François Serres

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.

Prospective Echocardiographic and Tissue Doppler Imaging Screening of a Population of Maine Coon Cats Tested for the A31P Mutation in the Myosin-Binding Protein C Gene: A Specific Analysis of the Heterozygous Status

BACKGROUND A mutation in the sarcomeric gene coding for the myosin-binding protein C gene has been identified in a colony of Maine Coon cats with hypertrophic cardiomyopathy (MyBPC3-A31P mutation). However, the close correlation between genotype and phenotype (left ventricular hypertrophy [LVH] and dysfunction) has never been assessed in a large population, particularly in heterozygous (Hetero) cats. OBJECTIVES To investigate LV morphology and function with echocardiography and tissue Doppler imaging (TDI) in a population of Maine Coon cats tested for the MyBPC3-A31P mutation with focus on Hetero animals. ANIMALS Ninety-six Maine Coon cats. METHODS Prospective observational study. Cats were screened for the MyBPC3-A31P mutation and examined with both echocardiography and 2-dimensional color TDI. RESULTS Fifty-two out of 96 cats did not have the mutation (wild-type genotype, Homo WT), 38/96 and 6/96 were Hetero- and homozygous-mutated (Homo M) cats, respectively. Only 11% of Hetero cats (4/38) had LVH and 29% (10/34) of Hetero cats without LVH were >4 years old (4.1-11.5 years). LVH was also detected in 2 Homo WT cats (4%). A significantly decreased (P < .05) longitudinal E/A (ratio between early and late diastolic myocardial velocities) in the basal segment of the interventricular septum was observed in Hetero cats without LVH (n = 34) compared with Homo WT cats without LVH (n = 50), thus confirming that the Hetero status is associated with regional diastolic dysfunction (P < .05). CONCLUSIONS The heterozygous status is not consistently associated with LVH and major myocardial dysfunction. Moreover, Homo WT cats can also develop LVH, suggesting that other genetic causes might be implicated.

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.

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 Doppler ultrasonography and high-definition oscillometry for blood pressure measurements in healthy awake dogs

OBJECTIVE To determine the intra- and interobserver variability of systolic arterial pressure (SAP) and diastolic arterial pressure (DAP) measurements obtained with 2 indirect methods in awake dogs and percentage of successful measurements. ANIMALS 6 healthy conscious adult dogs. PROCEDURES 4 observers with different levels of training measured SAP and DAP on 4 days by use of Doppler ultrasonography (DU) and high-definition oscillometry (HDO). The examinations were randomized. Measurements for each technique were recorded 5 consecutive times, and mean values (total, 720 measurements) were used for statistical analysis. RESULTS All within- and between-day coefficients of variation (CVs) for SAP were < 15% irrespective of the observer or method (HDO, 3.6% to 14.1%; DU, 4.1% to 12.4%). Conversely, half the CVs for DAP were > 15% with the highest within- and between-day CVs obtained by the least experienced observer by use of DU (19.5% and 25.9%, respectively). All attempts with HDO were successful, whereas DAP could not be measured by use of DU by the least experienced observer in 17% of attempts. CONCLUSIONS AND CLINICAL RELEVANCE SAP may be assessed in healthy dogs by use of DU and HDO with good repeatability and reproducibility after a short period of training. Conversely, the variability of DAP is higher and longer training is required to assess DAP via DU than via HDO.

Quantification of pulmonary to systemic flow ratio by a doppler echocardiographic method in the normal dog: repeatability, reproducibility, and reference ranges.

OBJECTIVE To determine if the pulmonary to systemic flow ratio (Qp/Qs) could be assessed in healthy awake dogs using Doppler echocardiography. BACKGROUND Qp/Qs could provide reliable information in assessing the severity of intracardiac shunts (ICS) by quantifying pulmonary overcirculation. Qp/Qs has been validated against electromagnetic flowmeter methods in experimental canine models. However, its clinical applicability in awake dogs has never been assessed. ANIMALS, MATERIALS AND METHODS Six healthy dogs were used to determine the repeatability and reproducibility of the technique (Study 1); Qp/Qs was then prospectively assessed in 50 healthy dogs (Study 2). In both studies Qp/Qs was calculated in awake animals using a standardized Doppler echocardiographic method. RESULTS Within- and between-day coefficients of variation for Qp/Qs were <10% (Study 1). For Study 2, a relatively wide range of Qp/Qs was found (reference range=0.71-1.29; mean+/-SD=1.00+/-0.15). CONCLUSIONS Qp/Qs can be assessed with good repeatability and reproducibility in healthy dogs. However, the wide range of Qp/Qs obtained in the healthy population may suggest a limited usefulness of this variable for accurately assessing ICS severity in diseased animals. This needs to be assessed in further prospective and longitudinal studies including a large number of animals with ICS of various grades.