Left-sided Chest Research Articles

SU‐E‐T‐583: Operated Left Breast and Chest Wall Radiotherapy: A Dosimetric Comparison Between 3DCRT,IMRT and VMAT

Purpose:To evaluate the comparative dosimetric efficacy between field and field 3DCRT(FnF), multiple field Intensity modulated radiotherapy (SnS IMRT) and, partial arc volumetric modulated arc therapy (VMAT) in case of post operative left side breast and chest wall irradiation.Methods:CT study set of fifteen post‐operative left breast and chest wall patient was tested for a treatment plan of 50Gy in 25 fraction using partial arc VMAT, SnSIMRT and tangential beam 3DCRT . 3DCRT FnF gantry angle was ranging for left medial tangential 290±170 and Lt lateral tangential l14°±120. For IMRT four fixed beam at gantry angle G1300 G1100 G3000 and G3300 was used, in case of insufficient dose another beam G1500 was added. In case of partial arc VMAT, lateral tangential arc G1300‐G1000 and medial tangential arc G2800‐G3100. Inverse optimization was opted to cover at least 95%PTV by 95% prescription dose (RxD) and a strong weightage on reduction of heart and lung dose. PTV coverage was evaluated for it's clinically acceptability depending on the tumor spatial location and its quadrant. Out of the three plans, any one was used for the actual patient treatment.Results:Dosimetric analysis done for breast PTV, left lung, heart and the opposite breast. PTV mean dose and maximum dose was 5129.8±214.8cGy, 4749.0±329.7cGy, 5024.6±73.4cGy and 5855.2±510.7cGy, 5340.7±146.1cGy, 5347.2±196.8cGy for FnF, VMAT and IMRT respectively. Ipsilateral lung volume receiving 20Gy and 5Gy was 23.6±9.5cGy and 32.7±10.3cGy for FnF, 18.6±8.7cGy and 38.8±15.2cGy for VMAT and 25.7±9.6cGy and 50.7±8.4cGy for IMRT respectively. Heart mean and 2cc dose was 867.9±456.7cGy and 5038.5±184.3cGy for FnF, 532.6±263cGy and 3632.1±990.6 for VMAT, 711±229.9cGy and 4421±463.7cGy for IMRT respectively. VMAT shows minimum contralateral breast dose 168±113.8cGy.Conclusion:VMAT shows a better tumor conformity, minimum heart, ipsilateral lung and opposite breast dose. Cardiac Toxicity and risk of contralateral breast cancer can be reduce using VMAT.

An Unusual Cause of Abdominal Pain in an Elderly Woman

Department of Radiodiagnosis and Imaging and Department of Gastroenterology, Postgraduate Institute of MedicalEducation and Research (PGIMER), Chandigarh, IndiaQuestion: A 70-year-old woman presentedwith acute epigastricpain radiating to theback associated withdifficulty in breathing.There were few epi-sodes of vomiting overthe last 2 days. Therewas no associated feveror jaundice. No similarepisodeshadbeenre-ported previously.On examination,there was mild pallor.No icterus was present.Abdominal examina-tion revealed mild tenderness in the epigastrium. Other findings on systemic examination were a dull note on the left side ofchest with added sounds on auscultation. Total (1.8 mg/dL) and direct bilirubin (1.2 mg/dL) were mildly elevated. Routinehematologic investigations were unremarkable except for mild anemia (10 g/dL). There was elevation of serum amylase(660 IU/L). A diagnosis of acute pancreatitis was considered. Abdominal ultrasonography failed to visualize the pancreas.However, there were no gallstones. Other workup for acute pancreatitis, including history of alcohol/ drug intake, lipidprofile, and serum calcium, was negative.Contrast-enhanced multidetector (MD)CT of the abdomen revealed bulky pancreas (Figure A, B, arrows) in an abnormalposition. Similarly, the collapsed stomach (Figure A, short arrows) and spleen (Figure A, B, arrow head) was found in anabnormal position. The superior mesenteric artery (Figure A, thin arrow) showed an abnormal orientation. There was milddilatation of the common bile duct (Figure B, long thin arrow) and the main pancreatic duct (Figure B, long thick arrow).What is your diagnosis?See the Gastroenterology web site (www.gastrojournal.org) for more information on submitting your favoriteimage to Clinical Challenges and Images in GI.

Left-sided foramen Morgagni hernia repair

Clinically evident hernia through the foramen of Morgagni is uncommon at any age. It is rarest of all the diaphragmatic hernias and incidence is 3–4 % of all the diaphragmatic hernias. About 90 % of Morgagni hernia occurs on the right, 8 % bilateral, and only 2 % are limited to the left. A 10-year-old child was referred to us with complaints of shortness of breath on exertion and repeated lower respiratory tract infections since age of 1 year. X-ray chest showed bowel loops in the left side of chest makes a diagnosis of diaphragmatic hernia. Computerized tomogram scan of the chest showed a large defect anteriorly retrosternally on left side herniating the small bowel, large bowel, and spleen in the left chest, and the left lung was hypoplastic. Surgical repair was done through the left thoracoabdominal approach and was repaired using polypropylene mesh. Postoperative recovery was uneventful. We are reporting this case because of a rare and unusual presentation in this patient. Foramen of Morgagni hernias are detected more often in women than in men and more often in obese people than in those of average or below-average weight. Our case was a young, underweight, male child.

Periorbital Subcutaneous Emphysema

Forty years old male was admitted with fever, cough and breathlessness since five days. Examination revealed signs of pleural effusion on left side of chest. Chest X-Ray showed left sided pleural effusion and left middle zone consolidation. Pleural fluid analysis suggested empyema. Patient was managed with intravenous antibiotics and left-sided inter-costal tube drainage. A day after thoracostomy patient developed swelling around eyes and thoracostomy site. Diffuse crepts were palpable around eyes, left side of chest and neck (Figure 1). CT confirmed the diagnosis of subcutaneous emphysema around eyes and chest wall. Swelling disappeared with conservative management within next three days (Figure 2). Periorbital emphysema is mostly due to disruption in the integrity of orbital boundaries because of trauma and subsequent orbital and sinus fractures. Less frequently follows dental surgeries. As a result of continuity of facial planes it can rarely occur as a result of spread from neck and chest subcutaneous tissue.

An unusual cause of pulmonary nodules in the emergency department.

We report a 51-year-old woman who presented to the emergency department with left-sided pleuritic chest pain 2 weeks after subtotal hysterectomy and bilateral salpingo-oophorectomy for a leiomyomatous uterus. Computed tomography scan of the chest revealed bilateral pulmonary nodules. Biopsy showed cytologically bland spindle cells without overt malignant features. Immunohistochemistry confirmed smooth muscle phenotype, in keeping with a clinicopathologic diagnosis of benign metastasizing leiomyoma (BML). BML does not frequently come to the attention of the emergency physician because it is rare and usually asymptomatic. When symptomatic, its clinical presentation depends on the site(s) of metastasis, number, and size of the smooth muscle tumors. Emergent presentations of BML are reviewed.

Cardiac allergy (Kounis Syndrome) and loss of motor neural sensaton during local anesthetic skin test

Methods 31 years old woman was admitted to our Immunology and Allergy outpatient clinic for drug allergy. Her history was; 4 weeks ago she took clindamycin capsule and 4th day she had generalized urticaria. She had dental abscess and dental decay, dentist had been given to her clindamycin and performed local anesthesia for filling her tooth. 5 minutes later she had piruritis in her body, dyspnea, numbness on her tongue and neck. And she had been admitted to the emergency room. We had to find local anesthetic because she has severe dental ache and cotton plug in her tooth. Prick test was performed with 1/1 dilution and after intradermal test was performed with 1/1000 dilution with lidocaine and articaine. They were negative and there wasn’t any systemic reaction. As soon as intradermal test was performed with 1/100 dilution she had nausea and severe left side chest, neck and back pain, dyspnea and left arm numbness. We administered anaphylaxis treatment (adrenalin 0.3 mg i.m., O2 5 lt/dk, rapid istonik saline serum infusion, feniramin maleat i.v, metylprednisolone 40 mg. i.v.). 5 minutes later urticarial hives were appeared her neck and face, stridor was heard. 0.3 mg adrenalin was injected about seven minutes later and five minutes later then she respiratory arrested. 0.3 mg adrenalin was administered intravenously and she recovered. But her chest pain progressed and left side of her body loosed of motor sensation. We analyzed her serum for cardiac enzymes three hours later and troponin was 2.9 ng/mL, CK-MB: 10.2 U/L. Myocardial infarction was diagnosed and she was transferred to the cardiology intensive care unit. Five hours later her enzymes elevated, 5.81 ng/mL,187 U/L, respectively.

Castleman's disease: A rare case report of unicentric type in a young female

Castleman's disease (CD), or angiofollicular lymph node hyperplasia, is a relatively rare disorder characterized by the benign proliferation of lymphoid tissue. Two clinical entities have been described: A unicentric presentation with the disease confined to a single anatomic lymph node and a multicentric presentation characterized by generalized lymphadenopathy and a more aggressive clinical course. In addition, three histopathological subtypes have been described: Hyaline-vascular (80–90%), plasma cell (10–20%), and a mixed variant. Preoperative diagnosis of CD is difficult, and the definitive result is based on postoperative pathological findings. The gold standard therapy for unicentric type is the complete surgical excision. Overall prognosis is good, particularly in the unicentric variety of disease. We report a case of 22-year-old female presenting with a large subpectoral mass on left side chest wall below clavicle. It was painless and gradually increasing since 6 months.

Feasibility study of deep inspiration breath-hold based volumetric modulated arc therapy for locally advanced left sided breast cancer patients.

The purpose of this study was to assess the feasibility of deep inspiration breath-hold (DIBH) based volumetric modulated arc therapy (VMAT) for locally advanced left sided breast cancer patients undergoing radical mastectomy. DIBH immobilizes the tumor bed providing dosimetric benefits over free breathing (FB). Ten left sided post mastectomy patients were immobilized in a supine position with both the arms lifted above the head on a hemi-body vaclock. Two thermoplastic masks were prepared for each patient, one for normal free breathing and a second made with breath-hold to maintain reproducibility. DIBH CT scans were performed in the prospective mode of the Varian real time position management (RPM) system. The planning target volume (PTV) included the left chest wall and supraclavicular nodes and PTV prescription dose was 5000cGy in 25 fractions. DIBH-3DCRT planning was performed with the single iso-centre technique using a 6MV photon beam and the field-in-field technique. VMAT plans for FB and DIBH contained two partial arcs (179o-300oCCW/CW). Dose volume histograms of PTV and OAR's were analyzed for DIBH-VMAT, FB-VMAT and DIBH-3DCRT. In DIBH mode daily orthogonal (0o and 90o) KV images were taken to determine the setup variability and weekly twice CBCT to verify gating threshold level reproducibility. DIBH-VMAT reduced the lung and heart dose compared to FB-VMAT, while maintaining similar PTV coverage. The mean heart V30Gy was 2.3% ±2.7, 5.1% ±3.2 and 3.3% ±7.2 and for left lung V20Gy was 18.57% ±2.9, 21.7% ±3.9 and 23.5% ±5.1 for DIBH-VMAT, FB-VMAT and DIBH-3DCRT respectively. DIBH-VMAT significantly reduced the heart and lung dose for left side chest wall patients compared to FB-VMAT. PTV conformity index, homogeneity index, ipsilateral lung dose and heart dose were better for DIBH-VMAT compared to DIBH-3DCRT. However, contralateral lung and breast volumes exposed to low doses were increased with DIBH-VMAT.

A Rare Case of Parathyroid Adenoma Presenting As Acute Pancreatitis

Acute pancreatitis as a first manifestation of primary hyperparathyroidism (PHPT) caused by parathyroid adenoma is exceptionally rare. A 24 year old female presented with pain in the left side of chest , upper abdomen and breathlessness. Laboratory studies showed elevated levels of calcium, amylase, lipase and parathormone. She was found to have associated gall stones, pancreatic and renal medullary calcifications and also left sided pleural effusion. Tc 99m scan showed increased activity of right inferior parathyroid gland. The patient underwent surgical resection of the functioning parathyroid adenoma. Although the actual causal relationship between hypercalcemia and pancreatitis has been a persistent topic of debate, detection of hypercalcemia may be a clue to diagnose PHPT due to parathyroid adenoma.

Left-sided approach video-assisted thymectomy for the treatment of thymic diseases.

BackgroundVideo-assisted thoracoscopic thymectomy was developed more than 10 years ago and has become a widely accepted surgical approach. Most published reports regarding this procedure have focused on the right-sided approach. Since left-sided approach chest surgery is the first choice in cases of right pleural adhesion, large left thymus tumors, and tumors in close contact with the great vessels of the left pericardium, we performed thoracoscopic thymectomy using the left-sided approach in 52 cases and summarize herein its technical feasibility, indications, and operative steps.MethodsBetween February 2004 and October 2014, 52 patients (24 men, 28 women, median age: 50 years, ranging from 18 to 85 years), underwent a video-assisted thoracoscopic thymectomy using the left-sided approach. All procedures were performed under general anesthesia with single-lung ventilation. Patients were placed in the right lateral decubitus position and three ports were made. The entire hemithorax was carefully examined, then mediastinal pleura was incised, and the thymus was bluntly dissected from the inferior polar extending to the superior polar. The thymic venous was clipped.ResultsAll procedures were carried out safely, including simple thymectomy (n = 43) and extended thymectomy (n = 9). There were no operative deaths or serious complications, and there were seven cases of conversion to open thoracotomy. The mean operative duration was 105.3 minutes (ranging from 80 to 140 minutes). The mean blood loss was 78.5 ml (ranging from 20 to 200 ml), and there was no blood transfusion required. All patients were well throughout the follow-up period.ConclusionsThe left-sided approach for video-assisted thoracoscopic thymectomy was a safe approach and could be an alternative procedure to the right-sided approach for the same procedure.

Thoracic Wall Metastasis from an Occult Thyroid Follicular Carcinoma

ABSTRACT Occult thyroid carcinoma presenting with clinically apparent metastasis is rare and is a diagnostic challenge. Here, we report a 67-year-old male who presented with a left side chest wall mass resembling a soft tissue sarcoma of 1 year duration. The mass showed rapid enlargement at the latter end of its course, following an initial asymptomatic period. Imaging studies showed a soft tissue mass eroding into several ribs. Wide local excision with primary reconstruction was performed. Histological studies and immune staining revealed metastasis from a follicular thyroid carcinoma. Total thyroidectomy followed, confirming the diagnosis. Postoperatively, radioisotope ablation (I131) was done. A suppression dose of thyroxin was continued with regular thyroglobulin assays. Painful bone metastasis responded well to analgesics, bisphosphonates and external beam radiotherapy. Follicular carcinoma comprises 10 to 15% of thyroid malignancies. Localized thyroid carcinoma has a very good prognosis, 10 years survival rates reducing by 50% with metastatic disease. Commonly, thyroid cancer presents as detectable thyroid nodules, 25% having metastasis. In contrast, metastatic manifestations are reported in less than 5% of occult thyroid cancers. How to cite this article Nawarathna NJ, Kumarasinghe NR, Chandrasekara D, Rathnayake P, Balasooriya BMRS, Senevirathne RJK. Thoracic Wall Metastasis from an Occult Thyroid Follicular Carcinoma. World J Endoc Surg 2014;6(3):119-122.

Thoracic Wall Metastasis from an Occult Thyroid Follicular Carcinoma

Occult thyroid carcinoma presenting with clinically apparent metastasis is rare and is a diagnostic challenge. Here we report a 68 year old male who presented with a left side chest wall mass of one year duration. The mass showed rapid enlargement at the latter end of its course, following an initial asymptomatic period. Imaging studies showed a soft tissue mass eroding into several ribs.Wide local excision with primary reconstruction was performed.Histological studies and immune staining revealed metastasis from a follicular thyroid carcinoma. Total thyroidectomy followed, confirming the diagnosis. Post-operatively radio isotope ablation (I131) was done.A suppression dose of thyroxin was continued with regular thyroglobulin assays. Painful bone responded well to analgesics, bisphosphonates and external beam radiotherapy. Follicular carcinoma comprise 10-15% of thyroid malignancies. Localized thyroid carcinoma has a very good prognosis, ten year survival rates reducing by 50% with metastatic disease. Commonly thyroid cancer presents as detectable thyroid nodules, 25% having metastasis. In contrast metastatic manifestations are reported in less than 5% of occult thyroid cancers.

Massive pulmonary tuberculosis cavity misdiagnosed as pneumothorax.

Massive pulmonary cavity is a rare and serious complication of chronic reactivation tuberculosis. A 38-year-old gentleman had a history of tuberculosis treatment noncompliance 2 years ago. His presenting symptoms were cough, fever, and left-sided pleuritic chest discomfort for 2 months. Chest radiographs showed extensive lung destruction associated with large thick-walled cavities and severe fibrosis of the residual lung. In the emergency department, this was initially misdiagnosed as a large pneumothorax and a chest tube was inserted. Subsequently, this was misdiagnosed again as bronchopleural fistula when brisk air leak was seen. The chest tube did not lead to any radiological or clinical improvement and was removed without incident. This case demonstrates that massive pulmonary cavity can easily be misdiagnosed and tube thoracostomy is unnecessary. Although this condition was previously reported to be associated with a high mortality rate, our patient survived as a result of accurate diagnosis and prompt antituberculosis therapy.

Two Systemic Lupus Erythematosus Patients With Severe Pleurisy: Similar Presentations, Different Causes

History of the present illness. A 25-year-old woman was diagnosed with systemic lupus erythematosus (SLE) 2 years prior to admission, after she presented with fever, malaise, lymphadenopathy, arthritis, myalgias, malar rash, and positive serologies for antinuclear antibody (ANA) and anti–double-stranded DNA (anti-dsDNA). Additional serology tests were negative for anti-Ro/SSA, anti-La/SSB, RNP, and Sm antibodies, as well as antiphospholipid antibodies (aPL). She was treated with intermittent courses of glucocorticoids (GC) for disease flares. Eight months before admission, she had a severe flare that manifested with high fevers, weight loss, delirium, spastic bladder, and non-nephrotic proteinuria. She was ultimately diagnosed with gray matter transverse myelitis of the conus medullaris and lupus nephritis. She was treated aggressively with pulse GC and intravenous (IV) cyclophosphamide (CYC), which led to resolution of all symptoms. After completion of a 6-month course of IV CYC, she was maintained on 20 mg of prednisone. One month prior to admission, she was admitted to another hospital with leftsided pleurisy, dyspnea, and high fever. A chest computed tomography (CT) scan excluded pulmonary embolism, but showed bilateral lung lower lobe consolidations with pleural effusions (left larger than right) and a small fluid collection adjacent to her spleen. Her blood cultures grew Salmonella. Her symptoms improved with cefepime and high-dose GC, and she was discharged home 2 weeks later on 60 mg of daily prednisone and oral levofloxacin for a total of 3 weeks of antibiotics. In addition, she was discharged on trimethoprim/sulfamethoxazole (TMP/SMX) 160/800 mg 3 times weekly for Pneumocystis jiroveci pneumonia (PCP) prophylaxis. One week before her current admission, she was started on 1,000 mg of mycophenolate mofetil (MMF) daily. She then presented to our hospital with acute left-sided pleuritic chest pain, dyspnea, and arthralgias. She did not have fever or cough.

Chest Pain as a presenting complaint in patients with acute myocardial infarction (AMI)

To study various characteristics of chest pain in acute myocardial infarction patients. A total of 331 patients of AMI admitted at Cardiology unit Nishtar Hospital Multan and Chaudhry Pervez Elahi Institute of Cardiology Multan, irrespective of the age and gender, were included in this study. The study duration was one year starting from June 2011 to June 2012. Non-probability purposive sampling technique was used in this descriptive study. Informed consent to participate in this study was taken. Data were entered and analyzed using SPSS-11. A total number of 331 patients with AMI were included in the study. Mean age was 54.99±11.25 years with minimum age 20 years and maximum age 90 years. It included 264(79.8%) male and 67(20.2%) female patients with male to female ratio of 3.9:1. Out of these 331 patients 308 (93.1%) patients reported chest pain as the presenting complaint. Remaining 23(6.9%) presented with clinical features other than chest pain. There were 127(38.4%) patients with pre-cordial chest pain, 115(34.7%) had retrosternal chest pain, 58(17.5%) were having epigastric pain. Severe chest pain was seen in 281(84.9%) patients while 26(7.9%) had only mild chest discomfort. Radiation of the pain to shoulder, neck and jaw was seen in 75 (22.7%) patients. In 42(12.7%) patients, pain radiated to both sides of chest. Another 55(16.6%) patients had pain radiation to chest, shoulder, upper arm and ulnar side of left forearm. Chest pain radiation to interscapular region along with both sides of chest was present in 10(3.0%) patients. In 11(3.3%) patients' pain radiated only to left side of chest. Pain persisting for >20 minutes was reported by 298 (90%) patients while only 10(3.1%) had pain persisting for <20 minutes. There is considerable overlap in chest pain of cardiac as well as non cardiac causes. However, vigilant evaluation of characteristics of chest pain in history taking may help to overcome this dilemma. Severe and prolonged precordial chest pain in a male patient between the age of 41-70 years, with pain radiation to left shoulder, neck and jaw is highly suggestive of AMI.

Allergic myocardial infarction

Allergic myocardial infarction

Different strokes for different folks

A 42-year-old woman, presented to our emergency room with chief complaints of acute onset of dyspnea, left-sided chest pain, and respiratory distress. On arrival, she had blood pressure of 90/50 mm Hg, respiratory rate of 40/min, and oxygen saturation of 95% breathing on 10 L oxygen. She was in significant respiratory distress. On examination, she was found to have diminished breath sounds on the left side of chest. Her chest radiograph showed left massive pleural effusion causing contralateral shift of mediastinum. Diagnostic pleural aspiration was done; results were consistent with hemothorax. Her multidetector computed tomography chest showed features of left-sided hemothorax (high attenuation) along with a 2 cm-enhancing lobulated opacity in the left lingular lobe, suggestive of pulmonary arteriovenous malformation (PAVM). She was successfully treated with surgical resection of PAVM.

Penetrating chest injury: A miraculous life salvage

An unusual penetrating chest injury was caused by high velocity road traffic accident. An 18-year-old had a four wheeler accident and was brought in emergency department with a 'bamboo' stick on the left side chest exiting through back. After the stabilization of vital parameters, an inter-costal tube drainage was done on the left side. <br>Except the minor brochopleural fistula which healed by 10 ^th day, his recovery was uneventful. The outcome was consistent with current aggressive management of penetrating chest injuries. Management of penetrating chest injury involving pulmonary trauma is based on three principles. One is stabilization of hemodynamics of patient with proper clinical evaluation. Second, a mere intercostal tube drainage sufficient for majority of the cases. Third, post-operative active as well as passive physiotherapy is necessary for speedy recovery.

An uncommon cause of pleural effusions in a dialysis patient

A 42-year-old woman presented in October, 2011, describing dyspnoea, a non-productive cough, left-sided pleuritic chest discomfort, and 10 kg weight loss over 2 months. She had been receiving maintenance haemodialysis via a right brachiocephalic arteriovenous fi stula (fi gure) for 2 years having reached end-stage renal failure (ESRF) due to glomerulonephritis. She had smoked heavily for many years. Clinical examination showed cachexia with a body-mass index of 17 kg/m2, fl uctuating pyrexia, and persistent tachycardia of 120 bpm. Blood pressure was 124/78 mm Hg. Heart sounds were normal and no murmurs were audible. There was a large left pleural eff usion. Blood tests showed a low haemoglobin of 84 g/L, a white cell count of 8∙0×109/L, and a high C-reactive protein (CRP) concentration of 249 mg/L. Serum albumin was low at 18 g/L. Chest radi ography confi rmed a large left pleural eff usion. ECG showed sinus tachycardia, and echocardiography showed an undilated left ventricle with moderate systolic impairment, mild left atrial dilatation, and moderate mitral regurgitation (MR). The right heart was normal. Of note, a year earlier the left atrium and ventricle had been normal with mild MR on echocardiography. CT showed no evidence of thromboembolism or malignancy. The pleural eff usion was drained and found to be an exudate. Despite serially negative microbiology, the patient was treated with broad-spectrum antibiotics, for presumed infection, with little improvement. 3 weeks into her hospital stay, the left pleural eff usion re-accumulated with a new right eff usion. At 6 weeks there was a marked deterioration with the patient developing worsening tachycardia and MR alongside a gallop rhythm. Blood pressure was maintained. Echocardiography (see webvideo 1 and 2) now showed a dilated left ventricle with severe systolic dysfunction, moderate MR, and new pulmonary hypertension (pul monary arterial pressure about 48 mm Hg). We noted that the patient’s fi stula seemed large for her body size, with a

Mobile radiofrequency does not interfere with antiarrhythmic drugs in patients with ischemic heart disease

Mobile radiofrequency does not interfere with antiarrhythmic drugs in patients with ischemic heart disease