Andrea V. Brasch

Noninvasive, Transthoracic, Low-Frequency Ultrasound Augments Thrombolysis in a Canine Model of Acute Myocardial Infarction

BACKGROUND Recently it has been demonstrated that transcutaneous delivery of ultrasound combined with tissue plasminogen activator (tPA) is more effective than tPA alone in recanalizing acutely thrombosed canine coronary arteries. In the present study, we investigated the incidence of partial (> or =50%) and complete (> or =70%) ST-segment elevation resolution in the precordial leads of dogs with experimental acute myocardial infarction that were treated with tissue plasminogen activator (tPA) alone or in combination with noninvasive transcutaneous delivery of high-intensity low frequency (27[emsp3 ]kHz) ultrasound. METHODS Thrombotic coronary occlusions were induced in the midportion of left anterior descending (LAD) coronary artery by electrical injury in 24 dogs. All dogs were given intravenous heparin and tPA. Dogs were randomized to tPA alone (n=12) or combined tPA and adjunctive transcutaneous ultrasound (US) delivery (n=12). Electrocardiograms were recorded at 1) baseline, 2) after coronary occlusion just before initiation of therapy, 3) when coronary angiography showed recanalization of the coronary artery (or at 90 minutes after initiation of therapy if reperfusion did not occur before then) and 4) 90 minutes later. ST amplitude was measured in all 6 precordial leads. RESULTS ST-segment amplitude at baseline was comparable between the tPA and the US group. Before initiation of therapy, sum of ST-segment elevation tended to be higher in the US group. At reperfusion and 90 minutes thereafter, sum of ST-segment amplitude tended to be smaller for the US group than in the tPA group (p<0.001 for the time effect; p=0.118 for the time x group interaction). Up to 90 minutes after initiation of therapy >/=50% resolution of the sum of precordial ST elevation was detected in 7 out of 11 dogs (63.6%) in the tPA group versus 10 out of 11 dogs (90.9%) in the US group. Ninety minutes thereafter, 3 out of 7 dogs in the tPA group (42.9%) versus 9 of 11 dogs in the US group (81.8%) had >/=50% resolution of the sum of precordial ST elevation. CONCLUSIONS The combination of tPA with noninvasive transcutaneous delivery of low frequency high-intensity ultrasound resulted in greater resolution of ST-segment elevation when reperfusion occurs and 90 minutes thereafter, as well as a higher rate of epicardial coronary artery reperfusion.

Association of mitral annulus calcification, aortic valve sclerosis and aortic root calcification with abnormal myocardial perfusion single photon emission tomography in subjects age ≤65 years old

OBJECTIVES We examined the hypothesis that mitral annulus calcification (MAC), aortic valve sclerosis (AVS) and aortic root calcification (ARC) are associated with coronary artery disease (CAD) in subjects age < or =65 years. BACKGROUND Mitral annulus calcification, AVS and ARC frequently coexist and are associated with coronary risk factors and CAD in the elderly. METHODS We studied 338 subjects age < or =65 years who underwent evaluation of chest pain with myocardial perfusion single photon emission computed tomography (SPECT) and a two-dimensional transthoracic echocardiogram for other indications. The association of MAC, AVS and ARC with abnormal SPECT was evaluated by using chi-square analyses and logistic regression analyses. RESULTS Compared with no or one calcium deposit and no or one coronary risk factor other than diabetes, multiple (> or =2) calcium (or sclerosis) deposits with diabetes or multiple (> or =2) coronary risk factors were significantly associated with abnormal SPECT in women age < or =55 years old (odds ratio [OR], 20.00), in women age >55 years old (OR, 10.00) and in men age < or =55 years old (OR, 5.55). Multivariate analyses identified multiple calcium deposits as a significant predictor for an abnormal SPECT in women (p < 0.001), younger subjects age < or =55 years (p < 0.05) and the total group of subjects (p < 0.01). CONCLUSIONS When coronary risk factors are also taken into consideration, the presence of multiple calcium deposits in the mitral annulus, aortic valve or aortic root appears to be a marker of CAD in men < or =55 years old and women.

The Usefulness of a 10% Air-10% Blood-80% Saline Mixture for Contrast Echocardiography: Doppler Measurement of Pulmonary Artery Systolic Pressure

OBJECTIVES We assessed an air-blood-saline mixture for Doppler measurement of pulmonary artery systolic pressure (PASP) and the mechanism of enhancement of the Doppler signal by this mixture. BACKGROUND Underestimation of PASP by Doppler echocardiography occurs with inadequate continuous wave (CW) signals of tricuspid regurgitation (TR). METHODS We assessed in vitro the diameter and concentration of microbubbles of agitated air-saline mixture, air-blood-saline mixture and 10% air-10% plasma-80% saline mixture immediately, 5, 10 and 20 s after agitation. In 20 patients, PASP was estimated by Swan-Ganz catheter and CW Doppler of TR: 1) without contrast injection; 2) with intravenous injection of 10% air-90% saline; and 3) 10% blood-10% air-80% saline mixture. RESULTS Compared to air-saline, addition of blood or plasma to the air-saline solution significantly increased the concentration of microbubbles (p < 0.001). The air-blood-saline (26.7 +/- 7.2 microm) and air-plasma-saline mixture (25.3 +/- 7.4 microm) had smaller microbubbles than air-saline mixture (31.6 +/- 8.2 microm) (p < 0.001). The correlation between Doppler- and catheter-measured PASP at baseline (r = 0.64) improved with agitated air-saline (r = 0.86). With the air-blood-saline mixture, the correlation further improved (r = 0.92) and the best limits of agreement were obtained. CONCLUSIONS The combination of the patients own blood is a method of making a sterile solution of numerous small microbubbles for injection into the right-sided cardiac chambers. Clinically, the air-blood-saline mixture is easily prepared at bedside and is superior to the air-saline mixture in assessing PASP in patients with inadequate CW Doppler signals.

Noninvasive Transcutaneous Low Frequency Ultrasound Enhances Thrombolysis in Peripheral and Coronary Arteries

Previous studies have shown that external ultrasound with low frequencies and high intensities can enhance thrombolytic drug‐induced clot dissolution during in vitro experiments. In this series of studies, we evaluated the efficacy of peripheral and coronary thrombolysis in vivo in animals by using noninvasive transcutaneous ultrasound combined with thrombolytic drugs (streptokinase and tPA) and/or microbubbles agents (dodecafluoropentane [DDFP] and perfluorocarbon‐exposed sonicated dextrose albumin [PESDA]). Thrombotic occlusions were induced in 74 rabbit iliofemoral arteries and 24 canine left anterior descending (LAD) coronary arteries in this in vivo study. By using the combination of transcutaneous ultrasound and streptokinase, the angiographic patency rate in rabbit iliofemoral arteries was higher (56%–100%) than with ultrasound (6%; P ≤ 0.0036) and streptokinase alone (6%; P ≤ 0.0012). Also, with transcutaneous ultrasound and microbubbles, the angiographic patency rates were 76%–100% as compared with ultrasound alone (0%, P ≤ 0.0003) or microbubbles alone (9%, P ≤ 0.0001). In the canine study of acute myocardial infarction, thrombolysis in myocardial infarction (TIMI) grade flow at 90 minutes in the tPA alone group was 0.92 ± 1.4 as compared with 2.42 ± 1.9 in the tPA plus transthoracic ultrasound group (P = 0.006). There was much improved reperfusion with tPA plus ultrasound as compared with tPA alone. In vivo animal studies demonstrate that noninvasive transcutaneous ultrasound can greatly enhance the effect of clot dissolution with thrombolytic drugs and/or microbubbles, and has the potential for clinical application as an adjunctive method to improve arterial thrombolysis.

Correlation of echo-Doppler aortic valve regurgitation index with angiographic aortic regurgitation severity

We assessed aortic regurgitation (AR) severity by utilizing multiple echo-Doppler variables in comparison with AR severity by aortic root angiography. Patients were divided into 3 groups: mild, moderate, and severe. An AR index (ARI) was developed, comprising 5 echocardiographic parameters: ratio of color AR jet height to left ventricular outlet flow diameter, AR signal density from continuous-wave Doppler, pressure half-time, left ventricular end-diastolic diameter, and aortic root diameter. There was a strong correlation between AR severity by angiography and the calculated echo-Doppler ARI (r = 0.84, p = 0.0001). As validated by aortic angiography, the ARI is an accurate reflection of AR severity.

Twenty-Year Follow-Up of Patients With New Perioperative Q Waves After Coronary Artery Bypass Grafting

It is unclear whether the development of new Q waves on the electrocardiogram after coronary artery bypass grafting (CABG) is associated with an adverse prognosis. We analyzed the 20-year survival of 227 patients who underwent CABG, and found that new perioperative Q waves had no impact on long-term survival; therefore, conservative management may be appropriate for uncomplicated patients with new Q waves after CABG.

Comparison of transthoracic and intraoperative transesophageal color flow doppler assessment of mitral and aortic regurgitation

Background: We examined the agreement between transthoracic echocardiography (TTE) and intraoperative prepump transesophageal echocardiography (TEE) in the assessment of left-sided regurgitant lesions and echocardiographic variables associated with grading discrepancies. Methods: The TTE and prepump TEE studies of 54 patients undergoing aortic-valve replacement for aortic stenosis were reviewed. Agreement and correlation in assessment of aortic (AR) and mitral regurgitation (MR) severity were evaluated. Results: There was no significant difference between mean TTE and prepump TEE grading of MR (0.23 ± 0.19 vs. 0.21 ± 0.15 jet area/area of the left atrium, p = 0.49), but the correlation between the two methods was weak (r = 0.40, p = 0.003), with an exact agreement of 54%. Prepump TEE tended to grade AR as more severe (mean grade 1.43 ± 0.94 vs. 1.24 ± 0.75, p = 0.058). The correlation between the two methods in AR assessment was fair (r = 0.70, p = 0.0001) with an agreement of 59%. For MR and AR grading, no significant correlations between valvular regurgitation severity and blood pressure differences between preoperative TTE and prepump TEE were found. In 17% of cases, discrepancies in identifying severe mitral or aortic valve regurgitation could have affected patient management. Conclusions: There is modest agreement in MR and AR assessment between TTE and prepump TEE. Cardiologists, cardiac surgeons, and anesthesiologists must be aware of differences between these methods when using prepump TEE to guide intraoperative decisions.

Superiority of 10% air–10% blood–saline mixture for measuring the velocity of tricuspid regurgitation in patients with severe emphysema

BACKGROUND Severe emphysema frequently is associated with elevated pulmonary artery systolic pressure. However, it is often difficult to obtain adequate tricuspid regurgitation (TR) signals for measurement of pulmonary artery systolic pressure in patients with severe emphysema. PURPOSE This study was conducted to evaluate the usefulness of air-blood-saline mixture in measuring TR velocity in severe emphysema. METHODS We studied 82 patients with severe emphysema (67.7 +/- 9.2 years, 57 males) who had no or mild TR on color Doppler. Contrast echocardiography studies were performed with agitated 10% air-90% saline and 10% air-10% blood-80% saline mixtures. Tracing quality and peak velocity were assessed on baseline continuous wave signals and contrast continuous wave signals with the 2 mixtures. RESULTS With the injection of an air-saline mixture, the quality of TR tracing improved in 45 patients (P <.0001) and a higher peak TR velocity was obtained (2.46 +/- 0.37 m/s vs 2.95 +/- 0.40 m/s, P <.0001) compared with baseline echocardiography. Compared with air-saline mixture, the air-blood-saline mixture further enhanced TR tracing quality in 17 patients (P <.0001) and the peak TR velocity increased to 3.13 +/- 0.42 m/s (P <.0001). CONCLUSIONS In patients with severe emphysema, an air-blood-saline mixture improves the quantifiable TR signals for more accurate estimation of pulmonary artery systolic pressure, even when there is minimal valve TR.

Transesophageal echocardiographic identification of an abdominal aortic pseudoaneurysm complemented by a transpulmonary echo contrast agent.

Pseudoaneurysm of the abdominal aorta, a rare complication after traumatic injuries, represents a diagnostic challenge for which sophisticated imaging modalities are often used for its early identification. We describe a case in which transesophageal echocardiographic examination complemented by a transpulmonary echo contrast agent was useful not only in demonstrating the pseudoaneurysm, but in helping to localize the intravascular communication between the aorta and the pseudoaneurysm.