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Biomedical subjects

N D Kon

Publications and source records attributed to N D Kon.

At least 19 recordsLinked to original sources
PubMed1999

Aortic root replacement with the freestyle stentless porcine aortic root bioprosthesis.

BACKGROUND: Stentless porcine prosthetic valves offer several advantages over traditional valves. Among these are superior hemodynamics, laminar flow patterns, lack of need for anticoagulation and perhaps improved durability. METHODS: One hundred and twelve patients were operated on from September 17, 1992 to April 13, 1998 as part of a multi-center worldwide investigation. All patients received a total aortic root replacement. Patients were evaluated postoperatively at discharge, 3 to 6 months, and yearly by clinical exam and color flow Doppler echocardiography. RESULTS: There were 4 deaths either in the hospital or within 30 days after surgery for an operative mortality of 3.6%. No patients experienced structural valve deterioration, non-structural valve deterioration, paravalvular leak, unacceptable hemodynamic performance, or postoperative endocarditis. The linearized rates for survival and thromboembolic complications at 5 years were 82.8% and 90.5% respectively. Excellent hemodynamic function is demonstrated by very low gradients, large EOA, and an exceedingly low incidence of any aortic regurgitation. CONCLUSIONS: The Medtronic Freestyle aortic root bioprosthesis can be used safely to replace the aortic root for aortic valve and aortic root pathology. Root replacement allows optimal hemodynamic performance with no significant aortic regurgitation. Early and intermediate results are encouraging, but further follow-up is needed to determine valve durability.

Adult↗
PubMed1998

Mitral valve replacement in sickle cell disease.

Cardiac dysfunction, including mitral valve regurgitation and congestive heart failure, can occur in patients with sickle cell disease. However, major surgery poses a greater risk in this population. This paper reports on the management of a patient with sickle cell disease who underwent successful replacement of the mitral valve.

Adult↗
PubMed1998

Three-dimensional surface area of the aortic valve orifice by three-dimensional echocardiography: clinical validation of a novel index for assessment of aortic stenosis.

BACKGROUND: A direct and accurate method of assessing aortic valve area (AVA) in patients with aortic stenosis (AS) is desirable because of the well-known theoretical and practical limitations of the currently available methods. We assessed the clinical feasibility and accuracy of a novel index, the 3-dimensional surface area (3-DSA) of the aortic valve orifice by 3-dimensional transesophageal echocardiography (3-DTEE) in patients with AS. METHODS: Intraoperative 3-DTEE was performed in 23 consecutive patients (mean age 58 +/- 15 years) with valvular AS using a Toshiba SSA-380A system with a multiplane TEE probe and a TomTec EchoScan system. The 3-DTEE acquisition, processing and reconstruction were conducted and the aortic valve orifice presented using a "surgeon's aortotomy view" (aortic valve orifice as if viewed through an open aortic root). The 3-D images were videotaped and calibrated and the 3-DSA measured by planimetry of the inner surface of the aortic valve leaflets at the maximal systolic opening using the dynamic 3-D images. For comparison, the 2-D cross sectional area (2-DCSA) of the aortic valve was also determined by 2-DTEE. The 3-DSA and 2-DCSA were compared with the AVA by the invasive Gorlin formula and the Doppler continuity equation method by transthoracic echocardiography. RESULTS: The 3-DSA and 2-DCSA measurements were feasible in all but one patient. Both 3-DSA and 2-DCSA correlated moderately well with the AVA by the Gorlin formula (n = 17, r = 0.66, standard error of the estimate [SEE] = 0.3 cm2, P <.05 for 3-DSA and r = 0.61, SEE = 0. 5 cm2 P <.05 for 2-DCSA, respectively). They also correlated well with the AVA by Doppler continuity equation method (n = 22, r = 0.90, SEE = 0.1 cm2, P <.05 for 3-DSA and r = 0.83, SEE = 0.3 cm2, P <.05 for 2-DCSA, respectively). There was no statistically significant difference between the 3-DSA and AVA by both the Gorlin formula (Delta = 0.1 +/- 0.3 cm2, P =.3) and the Doppler continuity equation (Delta = -0.0 +/- 0.3 cm2, P =.7). In contrast, the 2-DCSA significantly overestimated AVA by the Gorlin formula (Delta = 0.5 +/- 0.5 cm2, P <.005) and by the Doppler continuity equation (Delta = 0.5 +/- 0.6 cm2, P <.0001). CONCLUSIONS: Planimetry of 3-DSA of the aortic valve orifice by 3-DTEE is a clinically feasible and relatively accurate technique for assessment of AVA and is superior to 2-DCSA by 2-DTEE.

Adult↗
PubMed1998

Dobutamine antagonizes epinephrine's biochemical and cardiotonic effects: results of an in vitro model using human lymphocytes and a clinical study in patients recovering from cardiac surgery.

BACKGROUND: Patients may receive more than one positive inotropic drug to improve myocardial function and cardiac output, with the assumption that the effects of two drugs are additive. The authors hypothesized that combinations of dobutamine and epinephrine would produce additive biochemical and hemodynamic effects. METHODS: The study was performed in two parts. Phase 1 used human lymphocytes in an in vitro model of cyclic adenosine monophosphate (cAMP) generation in response to dobutamine (10(-8) to 10(-4) M) or epinephrine (10(-9) M to 10(-5) M), and dobutamine and epinephrine together. Phase 2 was a clinical study in patients after aortocoronary artery bypass in which isobolographic analysis compared the cardiotonic effects of dobutamine (1.25, 2.5, or 5 microg x kg(-1) x min(-1)) or epinephrine (10, 20, or 40 ng x kg(-l) x min(-1)), alone or in combination. RESULTS: In phase 1, dobutamine increased cAMP production 41%, whereas epinephrine increased cAMP concentration approximately 200%. However, when epinephrine (10(-6) M) and dobutamine were combined, dobutamine reduced cAMP production at concentrations between 10(-6) to 10(-4) M (P = 0.001). In patients, 1.25 to 5 microg x kg(-1) x min(-1) dobutamine increased the cardiac index (CI) 15-28%. Epinephrine also increased the CI with each increase in dose. However, combining epinephrine with the two larger doses of dobutamine (2.5 and 5microg x kg(-1) x mi(-1)) did not increase the CI beyond that achieved with epinephrine and the lowest dose of dobutamine (1.25 microg x kg(-1) x min(-1)). In addition, the isobolographic analysis for equieffective concentrations of dobutamine and epinephrine suggests subadditive effects. CONCLUSIONS: Dobutamine inhibits epinephrine-induced production of cAMP in human lymphocytes and appears to be subadditive by clinical and isobolographic analyses of the cardiotonic effects. These findings suggest that combinations of dobutamine and epinephrine may be less than additive.

Adrenergic Agonists↗
PubMed1997

Feasibility, accuracy, and incremental value of intraoperative three-dimensional transesophageal echocardiography in valve surgery.

In this prospective trial, intraoperative 2-dimensional (2-D) and 3-dimensional (3-D) transesophageal echocardiography (TEE) examinations were performed on 60 consecutive patients undergoing cardiac valve surgery. Both 2-D (including color flow and Doppler data) and 3-D images were reviewed by blinded observers, and major valvular morphologic findings recorded. In vivo morphologic findings were noted by the surgeon and all explanted valves underwent detailed pathologic examination. To test reproducibility, 6 patients also underwent 3-D TEE 1 day before surgery. A total of 132 of 145 attempted acquisitions (91%) were completed with a mean acquisition time of 2.8 +/- 0.2 minutes. Acquisition time was significantly shorter in patients with regular rhythms. Reconstructions were completed in 121 of 132 scans (92%) and there was at least 1 good reconstruction in 56 of 60 patients (93%). Mean reconstruction time was 8.6 +/- 0.7 minutes. Mean effective 3-D time, which was the time taken to complete an acquisition and a clinically interpretable reconstruction, was 12.2 +/- 0.8 minutes. Intraoperative 3-D echocardiography was clinically feasible in 52 patients (87%). Three-D echocardiography detected most of the major valvular morphologic abnormalities, particularly leaflet perforations, fenestrations, and masses, confirmed on pathologic examination. Three-D echocardiography predicted all salient pathologic findings in 47 patients (84%) with good quality images. In addition, in 15 patients (25%), 3-D echocardiography provided new additional information not provided by 2-D echocardiography, and in 1 case, 3-D echocardiographic findings resulted in a surgeon's decision to perform valve repair rather than replacement. In several instances, 3-D echocardiography provided complementary morphologic information that explained the mechanism of abnormalities seen on 2-D and color flow imaging. In the reproducibility subset, preoperative and intraoperative 3-D imaging detected a similar number of findings when compared with pathology. Thus, in routine clinical intraoperative settings, 3-dimensional TEE is feasible, accurately predicts valve morphology, and provides additional and complementary valvular morphologic information compared with conventional 2-D TEE, and is probably reproducible.

Adolescent↗
PubMed1997

Risk factors and solutions for the development of neurobehavioral changes after coronary artery bypass grafting.

BACKGROUND: As operative mortality for coronary artery bypass grafting has decreased, greater attention has focused on neurobehavioral complications of coronary artery bypass grafting and cardiopulmonary bypass. METHODS: To assess risk factors and to evaluate changes in surgical technique, between 1991 and 1994 we evaluated 395 patients undergoing coronary artery bypass grafting with an 11-part neurobehavioral battery administered preoperatively and at 1 and 6 weeks postoperatively. Patients were instrumented with 5-MHz focused continuous-wave carotid Doppler transducers intraoperatively to estimate cerebral microembolism as an instantaneous perturbation of the velocity signal. Microembolism data were quantitated and compared with surgical technical maneuvers during operation and with neurobehavioral deficit (> or = 20% decline from preoperative performance on two or more neurobehavioral tests) postoperatively. These data and patient demographics were statistically analyzed (chi2, t test) and the results at 2 years (1991 and 1992; group A) were used to influence surgical technique in 1993 and 1994 (group B). RESULTS: Significantly associated with new neurobehavioral deficits were increasing patient age (p < 0.05), more than 100 emboli per case (p < 0.04), and palpable aortic plaque (p < 0.02). Group B patients had a significant decline in the neurobehavioral event rate (group A, 69%, 140/203; versus group B, 60%, 115/192; p < 0.05) of postoperative neurobehavioral deficits at 1 week and at 1 month (group A, 29%, 52/180; versus group B, 18%, 35/198; p < 0.01). The stroke rate was less than 2% in both groups (p = not significant). Modifications of surgical technique used in group B patients included increased use of single cross-clamp technique, increased venting of the left ventricle, and application of transesophageal and epiaortic ultrasound scanning to locate and avoid trauma to aortic atherosclerotic plaques. CONCLUSIONS: Neurobehavioral changes after coronary artery bypass grafting are common and associated with cerebral microembolization. Surgical technical maneuvers designed to reduce emboli production may improve neurobehavioral outcome.

Aged↗
PubMed1997

Accuracy of transesophageal echocardiography in preoperative determination of aortic anulus size during valve replacement.

This prospective, blinded study evaluated the accuracy of transesophageal (TEE) and transthoracic echocardiography in predicting the size of the surgical aortic valve anulus in 20 consecutive patients undergoing aortic valve replacement. TEE was highly accurate in predicting surgical aortic valve anulus size (r = 0.98; p < 0.00001). The standard error of the TEE estimate of the size of the obturator anulus was only 0.04 mm, and in all cases the TEE estimate was within 1 mm of the direct surgical measurement. Both biplane and multiplane TEE probes were equally accurate and this accuracy was maintained over a wide range of sizes of surgical aortic anulus. Transthoracic echocardiography appeared less accurate in predicting anulus size (r = 0.64; p < 0.08). Therefore TEE can be used routinely for selection and preparation of aortic allografts before sternotomy, potentially reducing cardiopulmonary bypass pump time by 10 to 30 minutes and ensuring optimal size matching of the donor-recipient anulus.

Adolescent↗
PubMed1997

Morphology and dynamic change of discrete subaortic stenosis can be imaged and quantified with three-dimensional transesophageal echocardiography.

This report describes three-dimensional transesophageal echocardiographic findings in three consecutive patients with discrete subaortic stenosis. The discrete subaortic stenosis lesions included a circumferential, a remnant crescent, and a broken fibrotic subaortic membrane. The lesions were best imaged by using a three-dimensional transesophageal echocardiography-generated "aortotomy view" of the left ventricular outflow tract immediately below the plane of the aortic valve. The three-dimensional images correlated well with surgical and pathologic findings. The three-dimensional surface areas of the left ventricular outflow tract at the level of discrete subaortic stenosis during systole (0.8 +/- 0.5 cm2) and diastole (1.7 +/- 0.7 cm2) were measured by planimetry of the three-dimensional transesophageal echocardiographic images. The novel "aortotomy view" offered by three-dimensional transesophageal echocardiography provided direct visualization and quantification of discrete subaortic stenosis in a dynamic fashion. In summary, three-dimensional transesophageal echocardiography can accurately display and quantify discrete subaortic stenosis and could be a new clinically useful tool for assessing discrete subaortic stenosis and guiding surgical and transcatheter interventions.

Adult↗
PubMed1996

Acute right ventricular failure during aortic valvular operation due to mechanical problem in the right coronary artery.

BACKGROUND: When right ventricular failure occurs during aortic valvular operation, inadequate myocardial protection may be the culprit. However, other causes of right ventricular failure should be considered, such as air or particulate matter embolization. Right ventricular failure unexpectedly occurred during an aortic valvular operation, and the cause was found to be a mechanical problem with the right coronary ostium. METHODS: A mechanical problem with the right coronary artery (RCA) occurred in 9 patients undergoing aortic valvular procedures, which included isolated aortic valve replacement (4 patients), aortic valve replacement and coronary artery bypass (1 patient), Bentall procedure (2 patients), aortic valve reconstruction (1 patient), and double valve replacement and coronary artery bypass (1 patient). Although myocardial protection was considered to be the cause, a mechanical problem was subsequently identified in the RCA, leading that artery to be bypassed with a segment of saphenous vein. RESULTS: The 1 patient in whom the condition was not recognized at time of aortic valve operation died; at autopsy, a damaged and occluded right ostium was confirmed. The other 8 patients who had the RCA bypassed survived. CONCLUSIONS: We conclude that when right ventricular failure unexpectedly occurs during an aortic valvular operation and does not improve with reperfusion, a mechanical problem in the RCA should be considered. In this situation we recommend that the RCA be bypassed with a segment of saphenous vein graft.

Acute Disease↗
PubMed1995

Acquired cor triatriatum after orthotopic cardiac transplantation.

Orthotopic cardiac transplantation was performed in a 42-year-old woman with idiopathic cardiomyopathy. Postoperative right ventricular failure developed and a transesophageal echocardiogram demonstrated acquired cor triatriatum with marked obstruction to mitral valve inflow and severe right ventricular dilatation. At reexploration, redundant donor atrial tissue was excised correcting the cor triatriatum. She was alive and well with normal hemodynamic parameters 12 months after transplantation.

Adult↗
PubMed1995

Comparison of implantation techniques using freestyle stentless porcine aortic valve.

Stentless porcine aortic valves demonstrate superior hemodynamic performance when compared with their stented counterparts. The technical considerations for implanting these valves can be demanding. The Medtronic Freestyle aortic root bioprosthesis resembles an allograft, has zero-pressure-fixed leaflets treated with an antimineralization agent, and can be implanted using a variety of techniques. In this study of that valve, total root replacement (TRR) was compared with a partial scallop aortic inclusion technique (PSI). Implications were performed in 75 patients (49 PSI and 26 TRR). There were no significant differences with respect to age, sex, or incidence of concomitant procedures. Mean aortic cross-clamp times were significantly less in the PSI group than in the TRR group (51.8 +/- 11.7 minutes versus 125.5 +/- 19.7 minutes; p = 0.0001). At discharge, mean systolic gradients seen on color-flow Doppler echocardiography were less in the TRR group than in the PSI group (6.17 +/- 3.66 versus 10.01 +/- 4.83 mm Hg; p = 0.014). Discharge echocardiography revealed trivial valve regurgitation in 8.3% of the TRR group and in 41.7% of the PSI group (p = 0.004). No patient experienced any significant valvular regurgitation on discharge echocardiography. We conclude that early experience with the Medtronic Freestyle aortic root bioprosthesis shows excellent short-term function regardless of implantation technique. Shorter cross-clamp times, comparable with those of stented valve procedures, occurred with PSI implantation. We anticipate that effects on long-term durability will be beneficial.

Adult↗
PubMed1995

Effect of cardiopulmonary bypass on hand and forearm blood flow.

We have assessed the relationship between the aorto-radial pressure difference at the conclusion of cardiopulmonary bypass and blood flow to the hand. Hand blood flow was estimated from the difference between forearm blood flow measured without and with exclusion of the hand circulation. On the same hand, the skin temperature on the palm and on the middle finger was recorded, with the amplitude of the finger pulse oximeter trace. The aorto-radial pressure difference, after cardiopulmonary bypass, correlated with hand blood flow (r = 0.59, P = 0.002). There was a significant (P < 0.0001) palm-finger temperature gradient before and after cardiopulmonary bypass. In conclusion, while the mean aorto-radial pressure difference after bypass results from increased hand blood flow, the finger is not a reliable site to assess the state of the systemic circulation, before or after cardiopulmonary bypass.

Aged↗
PubMed1994

Reliability of the radial arterial pressure during anesthesia. Is wrist compression a possible diagnostic test?

STUDY OBJECTIVE: To evaluate wrist compression as a test to identify low radial from low systemic pressure and to see if the gradient found after cardiopulmonary bypass is also present whenever hand vascular resistance may decrease. DESIGN: This was a prospective study. SETTING: Operating room area of a university medical center. PARTICIPANTS: (1) Forty patients undergoing coronary bypass grafting studied at discontinuation of cardiopulmonary bypass. (2) Twenty-six patients received isoflurane anesthesia before major noncardiac operations. (3) Hydraulic model: a fluid container with a tube 66-cm long, 6- to 1.8-mm internal diameter, connected at its base. INTERVENTIONS: Before induction of anesthesia, the radial artery was cannulated and, in the first group, the aorta or femoral arteries as well. The radial pressure was compared consecutively with and without wrist compression. In the model, the pressure was recorded simultaneously at three sites along the tube while different flows ran through its distal end. MEASUREMENTS AND RESULTS: Overall, wrist compression increased radial (p < 0.001) systolic, diastolic, and mean arterial pressures. In the first group, compression reduced the femoral/aortic-radial mean pressure difference by 50 percent and never produced higher radial than central mean pressure. Plot of the pressure difference produced by wrist compression against the average of the (compared) radial pressures and considering increases > or = 4 mm Hg as real, showed that, in the first group, systolic arterial pressure (SAP) increased 13 +/- 1.4 mm Hg in 22 of 40 patients; diastolic arterial pressure (DAP) increased 7.8 +/- 1.1 mm Hg in 4; and mean arterial pressure (MAP) increased 7.7 +/- 1.6 mm Hg in 9 patients. In the second group, SAP increased 16.0 +/- 1.7 mm Hg in 24 of 26 patients, DAP increased 6.0 +/- 1.4 mm Hg in 5, and MAP increased 7.0 +/- 0.7 mm Hg in 18 of 26 patients. In the model, base pressure at 94 mm Hg, the pressures were 1.2 to 28.1 mm Hg lower for flows ranging from 10 to 122 ml/min at the 54-cm distance (wrist equivalent). CONCLUSION: The systemic-radial artery pressure gradient seen at the end of cardiopulmonary bypass seems to be a phenomenon common to patients with decreased hand vascular resistance. Wrist compression decreases or abolishes the gradient in most cases. It does not produce false positives, so an increase indicates a greater aortic than radial pressure. The difference is likely to be only temporary.

Anesthesia, General↗
PubMed1994

Cardiopulmonary bypass and forearm blood flow.

STUDY OBJECTIVE: To assess the effect of cardiopulmonary bypass (CPB) on muscle blood flow (MBF) when measured in the forearm by venous occlusion plethysmography. DESIGN: This was a prospective study. SETTING: Operating room area of a tertiary care university medical center. PARTICIPANTS: Twenty-seven patients (25 men and 2 women), aged 62 +/- 1.5 years, undergoing elective coronary bypass grafting. INTERVENTIONS: Measurements were made during the surgical procedure: before, during cold and warm, and after discontinuation of CPB. MEASUREMENTS AND RESULTS: Changes in forearm blood flow (FBF), derived forearm vascular resistance (FVR), mean arterial pressure (MAP), and cardiac output (CO) were evaluated by repeated measures analysis of variance. The control FBF (measured before CPB) was found to be approximately 50 percent lower than that previously reported for awake volunteers and patients. The FVR was similarly higher. From these low values, the FBF increased significantly (p < 0.001) during normothermic bypass and after CPB. Forearm vascular resistance decreased significantly (p < 0.001) throughout the cold, warm, and postbypass periods. Only during the warm and the postbypass periods did FBF and FVR reach normal values. Mean arterial pressure decreased significantly (p < 0.01) throughout. There was no statistically significant association between any of the variables and FBF or FVR. After correcting for patient and surgical phase variability, only MAP had a statistically significant effect (p = 0.042) on FVR; blood temperature, skin temperature, hematocrit level, PaCO2, serum potassium, and systemic vascular resistance (SVR) had no effect on either FBF or FVR when tested singly or in combination. When correction for multiple comparisons was applied, the lowest probability value became greater than 0.25. There was no correlation between combinations of covariates and FBF or FVR after adjustments for the surgical phase of the study either. CONCLUSION: These findings indicate that the increase in MBF seen during warm and the post-CPB periods is only a recovery toward normal blood flow. The role of this change in the low SVR that usually accompanies CPB is equivocal.

Blood Pressure↗
PubMed1993

Mitral valve operation via an extended transseptal approach.

The extended transseptal approach to the mitral valve has been used for 71 consecutive procedures. Four patients died; none had complications directly attributable to the exposure. Twenty underwent a primary reparative procedure; 30, a primary replacement procedure; and 21, a repeat procedure. Despite division of the sinus node artery, 26 of 32 patients with sinus rhythm preoperatively had sinus rhythm postoperatively; 4 had atrial fibrillation postoperatively. Twenty-seven of 37 patients with atrial fibrillation preoperatively had atrial fibrillation postoperatively; 8 had sinus rhythm postoperatively. Because the exposure provided by this extended transseptal approach is superior to that of standard approaches, we now use it routinely for mitral valve operations.

Adult↗
PubMed1993

Combined inotropic effects of amrinone and epinephrine after cardiopulmonary bypass in humans.

Amrinone, a phosphodiesterase inhibitor, and epinephrine, an alpha- and beta-adrenergic receptor agonist, are inotropic drugs used during cardiac surgery to reverse myocardial depression after cardiopulmonary bypass. However, these drugs have not been compared separately, or in combination, in this patient population. We hypothesized that the combination might have complementary actions in improving myocardial function. We, therefore, compared amrinone, epinephrine, and the combination of amrinone and epinephrine in a randomized, blinded, placebo-controlled study in patients undergoing coronary artery bypass grafting. Forty patients with ejection fractions > 0.45 were studied. Right ventricular ejection fraction pulmonary artery catheters and radial arterial catheters were inserted before fentanyl-midazolam anesthesia. After separation from bypass, patients received either a placebo (n = 20) or amrinone bolus (1.5 mg/kg, n = 20) at time 0 and a placebo (n = 20) or epinephrine (30 ng.kg-1.min-1, n = 20) infusion at time 5 min. This resulted in four study groups, n = 10 in each group. Data were collected every 2.5 min for 10 min. Epinephrine, amrinone, and the combination of both drugs significantly increased cardiac output, stroke volume, O2 delivery, and left ventricular stroke work. The increase in stroke volume (P < 0.05) was 12 +/- 6, 16 +/- 4, and 30 +/- 4 mL/beat with epinephrine, amrinone, and the combination of amrinone and epinephrine, respectively. The amrinone-epinephrine combination increased stroke volume as much as the sum of amrinone and epinephrine given separately. Systemic vascular resistance and pulmonary vascular resistance decreased with amrinone and amrinone-epinephrine, but not with epinephrine. Epinephrine increased mean arterial and mean pulmonary arterial pressures. Right ventricular ejection fraction did not significantly increase (P = 0.09) with epinephrine, but increased significantly with amrinone (0.45 to 0.53, P = 0.01), and with the combination (0.43 to 0.55, P = 0.006). These data indicate that amrinone and epinephrine effectively increase myocardial performance during cardiac surgery. Right ventricular function especially was improved with amrinone and the combination of amrinone and epinephrine. The combined effects of amrinone and epinephrine may be useful in patients recovering from the ischemia and reperfusion injury resulting from coronary artery bypass grafting.

Amrinone↗
PubMed1992

Magnetic resonance imaging evaluation of recipient for cryopreserved aortic allograft.

Aortic valve replacement with a cryopreserved aortic allograft is the procedure of choice for many patients with aortic valvular heart disease. We have used magnetic resonance imaging preoperatively to determine annular size and coronary artery orientation in the recipient, which not only has enabled us to select an allograft of appropriate size from a distant tissue bank, but also has helped us to identify preoperatively the recipient with a truly bicuspid valve in which the coronary arteries are oriented 180 degrees apart. Sixteen consecutive patients were evaluated preoperatively, the aortic annulus being measured with both magnetic resonance imaging and echocardiography. Cryopreserved aortic allografts were ordered on the basis of the magnetic resonance imaging measurement. Annular size was then measured intraoperatively with calibrated sizers. Magnetic resonance imaging annular measurements correlated highly with those found at operation (r = 0.92), whereas echocardiographic measurements correlated less well (r = 0.69). Coronary orientation was accurately predicted in every case (r = 1.0). Therefore, we have found magnetic resonance imaging to be useful in the preoperative evaluation of patients for aortic valve replacement with a cryopreserved aortic allograft.

Adolescent↗