Biomedical subjects

Natesa G Pandian

Publications and source records attributed to Natesa G Pandian.

46 records · Page 3Linked to original sources

PubMed2002

Postoperative cardiac tamponade in the modern surgical era.

BACKGROUND: Pericardial effusions resulting in cardiac tamponade (CT) are uncommon after open heart surgery (OHS) and are associated with significant morbidity and mortality. Characteristics and outcomes of patients who develop postoperative CT are poorly defined. Our objective was to further analyze the population at risk for developing postoperative CT, identify potential perioperative and surgical risk factors, and evaluate the impact of CT on patient outcomes. METHODS: A retrospective analysis of 4,561 consecutive patients undergoing OHS at our institution was performed. Patients with clinical suspicion of pericardial effusion following surgery were evaluated by transthoracic or transesophageal echocardiography, and clinical parameters were analyzed. RESULTS: Forty-eight (1%) of the 4,561 patients were found to have echocardiographic evidence of a moderate or large pericardial effusion, of whom 36 (74%) had evidence of CT. The mean age of the patients with CT was 61 years. Coronary artery bypass grafting (CABG) had been performed in 24% of these patients, valve +/- CABG in 73%, and other OHS procedures in 3%. The incidence of CT following CABG alone was 0.2%, whereas it was 0.6% after valve +/- CABG. Females had a higher risk for developing CT, and this occurred earlier in the postoperative period when compared with men. Aspirin, heparin, or warfarin were given to 84% of patients within 3 days of surgery. Mean time to diagnosis of CT was 10 +/- 1 days after OHS. Prior to diagnosis of CT, the maximum international normalized ratio (INR) and partial thromboplastin time (PTT) were 2.7 +/- 0.3 and 68 +/- 5 seconds, respectively. Forty-nine percent of pericardial effusions were posterior and 46% were circumferential; one-third of the effusions were considered large by echocardiography. There was one in-hospital cardiovascular death. CONCLUSIONS: CT after OHS is more common following valve surgery than CABG alone and may be related to the preoperative use of anticoagulants. Females appear to be at higher risk for developing early postoperative CT. When diagnosed and treated promptly, postoperative CT should not significantly increase mortality.

Cardiac Surgical Procedures↗

PubMed2002

The relationship between left ventricular shape and QT interval dispersion.

Left ventricular geometry is suspected to affect heterogeneity of myocardial repolarization; therefore, it is plausible but unproven that increased sphericity of the left ventricle is associated with greater QT interval dispersion. In 60 patients with dilated cardiomyopathy with left ventricular ejection fraction < or = 30%, we found that spherical distortion of the left ventricle was associated with increased QT dispersion, implying increased heterogeneity of myocardial repolarization.

Aged↗

PubMed2002

Intraoperative epicardial coronary artery imaging: rationale, methods, and applications.

Epicardial coronary imaging using high frequency (7-12 MHz) ultrasound probes could aid the surgeon performing coronary artery bypass procedures by localizing the coronary artery segments underneath epicardial fat, identifying the site of coronary stenosis to be bypassed, evaluating the integrity of distal coronary artery, assessing the efficacy of anastomosis, and detecting anastomotic complications. While an ideal coronary imaging probe is yet to be developed, early clinical experience with vascular imaging probes applied on the coronary vessels suggests that epicardial coronary artery imaging could enhance the optimum performance of coronary interventions. Fabrication of a flexible high frequency probe that could be applied not only on the arteries on the anterior surface of the heart but also on the lateral and posterior surfaces could facilitate development of newer surgical procedures as well.

Arteries↗

PubMed2002

A novel mechanism for the beneficial vascular effects of high-density lipoprotein cholesterol: enhanced vasorelaxation and increased endothelial nitric oxide synthase expression.

BACKGROUND: Low levels of high-density lipoprotein (HDL) cholesterol increase the risk of coronary artery disease (CAD), and recent clinical studies suggest that interventions in low-HDL patients are beneficial. The purpose of this study was to examine the effect of increased HDL levels on endothelium-dependent vasodilation. METHODS: We studied patients with CAD with a low-density lipoprotein (LDL) level of <100 mg/dL. Patients with an HDL level of < or =36 mg/dL were treated with niacin (n = 11), and patients with an HDL level of >36 mg/dL were followed as controls (n = 10). Baseline and 3-month follow-up studies of flow-mediated dilation (FMD) and blood lipid levels were obtained. RESULTS: HDL levels increased from 30.1 +/- 1.2 to 40.5 +/- 1.2 mg/dL in the niacin-treated patients (P <.001) but remained unchanged in the control patients. At baseline, FMD was impaired in both the treated (6.5% +/- 1%) and the control (7.3% +/- 1%) patients compared with 10 healthy subjects (16% +/- 2%, P <.01). After 3 months, FMD improved in the niacin-treated patients (11.8% +/- 1%, P =.001) but remained unchanged in the control patients (6.2% +/- 1%). Exposure of cultured human vascular endothelial cells to HDL in vitro enhanced expression of endothelial nitric oxide synthase (eNOS), as shown by immunoblotting. CONCLUSIONS: In patients with CAD and well-controlled LDL levels, elevation of HDL with niacin improves endothelial function. HDL increases eNOS protein expression in cultured vascular endothelial cells. Taken together, these observations suggest that HDL-mediated increases in eNOS expression may contribute to the observed enhancement in vasorelaxation and thus support a previously unrecognized mechanism for the beneficial cardiovascular effects of HDL.

Case-Control Studies↗

PubMed2002

Use of pulse wave and color flow Doppler echocardiography in mouse models of human disease.

The noninvasive assessment of cardiovascular physiology in mice is challenging because of their small size and extremely rapid heart rates. In this study, we sought to determine the feasibility and utility of pulse wave (PW) and color flow Doppler imaging techniques when applied to mouse models of cardiac remodeling. We performed transverse aortic banding, induced aortic insufficiency (AI), or sham procedures in wild-type mice. Animals were anesthetized and transthoracic echocardiography was performed, including PW and color flow Doppler imaging. In aortic banded mice, color flow Doppler imaging was used to identify flow around the aortic arch, and PW measurements were performed distal to the constriction. A high-velocity jet across the aortic constriction was detected in all 4 banded animals. Both modalities were applied to AI mice in which AI was detected in all 5 mice but in none of the 5 shams. Pulse wave and color flow Doppler imaging were also used to screen senescent mice for valve abnormalities; AI was detected in 3 of 20 and mitral regurgitation in 2 of 20. We demonstrate here that PW and color flow Doppler imaging techniques are useful in the evaluation of mouse models of cardiac remodeling. In addition, this study indicates that these modalities may be potentially useful to screen transgenic mice for valve abnormalities.

Animals↗

PubMed2002

Evaluation of a new ultrasound contrast agent (AI-700) using two-dimensional and three-dimensional imaging during acute ischemia.

BACKGROUND: A new intravenous contrast agent, AI-700, was evaluated to determine whether a bolus injection could be used to detect myocardial perfusion abnormalities during acute ischemia by using 2-dimensional (2D) and 3-dimensional (3D) myocardial contrast echocardiography. METHODS: 2D MCE was performed in 14 closed-chest dogs during coronary occlusion by using both continuous and triggered gray scale harmonic imaging and triggered power Doppler imaging. 3D MCE (open-chest) and nuclear perfusion imaging were performed in 10 of the 14 dogs. Postmortem triphenyl tetrazolium chloride (TTC) staining was performed to verify infarction. RESULTS: Thirteen of the 14 dogs had infarct by TTC; all 10 that had nuclear imaging showed a perfusion defect. Of the 13 dogs that had infarction, perfusion defects were detected in all (13 of 13) by gray scale harmonic imaging (sensitivity = 100%), and in 11 of 13 by power Doppler imaging (sensitivity = 85%). All 10 dogs that had nuclear imaging showed perfusion defects by gray scale harmonic imaging (sensitivity = 100%) and 8 of 10 by power Doppler imaging (sensitivity = 80%). The perfusion defect size, derived from 3D imaging (25% +/- 12%) correlated well with that from nuclear imaging (24% +/- 12%) (y = 0.9x + 3.8, r = 0.96, mean difference = 1.3% +/- 2.6%). The perfusion defect mass by 3D (22 +/- 14 g) also correlated well with the infarct mass by TTC staining (24 +/- 16 g) (y = 0.8x + 2.9, r = 0.89, P <.001, mean difference = -2.8 +/- 7.6 g). CONCLUSION: After a single bolus of AI-700, both 2D and 3D MCE could accurately detect perfusion defects representing the area at risk of infarction during acute ischemia compared with nuclear imaging and predicted the size of infarction as verified by TTC staining.

Animals↗

PubMed2002

Reduced risk of sudden death from chest wall blows (commotio cordis) with safety baseballs.

OBJECTIVES: In an experimental model of sudden death from baseball chest wall impact (commotio cordis), we sought to determine if sudden death by baseball impact could be reduced with safety baseballs. BACKGROUND: Sudden cardiac death can occur after chest wall impact with a baseball (commotio cordis). Whether softer-than-standard (safety) baseballs reduce the risk of sudden death is unresolved from the available human data. In a juvenile swine model, ventricular fibrillation (VF) has been shown to be induced reproducibly by precordial impact with a 30-mph baseball 10 to 30 ms before the T-wave peak, and this likelihood was reduced with the softest safety baseballs (T-balls). To further test whether safety baseballs would reduce the risk of sudden death at velocities more relevant to youth sports competition, we used our swine model of commotio cordis to test baseballs propelled at the 40-mph velocity commonly attained in that sport. METHODS: Forty animals received up to 3 chest wall impacts at 40 mph during the vulnerable period of repolarization for VF with 1 of 3 different safety baseballs of varying hardness, and also by a standard baseball. RESULTS: Safety baseballs propelled at 40 mph significantly reduced the risk for VF. The softest safety baseballs triggered VF in only 11% of impacts, compared with 19% and 22% with safety baseballs of intermediate hardness, and 69% with standard baseballs. CONCLUSION: In this experimental model of low-energy chest wall impact, safety baseballs reduced (but did not abolish) the risk of sudden cardiac death. More universal use of these safety baseballs may decrease the risk of sudden death on the playing field for young athletes.

Animals↗

PubMed2002

Qualitative and quantitative evaluation of mitral valve morphology by intraoperative volume-rendered three-dimensional echocardiography.

BACKGROUND AND AIM OF THE STUDY: Two-dimensional echocardiography (2DE) performed to evaluate mitral valve anatomy during valve repair has certain limitations and pitfalls. The study aim was to assess the feasibility, accuracy and incremental value of three-dimensional echocardiography (3DE), coupled with 2DE in evaluating mitral valve structure, before and after repair and pericardial posterior annuloplasty. METHODS: The site and extent of mitral valve prolapse, systolic and diastolic changes of mitral annular area were evaluated using 2D and 3D transesophageal echocardiography (TEE), both pre- and postoperatively in 34 patients before and after mitral valve repair and pericardial posterior annuloplasty. RESULTS: Concordance between 2DE and surgery in evaluating prolapsing mitral valve scallops was 76% for the anterior leaflet and 75% for the posterior leaflet; for 3DE and surgery, concordance was 87% and 93% respectively. There was a significant reduction in maximal and minimal annular area after surgery, with a statistically significant difference between systolic-diastolic changes. CONCLUSION: 3DE, coupled with 2DE, is feasible and accurate in delineating the extent and location of prolapsing scallops of the mitral valve. The combined approach is also valuable in planning mitral valve surgery and evaluating the mitral valve annulus in vivo.

Adult↗

PubMed2002

Doppler hemodynamics.

Your patient is in distress, and all an ECG can tell you is that he has had a previous heart attack. When are 2-dimensional (2-D) echocardiographic and Doppler studies appropriate options, and what special information can they provide? In the case presented, the Doppler recording profiled the hemodynamic status of the patient. Although the 2-D echocardiogram provided valuable information, only the Doppler study is shown to illustrate how sophisticated hemodynamic information can be gathered from Doppler examination. Check your review of the recording with the discussion on the next page.

Cardiomyopathy, Dilated↗

PubMedDate not supplied

Tissue Doppler echocardiography: principles and applications.

Tissue velocity imaging is an important development in the field of cardiac ultrasound that provides quantitative information for analysis of myocardial motion independent of the quality of gray-scale 2-D echocardiography data. It holds promise to reduce inter- and intraobserver variability in regional wall motion interpretation and is likely to improve the accuracy and reproducibility of stress echocardiography and myocardial viability assessment. It also enables regional diastolic function assessment independent of the loading conditions and offers a practical clinical tool to differentiate pathologic from physiologic myocardial hypertrophy, restrictive cardiomyopathy from constrictive pericarditis and for monitoring and selecting therapies in patients with advanced heart failure. The use of tissue velocity data for myocardial strain and strain rate imaging is likely to circumvent the limitations of tissue velocity in differentiating active and passive motion of a myocardial segment. However, its incremental utility and exact role in improving the diagnostic yield and clinical outcome needs to be addressed in future studies.

Coronary Disease↗