Impact of COVID-19 Pandemic on Cardiovascular Testing in Asia

Background

The coronavirus disease-2019 (COVID-19) pandemic significantly affected management of cardiovascular disease around the world. The effect of the pandemic on volume of cardiovascular diagnostic procedures is not known.

Objectives

This study sought to evaluate the effects of the early phase of the COVID-19 pandemic on cardiovascular diagnostic procedures and safety practices in Asia.

Methods

The International Atomic Energy Agency conducted a worldwide survey to assess changes in cardiovascular procedure volume and safety practices caused by COVID-19. Testing volumes were reported for March 2020 and April 2020 and were compared to those from March 2019. Data from 180 centers across 33 Asian countries were grouped into 4 subregions for comparison.

Results

Procedure volumes decreased by 47% from March 2019 to March 2020, showing recovery from March 2020 to April 2020 in Eastern Asia, particularly in China. The majority of centers cancelled outpatient activities and increased time per study. Practice changes included implementing physical distancing and restricting visitors. Although COVID testing was not commonly performed, it was conducted in one-third of facilities in Eastern Asia. The most severe reductions in procedure volumes were observed in lower-income countries, where volumes decreased 81% from March 2019 to April 2020.

Conclusions

The COVID-19 pandemic in Asia caused significant reductions in cardiovascular diagnostic procedures, particularly in low-income countries. Further studies on effects of COVID-19 on cardiovascular outcomes and changes in care delivery are warranted.

The Role of 18F-FDG PET/CT in Evaluating the Efficacy of Radiofrequency Ablation in Metastatic and Primary Liver Tumors: Preliminary Results

Objectives:

The aim of the study was to investigate the role of ¹⁸fluorine-fluorodeoxyglucose (¹⁸F-FDG) positron emission tomography/computed tomography (PET/CT) for evaluating the efficacy of radiofrequency ablation (RFA) in primary and metastatic liver tumors compared with contrast-enhanced ultrasound examination (CEUS) and to find its place in overall staging and the follow-up diagnostic algorithm.

Methods:

PET/CT examinations were performed 2 months after RFA for 20 patients with a total of 34 liver lesions. CEUS was performed within 10 days after PET/CT, and the results were compared. Seven patients were staged with PET/CT and the others with a contrast-enhanced CT.

Results:

A total of 48 ¹⁸F-FDG PET/CT examinations were performed. We observed complete response in 8 patients (40%), 2 patients (10%) had stable disease, one (5%) had partial response, and 9 patients (45%) had progression (including 2 cases with extrahepatic involvement). Compared with CEUS, there was a mismatch in 3 cases. Five patients underwent additional RFA for 7 lesions.

Conclusion:

According to our preliminary data, PET/CT may be a valuable method, with comparable or eventually even better sensitivity than CEUS, for early evaluation of the efficacy of RFA for the treatment of metastatic and primary liver lesions and planning of future treatment. PET/CT might be recommended as a staging method before undergoing RFA of liver lesions for determining the local extent of the disease in the liver in combination with CEUS with an advantage in visualization of extrahepatic involvement. However, more patients need to be investigated in order to demonstrate and confirm the obtained results with certainty.

Giant-cell arteritis without cranial manifestations presenting as fever of unknown origin: a diagnostic value of 18F-FDG PET/CT

We present a case of 68-year-old female with four months history of fever, fatigue, and weight loss. She was classified as case of fever of unknown origin. The physical examination was normal, the laboratory tests showed anemia, elevation of C-reactive protein, erythrocyte sedimentation rate and fibrinogen. The diagnosis was unclear and 18F-FDG PET/CT was performed. Images showed high glucose uptake in the wall of the ascending and descending aorta, in the walls of the subclavian arteries, abdominal aorta and proximal part of both iliac arteries. The diagnosis of GCA appeared most likely and steroid treatment was initiated. After the therapy, clinical signs disappeared, laboratory parameters normalized and follow-up 18F-FDG PET/CT demonstrated lack of glucose uptake in the vessels' walls. We observed remission. 18F-FDG PET/CT offers a possibility for early detection of inflammation in the vessels and could be used for assessment of therapy response. Performing this nuclear imaging method in a clinical setting, where there is suspicion of large-vessel vasculitis is of great benefit for the final outcome.

Is there an advantage in performing a combined examination: diuretic renal scintigraphy and low dose computed tomography compared to the separate use of these methods in urolithiasis

Ultrasonography (US), radiography of the kidneys, ureters and bladder (RKUB), intravenous urography (IVU) and especially non-enchanced CT are well established diagnostic modalities in screening patients with urolithiasis, while not always fully diagnostic especially when obstructive uropathy or calculous pyelonephritis are present . Diuretic renal scintigraphy (DRS) can determine obstruction, may differentiate between complete or partial, acute or chronic obstruction, but can not specify the cause and often the location of obstruction. The imaging protocol, including DRS with technetium-99m-mercaptylacetyltriglycine ((99m)Tc-MAG3) and single photon emission tomography/computed tomography (SPET/CT) of the kidneys, ureters, and urinary bladder allows for both functional and morphological information, visualization of renal stones and possible renal complications. The main advantages and limitations of this combined examination are discussed and the test is compared to the separate use of DRS and low dose of CT, in urolithiasis.

[Application of scintigraphy for preoperative localization of testis in a patient with Morris syndrome]

The paper presents the successful application for the first time in Bulgaria of the new hybrid imaging technique--tomographic scintigraphy combined with computed tomography--SPECT/CT for visualization and localization of the testis by injection of 99mTc-pertechnetate with activity of 185 MBq. The study was performed on a girl with 46XY karyotype and lack of sensitivity to androgens, known in gynecology as "testicular feminization syndrome" or Morris syndrome. Until now testicular scintigraphy has been used mainly as a very accurate technique for rapid diagnosis in cases of testicular torsion, acute epididymitis or after trauma. We found no published data in the literature concerning the use of hybrid SPECT-CT for testicular localization in Morris syndrome. Our experience is this case allows us to recommend SPECT/CT as a fast, accurate, noninvasive method with potential to be used for localization, visualization and perfusion of testicular tissue before performing surgery in cases of Morris syndrome.

Recently revised diagnostic reference levels in nuclear medicine in Bulgaria and in Finland

An EU twinning project entitled 'Strengthening of administrative structures for radiation protection and safe use of ionising radiation in diagnostics and therapy' was established between Bulgaria and Finland, lasting from June 2008 to May 2009. One component of the project was to improve the optimisation of patient protection in nuclear medicine (NM) through revising diagnostic reference levels (DRLs). The revised DRLs are based on national surveys on the numbers of NM procedures and activities given to the patients in different procedures. The survey in Bulgaria was carried out in 2008 and that in Finland in 2007. National DRLs were established for the most frequent and dose-relevant examinations. The proposed DRLs in both countries are in good agreement with other national recommendations in Europe.

Neostigmine, but not Metoclopramide, Abolishes Ethosuximide-Induced Functional Gastrointestinal Disturbances

Ethosuximide is a drug used for the treatment of absence seizures. Its prolonged application leads to gastrointestinal (GI) disturbances. The purpose of the present study was to determine the severity and nature of the disturbances, as well as the influence exerted upon them by neostigmine methylsulfate and metoclopramide. The drug-induced alterations, occurring in the rat GI tract, were registered by X-ray contrast examination. In vitro experiments were carried out on isolated GI smooth muscle (SM) preparations. The latter revealed that the drug hyperpolarized the SM tissues and inhibited their contractile activity. X-rays of ethosuximide-treated rats showed GI hypotonia, disturbed peristalsis and decreased evacuation activity. The inhibition of the GI functions was associated with hyperpolarization of SM and a reduction in Ca(2+) influx, ensuring spontaneous contractile activity. The application of neostigmine methylsulfate significantly removed ethosuximide-induced functional GI disturbances in rats treated for 15 days with ethosuximide.

Increased redistribution of 99mTc-MIBI under the action of nitrate administration--a good tool for detection of myocardial vitality in patients with severe CAD

BACKGROUND

The purpose of the study was to investigate and assess patients with severe, coronarographically documented coronary artery disease (CAD), previous myocardial infarction and left ventricular dysfunction, using radionuclide method for myocardial perfusion scintigraphy with 99mTc-MIBI and nitrate administration for detection of viable myocardium.

MATERIAL AND METHODS

We investigated 56 patients (37 male, 19 female, mean age 58 +/- 8 years) with CAD and previous myocardial infarction, mean EF 38% +/- 12; divided into 2 groups: Group I--28 patients, investigated at rest, i.v. injected 370 MBq (99m)Tc-MIBI, scintigraphy performed at 30 min and 4th hour; Group II--28 patients, investigated at rest, i.v. injected 37 MBq (99m)Tc-MIBI, scintigraphy performed at 30 min, immediately after that administration of 20 mg Isosorbitdinitrate per os and delayed scintigraphy at 2nd and 4th hour. Myocardial SPECT imaging using Siemens Diacam with semiquantitative analysis of acquisition data was performed.

RESULTS

The results established significant but low tracer redistribution in Gr. I, mean redistribution 17.5% +/- 5.6. After nitrate administration (Gr. II) we detected increased tracer redistribution, mean 30.4% +/- 7.8. The redistribution is higher at the 4th hour, compared to that obtained at 2nd hour after injection. Comparison of the results before and after PTCA showed sensitivity and specificity 93% and 67% respectively.

CONCLUSION

It is concluded that after nitrate administration (99m)Tc-MIBI redistribution enhances noticeably and may play a feasible role in detection of viable myocardium in patients with severe CAD.

Roentgenographic study of ethosuximide-induced functional changes in rat gastrointestinal tract and their modulation by Nivalin in a chronic experiment

Ethosuximide, a typical antiabsence drug, causes gastrointestinal complaints in the drug-treated patients. In the present study we investigated in an experimental model the functional disturbances occurring in rat gastrointestinal tract (GIT) after a 100-day chronic administration of ethosuximide. Contrast radiographic study of rat gastrointestinal tract was used. The mechanical activity of GIT smooth muscle (SM) preparations was measured using an in vitro isometric technique. The 100-day ethosuximide treatment induced atonia, disturbed peristalsis, and lead to a delay of the contrast material evacuation from the gastrointestinal tract combined with a reduction of the acetylcholine effect on the contractions of GIT smooth muscles in ethosuximide-treated rats. Nivalin cannot eliminate the ethosuximide-induced disturbances in the gastrointestinal tract after a 100-day administration of ethosuximide to the rats. It is thus assumed that Nivalin is not capable of compensating the inhibiting effect of ethosuximide. The authors assume that desensitization of acetylcholine receptors may occur and this reduces the effect of Nivalin action.

Effects of ethosuximide on the cerebral vasculature and hemodynamics of rats

The development of epileptogenic activity has been proven to be closely related to changes in cerebral blood flow. This study was designed to examine the effects of ethosuximide, a widely used anticonvulsant drug, on cerebral hemodynamics. White Wistar rats were treated (p.o.) with 100 mg/kg b.w. ethosuximide. Three hours after administration, changes in cerebral blood flow due to vasodilation were recorded by means of angiography. Using the single sucrose gap method it was found that ethosuximide caused hyperpolarization of smooth muscle sample from rat internal carotid artery by 5.4 +/- 1.6 mV. The hyperpolarization was related to relaxation of smooth muscle tissue of vessels, which was recorded isometrically. Ethosuximide significantly depressed vascular reactions to the vasoconstrictive agents noradrenaline and serotonin. Ethosuximide-induced reaction was not significantly influenced by the Ca2+ antagonist verapamil, but was reduced by caffeine (10(-4) M) and apamine (5.10(-6) M), the latter being a blocker of Ca2+ -dependent K+ channels. The experimental data strongly suggest that changes in bioelectric and contractile activity of arterial smooth muscle samples are a result of Ca2+ -dependent K+ efflux, provoked by calcium which has been derived from intracellular Ca2+ store. These results show that ethosuximide-induced changes in cerebral blood flow are caused by reduced reactivity of smooth muscle tissue and vascular dilatation.

The use of 99Tcm-EC for captopril test in patients with hypertension

The purpose of this study was to evaluate the new renal radiopharmaceutical 99Tcm-N,N-ethylene-L-dicysteine (99Tcm-EC) in patients with hypertension, applying the captopril test. Twelve controls, 45 patients with essential hypertension (EH) and 8 with renovascular hypertension (RVH) were investigated. The captopril test was assessed using different parameters of kidney function. In the controls they were: Tmax 3.33 min, T1/2 9.27 min, retention index 0.30. In the patients with EH they were: before captopril Tmax 4.87 min, T1/2 16.35 min, retention index 0.41; after captopril Tmax 4.19 min, T1/2 13.78 min, retention index 0.40. In the patients with RVH they were: before captopril Tmax 6.50 min, T1/2 not reached, retention index 0.70; after captopril Tmax 9.33 min, T1/2 not reached, retention index 0.90. Our results indicate that this new renal radiopharmaceutical can be reliably used for carrying out the captopril test in patients with hypertension, in order to screen those with RVH.

[A pharmacological analysis of the mechanism of action of ethosuximide]

Ethosuximide is one of the means of treatment of minor epilepsy but hardly any data on its mechanism of action are available in the literature. Anticonvulsant agents are known to bring about changes in the functions and in the interaction between some of the mediator systems within the central nervous system. An assessment of the status of neuromediator systems can be made on the basis of the response of isolated smooth muscle strips to the action of agonists and antagonists of various receptors. It was found by the pharmacological analysis of isolated strips from the rat stomach (antrum and corpus strips), the seminal duct and the cervical vein that ethosuximide induces a reduction in the physical contractile activity and the tone of smooth muscle preparations. Smooth muscle relaxation caused by ethosuximide is not blocked by different receptor inhibitors such as dihydroergotamine, propranolol, atropine, chlorpromazine, haloperidod and indomethacin. Ethosuximide causes a significant reduction in the physical contraction of smooth muscles produced by potassium chloride depolarization, with a stronger impact on the subsequent tonic contraction caused by calcium ions. A reduction in the potassium content of the solution has no effect on the nature of the action of ethosutimide. It is thus assumed that the probable mechanism of action of ethosuximide consists in lowering calcium transport since the inhibitors of calcium transport sodium nitroprusside and verapamil intensify the blocking effect of ethosuximide on smooth muscle contractile activity.

[Thrombokinetic study of patients with idiopathic thrombocytopenic purpura]

The kinetics of 111In-oxine-labeled platelets was studied in 37 patients with idiopathic thrombocytopenic purpura and in 12 control subjects using gamma-chamber. A comparison was made of the parameters of the kinetics, survival and sequestration type of platelets, as well as their recovery and exchange. In less severe processes the splenic type, while in more severe disease--the hepatic type of sequestration prevailed.

On octanoic acid-induced hyperventilation--implications for hepatic encephalopathy and Reye's syndrome

Medium chain fatty acid sodium octanoate was infused into rabbits as a 0.2 M solution over 4 h resulting in blood and brain octanoate levels of 200-800 mumol/l. The infused animals developed marked hyperventilation leading to a mild respiratory alkalosis. Additionally, octanoate infusion brought about hyperammonemia and hyperlactate acidemia. Another group of rabbits also infused with octanoate but pretreated with indomethacin (10 mg/kg b.wt.) developed neither hyperventilation nor hyperammonemia. Therefore, the conclusion made was that octanoate causes the above mentioned disorders through stimulation of prostaglandin synthesis and especially the PGE2 synthesis. Patients with hepatic encephalopathy and Reye's syndrome have elevated levels of plasma octanoate. The present study suggests that octanoate might be the cause for both the hyperventilation and hyperammonemia observed in patients with hepatic encephalopathy and Reye's syndrome.

[Thrombocyte kinetics in patients with thrombocytopenia]

Investigation of the kinetics of blood platelets is of paramount importance in cases where it is necessary to differentiate the cause of thrombocytopenia in patients: reduction of the output, changes in organ distribution or increase of sequestration of blood platelets. Using the method of labeling own blood platelets and a gamma-chamber, the kinetics of blood platelets (organ distribution, recovery and survival) was studied and computed in 40 patients with hypoplastic anemia, hypersplenism and thrombocytopenic purpura. A complex of the parameters characterizing the given disease has been defined.

[Late complications in patients having undergone a gastric resection]

A total of 37 patients who had undergone partial gastrectomy for duodenal or gastric ulcers, were investigated. The postoperative periods ranged from 5 to 28 years. All the patients were subjected to comprehensive clinical and neurologic examinations. The content of vitamin B12 and folic acid in the blood serum was studied by radioimmunoassay in 29 gastrectomized patients, hematological parameters (hemoglobin, serum iron, red blood cell morphology, proteinogram) were estimated in 19 patients. The mean content of vitamin B12 in the blood serum of patients was lower than in normal subjects. The mean level of folic acid in the blood of patients was also lower than in the control, however, this difference was insignificant. Nine patients had subnormal content of vitamin B12, eight of them showed manifest neurologic complications, such as myelopathy and polyneuropathy. Only 3 patients had subnormal content of folic acid in the blood serum. Weakly pronounced anemic syndrome was detected only in 2 out of 19 patients. The role of vitamin B12 deficiency in the development of neurologic symptoms has been considered.