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La exposición a ambientes de hipoxia, está asociada con una disminución de la saturación arterial de oxígeno y el aumento de las presiones de la arteria pulmonar. El pre-condicionamiento isquémico de una extremidad (IPC Ischemic Preconditioning), es un procedimiento que estimula las vías vasoactiva e inflamatoria, que protegen los sistemas de órganos remotos, de daño isquémico. Para evaluar los efectos de IPC, en la saturación de oxígeno y presiones de la arteria pulmonar, a gran altura; fueron evaluados 12 voluntarios adultos sanos, en un ensayo aleatorio randomizado cruzado (randomized cross-over trial). El IPC fue realizado, utilizando un protocolo estandarizado. Se realizó IPC o placebo diariamente, durante 5 días previos al ascenso a gran altura. Todos los participantes fueron evaluados dos veces a 4243 m de altura (en condiciones de IPC y placebo, con un intervalo de 4 semanas, aleatorizados). La presión sistólica de la arteria pulmonar (PASP) a 4342 m fue significativamente menor en condiciones de IPC, que en condiciones de placebo (36±6.0 mmHg vs. 38.1±7.6 mmHg, respectivamente, p=0.0035). La saturación de oxígeno a 4342 m fue significativamente más elevada en IPC en comparación con placebo (80.3±8.7 por ciento vs. 75.3±9.6 por ciento, respectivamente, p-0.003). IPC como tratamiento profiláctico está asociado con una saturación de oxígeno mayor y atenuación del incremento normal de la presión de arteria pulmonar por hipoxia, seguida al ascenso a gran altura.

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Exposure to hypoxic environments is associated with decreased arterial oxygen saturation and increased pulmonary artery pressures. Ischemic preconditioning of an extremity (IPC) is a procedure that stimulates vasoactive and inflammatory pathways that protect remote organ systems from ongoing or future ischemic injury. To test the effects of IPC on oxygen saturation and pulmonary artery pressures at high altitude, 12 healthy adult volunteers were evaluated in a randomized cross-over trial. IPC was administered utilizing a standardized protocol. IPC or placebo was administered daily for 5 days prior to ascent to altitude. All participants were evaluated twice at 4342 m altitude (placebo and IPC conditions separated by 4 weeks, randomized). The pulmonary artery systolic pressure (PASP) at 4342 m was significantly lower in the IPC condition than the placebo condition (36 ± 6.0 mmHg vs. 38.1 ± 7.6 mmHg, respectively, p = 0.035). Oxygen saturation at 4342 m was significantly higher with IPC compared to placebo (80.3 ± 8.7% vs. 75.3 ± 9.6%, respectively, p = 0.003). Prophylactic IPC treatment is associated with improved oxygen saturation and attenuation of the normal hypoxic increase in pulmonary artery pressures following ascent to high altitude.

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OBJECTIVE: To evaluate population-based cardiovascular risk scores and coronary artery calcification scores (CACS) in amputees. DESIGN: A retrospective cohort study of 1300 veterans in a cardiac computed tomography database. SETTING: 1B Veterans Administration medical center. PARTICIPANTS: A total of 76 amputees and similar number of age-, gender-, and Framingham Risk Scores (FRS)-matched control subjects. METHODS: The amputee population was identified and compared for CACS and traditional cardiac risk factors. Two control groups were used: control group 1, with known risk factors including diabetes mellitus, and control group 2, with all risk factors without diabetes mellitus. MAIN OUTCOME MEASURES: Statistical associations between amputee and control group FRS scores, CACS, and other cardiac risk factors were assessed. RESULTS: The study included 57 nontraumatic and 19 traumatic amputees with an average age of 62.4 years. Sixty-six amputees were in the low-to-intermediate cardiac risk groups according to FRS. Despite this classification, the mean CACS were significantly higher in amputees (1285 ± 18) than in either of the control groups: control group 1 (540 ± 84) and control group 2 (481 ± 11), P < .001. CACS also were significantly higher in the nontraumatic subject group (1595 ± 12) compared with the traumatic group (356 ± 57; P < .001). Upon categorization of CACS based on probability of coronary artery disease (CAD), 76% of amputees had a CACS >100 and 38% of amputees had a CACS >1000. Interestingly, CACS were almost the same in finger/toe amputations compared with an above-knee amputation, indicating an already ongoing CAD process irrespective of level of amputation. The predominant clinical significant cardiac risk factors in amputees are hypertension (89.5%), P < .005; chronic kidney disease (31.6%), P < .001; dyslipidemia (72.4%), P < .04; and insulin resistance. Total cholesterol, low-density lipoprotein, and high-density lipoprotein levels were nonsignificantly low in all amputees. Triglycerides were particularly higher in traumatic patients compared with nontraumatic patients, with the triglycerides/high-density lipoprotein ratio >7. CONCLUSION: This study demonstrates that amputees have a much greater burden of underlying atherosclerotic disease as detected by CACS than do control subjects matched by Framingham risk stratification. Early screening for CAD and aggressive targeted interventions may be an important part of management to reduce early mortality after amputation.

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Ischemic pre-condition of an extremity (IPC) induces effects on local and remote tissues that are protective against ischemic injury. To test the effects of IPC on the normal hypoxic increase in pulmonary pressures and exercise performance, 8 amateur cyclists were evaluated under normoxia and hypoxia (13% F(I)O(2)) in a randomized cross-over trial. IPC was induced using an arterial occlusive cuff to one thigh for 5 min followed by deflation for 5 min for 4 cycles. In the control condition, the resting pulmonary artery systolic pressure (PASP) increased from a normoxic value of 25.6±2.3 mmHg to 41.8±7.2 mmHg following 90 min of hypoxia. In the IPC condition, the PASP increased to only 32.4±3.1 mmHg following hypoxia, representing a 72.8% attenuation (p=0.003). No significant difference was detected in cycle ergometer time trial duration between control and IPC conditions with either normoxia or hypoxia. IPC administered prior to hypoxic exposure was associated with profound attenuation of the normal hypoxic increase of pulmonary artery systolic pressure.

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In an appropriate clinical setting, cardiac CT angiography (CCT) can be used as a safe and effective noninvasive imaging modality for defining coronary arterial anatomy by providing detailed three-dimensional anatomic information that may be difficult to obtain with invasive coronary angiography (ICA). We present a patient where coronary angiography by ICA was unsuccessful and where the subsequent CCT proved to be very useful in providing us relevant information.

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BACKGROUND: Mitral annular (MA) dimensions obtained by traditional two-dimensional echocardiography are poorly standardized and do not adhere to anatomic principles. Correct anatomic imaging planes of the anterior-posterior (AP) and commissure-commissure (CC) axes of the mitral annulus were compared with the traditional method and correlated with cardiac computed tomography (CT). METHODS: Seventeen subjects underwent traditional and correct anatomic imaging planes echocardiography and cardiac CT. The traditional method was obtained in the parasternal long-axis and apical 4-chamber views. Correct anatomic imaging planes were obtained in the apical long-axis view. The traditional and correct anatomic images planes methods were correlated with cardiac CT. RESULTS: The traditional method of MA measurement correlated poorly with cardiac CT (AP axis: r = 0.13; CC axis: r = 0.02). The correct anatomic imaging planes method of MA measurement correlated very well with cardiac CT (AP axis: r = 0.96; CC axis: r = 0.91) (P < .05). CONCLUSIONS: The correct anatomic imaging planes method provides accurate measurement of the AP and CC axes of the mitral annulus by adhering to geometric and anatomic principles.

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BACKGROUND: Previous studies have shown that vascular dysfunction measured by digital thermal monitoring (DTM) during an arm-cuff reactive hyperemia procedure correlates with the severity of coronary artery disease measured by coronary artery calcium in asymptomatic patients. Current study investigates the correlation between DTM and abnormal myocardial perfusion imaging (MPI). METHODS: About 116 consecutive patients with chest discomfort, age 57 +/- 10 years, underwent MPI, DTM and Framingham Risk Score (FRS) assessment. Fingertip temperature rebound (TR), DTM index of vascular reactivity, was assessed after a 2-minute arm-cuff reactive hyperemia test. The extent of myocardial perfusion defect was measured by summed stress score (SSS). RESULTS: TR decreased from SSS < 4 (1.61 +/- 0.15) to 4 < or = SSS < or = 8 (0.5 +/- 0.22) to 9 < or = SSS < or = 13 (0.26 +/- 0.15) to SSS > 13 (-0.37 +/- 0.19) (P = .0001). After adjusting for cardiac risk factors, the odds ratio of the lowest versus two upper tertiles of TR was 3.93 for SSS > or = 4 and 9.65 for SSS > or = 8 compared to SSS < 4. TR correlated well with SSS (r = -0.88, P = .0001). Addition of TR to FRS increased the area under the ROC curve to predict abnormal MPI, SSS > or = 4, from 0.65 to 0.84 (P < .05). CONCLUSION: Vascular dysfunction measured by DTM is associated with the extent of myocardial perfusion defect independent of age, gender, and cardiac risk factors.

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Hypoxic pulmonary vasoconstriction in response to high altitude ascent may contribute to decreased exercise capacity. Endothelin receptor antagonists reduce pulmonary artery pressure and improve exercise capacity in patients with pulmonary arterial hypertension, but their effects on exercise capacity at altitude are unknown. We studied the efficacy of bosentan started 5 days prior to ascent on exercise capacity and pulmonary artery systolic pressure (PASP) at 3800 m altitude. Eight healthy subjects completed a double-blinded, randomized, placebo-controlled, crossover study. The end-points were time to complete a cycle ergometer time trial, PASP, and hemoglobin oxygen saturation (SpO2). The time to complete the time trial at altitude in subjects on placebo and bosentan was 527+/-159 and 525+/-156 s respectively (P=0.90). PASP was not different on bosentan compared with placebo. Mean SpO2 during the altitude time trial was lower in subjects taking bosentan compared to placebo (78+/-6 vs. 85+/-8% respectively, P=0.03). Bosentan initiated 5 days prior to ascent to high altitude did not improve exercise capacity or reduce PASP, and worsened SpO2 during high intensity exercise at altitude.

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BACKGROUND: Coronary arteriography (CA) is the standard method to image coronary lesions. Multidetector cardiac computerized tomography (MDCT) provides high-resolution images of coronary arteries, allowing a noninvasive alternative to determine lesion type. To date, no studies have assessed the ability of MDCT to categorize coronary lesion types. HYPOTHESIS: The objective of this study was to determine the accuracy of lesion type categorization by MDCT using CA as a reference standard. METHODS: Patients who underwent both MDCT and CA within 2 months of each other were enrolled. MDCT and CA images were reviewed in a blinded fashion. Lesions were categorized according to the SCAI classification system (Types I-IV). The origin, proximal and middle segments of the major arteries were analyzed. Each segment comprised a data point for comparison. Analysis was performed using the Spearman Correlation Test. RESULTS: Four hundred eleven segments were studied, of which 110 had lesions. The lesion distribution was as follows: 35 left anterior descending (LAD), 29 circumflex (Cx), 31 right coronary artery (RCA), 2 ramus intermedius, 8 diagonal, 4 obtuse marginal and 2 left internal mammary arteries. Correlations between MDCT and CA were significant in all major vessels (LAD, Cx, RCA) (p < 0.001). The overall correlation coefficient was 0.67. Concordance was strong for lesion Types II-IV (97%) and poor for Type I (30%). CONCLUSION: High-risk coronary lesion types can be accurately categorized by MDCT. This ability may allow MDCT to play an important noninvasive role in the planning of coronary interventions.

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PURPOSE: We report a case of prostate brachytherapy seed migration to the right coronary artery (RCA) associated with an acute myocardial infarction (AMI). METHODS AND MATERIALS: A 69-year-old male was diagnosed with Prostate Adenocarcinoma Stage II (T(1c)N0M0) in October 2003. He underwent percutaneous transperineal interstitial permanent prostate brachytherapy with the implantation of 94 loose iodine (125I) seeds under transrectal ultrasound guidance on 15 December, 2003. The implantation was designed to deliver a minimum dose of 144 Gy. RESULTS: Postimplant pelvic radiography at Day 30 showed five seeds missing. No chest radiography was done until hospital admission on October 10, 2005 for AMI. Cine radiography from cardiac catheterization revealed 86 metallic seeds remaining in the pelvic region, 4 that had migrated to the lungs (2 left and 2 right) and 2 to the heart. Two seeds were unaccounted for. Of the two cardiac seeds, one was lodged in the right ventricle endocardium and the other in the midsegment of the RCA at the site of a severely stenotic lesion that resulted in an AMI. CONCLUSIONS: To our knowledge, this is the first case of brachytherapy seed migration to the RCA associated with an AMI. Echocardiography before brachytherapy seed implantation might be considered in patients felt to be at high risk for cardiac shunting.

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