RESUMO
Background and Aim: Cardiac time intervals (CTIs) can provide important information on the electrical and mechanical properties of the heart. We hypothesized that cardiac function can be described using the combined power of electrocardiography (ECG) and phonocardiography (PCG) signals. This study aimed to (1) validate a novel custom device in measuring CTI parameters; (2) compare CTI parameters with a commercially available device and standard transthoracic echocardiography (STE); and (3) compare calculated systolic performance index (SPI) and myocardial performance index (MPI) with Tei index from the STE. Materials and Methods: This study determined CTIs based on simultaneous ECG and PCG recordings in 14 healthy Beagle dogs using the custom-built device. These CTI parameters were compared with a commercially available device (Eko DUO ECG + Digital Stethoscope; Eko DUO) and the STE. Agreement of CTI parameters between the custom device and the commercially available device or STE was evaluated. Calculated SPI and MPI based on Wigger's diagram were proposed, compared with SPI and Tei index, and correlated with STE parameters. Results: We found that the ECG and PCG parameters measured from the custom-built device did not differ from the commercially available device and the STE. By combining ECG and PCG signals, we established CTI parameters in healthy dogs including indices for systolic function (SPI: QS1/S1S2) and global cardiac function {F1 ([QS1+S2]/S1S2), F2 ([RS1+S2]/S1S2), and F3 (RS1 + [QS2-QT]/S1S2)}. The SPI, F2, and F3 were comparable with echocardiographic parameters describing systolic (Pre-ejection period/left ventricular ejection time [LVET]) and Tei index ([MCOdur-LVET]/LVET), respectively. Only SPI and F3 were correlated significantly with MCOdur and heart rate, respectively. Conclusion: We have validated the use of the custom-built device to describe CTIs that are comparable to the commercially available device and STE in healthy Beagles. The proposed SPI and MPI derived from CTI parameters can be useful in clinical practice to describe the cardiac function, especially in areas where access to STE is constrained.
RESUMO
Sildenafil is a selective phosphodiesterase-5 inhibitor that has been demonstrated to delay ventricular remodeling in humans and experimental animals. The aim of this prospective study was to assess the chronic effects of sildenafil administration on echocardiographic indices and N-terminal pro-B-type natriuretic peptide (NT-proBNP) in dogs with naturally occurring, asymptomatic myxomatous mitral valve degeneration. Thirty client-owned dogs with ACVIM class B1 or B2 were enrolled. Dogs were randomly assigned to treatment (sildenafil 1-3 mg/kg, PO, BID for 180 days) or control groups. A total of 12 dogs completed the 180 days trial in the sildenafil group, whereas 10 dogs remained in control group. When comparing the difference from baseline values obtained over time between groups, the stroke volume (SV) at day 30 was significantly higher in the sildenafil group (P=0.038). The LA/Ao and the MR jet area were significantly lower beginning at day 30 (only MR jet area; P=0.006), day 90 (P=0.006 and P=0.027, respectively) and day 180 (P=0.029 and P=0.032, respectively). The 2D-LA was significantly lower at day 90 when compared with control group (P=0.028). The differences of NTproBNP from baseline were significantly lower when compared with control group at the same timepoint (D90, P=0.017 and D180, P=0.013). In conclusion, this study suggested that long-term treatment with sildenafil prevented aggravation of disease progression as suggested by several echocardiographic indices (i.e. SV, LA/Ao, MR jet area, 2D-LA) and reduced NTproBNP level at the indicated timepoints in dogs with asymptomatic mitral valve degeneration.
