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C J Davidson

Publications and source records attributed to C J Davidson.

At least 73 records · Page 4Linked to original sources
PubMed1991

Determinants of one-year outcome from balloon aortic valvuloplasty.

Balloon aortic valvuloplasty (BAV) has been a therapeutic alternative treatment for severe symptomatic aortic stenosis. Previous studies have been unable to predict 1-year outcome because of limited acute and follow-up clinical, invasive and echocardiographic data. The purpose of this study was to predict long-term outcome based on comprehensive data obtained at the time of valvuloplasty and at 3 and 6 months after the procedure. Of 170 consecutive patients undergoing BAV, 108 (mean age 78 years) were at least 1 year from their procedure. Prospective clinical, micromanometer hemodynamic, digital ventriculographic and echocardiographic/Doppler data were collected at baseline and immediately after the procedure. Echocardiographic data were also obtained at 3 and 6 months. With use of Cox model analysis, major events (defined as cardiac death [n = 30], aortic valve replacement [n = 21] or repeat BAV [n = 13]) were predicted by advanced age, baseline heart failure class, and baseline echocardiographic-determined diastolic left ventricular diameter. Only baseline left ventricular ejection fraction proved to be a significant predictor of cardiac death (p = 0.002) in a multivariate model. Absolute values after BAV (stroke work, first derivative of left ventricular pressure, valve area, end-systolic volume, Fick cardiac output, transvalvular gradient) and acute changes measured by catheterization or echocardiography did not provide additional predictive information over that of post procedure ejection fraction. Similarly, echocardiographic valve area and transvalvular gradient at 3 months added no further prognostic data. With an ejection fraction greater than or equal to 45% (n = 63), cardiac survival at 1 year was 80%, irrespective of age, sex, congestive heart failure class or severity of coronary artery disease.(ABSTRACT TRUNCATED AT 250 WORDS)

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PubMed1991

Intravascular ultrasound assessment of the renal artery.

OBJECTIVE: To determine the feasibility and diagnostic value of catheter-based intravascular ultrasound imaging compared with angiography for visualizing renal artery structure. DESIGN: Renal artery images were obtained in patients with renal artery stenosis having percutaneous balloon angioplasty and in normal subjects by digital angiography and by a 20-MHz, mechanically driven, catheter-based, intravascular ultrasound imaging system. SETTING: A referral-based university hospital. PATIENTS: Four randomly selected normal subjects without known renal disease and four consecutive patients with known renal artery stenosis referred for percutaneous balloon angioplasty. INTERVENTIONS: Digital angiograms and intravascular ultrasound images of nine renal artery segments were obtained. In patients with renal artery stenosis, imaging was done before and after balloon angioplasty. MAIN RESULTS: Digital angiography and ultrasonography correlated closely in the determination of arterial lumen diameter (r = 0.81) and cross-sectional area (r = 0.83). However, ultrasonography provided structural information not shown by angiography. All normal arteries showed discrete intimal, medial, and adventitial wall layers by ultrasonography. In the five stenotic segments, angiography identified the cause of stenosis to be atherosclerosis in four patients and fibromuscular dysplasia in one patient. Ultrasound imaging, however, identified the disease process as atherosclerosis in three patients and as fibromuscular dysplasia in two patients. After renal angioplasty, ultrasonography identified three arterial dissections, only one of which was shown by angiography. CONCLUSIONS: These preliminary data indicate that catheter-based intravascular ultrasound imaging of the renal artery is feasible and correlates well with angiography in assessing renal artery size and also provides potentially important additional structural information that permits a better characterization of arterial pathology.

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PubMed1991

Comparison of intravascular ultrasound, external ultrasound and digital angiography for evaluation of peripheral artery dimensions and morphology.

Validation of catheter-based intravascular ultrasound imaging has been based on comparisons with histology and digital angiography, each of which may have limitations in the assessment of arterial size and morphology. External, high-frequency ultrasound can accurately determine vessel dimensions and morphology and because, like ultravascular ultrasound, it also provides cross-sectional arterial ultrasound images, it may be a more appropriate technique for the in vivo comparison of arterial dimensions and morphology determined by intravascular ultrasound. Thus, intravascular ultrasound, external 2-dimensional ultrasound, Doppler color-flow imaging and digital angiography were compared for assessment of arterial dimensions and wall morphology at 29 femoral artery sites in 15 patients. Intravascular ultrasound and the other 3 imaging modalities correlated well in determination of lumen diameter (2-dimensional, r = 0.98, standard error of the estimate [SEE] = 0.14; Doppler color flow, r = 0.91, SEE = 1.11; angiography, r = 0.95, SEE = 0.91) and cross-sectional area (2-dimensional, r = 0.97, SEE = 0.04; Doppler color flow, r = 0.92, SEE = 0.14; angiography, r = 0.96, SEE = 0.08). However, lumen size measured by Doppler color flow was consistently smaller than that measured by the other 3 imaging modalities. Intravascular ultrasound detected arterial plaque at 15 sites, 5 of which were hypoechoic (soft) and 10 hyperechoic with distal shadowing (hard). Plaque was identified at 12 of 15 sites by Z-dimensional imaging (p = 0.30 vs intravascular ultrasound), but at only 6 of 15 sites by angiography (p = 0.003 vs intravascular ultrasound), only 1 of which was thought to be calcified plaque.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1991

Surgical aortic valvuloplasty using the Cavitron Ultrasonic Surgical Aspirator: an invasive hemodynamic follow-up study.

Valve repair and calcium debridement in patients with calcific aortic stenosis, using the Cavitron Ultrasonic Surgical Aspirator (CUSA), results in a reduction in the aortic valve gradient while potentially avoiding long-term problems inherent to prosthetic valves. Invasive followup data in these patients has not previously been reported. Ten patients in whom CUSA debridement was performed underwent cardiac catheterization prior to and 8.0 +/- 2.5 months following the procedure. Compared to baseline, the aortic valve area significantly increased from 0.75 +/- 0.2 to 1.1 +/- 0.3 cm2 (p = 0.009) and the mean gradient was significantly reduced from 54 +/- 21 to 27 +/- 21 mmHg (p = 0.02) at followup. No significant change was noted in cardiac output, ejection fraction, left ventricular end systolic or diastolic volumes or left ventricular end diastolic pressure. However, 6 patients were found to have at least one grade worsening of aortic regurgitation. The development of increased aortic insufficiency in many patients after CUSA aortic valve debridement will likely limit this procedure's clinical utility.

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PubMed1991

Follow-up recatheterization after balloon aortic valvuloplasty. Mansfield Scientific Aortic Valvuloplasty Registry Investigators.

The results of recatheterization were assessed in a select group of 95 patients enrolled in the Mansfield Scientific Aortic Valvuloplasty Registry to determine whether any procedural or patient-related variables at baseline predicted either initial immediate or follow-up (6.2 +/- 3.3 months) results. At the follow-up catheterization, 39 (41%) of the patients were in improved condition and 56 patients (59%) had recurrence of symptoms, allowing for analysis of the effect of the procedure in two symptomatic patient subsets. In the total group the aortic valve area increased initially from 0.56 +/- 0.16 to 0.87 +/- 0.27 cm2 but partial return to the baseline valve area was evident at follow-up (0.63 +/- 0.25 cm2). Similarly, the mean aortic gradient initially decreased from 72 +/- 30 to 35 +/- 16 mm Hg but then increased to 55 +/- 25 mm Hg at follow-up. Neither the initial nor the late hemodynamic results appeared affected by any definable procedural variable at the time of valvuloplasty, including the maximal diameter of balloons, number of balloons simultaneously used, mean inflation time or total number of inflations. Such technical concerns also did not seem to affect short- or long-term outcome. Similarly, no baseline hemodynamic variable clearly separated those who became increasingly symptomatic from those whose condition was improved at the 6 month interval. At recatheterization, a reduction in the aortic valve area toward baseline was observed in 24 (62%) of the 39 improved patients and in 45 (80%) of the 56 who were symptomatic.(ABSTRACT TRUNCATED AT 250 WORDS)

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PubMed1991

Mechanisms of angioplasty in hemodialysis fistula stenoses evaluated by intravascular ultrasound.

Quantification of luminal dimensions and the mechanisms by which angioplasty (PTA) corrects non-atheroma venous fistula stenoses have been poorly studied. In 38 consecutive percutaneous balloon angioplasties of hemodialysis fistula stenoses, catheter-based, mechanically-rotated intravascular ultrasound (IVUS) images were obtained along with cineangiography. Images from 24 brachial vein, 11 central vein, 2 graft anastomoses, and 1 brachial artery were quantitatively and qualitatively evaluated. Semiautomated quantitative angiographic stenosis was 64 +/- 13% pre-PTA and reduced to 36 +/- 19% post-PTA (P less than 0.001). Post-PTA IVUS minimal lesion diameter and cross sectional area were 5.7 +/- 1.5 mm and 2.9 +/- 1.5 mm2, respectively. With IVUS, mechanisms observed were: vessel dissection in 16 (42%), arterial stretch (defined as vessel diameter: balloon diameter ratio = 0.75 to 1.0) in 19 (50%), and elastic recoil (defined as vessel diameter: balloon diameter ratio less than 0.75) in 19 (50%). Compared to angiography, morphologic information provided by IVUS were plaque composition (hard 11%, soft 89%), plaque topography (eccentric 94%, concentric 6%), thrombus (IVUS: N = 6 vs. angio: N = 1), dissection (IVUS: N = 16 vs. angio: N = 1). Thus, IVUS can evaluate lesion morphology and define luminal dimensions after angioplasty. Mechanisms of successful angioplasty of hemodialysis fistula stenosis occur primarily by vessel stretching and dissection, and significant post-PTA narrowing is due to elastic recoil.

Adult↗
PubMed1991

Rapid and accurate diagnosis of pulmonary emboli in a canine model using intravascular ultrasound imaging.

We utilized intravascular ultrasound (IVUS) imaging in a canine pulmonary embolism model to visualize experimental emboli. The images obtained were compared with those obtained by single-plane pulmonary arteriography in each of six animals. The vessel lumen appeared patent by both methods prior to injection of autologous clot. After thrombi were injected, the vessels were again imaged using both techniques. Intravascular ultrasound was 100 percent sensitive in detecting emboli, and visualization was always rapid. There were no complications. It appears that IVUS imaging is a sensitive method for documenting the presence of clot in a canine pulmonary embolism model.

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PubMed1990

Early and late changes in left ventricular systolic performance after percutaneous aortic balloon valvuloplasty.

To evaluate early and late hemodynamics after aortic valvuloplasty, 17 patients underwent first-pass radionuclide angiocardiography with simultaneous high-fidelity micromanometer pressure before, 10 minutes after and 6 months after aortic valvuloplasty. Pressure-volume and stress data were assessed. Immediately after the procedure, no significant change was observed in heart rate, systemic blood pressure, cardiac output or aortic insufficiency (as measured by visual or quantitative aortography). The mean and peak transvalvular gradient decreased from 64 to 36 mm Hg (p less than 0.001) and 76 to 38 mm Hg (p less than 0.001), respectively. The mean aortic valve area increased from 0.5 to 0.8 cm2 (p less than 0.001). Using echocardiography, meridional end-systolic wall stress decreased from 81 to 63 x 10(3) dynes/cm2 (p less than 0.001). Left ventricular ejection fraction increased from 0.48 to 0.54 (p less than 0.01), end-diastolic volume decreased from 161 to 143 ml (p less than 0.001) and end-diastolic pressure decreased from 18 to 13 mm Hg (p less than 0.01). Left ventricular stroke work (the area of the pressure-volume loop) also decreased from 17.5 to 14.7 x 10(6) ergs (p less than 0.001). The loop shifted to the left and downward. At the 6-month study, the mean and peak aortic valve gradient increased from 36 to 56 mm Hg (p less than 0.001) and 38 to 61 mm Hg (p less than 0.001), respectively.(ABSTRACT TRUNCATED AT 250 WORDS)

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PubMed1990

Thrombotic and cardiovascular complications related to nonionic contrast media during cardiac catheterization: analysis of 8,517 patients.

The incidence of major complications associated with nonionic contrast media has not been defined in a large study. Accordingly, cardiovascular complications, especially thrombotic events, were prospectively evaluated in 8,517 consecutive patients undergoing diagnostic cardiac catheterization with either iopamidol (n = 6,293) or iohexol (n = 2,224). Thrombotic events were defined as coronary embolus, coronary occlusion, transient ischemic attack or stroke occurring at the time of catheterization. Thrombotic events occurred in 15 patients (0.18%). Coronary thrombus or embolus occurred in 7 patients, a thromboembolus from the ventricular catheter occurred in 1 patients and transient ischemic attack or stroke occurred in 7 patients. Six of 15 patients with thrombotic events were premedicated with heparin. Thrombotic events were unusual in that they tended to occur in clusters within short time intervals. On 1 occasion, a thrombus was observed in the catheter tip before embolization. Other cardiovascular complications were similarly low with an incidence of ventricular tachycardia/fibrillation of 0.1%, profound bradycardia of 0.2% and prolonged angina of 0.3%. There were 2 deaths unrelated to thrombotic events. Although the clinical thrombotic events associated with nonionic contrast have an unusual temporal clustering and may result in major complications, the overall incidence (0.18%) of these thrombotic complications with nonionic contrast agents is quite similar to that reported with ionic contrast media.

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PubMed1990

Changes in left ventricular systolic performance immediately after percutaneous aortic balloon valvuloplasty.

To evaluate the acute changes in left ventricular (LV) performance before and immediately after percutaneous aortic valvuloplasty, 25 patients underwent first-pass radionuclide angiocardiography for construction of pressure-volume loops. Simultaneously, high-fidelity micromanometric aortic and LV pressures were recorded. Echocardiographic wall thickness was used to define wall stress. After valvuloplasty, no acute changes were observed in the heart rate, aortic systolic pressure, cardiac output or degree of aortic insufficiency. Valvuloplasty decreased the peak aortic valve gradient from 73 to 40 mm Hg (p less than 0.001) and the mean gradient from 61 to 30 mm Hg (p less than 0.001); aortic valve area increased from 0.55 to 0.80 cm2 (p less than 0.001). Meridional end-systolic wall stress decreased from 83 to 55 X 10(3) dynes/cm2 (p less than 0.01). LV ejection fraction increased from 0.41 to 0.48 (p less than 0.01). LV end-diastolic volume decreased from 186 to 160 ml (p less than 0.001), end-systolic volume decreased from 115 to 87 ml (p less than 0.001) and end-diastolic pressure decreased from 22 to 17 mm Hg (p less than 0.01). LV stroke work decreased from 16.0 to 14.0 X 10(6) erg (p less than 0.001). No change was observed in peak positive LV dP/dt or the end-systolic pressure-volume ratio. This study documents variable and complex changes in the measures of cardiac function after aortic valvuloplasty. A decrease in the amount of LV outflow obstruction with maintenance of the cardiac output at a decreased level of LV filling occurs.

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PubMed1990

Balloon angioplasty of coarctation of the aorta evaluated with intravascular ultrasound imaging.

Intravascular ultrasound images were employed to evaluate aortic coarctation before and after balloon angioplasty. Measurements obtained with use of an ultrasound imaging catheter correlated well with measurements made with digital aortography, both in the area of coarctation and in areas proximal and distal to it. The intravascular ultrasound images dramatically revealed dissection of the aortic wall and an intimal flap that was not appreciated on cineaortography or digital subtraction angiography. Intravascular ultrasound imaging may yield important morphologic information unavailable by other imaging techniques. Such information may allow more precise definition of the results of intravascular procedures and improve understanding of lesion characteristics predictive of a successful outcome.

Adult↗
PubMed1990

Failure of balloon aortic valvuloplasty to result in sustained clinical improvement in patients with depressed left ventricular function.

Although balloon aortic valvuloplasty usually results in acute hemodynamic improvement, recurrent symptoms often occur within several months. The current study was designed to determine whether clinical characteristics, including invasive hemodynamic parameters of left ventricular (LV) performance, are predictive of short-term patient outcome. Eighty-one consecutive patients were prospectively enrolled in the study protocol. High-fidelity dual sensor micromanometer catheters, digital ventriculography and aortography and Fick cardiac output were measured before and immediately after balloon aortic valvuloplasty. Stroke work was defined from pressure-volume loops. The acute hemodynamic results obtained in patients with overall improved symptoms were compared to those with recurrent symptoms at 3 months. Fifty-three patients (65%) were improved at 3-month evaluation (group 1), whereas 28 patients (35%) had either returned to symptoms at baseline (17), had undergone aortic valve replacement (3) or had cardiac death (8). Compared to patients with improved symptoms, patients with recurrent symptoms demonstrated a lower cardiac output, higher LV end-systolic volume, decreased LV ejection fraction, diminished LV stroke work and decreased LV peak positive dP/dt. The final aortic valve area and change in aortic valve area did not predict which patients would develop recurrent symptoms. Stepwise logistic regression revealed that LV ejection fraction was the only independent predictor of overall status at 3 months (p = 0.002). Eighty-four percent of patients with an ejection fraction greater than 45% were improved. In the group with an ejection fraction greater than 45%, less than half of the patients demonstrated improved symptoms at short-term followup. Parameters of LV performance can accurately predict short-term patient outcome after balloon aortic valvuloplasty.

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PubMed1990

A rapid, effective technique for retrograde crossing of valvular aortic stenosis using standard coronary catheters.

Retrograde crossing of valvular aortic stenosis can be challenging even to experienced angiographers. In 446 of 447 consecutive patients with aortic stenosis catheterized during the past 3 years, a technique using a standard Judkins right coronary catheter and a floppy straight tipped guide wire was successful in rapidly and efficiently crossing these pathologically distorted valves in retrograde fashion. Once the valve was crossed, the coronary catheter was replaced with a pigtail catheter for pressure and ventriculography. The majority of these valves required less than 2 min to cross using this technique. This method is valuable in limiting the time required for catheterization, thus helping to reduce procedure related morbidity in these oftimes critically ill patients.

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