickness (that we had proposed) during septal myectomy.Materials and methods: The proposed technique is based on the transillumination method. The experimental models were cadaveric porcine hearts, as well as fragments of the human myocardium removed during septal myectomies. The thickness of the translucent myocardium was estimated depending on the local illumination value at the entrance to the myocardium and the external illumination of the surgical field. We compared the results of 67 septal myectomies performed in the clinic of the Almazov National Medical Research Centre with the results of 35 similar experimental procedures with cadaveric porcine hearts using the proposed way of measurement.Results: A graph of the illumination at the entrance to the myocardium against the thickness of the translucent myocardium was constructed. After conventionally performed septal myectomies the median variation of the myocardial thickness was 4 [3; 6] mm. In the experiment using the proposed control method, the median variation was 1 [1; 2] mm, i.e. significantly less than with the conventional approach (p = 3 x 10-10).Conclusion: The method to control the IVS thickness when performing septal myectomy makes it possible to achieve the required myocardial thickness the resection area with much greater accuracy than with the conventional one.