Valérie Chetboul

Diagnostic Value of Echo-Doppler and Tissue Doppler Imaging in Dogs with Pulmonary Arterial Hypertension

BACKGROUND Diagnosis of pulmonary arterial hypertension (PAH) relies on Doppler measurement of pulmonic and tricuspid regurgitation (TR). However, these are not always detectable. HYPOTHESIS Tissue Doppler imaging (TDI), a novel noninvasive ultrasound technique, provides indirect but sensitive and specific assessment of elevated systolic pulmonary artery pressure (SPAP) in dogs. ANIMALS One hundred and five dogs with TR. METHODS Prospective observational study. Dogs were categorized as presenting normal (group 1, n = 45), mildly increased (group 2, n = 19), or moderately to severely increased (group 3, n = 41) SPAP, based on TR peak velocities (< 2.5, 2.5-3.0, and > 3.0 m/s, respectively). Ten quantitative echo-Doppler- and TDI-derived variables were assessed, including the main pulmonary arterial diameter to aortic diameter ratio, pulmonary flow acceleration time, and acceleration-to-ejection time ratio, the Tei index of right ventricular function, and 6 longitudinal basal right ventricular TDI variables. RESULTS A significant correlation was observed between SPAP and each of the 10 tested variables (P < .05). Conventional echo-Doppler variables were less discriminating than the TDI for predicting increased SPAP. The combined systolic and diastolic right TDI index had the highest sensitivity and specificity (89% and 93% respectively, for a cutoff of 11.8 cm/s) and could discriminate between dogs in group 1 from dogs in group 2. CONCLUSIONS AND CLINICAL IMPORTANCE TDI provided effective predictors of systolic PAH and demonstrated that both alterations in right-sided systolic and diastolic myocardial function can occur with mild increases in SPAP.

Association of Plasma N-Terminal Pro-B-Type Natriuretic Peptide Concentration with Mitral Regurgitation Severity and Outcome in Dogs with Asymptomatic Degenerative Mitral Valve Disease

BACKGROUND The clinical outcome of dogs affected by degenerative mitral valve disease (MVD) without overt clinical signs is still poorly defined, and criteria for identification of animals that are at a higher risk of early decompensation have not yet been determined. HYPOTHESIS N-terminal pro-B-type natriuretic peptide plasma concentration (NT-proBNP) is correlated with mitral regurgitation (MR) severity and can predict disease progression in dogs with asymptomatic MVD. ANIMALS Seventy-two dogs with asymptomatic MVD, with or without heart enlargement (International Small Animal Cardiac Health Council: ISACHC classes 1a and 1b), and a control group of 22 dogs were prospectively recruited. METHODS Severity of MR was quantitatively assessed from the regurgitation fraction (RF) by the proximal isovelocity surface area method. Consequences of MR were evaluated from measurements of the left atrium/aorta ratio (LA/Ao), fractional shortening (FS), end-diastolic and end-systolic left ventricular volumes indexed to body surface area (EDVI and ESVI). The relevance of these echo-Doppler indices and NT-proBNP for prediction of outcome at 12 months was studied. RESULTS A significant correlation was found between NT-proBNP and RF, LA/Ao, FS, and EDVI (P < .05). NT-proBNP was higher in dogs with MVD (ISACHC classes 1a and 1b) compared with the control group (P= .025 and < .001, respectively). The difference was not significant when only dogs from ISACHC class 1a with RF < 30% were considered. Lastly, NT-proBNP was higher in dogs that underwent MVD decompensation at 12 months (P < .05). CONCLUSIONS AND CLINICAL IMPORTANCE NT-proBNP is correlated with MVD severity and prognosis in dogs with asymptomatic MVD.

Comparison of 3 Ultrasound Methods for Quantifying Left Ventricular Systolic Function: Correlation with Disease Severity and Prognostic Value in Dogs with Mitral Valve Disease

BACKGROUND End-systolic volume index (ESVI) is a marker of systolic function, which can be assessed by the geometric (GM, based on Teichholz formula) or 2 planimetric methods (PM, Simpsons derived and length area methods). HYPOTHESIS Systolic dysfunction (SyD) may be observed in dogs with mitral valve disease (MVD) and is better assessed by PM than GM, which does not take into account the longitudinal left ventricular systolic shortening. ANIMALS Six healthy dogs were used to determine the variability of the tested variables (Study 1). These variables were then prospectively assessed (Study 2) in 101 small breed dogs: 77 dogs with MVD and 24 healthy controls (CD). METHODS ESVI was measured by GM and PM in awake dogs. RESULTS All within- and between-day coefficients of variation were <11% (Study 1). For Study 2, a nonlinear overestimation of ESVI was observed by GM compared with PM. PM-derived ESVI was significantly increased in ISACHC class 3 dogs compared with ISACHC class 1 dogs and exerted a significant influence on cardiac events at 5 months in dogs with MVD from ISACHC classes 2 and 3 (P < .05). CONCLUSIONS AND CLINICAL IMPORTANCE ESVI can be calculated by GM and PM with good repeatability and reproducibility. However, GM overestimates ESVI in a nonlinear way. Therefore, PM-derived ESVI should be preferred for the detection of SyD that is present at the late stages of the disease.

Plasma N-terminal pro-B-type natriuretic peptide concentration helps to predict survival in dogs with symptomatic degenerative mitral valve disease regardless of and in combination with the initial clinical status at admission.

OBJECTIVES Although mitral valve disease (MVD) is the most common canine heart disease, readily available prognostic markers of the disease are still lacking. The aim of this study was to evaluate the comparative ability of N-terminal pro-B-type natriuretic peptide plasma concentration (NT-proBNP) and various echocardiographic variables to predict outcome in dogs with MVD. ANIMALS, MATERIALS AND METHODS Seventy-four dogs with ISACHC classes 2 and 3 MVD (Groups A and B, respectively) were prospectively recruited. NT-proBNP and several echo-Doppler variables at inclusion were compared as predictors of outcome at 6 months in 54/74 dogs. RESULTS NT-proBNP was significantly higher in Group B than in Group A (P<0.0001), and was the only tested variable significantly different between survivor and non-survivor dogs in both groups (P<0.05). In the whole canine population, a threshold of 1500 pmol/L could discriminate survivor from non-survivor dogs with a sensitivity and specificity of 80% and 73%, respectively. When combining ISACHC class with NT-proBNP levels, a cut-off of 1265 pmol/L was predictive of survival in Group A, whereas the cut-off was 2700 pmol/L for Group B. CONCLUSIONS NT-proBNP is correlated with MVD severity and could be used in combination with clinical status to predict cardiac outcome.

Chordae tendineae Rupture in Dogs with Degenerative Mitral Valve Disease: Prevalence, Survival, and Prognostic Factors (114 Cases, 2001–2006)

BACKGROUND Degenerative mitral valve disease (MVD) is the most common heart disease in small breed dogs, and chordae tendineae rupture (CTR) is a potential complication of this disease. The survival time and prognostic factors predictive of survival in dogs with CTR remain unknown. HYPOTHESIS The prevalence and prognosis of CTR in dogs with MVD increases and decreases, respectively, with heart failure class. ANIMALS This study used 706 dogs with MVD. METHODS The diagnosis of CTR was based on a flail mitral leaflet with the tip pointing into the left atrium during systole, which was confirmed in several 2-dimension imaging planes using the left and right parasternal 4-chamber views. RESULTS CTR was diagnosed in 114 of the 706 dogs with MVD (16.1%) and most of these (106/114, 93%) had severe mitral valve regurgitation as assessed by color Doppler mode. CTR prevalence increased with International Small Animal Cardiac Health Council (ISACHC) clinical class (i.e., 1.9, 20.8, 35.5, and 69.6% for ISACHC classes Ia, Ib, II, and III, respectively [P < .05]). Long-term follow-up was available for 57 treated dogs (angiotensin-converting enzyme inhibitors and diuretics) and 58% of these (33/57) survived > 1 year after initial CTR diagnosis (median survival time, 425 days). Clinical class, the presence of ascites or acute dyspnea at the time of diagnosis, heart rate, plasma urea concentration, and left atrial size were predictors of survival. CONCLUSIONS AND CLINICAL RELEVANCE CTR is associated with a higher overall survival time than previously supposed. Its prognosis mostly depends on a combination of clinical and biochemical factors.

Ultrasonographic Assessment of Regional Radial and Longitudinal Systolic Function in Healthy Awake Dogs

BACKGROUND Strain (St) and strain rate (SR) imaging are new ultrasound modalities based on tissue Doppler imaging (TDI) that allow quantitative assessment of segmental myocardial contraction or stretching and rate of deformation, respectively. HYPOTHESIS Regional peak systolic St and SR could allow repeatable and reproducible assessment of systolic function of the right (RVW) and left (LVFW) myocardial walls in dogs. ANIMALS Six healthy Beagle dogs were used to determine the repeatability and reproducibility of regional peak systolic St and SR in the RVW and LVFW (Study 1). These variables were also assessed in 30 healthy dogs of several breeds (Study 2). METHODS Longitudinal peak systolic St and SR were recorded in 2 segments (basal and apical) of the RVW and LVFW. Radial peak systolic St and SR of the LVFW were also assessed. RESULTS All within- and most (7/10) between-day coefficients of variation were <15%. Absolute values of the longitudinal deformation indices were significantly higher (P < .001) in the RVW (St = -39.5 +/- 5.5% and SR = -5.2 +/- 0.8 s(-1) at the base; St = -36.3 +/- 4.3% and SR = -4.7 +/- 1.1 s(-1) at the apex) than in the LVFW. Absolute values were also higher for the radial (St = 62.9 +/- 10.4% and SR = 5.8 +/- 1.1 s(-1), P < .001) than for the longitudinal LFVW motions. CONCLUSIONS AND CLINICAL IMPORTANCE St and SR imaging is a repeatable and reproducible method for assessing systolic myocardial function. The combination of these indices with conventional echocardiographic variables may be useful for screening canine myocardial diseases.

Noninvasive Assessment of Systolic Left Ventricular Torsion by 2-Dimensional Speckle Tracking Imaging in the Awake Dog : Repeatability, Reproducibility, and Comparison with Tissue Doppler Imaging Variables

BACKGROUND Left ventricular (LV) torsional deformation plays an important role in myocardial function. However, it has never been assessed in the awake dog, because magnetic resonance imaging and sonomicrometry have been the only methods available so far. HYPOTHESIS Two dimensional speckle tracking echocardiography (STE), a new ultrasound imaging technique, provides a repeatable and reproducible noninvasive assessment of systolic LV wringing motion in the awake dog. ANIMALS Six healthy dogs were used to determine the repeatability and reproducibility of STE variables (study 1). These variables also were prospectively assessed in a population of 35 healthy dogs (study 2). METHODS Peak LV basal and apical systolic rotations were measured by STE from right parasternal short-axis views using automatic frame-to-frame tracking of gray-scale speckle patterns. Systolic LV torsion (LVtor, degrees ) was defined as apical rotation relative to the base. RESULTS All within-day and between-day coefficients of variation were <20% (6.8-18.0%). Amplitude of apical systolic rotation was significantly higher (P < .001) than the basal value (5.4 +/- 3.2 degrees and -3.1 +/- 1.3 degrees , respectively). Global LVtor was significantly correlated with systolic longitudinal LV myocardial velocity gradient assessed by tissue Doppler (P < .05), but not with either systolic radial LV myocardial velocity gradient or the ratio of early mitral inflow velocity to early mitral annular velocity (Em/Ea). CONCLUSIONS AND CLINICAL IMPORTANCE Speckle tracking echocardiography is a repeatable and reproducible method for assessing systolic LV torsional deformation. The combination of these new STE indices with tissue Doppler variables could provide a new approach for quantifying canine LV systolic function.

Angiotensin-converting enzyme inhibitors in veterinary medicine.

Angiotensin-converting enzyme (ACE) inhibitors represent one of the most commonly used categories of drugs in canine and feline medicine. ACE inhibitors currently approved for use in veterinary medicine are benazepril, enalapril, imidapril and ramipril. They are all pro-drugs administered by oral route. A physiologically based model taking into account the saturable binding to ACE has been developed for pharmacokinetic analysis. The bioavailability of the active compounds from their respective pro-drug is low. The active metabolites are eliminated by renal, hepatorenal or biliary excretion, according to the drug. The elimination half-life of the free fraction of the active compounds is very short (ranging from approximately 10 min to 2 h). ACE inhibitors are generally well tolerated. Benazepril, enalapril, imidapril and ramipril are approved for dogs with chronic heart failure (CHF). The efficacy of ACE inhibitors has been convincingly demonstrated in dogs with CHF, especially in those with chronic valvular disease. In such clinical settings, ACE inhibitors improve hemodynamics and clinical signs, and increase survival time. In cats with cardiovascular disease, little information is available except for reports of some benefit in cats with hypertrophic cardiomyopathy in two non-controlled investigations. ACE inhibitors have also a mild to moderate hypotensive effect. There is also evidence to recommend ACE inhibitors in dogs and cats with chronic renal failure (CRF). They decrease the glomerular capillary pressure, have antiproteinuric effects, tend to delay the progression of CRF and to limit the extent of renal lesions.

Effect of benazepril on survival and cardiac events in dogs with asymptomatic mitral valve disease: a retrospective study of 141 cases.

BACKGROUND Angiotensin-converting enzyme inhibitors (ACEIs) improve quality of life and extend the life span of dogs with naturally acquired ISACHC class II-III congestive heart failure (CHF). However, their effects on asymptomatic heart disease remain controversial. HYPOTHESIS Benazepril (BNZ), an ACEI, could have beneficial effects at the asymptomatic stage of degenerative mitral valve disease (MVD). ANIMALS Dogs with ISACHC class Ia MVD and moderate-to-severe mitral regurgitation (MR) assessed by the color Doppler mapping technique at entry (Day 0) were retrospectively included. METHODS Dogs were assigned to the treated group (BNZ group) if they received BNZ (and no other cardiac medication) from Day 0 or to the untreated group (UT group) if they did not receive any cardioactive treatment until occurrence of CHF. RESULTS A total of 141 dogs were included in the study, 66 in the BNZ group (dosage: 0.30 +/- 0.13 mg/kg) and 75 in the UT group. In the population (n = 93) including all breeds except Cavalier (CKC) and King Charles Spaniels (KC), median survival time to all causes of death in the BNZ group (n = 34, 3.3 years) was significantly longer than in the UT group (n = 59, 1.9 years) as was time to cardiac event (P < .05). Conversely, no effect of the BNZ treatment was observed in the CKC and KC population. CONCLUSIONS AND CLINICAL RELEVANCE BNZ had beneficial effects in asymptomatic dogs other than CKC and KC affected by MVD with moderate-to-severe MR. Breed distribution should be taken into account for interpretation of clinical trials performed in dogs with cardiac disease.

Comparison of the effects of imidapril and enalapril in a prospective, multicentric randomized trial in dogs with naturally acquired heart failure

OBJECTIVE To compare the efficacy and tolerability of the long-term administration of two different angiotensin-converting enzyme inhibitors, imidapril and enalapril, in a multicentric, prospective, randomized parallel-group scheme clinical trial in dogs with naturally acquired heart disease. ANIMALS One hundred twenty eight dogs with clinical signs of heart failure (stage II (64-50%) - III (45-35%) - IV (19-15%) New York Heart Association) caused by chronic valvular disease or dilated cardiomyopathy were selected. PROCEDURE Imidapril (minimum dosage 0.25 mg/kg) or enalapril (median dosage 0.5 mg/kg) was administered orally once daily for 12 months, either alone or as an add-on therapy to diuretics and/or digoxin. RESULTS The primary outcome measure was the quality of life score after 3 months of therapy. Sixty-one percent of the dogs in the imidapril group (36/59) and 52 % in the enalapril group (30/58) were considered responders. After 12 months, a clear improvement compared to baseline was maintained in each treatment group for most parameters reflecting the quality of life such as fatigue, exercise tolerance, dyspnea, cough and general condition. Quality of life scores and survival times were similar in both groups after 12 months. Both drugs were well tolerated over the one-year follow-up. CONCLUSIONS Imidapril proved to be as effective as the reference drug enalapril in the treatment of dogs with NYHA class II-IV heart failure. As with enalapril, imidapril was well tolerated during the long-term treatment period of one year in the dose range used in the study.