José Sebastião de Abreu

pSnakes: A new radial active contour model and its application in the segmentation of the left ventricle from echocardiographic images

Active contours are image segmentation methods that minimize the total energy of the contour to be segmented. Among the active contour methods, the radial methods have lower computational complexity and can be applied in real time. This work aims to present a new radial active contour technique, called pSnakes, using the 1D Hilbert transform as external energy. The pSnakes method is based on the fact that the beams in ultrasound equipment diverge from a single point of the probe, thus enabling the use of polar coordinates in the segmentation. The control points or nodes of the active contour are obtained in pairs and are called twin nodes. The internal energies as well as the external one, Hilbertian energy, are redefined. The results showed that pSnakes can be used in image segmentation of short-axis echocardiogram images and that they were effective in image segmentation of the left ventricle. The echo-cardiologists golden standard showed that the pSnakes was the best method when compared with other methods. The main contributions of this work are the use of pSnakes and Hilbertian energy, as the external energy, in image segmentation. The Hilbertian energy is calculated by the 1D Hilbert transform. Compared with traditional methods, the pSnakes method is more suitable for ultrasound images because it is not affected by variations in image contrast, such as noise. The experimental results obtained by the left ventricle segmentation of echocardiographic images demonstrated the advantages of the proposed model. The results presented in this paper are justified due to an improved performance of the Hilbert energy in the presence of speckle noise.

Internal thoracic artery graft (ITAG): patency and functional status at rest and during dobutamine-stress echocardiography

BACKGROUND: The patent internal thoracic artery graft (ITAG) usually has a diastolic fraction (DF) > 50% of the flow. The functional assessment can be evaluated by the coronary reserve index (CRI). OBJECTIVE: The objective was to evaluate the patency and functional status of the ITAG through echocardiography and Doppler. METHODS: Data from sixty-six patients who underwent dobutamine-stress echocardiography (DSE) were prospectively collected and analyzed. Group I (GI) had 49 ITAG without stenosis, Group II (GII), 10 ITAG with significant stenosis (> 50% and 50%, it was observed in 49 ITAG (GI= 40, GII= 8 and GIII= 1) at rest and in 61 ITAG (GI=49, GII=10 and GIII=2) during DSE. The sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV) and accuracy were respectively, 81%, 86%, 98%, 35% and 82%, and 100%, at rest and 71%, 97%, 100% and 97% in the DSE. The ITAG with DF>50% at rest were patent and the ones with DF 1.8 for a good functional status, it was observed in 42 ITAG (39 from GI, 2 from GII and 1 from GIII), determining sensitivity=79%, specificity=85.7%, PPV=94%, NPV=59% and accuracy= 80.9%. The CRI in GI was higher (p= 0.02) than in GII or GIII. CONCLUSION: In our study, the non-invasive assessment of the ITAG was effective to verify the patency and the functional status.

Coronary Flow Velocity Reserve during Dobutamine Stress Echocardiography

Background A coronary flow velocity reserve (CFVR) ≥ 2 is adequate to infer a favorable prognosis or the absence of significant coronary artery disease. Objective To identify parameters which are relevant to obtain CFVR (adequate or inadequate) in the left anterior descending coronary artery (LAD) during dobutamine stress echocardiography (DSE). Methods 100 patients referred for detection of myocardial ischemia by DSE were evaluated; they were instructed to discontinue the use of β-blockers 72 hours prior to the test. CFVR was calculated as a ratio of the diastolic peak velocity (cm/s) (DPV) on DSE (DPV-DSE) to baseline DPV at rest (DPV-Rest). In group I, CFVR was < 2 and, in group II, CFVR was ≥ 2. The Fishers exact test and Students t test were used for the statistical analyses. P values < 0.05 were considered statistically significant. Results At rest, the time (in seconds) to obtain Doppler in LAD in groups I and II was not different (53±31 vs. 45±32; p=0.23). During DSE, LAD was recorded in 92 patients. Group I patients were older (65.9±9.3 vs. 61.2±10.8 years; p=0.04), had lower ejection fraction (61±10 vs. 66±6%; p=0.005), higher DPV-Rest (36.81±08 vs. 25.63 ± 06cm/s; p<0.0001) and lower CFVR (1.67 ± 0.24 vs. 2.53 ± 0.57; p<0.0001), but no difference was observed regarding DPVDSE (61.40±16 vs. 64.23±16cm/s; p=0.42). β-blocker discontinuation was associated with a 4-fold higher chance of a CFVR < 2 (OR= 4; 95% CI [1.171-13.63], p=0.027). Conclusion DPV-Rest was the main parameter to determine an adequate CFVR. β-blocker discontinuation was significantly associated with inadequate CFVR. The high feasibility and the time to record the LAD corroborate the use of this methodology.

Who Are the Super-Responders to Cardiac Resynchronization Therapy?

Fundamento: Pacientes submetidos a ressincronizacao cardiaca podem evoluir com padroes de resposta acima do esperado, com normalizacao dos parâmetros clinicos e ecocardiograficos. Objetivo: Analisar as caracteristicas clinicas e ecocardiograficas desta populacao de super-respondedores, comparando-as com os demais pacientes submetidos a terapia de ressincronizacao cardiaca. Metodos: Estudo de coorte observacional, prospectivo, envolvendo 146 pacientes, consecutivamente submetidos a implantes de ressincronizador cardiaco. Para comparacao das variaveis, foram realizados o teste exato de Fisher e o teste de Mann-Whitney. Foram considerados super-respondedores os pacientes com fracao de ejecao > 50 % e classe funcional I/II (New York Heart Association) apos 6 meses da terapia de ressincronizacao cardiaca. Resultados: A idade media foi de 64,8 ± 11,1 anos, sendo 69,8% do sexo masculino, com mediana da fracao de ejecao de 29%, sendo 71,5% com bloqueio de ramo esquerdo, 12% com bloqueio de ramo direito associado a bloqueios divisionais; 16,3% com marca-passo cardiaco definitivo, 29,3% com miocardiopatia isquemica, 59,4% com miocardiopatia dilatada e 11,2% com miocardiopatia chagasica. Foram observados 24 (16,4%) super-respondedores, sendo que 13 (8,9%) apresentaram normalizacao da fracao de ejecao, dos diâmetros diastolicos do ventriculo esquerdo e da classe funcional. Quando comparados com os pacientes nao super-respondedores, em relacao as caracteristicas pre-implante, os super-respondedores apresentaram-se mais no sexo feminino (58,3% vs. 22,8%; p = 0,002), maior indice de massa corporal (26,8 vs. 25,5; p = 0,013), maior fracao de ejecao basal (31,0 vs. 26,9; p = 0,0003) e menores diâmetros diastolicos do ventriculo esquerdo (65,9 mm vs. 72,6 mm; p = 0,0032). Dez pacientes (41,6% dos super-respondedores) com bloqueio de ramo direito e bloqueio divisional evoluiram como super-respondedores, entretanto apenas um paciente com doenca de Chagas e apenas na primeira avaliacao. Conclusoes: Os super-respondedores apresentaram cardiopatia de base menos avancada e sem diferencas em relacao ao tipo de disturbio de conducao basal. Pacientes com bloqueio de ramo direito e bloqueio divisional, mas sem cardiopatia chagasica podem tambem evoluir como super-respondedores.

Development and Validation of Predictive Models of Cardiac Mortality and Transplantation in Resynchronization Therapy

Background 30-40% of cardiac resynchronization therapy cases do not achieve favorable outcomes. Objective This study aimed to develop predictive models for the combined endpoint of cardiac death and transplantation (Tx) at different stages of cardiac resynchronization therapy (CRT). Methods Prospective observational study of 116 patients aged 64.8 ± 11.1 years, 68.1% of whom had functional class (FC) III and 31.9% had ambulatory class IV. Clinical, electrocardiographic and echocardiographic variables were assessed by using Cox regression and Kaplan-Meier curves. Results The cardiac mortality/Tx rate was 16.3% during the follow-up period of 34.0 ± 17.9 months. Prior to implantation, right ventricular dysfunction (RVD), ejection fraction < 25% and use of high doses of diuretics (HDD) increased the risk of cardiac death and Tx by 3.9-, 4.8-, and 5.9-fold, respectively. In the first year after CRT, RVD, HDD and hospitalization due to congestive heart failure increased the risk of death at hazard ratios of 3.5, 5.3, and 12.5, respectively. In the second year after CRT, RVD and FC III/IV were significant risk factors of mortality in the multivariate Cox model. The accuracy rates of the models were 84.6% at preimplantation, 93% in the first year after CRT, and 90.5% in the second year after CRT. The models were validated by bootstrapping. Conclusion We developed predictive models of cardiac death and Tx at different stages of CRT based on the analysis of simple and easily obtainable clinical and echocardiographic variables. The models showed good accuracy and adjustment, were validated internally, and are useful in the selection, monitoring and counseling of patients indicated for CRT.

Spasm of the Internal Thoracic Artery. Value of Echocardiography and Doppler in Long-term Follow-up

Spasm of the Internal Thoracic Artery. Value of Echocardiography and Doppler in Long-term Follow-up José Sebastião de Abreu,1,2 Tereza Cristina Pinheiro Diogenes,1,2 Ana Gardenia L. Ponte Farias,2,3 Marilia Esther Benevides Abreu,1,2 Renan Abreu Freire,1,2 José Erirtônio Façanha Barreto4 Clinicárdio de Fortaleza;1 Cardioexata de Fortaleza;2 Hospital das Clínicas, Universidade Federal do Ceará;3 Hospital Regional da Unimed,4 Fortaleza, Ceará − Brazil

Ligation of the Branches of the Anastomosed Internal Thoracic Artery in the Anterior Descending Coronary Artery and the Effect on Flow Velocities and Functional Status of the Graft

Ligation of the Branches of the Anastomosed Internal Thoracic Artery in the Anterior Descending Coronary Artery and the Effect on Flow Velocities and Functional Status of the Graft José Sebastião de Abreu,1 Tereza Cristina D. Pinheiro,1 José Acácio Feitosa,2 Marilia Esther B. Abreu,1 Ana Gardenia L. P. Farias,3 Marcia Maria Carneiro,3 Sandra Nívea R. Falcão2,3 Clinicárdio e Cardioexata de Fortaleza;1 Hospital de Messejana;2 Hospital das Clínicas da Universidade Federal do Ceará,3 Fortaleza, Ceará Brazil

Prognostic Value of Coronary Flow Reserve Obtained on Dobutamine Stress Echocardiography and its Correlation with Target Heart Rate

Background Normal coronary flow velocity reserve (CFVR) (≥ 2) obtained in the left anterior descending coronary artery (LAD) from transthoracic echocardiography is associated with a good prognosis, but there is no study correlating CFVR with submaximal target heart rate (HR). Objective To evaluate the prognostic value of CFVR obtained in the LAD of patients with preserved (>50%) left ventricular ejection fraction (LVEF) who completed a dobutamine stress echocardiography (DSE), considering target HR. Methods Prospective study of patients with preserved LVEF and CFVR obtained in the LAD who completed DSE. In Group I (GI = 31), normal CFVR was obtained before achieving target HR, and, in Group II (GII = 28), after that. Group III (G III=24) reached target HR, but CFVR was abnormal. Death, acute coronary insufficiency, coronary intervention, coronary angiography without further intervention, and hospitalization were considered events. Results In 28 ± 4 months, there were 18 (21.6%) events: 6% (2/31) in GI, 18% (5/28) in GII, and 46% (11/24) in GIII. There were 4 (4.8%) deaths, 6 (7.2%) coronary interventions and 8 (9.6%) coronary angiographies without further intervention. In event-free survival by regression analysis, GIII had more events than GI (p < 0.001) and GII (p < 0.045), with no difference between GI and GII (p = 0.160). After adjustment, the only difference was between GIII and GI (p = 0.012). Conclusion In patients with preserved LVEF and who completed their DSE, normal CFVR obtained before achieving target HR was associated with better prognosis.

Echocardiographic Predictors of Worse Outcome After Cardiac Resynchronization Therapy

Background Cardiac resynchronization therapy (CRT) is the recommended treatment by leading global guidelines. However, 30%-40% of selected patients are non-responders. Objective To develop an echocardiographic model to predict cardiac death or transplantation (Tx) 1 year after CRT. Method Observational, prospective study, with the inclusion of 116 patients, aged 64.89 ± 11.18 years, 69.8% male, 68,1% in NYHA FC III and 31,9% in FC IV, 71.55% with left bundle-branch block, and median ejection fraction (EF) of 29%. Evaluations were made in the pre-implantation period and 6-12 months after that, and correlated with cardiac mortality/Tx at the end of follow-up. Cox and logistic regression analyses were performed with ROC and Kaplan-Meier curves. The model was internally validated by bootstrapping. Results There were 29 (25%) deaths/Tx during follow-up of 34.09 ± 17.9 months. Cardiac mortality/Tx was 16.3%. In the multivariate Cox model, EF < 30%, grade III/IV diastolic dysfunction and grade III mitral regurgitation at 6-12 months were independently related to increased cardiac mortality or Tx, with hazard ratios of 3.1, 4.63 and 7.11, respectively. The area under the ROC curve was 0.78. Conclusion EF lower than 30%, severe diastolic dysfunction and severe mitral regurgitation indicate poor prognosis 1 year after CRT. The combination of two of those variables indicate the need for other treatment options.

Análise Comparativa de técnicas de Contornos Ativos aplicadas na Segmentação do Ventrículo Esquerdo em Imagens Digitais Ecocardiográficas de eixo curto

To aid in the diagnosis of heart disease is necessary to accurate segmentation of the left ventricle. In this con-text a method that stands out is the method of active contours (MAC) also called Snakes. This method consists of generating an initial contour around or within the region of interest, which is deformed by some forces acting on it and pushes it to the edges of the object. Although it is efficient compared to other methods of segmentation, the traditional MAC has some limitations: the difficulty of targeting based on an initial contour away from the edges of the object of interest and non-targeting of concave objects. This work aims at performing a comparative analysis between the traditional model, the balloon and GVF applied to segmentation of the left ventricle in digital images of short-axis echocardiography. The comparison is performed by calculating the maximum radial error, the average deviation of pixel and the mean square error. To obtain these results, tests were performed with 34 images with which you can compare the segmented image with a reference image. Among the methods compared, which shows a better continuity of contour and better segmentation is MAC GVF, but with a greater computational cost.