Edith Valenzuela

SCATTER AND STAFF DOSE LEVELS IN PAEDIATRIC INTERVENTIONAL CARDIOLOGY: A MULTICENTRE STUDY

Interventional cardiology procedures usually imply high doses to the staff, as paediatric cardiologists need to stay closer to the patient than during adult procedures. Also, biplane systems are used that imply an additional source of staff doses. The objective of this paper is to measure scatter doses in four X-ray systems, using polymethyl methacrylate phantoms with thicknesses ranging from 4 to 16 cm to simulate paediatric patients, for the different acquisition modes. Scatter dose rates measured at the position of cardiologists eyes ranged from 0.8 to 12 mSv h(-1), and about twice the above values at lower extremities, as a linear function of the surface air kerma at the phantom, keeping the irradiated area constant. Therefore, the respective personal dose equivalent for the lens of the eyes may be around 0.5 and 1 mSv throughout the procedure, if additional protection is not used. Simultaneous cine acquisition in biplane systems yielded scatter doses to cardiologists, increased by factors from 5 to 21, compared with a single C-arm acquisition case and depending on geometry. Knowledge of scatter doses for different operation modes, patient thicknesses and the biplane operation should help paediatric cardiologists to adopt conservative attitudes in respect of their occupational radiation risks.

Evaluation of patient doses and lens radiation doses to interventional cardiologists in a nationwide survey in Chile.

The objective of this study was to perform a nationwide survey in Chile to determine dose levels to patients and staff in four risk scenarios during cardiac catheterisation procedures. Different phantom thicknesses of polymethyl methacrylate (PMMA) were used to simulate adult patients. Scenario 1: 10-min fluoroscopy and 800 cine frames for 20 cm of PMMA; Scenario 2: 10-min fluoroscopy and 800 cine frames for 28 cm of PMMA; Scenario 3: 30-min fluoroscopy and 2400 cine frames for 20 cm of PMMA; Scenario 4: 30-min fluoroscopy and 2400 cine frames for 28 cm of PMMA. The average values regarding dose-area product and scattered doses at the cardiologist eye lens achieved for the four scenarios were 94, 249, 281, 747 Gy cm(2) and 0.3, 0.8, 0.9 and 2.5 mSv, respectively. Large variations in radiation doses received by both patients and staff for the same type of procedure suggest that optimising procedure protocols and using the most effective types of protective devices may substantially reduce the dose values found here.

Radiation dose and image quality for adult interventional cardiology in Chile: a national survey

The aim of this work was to investigate the differences in dose settings and image quality among 10 X-ray systems used for interventional cardiology in Chile. Entrance surface air kerma (ESAK) was measured on a phantom of 20 cm thickness of polymethyl methacrylate slabs. Image quality was evaluated using DICOM images of a test object Leeds TOR 18-FG for cine mode acquisition, through the numerical parameters signal-to-noise ratio (SNR), high-contrast spatial resolution (HCSR) and figure of merit. ESAK rate values for fluoroscopy modes ranged between 7.1 and 121.7 mGy min(-1). For cine mode, ESAK values per frame ranged from 63 to 400 µGy fr(-1). SNR and HCSR parameters for cine mode varied from 4.8 to 8.6 and 0.4 to 10, respectively. FOM values resulted from 6.9 to 64.5 among the different X-ray systems. Results show important differences between systems and point out the need to launch an optimisation programme.

Entrance surface air kerma in X-ray systems for paediatric interventional cardiology: a national survey

The aims of this work were to report the results of a national survey on entrance surface air kerma (ESAK) values for different phantom thicknesses and operation modes in paediatric interventional cardiology (IC) systems and to compare them with previous values. The national survey also offers suggested investigation levels (ILs) for ESAK in paediatric cardiac procedures. ESAK was measured on phantoms of 4-16 cm thickness of polymethyl methacrylate slabs. For low fluoroscopy mode (FM), ESAK rates ranged from 0.11 to 33.1 mGy min(-1) and for high FM from 0.34 to 61.0 mGy min(-1). For cine mode, values of ESAK per frame were from 1.9 to 78.2 µGy fr(-1). The ILs were suggested as the third quartile of the values measured. This research showed lower ESAK values than in previous research, particularly for ESAK values in cine modes. This work represents a first step towards launching a national programme in paediatric dosimetry for IC procedures.

Experiencia preliminar: STENT MGUARD en angioplastía coronaria con alta carga trombótica, ¿una nueva alternativa en protección embólica?

Resumen: Introduccion: La microembolizacion se asocia a mas eventos cardiovasculares adversos (MACE) especial-mente en angioplastia (PTCA) de puentes venosos aorto-coronarios (PAC) o en sindrome coronario agudo (SCA). El stent MGuard evitaria la embolizacion distal. Nuestro objetivo: evaluar el stent con micromalla de dacron como alternativa de proteccion embolica. Metodos: Registro prospectivo de PTCA con stent MGuard en de SCA de PAC y vasos nativos. Resultados: 15 angioplastias, de ellas 53% con infarto agudo miocardico con supradesnivel de ST (IAM con SDST). PTCA en vasos nativos: 60% y PAC: 40% (anti-guedad: 13 ± 3 anos). El 53% tuvo flujo inicial TIMI 0-1, alto contenido trombotico (66%: 4-5 en escala de trom-bos TIMI). Se predilato la lesion en 73% de los casos, se empleo Reopro en 2 casos, no se uso filtros de protec-cion ni aspirador de trombos. Las dimensiones del stent MGuard: 22.2 ± 4.4 mm de largo por 3.7 ± 0.44 mm de diametro. El 100% con flujo TIMI 3 final, 93% con im-pregnacion miocardica grado 3. Subgrupo de IAM con SDST: 71% obtuvo < 23 cuadros TIMI/segundo, 100% con regresion del SDST mayor de 50% a 90 minutos de PTCA. Subgrupo de PTCA de PAC: (excepto caso de PTCA de PAC en IAM c/SDST) no se registro elevacion de la CK total o MB post PTCA. Seguimiento: un caso de trombosis al mes. Conclusion: El MGuard stent parece ser efectivo en la proteccion de la microcirculacion. Se requieren estudios para evaluar la seguridad clinica y eficacia en proteccion embolica.

Resultados a largo plazo de la valvuloplastía mitral con balón

BACKGROUND Mitral balloon valvuloplasty (MBV) is the therapy of choice for the treatment of symptomatic mitral stenosis with suitable anatomy. Although its short and mid-term results are favorable, there is a paucity of information about long-term follow-up. AIM To assess the late results of MBV. MATERIAL AND METHODS A cohort of 225 patients aged 8 to 20 years who were subjected to a MBV from 1989 to 2001, was studied. All variables at the time of the procedure, short and long-term results and major events during follow-up (new mitral intervention and mortality) were recorded. Uni and multivariate analysis were used to assess prognosis. RESULTS The mean follow-up lapse was 13.5 years (range 8 to 20 years). During this period, 88 patients (39.1%) remained event-free and in acceptable functional capacity. Eight percent died, 8% required a second MBV and 43.5% required a surgical mitral valve replacement. A post-procedural area equal or greater to 1.9 cm² was associated with a greater likelihood of free-event survival (log rank test: p = 0.02/Cox proportional regression model: coefficient 0.54, p = 0.04). CONCLUSIONS MBV is effective, although there is a high chance of new interventions in the long-term follow-up. A larger post-procedure mitral area is associated with a better prognosis.

Acceso radial derecho versus izquierdo para cateterismo coronario en pacientes mayores de 70 años

Introducción: El acceso radial izquierdo (ARI) puede ser una alternativa para la realización de cateterismos coronarios, especialmente en pacientes añosos, donde modificaciones anatómicas pueden dificultar el procedimiento por acceso radial derecho (ARD). Objetivo: Determinar si el uso del ARI en pacientes mayores de 70 años disminuye el tiempo de fluoroscopía y la dosis de radiación durante una coronariografía realizada por operadores entrenados. Métodos: De forma prospectiva se evaluaron pacientes mayores de 70 años sometidos a cateterismo coronario por vía radial por operadores experimentados (>200 procedimiento por vía radial/año), utilizando la misma técnica. El acceso derecho o izquierdo fue asignado de forma aleatoria y se registraron los tiempos de procedimiento, la exposición a radiación, insumos utilizados y apreciación de dificultad del operador. Resultados: Se incluyeron 102 pacientes (ARD 52 / ARI 50). Ambos accesos fueron comparables en los tiempos utilizado para realizar el procedimiento (ARD 782 vs ARI 695 segundos, p= 0,06), aunque hubo un significativo menor tiempo utilizado para canular la arteria coronaria derecha en aquellos pacientes que se accedieron por ARI (206 vs 169 segundos; p= 0,01). No hubo diferencias en la radiación producida por el examen entre ambos grupos (PDA ARD 56,7 vs ARI 59,3 Gy/ cm2, p= 0,09), ni en la cantidad de medio de contraste utilizado (ARD 106,33 (31,04) vs ARI 108,13 (30,23), p=0,24). Se encontró una mayor frecuencia de tortuosidad (25% vs 6%, p <0,01) y de dificultad del procedimiento (58% vs 28%, p <0,01) en el grupo de ARD, principalmente debido al uso de una guía adicional (33% vs 4%, p< 0,01). Conclusión: Tanto el acceso radial derecho como el izquierdo son alternativas factibles para la realización de una coronariografía en pacientes de edad avanzada, no existiendo diferencias entre éstos en el tiempo total del procedimiento. Sin embargo, el ARD en pacientes añosos se asocia más frecuentemente con dificultades a nivel braquiocefálico y mayor uso de guías adicionales para sortear estos desafíos. Gonzalo Martínez1, 2, Martín Valdebenito1, Manuel Méndez1, 2, Alejandro Martínez1, Dante Lindefjeld2, 3, Osvaldo Pérez1, 2, Úrsula Valdivia1, Catherine Unzueta1, Edith Valenzuela.1