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Abnormal Ventilation-Perfusion Scan Is Associated with Pulmonary Hypertension in Sickle Cell Adults.

ABSTRACT: Pulmonary hypertension (PH) in adults with sickle cell disease (SCD) is associated with early mortality. Chronic thromboembolic PH (CTEPH) is an important complication and contributor to PH in SCD but is likely underappreciated. Guidelines recommend ventilation-perfusion (V/Q) scintigraphy as the imaging modality of choice to exclude CTEPH. Data on V/Q scanning are limited in SCD. Our objective was to compare the performance of V/Q scanning with that of CT pulmonary angiography (CTPA) and to report clinical outcomes associated with abnormal V/Q findings. Methods: Laboratory data, echocardiography, 6-min-walk testing, V/Q scanning, CTPA, and right heart catheterization (RHC) were prospectively obtained. High-probability and intermediate-probability V/Q findings were considered to be abnormal. Included for analysis were 142 SCD adults (aged 40.1 ± 13.7 y, 83 women, 87% hemoglobin SS) in a stable state enrolled consecutively between March 13, 2002, and June 8, 2017. Results: V/Q results were abnormal in 65 of 142 patients (45.8%). CTPA was positive for pulmonary embolism in 16 of 60 (26.7%). RHC confirmed PH (mean pulmonary artery pressure ? 25 mmHg) in 46 of 64 (71.9%), of whom 34 (73.9%) had abnormal V/Q findings. Among those without PH by RHC (n = 18), 2 of 18 patients had abnormal V/Q findings. Thirty-three patients had a complete dataset (V/Q scanning, CTPA, and RHC); 29 of 33 had abnormal RHC findings, of whom 26 had abnormal V/Q findings, compared with 11 who had abnormal CTPA findings. There was greater concordance between V/Q findings and RHC (?-value = 0.53; P < 0.001) than between CTPA and RHC (?-value = 0.13; P = 0.065). The sensitivity and specificity for V/Q scanning was 89.7% and 75.0%, respectively, whereas CTPA had sensitivity of 37.3% and specificity of 100%. Abnormal V/Q finding swere associated with hemodynamic severity (mean pulmonary artery pressure, 35.2 ± 9.6 vs. 26.9 ± 10.5 mm Hg, P = 0.002; transpulmonary gradient, 21.5 ± 9.7 vs. 12.16 ± 11 mmHg, P = 0.005; and pulmonary vascular resistance, 226.5 ± 135 vs. 140.7 ± 123.7 dynes?s?cm-5, P = 0.013) and exercise capacity (6-min-walk distance, 382.8 ± 122.3 vs. 442.3 ± 110.6 m, P < 0.010). Thirty-four deaths were observed over 15 y. All-cause mortality was higher in the abnormal-V/Q group (21 [61.8%]) than in the normal-V/Q group (13 [38.2%]) (log-rank test, P = 0.006; hazard ratio, 2.54). Conclusion: V/Q scanning is superior to CTPA in detecting thrombotic events in SCD. Abnormal V/Q findings are associated with PH, worse hemodynamics, lower functional capacity, and higher mortality. Despite high sensitivity in detecting CTEPH, V/Q scanning is underutilized. We recommend the use of V/Q scanning in the evaluation of dyspnea in adult SCD patients given the important implications toward management.

SUBMITTER: Mehari A

PROVIDER: S-EPMC6910625 | biostudies-literature | 2019 Jan

REPOSITORIES: biostudies-literature

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Abnormal Ventilation-Perfusion Scan Is Associated with Pulmonary Hypertension in Sickle Cell Adults.

Mehari Alem A Igbineweka Norris N Allen Darlene D Nichols Jim J Thein Swee Lay SL Weir Nargues A NA

Journal of nuclear medicine : official publication, Society of Nuclear Medicine 20180607 1

Pulmonary hypertension (PH) in adults with sickle cell disease (SCD) is associated with early mortality. Chronic thromboembolic PH (CTEPH) is an important complication and contributor to PH in SCD but is likely underappreciated. Guidelines recommend ventilation-perfusion (V/Q) scintigraphy as the imaging modality of choice to exclude CTEPH. Data on V/Q scanning are limited in SCD. Our objective was to compare the performance of V/Q scanning with that of CT pulmonary angiography (CTPA) and to rep ...[more]

PMID: 29880507

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Project description:Key pointsThe distribution of pulmonary perfusion is affected by gravity, vascular branching structure and active regulatory mechanisms, which may be disrupted by cardiopulmonary disease, but this is not well studied, particularly in rare conditions. We evaluated pulmonary perfusion in patients who had undergone Fontan procedure, patients with pulmonary arterial hypertension (PAH) and two groups of controls using a proton magnetic resonance imaging technique, arterial spin labelling to measure perfusion. Heterogeneity was assessed by the relative dispersion (SD/mean) and gravitational gradients. Gravitational gradients were similar between all groups, but heterogeneity was significantly increased in both patient groups compared to controls and persisted after removing contributions from large blood vessels and gravitational gradients. Patients with Fontan physiology and patients with PAH have increased pulmonary perfusion heterogeneity that is not explainable by differences in mean perfusion, gravitational gradients, or large vessel anatomy. This probably reflects vascular remodelling in PAH and possibly in Fontan physiology.AbstractMany factors affect the distribution of pulmonary perfusion, which may be disrupted by cardiopulmonary disease, but this is not well studied, particularly in rare conditions. An example is following the Fontan procedure, where pulmonary perfusion is passive, and heterogeneity may be increased because of the underlying pathophysiology leading to Fontan palliation, remodelling, or increased gravitational gradients from low flow. Another is pulmonary arterial hypertension (PAH), where gravitational gradients may be reduced secondary to high pressures, but remodelling may increase perfusion heterogeneity. We evaluated regional pulmonary perfusion in Fontan patients (n = 5), healthy young controls (Fontan control, n = 5), patients with PAH (n = 6) and healthy older controls (PAH control) using proton magnetic resonance imaging. Regional perfusion was measured using arterial spin labelling. Heterogeneity was assessed by the relative dispersion (SD/mean) and gravitational gradients. Mean perfusion was similar (Fontan = 2.50 ± 1.02 ml min-1 ml-1 ; Fontan control = 3.09 ± 0.58, PAH = 3.63 ± 1.95; PAH control = 3.98 ± 0.91, P = 0.26), and the slopes of gravitational gradients were not different (Fontan = -0.23 ± 0.09 ml min-1 ml-1 cm-1 ; Fontan control = -0.29 ± 0.23, PAH = -0.27 ± 0.09, PAH control = -0.25 ± 0.18, P = 0.91) between groups. Perfusion relative dispersion was greater in both Fontan and PAH than controls (Fontan = 1.46 ± 0.18; Fontan control = 0.99 ± 0.21, P = 0.005; PAH = 1.22 ± 0.27, PAH control = 0.91 ± 0.12, P = 0.02) but similar between patient groups (P = 0.13). These findings persisted after removing contributions from large blood vessels and gravitational gradients (all P < 0.05). We conclude that patients with Fontan physiology and PAH have increased pulmonary perfusion heterogeneity that is not explained by differences in mean perfusion, gravitational gradients, or large vessel anatomy. This probably reflects the effects of remodelling in PAH and possibly in Fontan physiology.

Project description:Pulmonary hypertension affects ∼10% of adult patients with sickle cell disease (SCD), particularly those with the homozygous genotype. An increase in pulmonary artery systolic pressure, estimated noninvasively by echocardiography, helps identify SCD patients at risk for pulmonary hypertension, but definitive diagnosis requires right-heart catheterization. About half of SCD-related pulmonary hypertension patients have precapillary pulmonary hypertension with potential etiologies of (1) a nitric oxide deficiency state and vasculopathy consequent to intravascular hemolysis, (2) chronic pulmonary thromboembolism, or (3) upregulated hypoxic responses secondary to anemia, low O2 saturation, and microvascular obstruction. The remainder have postcapillary pulmonary hypertension secondary to left ventricular dysfunction. Although the pulmonary artery pressure in SCD patients with pulmonary hypertension is only moderately elevated, they have a markedly higher risk of death than patients without pulmonary hypertension. Guidelines for diagnosis and management of SCD-related pulmonary hypertension were published recently by the American Thoracic Society. Management of adults with sickle-related pulmonary hypertension is based on anticoagulation for those with thromboembolism; oxygen therapy for those with low oxygen saturation; treatment of left ventricular failure in those with postcapillary pulmonary hypertension; and hydroxyurea or transfusions to raise the hemoglobin concentration, reduce hemolysis, and prevent vaso-occlusive events that cause additional increases in pulmonary pressure. Randomized trials have not identified drugs to lower pulmonary pressure in SCD patients with precapillary pulmonary hypertension. Patients with hemodynamics of pulmonary arterial hypertension should be referred to specialized centers and considered for treatments known to be effective in other forms of pulmonary arterial hypertension. There have been reports that some of these treatments improve SCD-related pulmonary hypertension.

Project description:BackgroundClinicians' interpretation of lung scan reports will determine which further management decisions are taken when potentially fatal pulmonary embolism (PE) is suspected.ObjectivesTo assess current referring clinicians' interpretation of the terminology used in ventilation/perfusion (V/Q) scan reports, whether this interpretation is affected by experience level, and how it affects clinical management decisions.MethodsThis was a questionnaire-based cross-sectional study. Between September 2020 and May 2021, 300 questionnaires were distributed among clinicians who refer patients for V/Q scans.ResultsOf the 162 clinicians who responded, 94% thought that there is >85% likelihood of PE or definitely PE present when a scan is reported as 'high probability of PE'; 87% interpreted 'low probability of PE' as <10% likelihood of PE or definitely no PE present. Overall, >70% of clinicians across all experience levels correctly interpreted the intended meaning of probability categories according to the Modified Prospective Investigation of Pulmonary Embolism Diagnosis (PIOPED) II criteria. Of the respondents, 77% agreed that clinically significant PE is ruled out by a normal scan. Further investigation for inconclusive findings, features of parenchymal lung disease and cardiomegaly were selected by 72%, 93% and 98% of clinicians, respectively.ConclusionThe findings of this study regarding high-probability scan results were in line with existing literature on lung scan report interpretation. However, our findings regarding low-probability scan results and negative V/Q scan specificity contrasted with the findings in these articles, suggesting that clinicians are now more familiar with lung scan interpretation guidelines. Experience level did not significantly affect interpretation of reports. Although most clinicians agreed that a negative scan excludes clinically significant PE, two-thirds of them would still subject the patient to further unnecessary investigations to exclude PE.Study synopsisWhat the study adds. Our findings regarding a low-probability ventilation/perfusion (V/Q) scan and the specificity of a negative V/Q scan contrasted with previous articles on lung scan interpretation, suggesting that clinicians are now more familiar with lung scan interpretation guidelines.Implications of the findings. Although most clinicians understood the negative predictive value of a V/Q scan, 20% would still investigate further with computed tomography pulmonary angiography or treat as confirmed pulmonary embolism. Education of clinicians about the negative predictive value of V/Q scans is important to avoid unnecessary radiation or anticoagulation.

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Abnormal Ventilation-Perfusion Scan Is Associated with Pulmonary Hypertension in Sickle Cell Adults.

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Abnormal Ventilation-Perfusion Scan Is Associated with Pulmonary Hypertension in Sickle Cell Adults.

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