Intraoperative Analysis of Flow Dynamics in Arteriovenous Composite Y Grafts.

Objective: Composite graft of left internal thoracic artery and great saphenous vein in revascularization of the left coronary system is a technique well described in literature. The aim of this study is to analyze blood flow dynamics in this configuration of composite graft especially in what concerns left internal thoracic artery's adaptability and influence of great saphenous vein segment on left internal thoracic artery's flow. Methods: Revascularization of left coronary system with composite graft, with left internal thoracic artery revascularizing the anterior interventricular artery and a great saphenous vein segment, anastomosed to the left internal thoracic artery, revascularizing another branch of the left coronary system, was performed in 23 patients. Blood flow was evaluated by transit time flowmetry in all segments of the composite graft (left internal thoracic artery proximal segment, left internal thoracic artery distal segment and great saphenous vein segment). Measures were performed in baseline condition and after dobutamine-induced stress, without and with non-traumatic temporary clamping of the distal segments of the composite graft. Results: Pharmacological stress resulted in increase of blood flow values in the analyzed segments (P<0.05). Non-traumatic temporary clamping of great saphenous vein segment did not result in statistically significant changes in the flow of left internal thoracic artery distal segment, both in baseline condition and under pharmacological stress. Similarly, non-traumatic temporary clamping of left internal thoracic artery distal segment did not result in statistically significant changes in great saphenous vein segment flow. Conclusion: Composite grafts with left internal thoracic artery and great saphenous vein for revascularization of left coronary system, resulted in blood flow dynamics with physiological adaptability, both at rest and after pharmacological stress, according to demand. Presence of great saphenous vein segment did not alter physiological blood flow dynamics in distal segment of left internal thoracic artery.

Intraoperative analysis of flow dynamics in arteriovenous composite y grafts

Abstract Objective: Composite graft of left internal thoracic artery and great saphenous vein in revascularization of the left coronary system is a technique well described in literature. The aim of this study is to analyze blood flow dynamics in this configuration of composite graft especially in what concerns left internal thoracic artery's adaptability and influence of great saphenous vein segment on left internal thoracic artery's flow. Methods: Revascularization of left coronary system with composite graft, with left internal thoracic artery revascularizing the anterior interventricular artery and a great saphenous vein segment, anastomosed to the left internal thoracic artery, revascularizing another branch of the left coronary system, was performed in 23 patients. Blood flow was evaluated by transit time flowmetry in all segments of the composite graft (left internal thoracic artery proximal segment, left internal thoracic artery distal segment and great saphenous vein segment). Measures were performed in baseline condition and after dobutamine-induced stress, without and with non-traumatic temporary clamping of the distal segments of the composite graft. Results: Pharmacological stress resulted in increase of blood flow values in the analyzed segments (P<0.05). Non-traumatic temporary clamping of great saphenous vein segment did not result in statistically significant changes in the flow of left internal thoracic artery distal segment, both in baseline condition and under pharmacological stress. Similarly, non-traumatic temporary clamping of left internal thoracic artery distal segment did not result in statistically significant changes in great saphenous vein segment flow. Conclusion: Composite grafts with left internal thoracic artery and great saphenous vein for revascularization of left coronary system, resulted in blood flow dynamics with physiological adaptability, both at rest and after pharmacological stress, according to demand. Presence of great saphenous vein segment did not alter physiological blood flow dynamics in distal segment of left internal thoracic artery.

Doppler echocardiographic criteria in patency assessment of composite grafts from left internal thoracic artery.

OBJECTIVES: The purpose of our study was to establish, with an entirely noninvasive method, transthoracic Doppler echocardiography, criteria for patency of composite left internal thoracic artery grafts when placed on the left anterior descending artery and other branches of the left coronary system. METHODS: The control group comprised 20 patients with single graft and 20 patients with composite graft; all forty having their patency confirmed by coronary angiogram (CA). In this control group, two Doppler echocardiographic variables, diastolic mean velocity-time and integral diastolic peak velocity to systolic peak velocity ratio were recorded. For each variable, established cut-off points were established, using the ROC (Receiver Operator Characteristic) curves, to identify criteria which could differentiate the composite grafts. Only patients with composite grafts were included in the 159-patients study group. The criteria established by the cut-off points in the control group were then applied to detect patency using a diastolic fraction of > 0.5 as the gold standard. The sensitivity, specificity, and positive and negative predictive values of these two criteria were determined. RESULTS: In the control group, cut-off points of 0.71 and 0.09 m were established for the diastolic peak velocity/systolic peak velocity ratio and for diastolic mean velocity-time integral, respectively. In the study group phase, the sensitivity and negative predictive value of the diastolic peak velocity/systolic peak velocity > 0.71 criterion were 36% and 11%, respectively. Diastolic mean velocity-time integral > 0.09 m criterion, were 40% and 10.48%. The specificities and positive predictive values of each criterion were 100%. CONCLUSION: Values reaching the criteria established for each variable indicate high probability of composite graft patency. Lower values have a large proportion of false negatives and are not conclusive as patency criteria.

Doppler echocardiographic criteria in patency assessment of composite grafts from left internal thoracic artery / Parâmetros Dopplerfluxométricos de perviedade do enxerto composto de artéria torácica interna esquerda

OBJECTIVES: The purpose of our study was to establish, with an entirely noninvasive method, transthoracic Doppler echocardiography, criteria for patency of composite left internal thoracic artery grafts when placed on the left anterior descending artery and other branches of the left coronary system. METHODS: The control group comprised 20 patients with single graft and 20 patients with composite graft; all forty having their patency confirmed by coronary angiogram (CA). In this control group, two Doppler echocardiographic variables, diastolic mean velocity-time and integral diastolic peak velocity to systolic peak velocity ratio were recorded. For each variable, established cut-off points were established, using the ROC (Receiver Operator Characteristic) curves, to identify criteria which could differentiate the composite grafts. Only patients with composite grafts were included in the 159-patients study group. The criteria established by the cut-off points in the control group were then applied to detect patency using a diastolic fraction of > 0.5 as the gold standard. The sensitivity, specificity, and positive and negative predictive values of these two criteria were determined. RESULTS: In the control group, cut-off points of 0.71 and 0.09m were established for the diastolic peak velocity/systolic peak velocity ratio and for diastolic mean velocity-time integral, respectively. In the study group phase, the sensitivity and negative predictive value of the diastolic peak velocity/systolic peak velocity > 0.71 criterion were 36% and 11%, respectively. Diastolic mean velocity-time integral > 0.09m criterion, were 40% and 10.48%. The specificities and positive predictive values of each criterion were 100%. CONCLUSION: Values reaching the criteria established for each variable indicate high probability of composite graft patency. Lower values have a large proportion of false negatives and are not conclusive as patency criteria.

OBJETIVO: O objetivo deste estudo é estabelecer parâmetros preditores de perviedade, avaliados por Dopplerfluxometria, do enxerto composto de artéria torácica interna esquerda, quando revasculariza a artéria interventricular anterior e outro ramo do sistema esquerdo. MÉTODOS: O grupo controle foi formado por 20 pacientes com enxerto simples e 20 pacientes com enxerto, composto cuja perviedade foi confirmada por cineangiocoronariografia. No grupo controle, as variáveis de fluxo relação velocidade pico diastólico/velocidade pico sistólico e integral da velocidade média/tempo na diástole foram registradas. Para cada variável, estabeleceram-se pontos de corte para identificar enxertos compostos, usando-se curvas ROC (receiver operator characteristic). No grupo estudo, foram avaliados 159 pacientes com enxerto composto, determinando-se os dois parâmetros de fluxo. Pontos de cortes estabelecidos no grupo controle foram usados para determinar sensibilidade, especificidade, valores preditivos positivo e negativo de cada variável relacionada à perviedade dos enxertos, tomando-se como referência a fração diastólica > 0,5. RESULTADOS: No grupo controle, os pontos de corte estabelecidos para as variáveis velocidade pico diastólico/velocidade pico sistólico e integral velocidade média/tempo na diástole foram, respectivamente, 0,71 e 0,09m. No grupo estudo, a sensibilidade para a velocidade pico diastólico/velocidade pico sistólico e integral da velocidade média/tempo na diástole, considerando seus pontos de corte, foi de 36,4% e 40%, respectivamente. Os respectivos valores preditivos negativos foram 11% e 10.48%, enquanto especificidade e valor preditivo positivo foram de 100% para os dois parâmetros. CONCLUSÃO: Valores maiores ou iguais aos estabelecidos para cada variável indicam alta probabilidade de perviedade do enxerto composto. Valores inferiores apresentam grande proporção de falsos negativos, não sendo conclusivos quanto à perviedade.