RESUMO
Trans-mitral blood flow produces a three-dimensional rotational body of fluid, known as a vortex ring, that enhances the efficiency of left ventricular (LV) filling compared with a continuous linear jet. Vortex ring development is most often quantified with vortex formation time (VFT), a dimensionless parameter based on fluid ejection from a rigid tube. Our group is interested in factors that affect LV filling efficiency during cardiac surgery. In this report, we describe how to use standard two-dimensional (2D) and Doppler transesophageal echocardiography (TEE) to noninvasively derive the variables needed to calculate VFT. We calculate atrial filling fraction (ß) from velocity-time integrals of trans-mitral early LV filling and atrial systole blood flow velocity waveforms measured in the mid-esophageal four-chamber TEE view. Stroke volume (SV) is calculated as the product of the diameter of the LV outflow track measured in the mid-esophageal long axis TEE view and the velocity-time integral of blood flow through the outflow track determined in the deep transgastric view using pulse-wave Doppler. Finally, mitral valve diameter (D) is determined as the average of major and minor axis lengths measured in orthogonal mid-esophageal bicommissural and long axis imaging planes, respectively. VFT is then calculated as 4 × (1-ß) × SV/(πD3). We have used this technique to analyze VFT in several groups of patients with differing cardiac abnormalities. We discuss our application of this technique and its potential limitations and also review our results to date. Noninvasive measurement of VFT using TEE is straightforward in anesthetized patients undergoing cardiac surgery. The technique may allow cardiac anesthesiologists and surgeons to assess the impact of pathological conditions and surgical interventions on LV filling efficiency in real time.
Assuntos
Procedimentos Cirúrgicos Cardíacos/métodos , Ecocardiografia Doppler/métodos , Ecocardiografia Transesofagiana/métodos , Cardiopatias/diagnóstico por imagem , Cardiopatias/cirurgia , Monitorização Intraoperatória/métodos , Idoso , Velocidade do Fluxo Sanguíneo/fisiologia , Feminino , Frequência Cardíaca/fisiologia , Ventrículos do Coração/diagnóstico por imagem , Ventrículos do Coração/fisiopatologia , Hemodinâmica/fisiologia , Humanos , Masculino , Pessoa de Meia-Idade , Valva Mitral/fisiologia , Volume Sistólico/fisiologia , Fatores de Tempo , Função Ventricular Esquerda/fisiologiaRESUMO
OBJECTIVE: Transmitral blood flow produces a vortex ring (quantified using vortex formation time [VFT]) that enhances the efficiency of left ventricular (LV) filling. VFT is attenuated in LV hypertrophy resulting from aortic valve stenosis (AS) versus normal LV geometry. Many patients with AS also have aortic insufficiency (AI). The authors tested the hypothesis that moderate AI falsely elevates VFT by partially inhibiting mitral leaflet opening in patients with AS. DESIGN: Observational study. SETTING: Veterans Affairs medical center. PARTICIPANTS: Patients with AS in the presence or absence of moderate AI (n = 8 per group) undergoing aortic valve replacement (AVR) were studied after institutional review board approval. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: Under general anesthesia, peak early LV filling (E) and atrial systole (A) blood flow velocities and their corresponding velocity-time integrals were obtained using pulse-wave Doppler transesophageal echocardiography (TEE) to determine E/A and atrial filling fraction (beta). Mitral valve diameter (D) was calculated as the average of major and minor axis lengths obtained in the midesophageal bicommissural (transcommissural anterior-lateral-posterior medial) and LV long-axis (anterior-posterior) TEE imaging planes, respectively. VFT was calculated as 4·(1-beta)·SV/πD(3), where SV = stroke volume measured using thermodilution. Hemodynamics, diastolic function, and VFT were determined during steady-state conditions before cardiopulmonary bypass. The severity of AS (mean and peak pressure gradients, peak transvalvular jet velocity, aortic valve area) and diastolic function (E/A, beta) were similar between groups. Moderate centrally directed AI was present in 8 patients with AS (ratio of regurgitant jet width to LV outflow tract diameter of 36±6%). Pulse pressure and mean pulmonary artery pressure were elevated in patients with versus without AI, but no other differences in hemodynamics were observed. Mitral valve minor and major axis lengths, diameter, and area were reduced in the presence versus the absence of AI. VFT was increased significantly (5.7±1.7 v 3.2±0.6; p = 0.00108) in patients with AS and AI compared with AS alone. CONCLUSION: Moderate AI falsely elevates VFT in patients with severe AS undergoing AVR by partially inhibiting mitral valve opening. VFT may be an unreliable index of LV filling efficiency with competitive diastolic flow into the LV.
Assuntos
Insuficiência da Valva Aórtica/fisiopatologia , Estenose da Valva Aórtica/complicações , Estenose da Valva Aórtica/fisiopatologia , Valva Aórtica/patologia , Calcinose/complicações , Calcinose/fisiopatologia , Implante de Prótese de Valva Cardíaca , Hipertrofia Ventricular Esquerda/complicações , Hipertrofia Ventricular Esquerda/fisiopatologia , Idoso , Valva Aórtica/fisiopatologia , Feminino , Próteses Valvulares Cardíacas , Humanos , Masculino , Pessoa de Meia-Idade , Reprodutibilidade dos Testes , Índice de Gravidade de Doença , Fatores de TempoAssuntos
Ecocardiografia Transesofagiana/métodos , Átrios do Coração/anormalidades , Átrios do Coração/diagnóstico por imagem , Valva Tricúspide/anormalidades , Valva Tricúspide/diagnóstico por imagem , Átrios do Coração/cirurgia , Humanos , Masculino , Pessoa de Meia-Idade , Valva Tricúspide/cirurgiaAssuntos
Insuficiência da Valva Aórtica/diagnóstico por imagem , Endocardite Bacteriana/diagnóstico por imagem , Prolapso das Valvas Cardíacas/diagnóstico por imagem , Infecções Estafilocócicas/diagnóstico por imagem , Insuficiência da Valva Aórtica/complicações , Diagnóstico Diferencial , Endocardite Bacteriana/complicações , Prolapso das Valvas Cardíacas/complicações , Humanos , Masculino , Pessoa de Meia-Idade , Infecções Estafilocócicas/complicações , Staphylococcus aureus/isolamento & purificação , UltrassonografiaAssuntos
Estenose da Valva Aórtica/diagnóstico por imagem , Calcinose/diagnóstico por imagem , Neoplasias Cardíacas/diagnóstico por imagem , Trombose/diagnóstico por imagem , Obstrução do Fluxo Ventricular Externo/diagnóstico por imagem , Idoso de 80 Anos ou mais , Estenose da Valva Aórtica/complicações , Estenose da Valva Aórtica/cirurgia , Calcinose/complicações , Calcinose/cirurgia , Diagnóstico Diferencial , Neoplasias Cardíacas/complicações , Neoplasias Cardíacas/cirurgia , Humanos , Masculino , Trombose/complicações , Trombose/cirurgia , Ultrassonografia , Obstrução do Fluxo Ventricular Externo/complicações , Obstrução do Fluxo Ventricular Externo/cirurgiaAssuntos
Falso Aneurisma/diagnóstico , Artrite Infecciosa/diagnóstico , Endocardite Bacteriana/diagnóstico , Exposição Ocupacional/efeitos adversos , Pneumonia Bacteriana/diagnóstico , Infecções Estafilocócicas/diagnóstico , Adulto , Falso Aneurisma/complicações , Falso Aneurisma/cirurgia , Valva Aórtica/diagnóstico por imagem , Valva Aórtica/microbiologia , Valva Aórtica/cirurgia , Artrite Infecciosa/complicações , Artrite Infecciosa/cirurgia , Diagnóstico Diferencial , Endocardite Bacteriana/complicações , Endocardite Bacteriana/cirurgia , Humanos , Masculino , Pneumonia Bacteriana/complicações , Pneumonia Bacteriana/cirurgia , Infecções Estafilocócicas/complicações , Infecções Estafilocócicas/cirurgia , UltrassonografiaAssuntos
Doença das Coronárias/etiologia , Neoplasias Cardíacas/complicações , Mixoma/complicações , Idoso , Septo Interatrial/diagnóstico por imagem , Septo Interatrial/patologia , Circulação Coronária , Doença das Coronárias/diagnóstico por imagem , Doença das Coronárias/patologia , Forame Oval/diagnóstico por imagem , Forame Oval/patologia , Neoplasias Cardíacas/diagnóstico por imagem , Humanos , Masculino , Miocárdio/patologia , Mixoma/diagnóstico por imagem , UltrassonografiaAssuntos
Bioprótese , Cardiopatias Congênitas/cirurgia , Doenças das Valvas Cardíacas/cirurgia , Próteses Valvulares Cardíacas , Quadril/cirurgia , Idoso , Valva Aórtica/diagnóstico por imagem , Valva Aórtica/cirurgia , Doença da Válvula Aórtica Bicúspide , Bioprótese/efeitos adversos , Cardiopatias Congênitas/diagnóstico por imagem , Doenças das Valvas Cardíacas/diagnóstico por imagem , Próteses Valvulares Cardíacas/efeitos adversos , Quadril/diagnóstico por imagem , Quadril/microbiologia , Humanos , Masculino , UltrassonografiaRESUMO
OBJECTIVE: Standard methods of quantifying aortic valve stenosis (AS), which focus entirely on the valve itself, do not adequately characterize the magnitude, predict the onset, progression, and severity of symptoms, or identify the incidence of subsequent adverse events. Valvuloarterial impedance (Z(va)) is an index of global left ventricular (LV) afterload that incorporates valvular and arterial loads. The authors tested the hypothesis that aortic valve replacement (AVR) reduces Z(va) but does not affect the arterial component of LV afterload in elderly patients with degenerative calcific trileaflet AS. DESIGN: Observational study. SETTING: Veterans affairs medical center. PARTICIPANTS: Eight elderly (age, 79 ± 4 years) men with moderate-to-severe AS and normal preoperative LV function (ejection fraction, 61% ± 9%) scheduled for AVR with or without coronary artery bypass graft surgery were studied after institutional review board approval. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: A comprehensive TEE examination was performed during isoflurane-fentanyl-rocuronium anesthesia. Doppler echocardiography was used to measure pressure gradients across the aortic valve, stroke volume (continuity equation), and aortic valve area using standard techniques. Z(va) was determined as (systolic arterial pressure+mean gradient)/stroke volume index. Energy loss index was calculated as (aortic area × aortic valve area)/([aortic area--aortic valve area]× body surface area). The stroke work loss was obtained as (mean gradient × 100/[systolic arterial pressure+mean gradient]). The ratio of stroke volume index to pulse pressure was used to measure systemic arterial compliance. Z(va), energy loss index, stroke work loss, and systemic arterial compliance were assessed before and 15 minutes after cardiopulmonary bypass. Systemic and pulmonary hemodynamics (invasive catheters) were similar after versus before AVR. Aortic valve area increased significantly (p<0.05) with AVR (0.92 ± 0.26 cm(2) to 1.94 ± 0.35 cm(2)), concomitant with decreases in peak and mean gradients (60 ± 17 mmHg to 15 ± 8 mmHg and 38 ± 11 mmHg to 8 ± 5 mmHg, respectively) and peak blood flow velocity (3.9 ± 0.5 m · s(-1) to 1.9 ± 0.5 m · s(-1)). AVR reduced Z(va) (4.6 ± 1.0 mmHg · mL(-1) · m(-2) to 3.5 ± 0.3 mmHg · mL(-1) · m(-2)) and improved energy loss index (0.55 ± 0.16 cm(2) · m(-2) to 1.58 ± 0.48 cm(2) · m(-2)) concomitant with a decline in stroke work loss (25% ± 6% to 7% ± 4%), but systemic arterial compliance remained unchanged (0.63 ± 0.13 compared with 0.70 ± 0.12 mL · mmHg(-1)· m(-2)). CONCLUSION: The current results showed that AVR acutely reduced Zva, improved energy loss index, and decreased stroke work loss, but did not affect systemic arterial compliance in elderly men with degenerative calcific trileaflet AS.