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Biomedical subjects

G G Hartnell

Publications and source records attributed to G G Hartnell.

At least 37 records · Page 2Linked to original sources
PubMed1997

Safety of MR imaging in patients who have retained metallic materials after cardiac surgery.

OBJECTIVE: Epicardial pacing wires retained in patients who undergo cardiac surgery are thought to be a relative contraindication to MR imaging. However, to our knowledge no published evidence supports this belief. Because other metallic materials retained after cardiac surgery might represent a hazard to patients who undergo MR imaging, we sought to determine the safety of such imaging. SUBJECTS AND METHODS: We examined 200 patients who underwent MR imaging at 1 or 1.5 T after cardiac surgery. Eighty-one were examined with ECG monitoring. The presence of temporary epicardial pacing wires, prosthetic valves, and other metal materials was confirmed by chest radiography. RESULTS: Of the 200 patients reviewed, all had postoperative metallic material visible on chest radiographs. Temporary epicardial pacing wire, cut short at the skin, was seen in 51 patients. Of the 81 patients examined with ECG monitoring, we found that MR imaging produced no changes from baseline ECG rhythms. None of the 200 patients reported symptoms suggesting arrhythmia or other cardiac dysfunction during MR imaging. CONCLUSION: MR imaging can be performed safely in patients who have undergone cardiac surgery and have retained metallic material, including valve replacements and temporary epicardial pacing wires cut short at the skin. MR imaging of patients with pacemakers was not evaluated, and we recommend that pacemakers remain a contraindication to MR imaging.

Cardiac Surgical Procedures↗
PubMed1997

Thrombolysis of infrapopliteal bypass grafts: efficacy and underlying angiographic pathology.

OBJECTIVE: The purpose of this study was to determine retrospectively the effectiveness of thrombolysis of occluded infrapopliteal bypass grafts and to identify factors affecting success. MATERIALS AND METHODS: The records of 52 consecutive patients (52 grafts) who underwent selective urokinase thrombolysis of grafts to the pedal or tibial arteries were reviewed. The need for subsequent surgery and the influence of diabetes on outcome were analyzed. RESULTS: There were 43 vein and nine Goretex (W-L Gore, Flagstaff, AZ) and vein composite grafts inserting into tibial and peroneal arteries (n = 28) or pedal arteries (n = 24). Mean time of follow-up was 19 months. All grafts were entered, and technical success was achieved in 73% of patients. Twenty-six patients required some form of graft revision. Overall patency at 30 days was 76%. Thirty-day limb-salvage and mortality rates were 82% and 4%, respectively. No significant difference was found in 1-yr outcomes between diabetic and nondiabetic patients or between pedal and tibial grafts. Major complications occurred in eight patients (15%). CONCLUSION: Thrombolysis of occluded grafts that insert into the pedal or tibial vessels was as effective as thrombolysis of more proximal grafts and native arterial thrombolysis, which have reported 30-day limb-salvage rates that range between 80% and 90%. Diabetes and grafting to foot vessels did not adversely affect response to thrombolysis. Surgery was often required to correct an underlying lesion revealed by thrombolysis. Despite the small size of the arteries to which the grafts were anastomosed, selective thrombolysis of occluded infrapopliteal bypass grafts proved to be an effective procedure.

Adult↗
PubMed1996

Magnetic resonance angiography demonstration of congenital heart disease in adults.

OBJECTIVE: There are limitations when using spin-echo MR imaging to evaluate congenital heart disease (CHD). These include limited ability to detect small shunts, long acquisition times, in-plane or slow flow signal and limited ability to represent complicated three-dimensional (3D) anatomy. However, MR angiography can image flow direction and disturbances, assess function and easily represents 3D anatomy. This may be valuable when evaluating adults with CHD. PATIENTS AND METHODS: Fifty consecutive adult patients were referred for MR evaluation of possible or known CHD using time-of-flight MR angiography. Cine, breathhold and presaturation cine MR angiography were acquired as appropriate, with 3D (MIP) reconstruction of all extracardiac anomalies. RESULTS: Forty-nine patients had a diagnostic examination (one was unsatisfactory because of arrhythmia). Correlation with alternative imaging (TTE = 36, TOE = 13, cardiac catheter = 16) or surgery was available in 39 patients (MR angiography correct in 36 patients). MRA demonstrated or excluded all confirmed congenital valve (12/12), aortic (9/9), and venous (7/7) anomalies. Thirty-five patients were evaluated for shunts. MR angiography detected 31/33 confirmed shunts (shunts present in 26 patients, sensitivity 94%, specificity 95%). Although not used in all cases, spin-echo was unreliable in demonstrating shunts as signal loss in the region of the secundum septum frequently mimicked atrial septal defects (reducing accuracy for excluding intracardiac shunts, specificity 58%). CONCLUSION: MR angiography accurately defines intra- and extra-cardiac anatomy and is superior to spin-echo in detecting or excluding shunts. MR angiography safely and accurately demonstrates many aspects of CHD in adults.

Adult↗
PubMed1996

Magnetic resonance imaging of pericardial constriction: comparison of cine MR angiography and spin-echo techniques.

AIM: Spin-echo (SE) MRI detects pericardial thickening in pericardial constriction but the validity of extrapolating SE criteria to cine MRA imaging has not been tested. Pericardial thickness measured by SE and cine MRA was compared in patients with and without pericardial thickening to determine if the range of pericardial thickness measured by the two techniques is the same. PATIENT AND METHODS: Fourteen patients, investigated for possible pericardial constriction (PC), were compared with 24 subjects without evidence of pericardial disease (controls). Images were acquired using SE and cine MRA. Pericardial thickness was compared with final diagnosis. RESULTS: Pericardial thickening ( > 3.5 mm) by SE detected pericardial constriction: sensitivity = 100% specificity = 96%, kappa = 0.91. Cine MRA had a sensitivity = 86%, specificity = 63%, kappa = 0.33. Maximum differences between SE and cine MRA pericardial thickness ranged from +2.5 mm to -2/7 mm. CONCLUSIONS: Spin-echo identifies pericardial thickening with little overlap between measurements in patients with and without pericardial constriction. Pericardial thickness on cine MRA usually exceeds SE thickness, but with considerable overlap of thickness measurements in patients with and without pericardial constriction. Cine MRA cannot be used alone to diagnose pericardial thickening.

Diagnosis, Differential↗
PubMed1996

First-pass evaluation of myocardial output during dipyridamole stress using turbo-FLASH magnetic resonance imaging.

RATIONALE AND OBJECTIVES: This study evaluated the value of dynamically enhanced fast low-angle shot (FLASH) magnetic resonance (MR) imaging in measuring cardiac output with and without dipyridamole pharmacological stress. METHODS: Ten subjects underwent rest and stress MR imaging. Rest images were acquired using electrocardiogram gated MR (turbo-FLASH: repetition time = 6 mseconds; echo time = 12 mseconds; flip angle = 12 degrees, inversion time = 100) 10 to 45 seconds after intravenous bolus of 0.04 mmol/kg gadolinium (Gd)-DTPA using a Siemens 1.0-tesla Magnetom SP. Stress was induced within the MR imaging scanner with 0.56 mg/kg dipyridamole over 4 minutes with stress MR images obtained after a second bolus of Gd-DTPA in exactly the same position and time intervals. Cardiac output was calculated with a least squares error analysis before and after dipyridamole stress for the left and right ventricles in all 10 patients, and comparison was made with cardiac output by Fick dilution technique during cardiac catheterization in seven patients. RESULTS: This MR analysis methodology shows reasonable correlation (r = 0.953) between left ventricular and right ventricular cardiac output with no effect on cardiac output during immediate dipyridamole stress. Fick dilution studies demonstrated a correlation of 0.96. CONCLUSIONS: Turbo-FLASH MR can demonstrate time-activity curves and cardiac output calculations consistent with theoretical predictions.

Aged↗
PubMed1996

Cardiac radiology.

Explore the source record for details and available documents.

Cardiovascular Diseases↗
PubMed1996

Time-of-flight MR angiography of the portal venous system: value compared with other imaging procedures.

OBJECTIVE: The purpose of this study was to retrospectively compare two-dimensional time-of-flight MR angiography with other imaging procedures in the evaluation of the portal venous system in 152 consecutive patients. MATERIALS AND METHODS: The findings on MR angiography performed on 152 patients to depict breath-hold, two-dimensional time of flight MR angiography. Selective arterial presaturation, bolus tracking, and three-dimensional reconstruction were used routinely. Findings were correlated with findings on sonography (104 patients), CT (8 patients), and conventional digital subtraction angiography (19 patients) as well as surgery (23 patients). RESULTS: Agreement between results of MR angiography and alternative types of imaging was excellent (99%). Agreement with sonography (100 of 104), CT (8 of 8), conventional angiography (18 of 19), and surgery (23 of 23) was good. Visualization of varices and spontaneous shunts by MR angiography was superior to that by other imaging techniques. CONCLUSION: Our experience shows that time-of-flight MR angiography is reliable and accurate for depicting portal venous anatomy. MR angiography shows vessels that are not visible with sonography. Complicated pathology is clearly visualized in a way that is not possible with other techniques.

Angiography, Digital Subtraction↗
PubMed1995

Nonatherosclerotic coronary artery disease: more than just stenosis.

Coronary angiography is most commonly performed to evaluate atherosclerotic coronary artery stenosis. However, it is important to be aware of the spectrum of coronary anomalies, including congenital and acquired nonatherosclerotic conditions. Potentially fatal congenital coronary anomalies may manifest at any age. If not recognized, such anomalies may prevent complete assessment of coronary anatomy in patients evaluated for atherosclerotic disease. Detection of coronary anomalies associated with congenital conditions, such as transposition of the great arteries, a single ventricle, or tetralogy of Fallot, is important prior to surgery to prevent complications and allow appropriate bypass during surgery. Acquired nonatherosclerotic coronary disease may occur as a primary abnormality or as part of a multisystem disorder and may mimic atherosclerotic disease. Although most nonstenosing coronary anomalies are uncommon or rare, they are individually important and many are treatable. Knowledge of variant coronary anatomy and the appearances of nonatherosclerotic coronary anomalies is essential for good patient care.

Adult↗
PubMed1995

MR angiography of congenital heart disease in adults.

Magnetic resonance (MR) angiographic techniques are useful in evaluation of adult patients with congenital heart disease (CHD). The available techniques include cine, breath-hold ungated, and segmented k-space time-of-flight MR angiography. Three-dimensional (3D) image reconstruction with maximum-intensity projection can be used with all of these techniques to demonstrate great vessel anomalies associated with CHD. Selective presaturation MR angiography can be used to detect intracardiac shunts. MR angiography allows clarification of difficult diagnostic points that are not fully demonstrated with other imaging techniques, such as cardiac catheterization and angiocardiography, echocardiography, nuclear medicine studies, and conventional spin-echo MR imaging. In many patients with CHD in adulthood, the use of appropriate MR angiographic techniques may allow definitive diagnosis and preclude the need for cardiac catheterization. The wide field of view, sensitivity to shunts, and rapid 3D imaging capability of MR angiography make it a valuable method of evaluating CHD in adults.

Adult↗
PubMed1995

Do hydrophilic guidewires affect the technical success rates of percutaneous angioplasty?

To determine whether the use of hydrophilic guidewires has influenced the success of peripheral percutaneous transluminal angioplasty (PTA), the results of PTA performed before and after the introduction of such guidewires (end of 1989) were analyzed. Before hydrophilic guidewires became generally available, the technical success rates for iliac stenosis PTA were 96%, for femoral stenosis PTA 84%, and for femoral occlusion 78%. After the introduction of hydrophilic guidewires, technical success rates were 100% (NS), 97% (P = 0.018), and 97% (P = 0.011), respectively. A prospective study of 33 patients randomly selected for PTA of femoropopliteal occlusion using either conventional or hydrophilic guidewires was performed. In this group, the technical success rate was 14/15 in the hydrophilic group, and 18/18 in the conventional group (NS). Since the introduction of hydrophilic guidewires, the technical success rates of PTA have improved and are now approaching 100%.

Angioplasty, Balloon↗
PubMed1995

Body magnetic resonance angiography and its effect on the use of alternative imaging--experience in 1026 patients.

Time-of-flight magnetic resonance (MR) angiography has been described for numerous applications but the number of patients described in published reports is usually relatively small. There is little information concerning the general utility of MR angiography in the body, outside the cranial circulation, or its effect on use of other imaging studies. Utilization of two-dimensional (2D) time-of-flight MR angiography over a 3 year period was reviewed to determine its accuracy and impact on other imaging modalities. Cranial and cardiac studies were excluded. Correlation was made with alternative imaging and surgical findings. Between January 1990 and December 1992 2D time-of-flight MR angiography was used to examine 1026 patients. MR angiography was used most frequently to examine the venous system. There was a slight reduction in the use of alternative imaging with two exceptions. When chest MR venography was performed, alternative imaging was completely abolished. Also, contrast portal venography was virtually eliminated. Five errors (0.2% of total MR angiography examinations) were recorded. Time-of-flight MR angiography, especially MR venography, is accurate and can replace contrast venography for abdominal and thoracic applications. Cost and limited availability means that other imaging, usually ultrasound, often precedes MR angiography.

False Negative Reactions↗