Search Results

You are looking at 11 - 20 of 22 items for

  • Author or Editor: John D. Bonagura x
  • Refine by Access: All Content x
Clear All Modify Search
in Journal of the American Veterinary Medical Association

Abstract

Case Description—4 dogs with acquired pulmonary artery stenosis (PAS) were examined for various clinical signs. One was a mixed-breed dog with congenital valvular PAS that subsequently developed peripheral PAS, one was a Golden Retriever with pulmonary valve fibrosarcoma, one was a Pembroke Welsh Corgi in which the left pulmonary artery had inadvertently been ligated during surgery for correction of patent ductus arteriosus, and one was a Boston Terrier with a heart-base mass compressing the pulmonary arteries.

Clinical Findings—All 4 dogs were evaluated with 2-dimensional and Doppler echocardiography to characterize the nature and severity of the stenoses; other diagnostic tests were also performed.

Treatment and Outcome—The mixed-breed dog with valvular and peripheral PAS was euthanized, surgical resection of the pulmonic valve mass was performed in the Golden Retriever, corrective surgery was performed on the Pembroke Welsh Corgi with left pulmonary artery ligation, and the Boston Terrier with the heart-base mass was managed medically.

Clinical Relevance—Acquired PAS in dogs may manifest as a clinically silent heart murmur, syncope, or right-sided heart failure. The diagnosis is made on the basis of imaging findings, particularly results of 2-dimensional and Doppler echocardiography. Treatment may include surgical, interventional, or medical modalities and is targeted at resolving the inciting cause.

Full access
in Journal of the American Veterinary Medical Association

Abstract

Objective—To evaluate the accuracy of a commercial ultrasonographic cardiac output (CO) monitoring system (UCOMS) in anesthetized Beagles as assessed by comparison with thermodilution CO (TDCO).

Animals—8 healthy anesthetized Beagles.

Procedures—Simultaneous UCOMS and TDCO measurements of CO were obtained during 4 hemodynamic states: baseline anesthesia (0.5% to 1.5% isoflurane), a higher depth of anesthesia (2% to 3.5% isoflurane) to yield a ≥ 15% reduction in systolic arterial blood pressure, IV infusion of colloidal solution to a mean right atrial pressure of ≥ 15 mm Hg, and IV infusion of dobutamine at 5 μg/kg/min. Measurements were obtained at 2 probe positions: the subxiphoid region and the right thoracic inlet. Correlation and agreement of results between methods were determined via linear regression analysis and Bland-Altman plots.

Results—A significant positive correlation was detected between UCOMS andTDCO measurements obtained at the subxiphoid (R = 0.86) and thoracic inlet (R = 0.83) positions. Bland-Altman plots revealed minimal bias between methods (bias ± SD, −0.03 ± 0.73 L/min and −0.20 ± 0.80 L/min for subxiphoid and thoracic inlet measurements, respectively). However, the percentage error associated with UCOMS measurements made at the 2 positions was > 45%.

Conclusions and Clinical Relevance—When compared with the results of TDCO, CO measured with the UCOMS exceeded commonly accepted limits of error in healthy dogs. The UCOMS was, however, able to track changes in CO across hemodynamic states. Additional research is needed to assess the usefulness of the UCOMS for monitoring CO in critically ill dogs.

Full access
in American Journal of Veterinary Research

Abstract

Objective—To identify Doppler echocardiographic (DE) variables that correlate with left ventricular filling pressure (LVFP).

Animals—7 healthy dogs (1 to 3 years old).

Procedures—Dogs were anesthetized and instrumented to measure left atrial pressure (LAP), left ventricular pressures, and cardiac output. Nine DE variables of LVFP derived from diastolic time intervals, transmitral and pulmonary venous flow, and tissue Doppler images were measured over a range of hemodynamic states induced by volume loading and right atrial pacing. Associations between simultaneous invasive measures of LVFP and DE measures of LVFP were determined by use of regression analysis. Receiver operating characteristic analysis was used to predict increases in mean LAP on the basis of DE variables.

Results—Mean LAP was correlated with several DE variables: the ratio between peak velocity during early diastolic transmitral flow and left ventricular isovolumic relaxation time (peak E:IVRT) during sinus rhythm and during right atrial pacing, IVRT, the ratio between late diastolic transmitral flow velocity and pulmonary venous flow duration, and the interval between onset of early diastolic mitral annulus motion and onset of early diastolic transmitral flow. Cutoff values of 2.20 and 2.17, for peak E:IVRT in dogs with sinus rhythm and atrial pacing predicted increases in mean LAP (≥ 15 mm Hg) with sensitivities of 90% and 100% and specificities of 92% and 100%, respectively.

Conclusions and Clinical Relevance—Doppler echocardiography can be used to predict an increase in LVFP in healthy anesthetized dogs subjected to volume loading.

Full access
in American Journal of Veterinary Research

Abstract

Objective—To evaluate the effects of the pacemaker funny current (If) inhibitor ivabradine on heart rate (HR), left ventricular (LV) systolic and diastolic function, and left atrial performance in healthy cats and cats with hypertrophic cardiomyopathy (HCM).

Animals—6 healthy cats and 6 cats with subclinical HCM.

Procedures—Anesthetized cats underwent cardiac catheterization and were studied over a range of hemodynamic states induced by treatment with esmolol (200 to 400 μg/kg/min, IV), esmolol and dobutamine (5 μg/kg/min, IV), ivabradine (0.3 mg/kg, IV), and ivabradine and dobutamine. Left ventricular systolic and diastolic function, cardiac output, and left atrial function were studied via catheter-based methods and echocardiography.

Results—Treatment with ivabradine resulted in a significant reduction of HR, rate-pressure product, and LV contractile function and a significant increase in LV end-diastolic pressure, LV end-diastolic wall stress, and LV relaxation time constant (tau) in cats with HCM. Concurrent administration of ivabradine and dobutamine resulted in a significant increase of LV contractility and lusitropy, with blunted chronotropic effects of the catecholamine. Left atrial performance was not significantly altered by ivabradine in cats with HCM. Regression analysis revealed an association between maximum rate of LV pressure rise and tau in cats with HCM.

Conclusions and Clinical Relevance—Ivabradine had significant effects on several cardiovascular variables in anesthetized cats with HCM. Studies in awake cats with HCM are needed to clinically validate these findings.

Full access
in American Journal of Veterinary Research

Abstract

Objective—To determine aortic ejection velocity in healthy adult Boxers with soft ejection murmurs without overt structural evidence of left ventricular outflow tract obstruction and in healthy Boxers without cardiac murmurs.

Design—Retrospective study.

Animals—201 Boxers.

Procedure—Dogs were examined independently by 2 individuals for evidence of a cardiac murmur, and a murmur grade was assigned. Maximal instantaneous (peak) aortic ejection velocity was measured by means of continuous-wave Doppler echocardiography from a subcostal location. Forty-eight dogs were reexamined approximately 1 year later.

Results—A soft (grade 1, 2, or 3) left-basilar ejection murmur was detected in 113 (56%) dogs. Overall median aortic ejection velocity was 1.91 m/s (range, 1.31 to 4.02 m/s). Dogs with murmurs had significantly higher aortic ejection velocities than did those without murmurs (median, 2.11 and 1.72 m/s, respectively). Auscultation of a murmur was 87% sensitive and 66% specific for the identification of aortic ejection velocity > 2.0 m/s. An ejection murmur and aortic ejection velocity > 2.0 m/s were identified in 73 (36%) dogs. For most dogs, observed changes in murmur grade and aortic ejection velocity during a follow-up examination 1 year later were not clinically important.

Conclusions and Clinical Relevance—Results suggested that ejection murmurs were common among healthy adult Boxers and that Boxers with murmurs were likely to have high (> 2.0 m/s) aortic ejection velocities. The cause of the murmurs in these dogs is unknown. (J Am Vet Med Assoc 2003;222:770–774)

Full access
in Journal of the American Veterinary Medical Association

Abstract

CASE DESCRIPTION A 2.5-year-old 12-kg (26.4-lb) castrated male Miniature American Shepherd was referred because of a 3-week history of a localized crusted skin lesion on the digital pad of digit 3 of the right hind limb.

CLINICAL FINDINGS Skin lesions were noted on the digital pads of the right hind limb. Serum biochemical analyses indicated severe hypercholesterolemia and hypertriglyceridemia. Ultrasonography of the terminal portion of the aorta and other major arterial vessels revealed substantial arteriosclerotic change.

TREATMENT AND OUTCOME Medical treatments included administration of atorvastatin calcium, a low-fat diet, and omega-3 fatty acids to reduce serum lipids concentration; clopidogrel to prevent thrombosis; pentoxifylline to improve microcirculatory blood flow; clomipramine hydrochloride and trazodone hydrochloride to help with the behavioral problems; and gabapentin to help with pain management and behavioral problems. Surgical management included amputation of the initial digit involved, then eventually the entire initial limb involved. The response to treatment was poor, and euthanasia was elected. Postmortem findings revealed severe, widespread, and chronic intimal atherosclerosis; mild, widespread, and degenerative changes in the cerebral cortex; and edema and vascular congestion in the meninges.

CLINICAL RELEVANCE To the authors' knowledge, this was the first report of skin necrosis secondary to atherosclerosis in a dog. Although the incidence of atherosclerosis has been considered very low in dogs, it should be investigated in dogs with severe hyperlipidemia. Primary hyperlipidemia has not been previously described in Miniature American Shepherd dogs but was the suspected underlying metabolic disorder.

Full access
in Journal of the American Veterinary Medical Association

SUMMARY

Cardiorespiratory effects of the combination of acepromazine maleate (acp) and buprenorphine hydrochloride (bpn) were studied in 11 healthy, conscious dogs. Values for systemic and pulmonary artery blood pressure, cardiac output, arterial and venous pH and blood gas tensions, and invasive and noninvasive estimates of ventricular systolic function, preload, and afterload were obtained before sedation and after administration of each drug. Acepromazine maleate (0.1 mg/kg, iv) depressed cardiac function, compared with baseline values for unsedated dogs. Cardiac output decreased from a mean (± sd) value of 4.2 (± 1.5) L/min to 3.1 (± 0.8) L/min (P < 0.001), a change not attributed to heart rate. Pulmonary capillary wedge pressure decreased from 8.3 (± 4.2) mm of Hg to 6.5 (± 4.3) mm of Hg (P < 0.01), but mean right atrial pressure did not change. Left ventricular measurement of the maximal positive rate of pressure change (dP/dtmax) decreased from 2,668 (± 356)/mm of Hg/s to 2,145 (± 463) mm of Hg/s (P < 0.001), and ventricular stroke volume decreased from 43.2 (± 15.2) ml/beat to 32.3 (± 8.6) ml/beat. Noninvasive indices of left ventricular function, ventricular shortening fraction, peak aortic velocity, and aortic average acceleration were decreased after acp administration, but were not statistically different from baseline values. Mean systemic arterial blood pressure decreased from 121 ± 12 mm of Hg to 96 ± 13 mm of Hg 15 minutes after acp administration (P < 0.001). Total systemic vascular resistance was not significantly different from the baseline value. Sequential administration of cumulative doses of bpn (0.005, 0.01, and 0.1 mg/kg of body weight, iv), initiated 15 minutes after administration of acp, did not cause statistically significant depression of hemodynamic variables, except for heart rate, which decreased after bpn, and left ventricular dP/dtmax, which decreased slightly at the highest dose of bpn. Small, clinically insignificant changes in blood pH, venous bicarbonate concentration, and Paco2 were observed after administration of acp and bpn. Respiratory rate decreased from 60 ± 48 breaths/min to 24 ± 12 breaths/min, and sedation level was significantly (P < 0.05) increased from baseline values by administration of acp. Sedation level was further increased by administration of bpn at the lowest dose (P < 0.05). The combination of acp and bpn resulted in good to excellent sedation, but depressed ventricular function; however, most of the hemodynamic effects could be attributed to administration of acp and withdrawal of sympathetic activity.

Free access
in American Journal of Veterinary Research

Abstract

Objective—To compare measurements of blood flow in the common femoral artery obtained by duplex Doppler ultrasonography (DDU) and a reference ultrasonic transit-time flow (TTF) method and to examine the impact of Doppler spectral waveform measurement techniques on volumetric estimates.

Animals—5 healthy female pigs.

Procedure—Femoral arterial blood flow was measured simultaneously in anesthetized pigs by use of a TTF probe (left femoral artery) and transcutaneous DDU (right femoral artery). A range of flow states was induced pharmacologically by using xylazine, bradykinin, dobutamine, and isoflurane. Volumetric blood flow was calculated from DDU waveforms, using the product of the flow velocity integral (FVI), the cross-sectional vessel area, and heart rate. Three calculations of FVI were obtained by manually tracing the Doppler spectral envelopes at the outer envelope, the modal, and the inner envelope of the spectral dispersion pattern. Data analysis included calculation of Pearson correlation coefficients and Bland-Altman limits of agreement.

Results—Blood flow measured by DDU was more closely correlated with TTF measurements when the modal or inner envelope tracing method was used ( r, 0.76 and 0.78; limits of agreement, –100 to 54.2 and –48.5 to 77.0 mL/min, respectively). Limits of agreement for the outer envelope tracing method were –238.5 to 64 mL/min.

Conclusion and Clinical Relevance—Transcutaneous DDU is a reliable noninvasive technique for measuring blood flow in the femoral artery of pigs over a range of flow states. Tracing the inner envelope of the Doppler spectral dispersion pattern provided the best estimate of blood flow in this study. (Am J Vet Res 2003;64:43–50)

Full access
in American Journal of Veterinary Research