Volume loading-related changes in tissue Doppler images derived from the tricuspid valve annulus in dogs

Positive correlation between echocardiographic tricuspid E peak velocity and central venous pressure in dogs: A preliminary study

In the absence of vascular obstruction, central venous pressure (CVP) is a hydrostatic pressure in the cranial and caudal vena cava, providing valuable information about cardiac function and intravascular volume status. It is also a component in evaluating volume resuscitation in patients with septic shock and monitoring patients with right heart disease, pericardial disease, or volume depletion. Central venous pressure is calculated in dogs by invasive central venous catheterization, which is considered high-risk and impractical in critically ill patients. This study aimed to investigate the feasibility of using echocardiographic tricuspid E/E' as a noninvasive method to estimate CVP in anesthetized healthy dogs under controlled hypovolemic conditions. Ten male mixed-breed dogs were included in the study after a thorough health assessment. For hypovolemia induction, blood withdrawal was performed, and echocardiographic factors of the tricuspid valve, including peak E and E' velocities, were measured during CVP reduction. Repeated measures analysis of variance and Bonferroni post hoc tests were employed to compare the average difference between measured echocardiographic indices and CVP values derived from catheterization and intermittent measurement methods. Spearman's ρ correlation coefficient was used to evaluate the correlation between echocardiographic indices and CVP. E peak velocity had a significant negative correlation with venous blood pressure phases (r = -0.44, P = .001), indicating a decrease in peak E velocity with progressive CVP reduction. However, tricuspid valve E' peak velocity and E/E' did not correlate with CVP, suggesting that these parameters are not reliable for CVP estimation in dogs.

Right Ventricle Response to Major Lung Resection (the RIVER Study)

Backgrounds

Major lung resection is associated with high postoperative morbidity and mortality, especially due to cardiorespiratory complications. Right ventricle (RV) ejection, pulmonary artery (PA) pressure, and tone are tightly coupled. Since the RV is exquisitely sensitive to changes in afterload, an acute increase in RV outflow resistance (i.e., acute pulmonary embolism [PE]) will cause acute RV dilatation and, a reduction of left ventricle compliance too, rapidly spiraling to acute cardiogenic shock and death. We investigated the changing in RV performance after major lung resection.

Materials and Methods

We carried out transthoracic echocardiography (TTE) aiming at searching for the incidence of early RV systolic dysfunction (defined as tricuspid annulus plane systolic excursion [TAPSE] <17 cm, S'-tissue Doppler imaging <10 cm/s) and estimate the RV-PA coupling by the TAPSE/pulmonary artery pressures (PAPs) ratio after major lung resection. The TTE has been performed before and immediately after surgery.

Results

After the end of the operation the echocardiographic parameters of the RV function worsened. TAPSE decreased from 24 (21 ÷ 28) to 18 (16 ÷ 22) mm (P = 0.015) and PAPs increased from 26 (25 ÷ 30) to 30 (25 ÷ 39) mmHg (P = 0.013). TAPSE/PAPs ratio decreased from 0.85 (0.80 ÷ 0.90) to 0.64 (0.54 ÷ 0.79) mm/mmHg (P = 0.002).

Conclusions

In line with previous reports, after major lung resection the increase in afterload reduces the RV function, but the impairment remains clinically not relevant. The different clinical picture of an acute cor pulmonale due to PE implies that the pathogenesis of cardiac failure involves more pathways than the mere mechanic occlusion of the blood flow.

Maternal Left Ventricular Diastolic and Systolic Function during Normal Pregnancy in Saint Bernard Dogs

This study aimed to evaluate maternal left ventricular (LV) systo-diastolic function using conventional and TDI echocardiography and included 10 healthy Saint-Bernard pregnant bitches. M-mode, peak transmitral flow velocities during early diastole (E) and atrial contraction (A), aortic and pulmonic flow, myocardial performance index (MPI), TDI studies (peak myocardial velocities during early diastole (E’), atrial contraction (A’) and peak systole (S’)), and blood pressure were measured at 21 to 28 (T1), 40 (T2) and 60 (T3) days of gestation and four to eight weeks postpartum (T4). Cardiac output and heart rate were 20% and 9% higher at T3, respectively, compared to T4 (p < 0.01). Lateral S’ was 36% higher at T3 than at T1 (p < 0.05). Changes in diastolic function were demonstrated by 10% lower E wave and 15% A wave at T1, compared to T4 (p < 0.05). E’ and A’ were 23% and 42% higher at T3 compared to T4 (p < 0.01). Both lateral E/E’ and E’/A’ were 6% and 19% lower at T3 compared to T1 (p < 0.01 and p < 0.05, respectively). At T3, MPI was 51% and 34% lower when compared to T1 or T2 (p < 0.05). The echocardiographic evaluation of maternal cardiac function is important, as structural, and functional changes occur throughout pregnancy.

A novel technique to predict pulmonary capillary wedge pressure utilizing central venous pressure and tissue Doppler tricuspid/mitral annular velocities

Assessing left ventricular (LV) filling pressure (pulmonary capillary wedge pressure, PCWP) is an important aspect in the care of patients with heart failure (HF). Physicians rely on right ventricular (RV) filling pressures such as central venous pressure (CVP) to predict PCWP, assuming concordance between CVP and PCWP. However, the use of this method is limited because discordance between CVP and PCWP is observed. We hypothesized that PCWP can be reliably predicted by CVP corrected by the relationship between RV and LV function, provided by the ratio of tissue Doppler peak systolic velocity of tricuspid annulus (S(T)) to that of mitral annulus (S(M)) (corrected CVP:CVP·S(T)/S(M)). In 16 anesthetized closed-chest dogs, S T and S M were measured by transthoracic tissue Doppler echocardiography. PCWP was varied over a wide range (1.8-40.0 mmHg) under normal condition and various types of acute and chronic HF. A significantly stronger linear correlation was observed between CVP·S(T)/S(M) and PCWP (R2 = 0.78) than between CVP and PCWP (R2 = 0.22) (P < 0.01). Receiver-operating characteristic (ROC) analysis indicated that CVP·S(T)/S(M) >10.5 mmHg predicted PCWP >18 mmHg with 85% sensitivity and 88% specificity. Area under ROC curve for CVP·S T/S M to predict PCWP >18 mmHg was 0.93, which was significantly larger than that for CVP (0.66) (P < 0.01). Peripheral venous pressure (PVP) corrected by S T/S M (PVP·S(T)/S(M) also predicted PCWP reasonably well, suggesting that PVP·S(T)/S (M) may be a minimally invasive alternative to CVP·S(T)/S(M) In conclusion, our technique is potentially useful for the reliable prediction of PCWP in HF patients.