Citation Nr: 21020967 Decision Date: 04/08/21 Archive Date: 04/08/21 DOCKET NO. 10-46 902 DATE: April 8, 2021 ORDER Service connection for a cardiovascular (CV) disorder is denied. Service connection for residuals of a stroke is denied. FINDINGS OF FACT 1. The Veteran served on active duty from October 1968 to October 1970 and had no foreign service. 2. A current CV disorder, diagnosed as atrioventricular node reentry tachyarrhythmia, was not shown in service, was not shown to a compensable degree within one year of service, was not continuous since service, is not etiologically related to service, was not shown to be caused, related to, or worsened in severity by a service-connected disability, and is not related to herbicide exposure. 3. Current residuals of a stroke were not shown in service, were not shown to a compensable degree within one year of service, were not continuous since service, are not causally or etiologically related to service, were not caused or worsened in severity by a service-connected disability, and are not related to herbicide exposure. CONCLUSIONS OF LAW 1. A CV disorder was not incurred in service, is not presumed to have been incurred in service, was not proximately due to, aggravated by, or the result of a service-connected disability, or related to herbicide exposure. 38 U.S.C. §§ 1110, 1112, 5103(a), 5103A, 5107 (2012); 38 C.F.R. §§ 3.159, 3.303, 3.307, 3.309, 3.310 (2020). 2. The residuals of a stroke were not incurred in service, are not presumed to have been incurred in service, were not proximately due to, aggravated by, or the result of a service-connected disability, or related to herbicide exposure. 38 U.S.C. §§ 1110, 1112, 5103(a), 5103A, 5107 (2012); 38 C.F.R. §§ 3.159, 3.303, 3.307, 3.309, 3.310 (2020). REASONS AND BASES FOR FINDINGS AND CONCLUSIONS This appeal has been the subject of nine various prior decisions and remand orders, as well as three prior joint motions for remand (JMR) and a remand decision of the Veterans Claims Court. The November 2014 JMR instructed the Board to consider whether the claimed CV (heart) disorder also included a cerebrovascular disorder (stroke). Thus, these two distinct claims for benefits will be discussed separately. In April 2020, the Court Clerk granted another JMR and remanded the CV disorder and stroke residuals to the Board for action consistent with the terms of the JMR. It was agreed that a May 2019 Board decision should remain undisturbed to the extent that it denied service connection for a CV disorder and residuals of a stroke on a direct basis. As to those claims, therefore, the only issues presently before the Board for review are whether service connection is warranted on a secondary or a presumptive basis. The Board was ordered to provide an adequate statement of reasons and bases addressing two issues. The first issue was whether VA examinations of the CV disorder and stroke residuals performed from October to December 2017 substantially complied with the Board’s August 2017 remand directives that new examinations be conducted by different examiners than had evaluated him in September 2015, and preferably by, respectively, a cardiologist and a neurologist. The second issue was whether a December 2017 VA examiner’s opinion on which the Board had relied in the May 2019 decision contradicted its own findings as to the nature and etiology of the CV disorder and was thus inadequate. To that end, the Board finds that the RO did not violate the Board’s August 2017 remand directives. Notably, only substantial compliance with a prior remand order is required. See D’Aries v. Peake, 22 Vet. App. 97 (2008). As directed, the RO associated additional VA treatment records with the claims file, afforded the Veteran new VA examinations, and obtained further medical opinions as to the nature and etiology of his CV disorder and residuals of a stroke. The RO then issued a supplemental statement of the case (SSOC) readjudicating, and again denying, service connection for those disorders. Accordingly, the RO returned the case to the Board for review. Based on the foregoing actions, there has been substantial compliance with the remand directives in the Board’s August 2017 decision. In particular, the record shows that, as directed, the RO provided appropriate VA examinations aimed at determining the nature and etiology of the claimed disorders. To do so, the examinations were to be performed by different examiners than had previously assessed those disorders. And the RO fully complied with this remand directive. Nevertheless, the Veteran contends that the RO failed to comply with the August 2017 remand directives when it assigned non-specialists to perform the new VA examination of his CV disorder and stroke residuals. Those examinations were performed by a Physician Assistant, a Certified Nurse Practitioner specializing in family medicine, and a Medical Doctor with no stated specialty, none of whom was involved in his prior VA examinations. He contends that compliance with the remand directives requires more, however, because the Board also stated that it would be preferable if the CV disorder were assessed by a cardiologist and if the stroke were assessed by a neurologist. To the contrary, provided that a VA examination report contains adequate reasons and bases for the opinions offered, VA has satisfied its duty to assist a veteran to obtain an examination performed by a person qualified through education, training, or experience to offer such opinions. That is so regardless of whether that examiner is a specialist in the relevant field, or whether the examiner is a doctor, a nurse practitioner, or a physician assistant. Thus, the Veteran’s sole assertion that the RO chose medical professionals other than the suggested specialists to conduct the requisite new examinations is insufficient to show a lack of substantial compliance with the August 2017 remand directives. Rather, unless a veteran specifically demonstrates that a VA examiner lacks the requisite medical competence to offer a certain opinion, it is to be presumed that VA has chosen a person qualified to provide a medical opinion in a particular case. Parks v. Shinseki, 716 F.3d 581, 585 (Fed. Cir. 2013). Here, the Veteran has not made any specific objected to any of the actual examiners’ competence to perform the requisite evaluations, to properly diagnose his disorders, or to adequately opine as to the nature and etiology of those disorders, except to broadly argue that they are not specialist. This alone is insufficient. In the absence of any such argument or supporting evidence, the VA examiners’ competence to provide the requested opinions remains unrebutted and is presumed and relied on to decide the merits of this appeal. See Sickels v. Shinseki, 643 F.3d 1362, 1366 (Fed. Cir. 2011). As a final procedural matter, in September 2020, the Board remanded the Veteran’s claim of service connection for a hiatal hernia to the RO for further development. As that claim presently remains before the RO, the issue of a hiatal hernia is not before the Board at this time. Turning to the merits of the appeals, the Veteran contends that service connection for a CV disorder and residuals of a stroke is warranted as secondary to his service-connected duodenal ulcer, his only service-connected disability rated at 10 percent disabling. In addition, he asserts that service connection is warranted on a presumptive basis as, in his view, they are chronic disorders. Finally, he suggests that service connection for these disorders is warranted on a presumptive or direct basis as disorders purportedly linked to exposure to herbicide agents in service. The analysis of whether the Veteran is entitled to secondary service connection for either claimed disorders varies, so they will be discussed separately; however, because the analysis of whether either condition qualifies as a chronic disease presumptively linked to service is similar, they will be analyzed together. Likewise, whether either condition may be service connected on the basis of alleged exposure to herbicide agents will be analyzed together. Turning to the relevant laws and regulations, service connection may be granted on a secondary basis for a disability which is aggravated by, proximately due to, or the result of a service-connected disease or injury under 38 C.F.R. § 3.310. Allen v. Brown, 7 Vet. App. 439 (1995). In order to establish service connection on a secondary basis, there must be: (1) evidence of a current disability; (2) evidence of a service-connected disability; and (3) medical evidence establishing a link between the service-connected disability and the current disability. See Wallin v. West, 11 Vet. App. 509, 512 (1998). Service connection may be granted on a presumptive basis for diseases listed in 38 C.F.R. § 3.309 under the following circumstances: (1) where a chronic disease or injury is shown in service and subsequent manifestations of the same disease or injury are shown at a later date, unless clearly attributable to an intercurrent cause; (2) where there is continuity of symptomatology since service; or (3) by showing that the disorder manifested to a degree of 10 percent or more within one year from the date of separation from service. See 38 C.F.R. § 3.307. Service connection may also be granted on a presumptive basis for diseases associated with herbicide agent exposure under 38 C.F.R. § 3.309 if a veteran: (1) served in the Republic of Vietnam between January 1962 and May 1975; (2) served between April 1968 and August 1971 in or near the Korean Demilitarized Zone; (3) served near the base perimeter of certain Thailand Air Force Bases during the Vietnam War era; or (4) regularly and repeatedly operated, maintained, or served aboard aircraft known to have been used to spray herbicide agents during the Vietnam War era. 38 C.F.R. § 3.307(a)(6). Notwithstanding the foregoing provisions regarding presumptive service connection, a veteran is not precluded from establishing service connection with proof of direct causation. Combee v. Brown, 34 F.3d 1039 (Fed. Cir. 1994).   Secondary Service Connection for a CV Disorder The Veteran claims secondary service connection for a CV disorder is warranted as it is related to a service-connected duodenal ulcer. Specifically, he contends that his peptic ulcer disease stemming from that ulcer, a helicobacter pylori bacterium associated with such ulcers, or his use since about 2001 of proton pump inhibitors (PPIs) prescribed to treat that ulcer may have caused or aggravated beyond its natural progression a CV disorder. Turning to the medical evidence, the first element of secondary service connection – a current disability – is met. The first recorded diagnosis of a CV disorder was in June 2014 when he was diagnosed with supraventricular tachycardia. Thus, a current CV disorder is shown. The second element of secondary service connection – a current service-connected disability – also is met. Specifically, the Veteran has been service connected for a duodenal ulcer at 10 percent disabling since October 1970. Thus, the second element of secondary service connection has been met. As to the third element – a link between the service-connected duodenal ulcer and the current tachyarrhythmia – the medical evidence weighs against the appeal. To this end, the Veteran has been treated for arrhythmias disorder since it was first diagnosed and has been afforded two in-person VA examinations, the first of which was also subject to several addendum opinions, to assess the nature and etiology of his disorder, including any link to his ulcer. Yet, the record is devoid of any VA medical opinion that the requisite evidence of a nexus exists to show that the ulcer or the PPIs used to treat it either caused or aggravated the extent of the arrhythmia. One of the Court remands returned the appeal to the Board questioning the Board’s reliance on a December 2017 VA examiner’s opinion that the CV disorder had resolved and, thus, no nexus could be shown. Even without relying on the December 2017 opinion, adequate medical evidence addressing the nexus element of that claim is of record. To that end, the October 2017 VA examiner’s opinion as to the etiology of the Veteran’s CV disorder is highly probative as it is based on an accurate medical history and provides an explanation containing clear conclusions and supporting data. The opinion was based on a review of the medical records, medical literature, and the examiner’s clinical experience, including an in-person examination. During the examination, the Veteran reported having had intermittent CV issues for years, beginning with sporadic instances of rapid heartbeat occurring prior to his separation from service. He described these symptoms as feeling as if his heart was racing or that it would suddenly flip flop, beating so slowly that he would almost pass out. He reported that, after he left service, he began having episodes in which he could feel his heartbeat as if slowly booming in his chest, followed by a sensation as if he was going to lose consciousness. He also told the examiner that, over the last couple of years, these episodes had grown worse and more frequent. Based on the medical evidence, however, the October 2017 VA examiner concluded that the Veteran’s arrhythmia was unrelated to service. The examiner reasoned that that the results of a November 1996 echocardiogram were normal. Though remarking that the Veteran was a poor historian, the examiner also pointed out that the earliest diagnosis of a CV disorder was of the current supraventricular tachycardia, reportedly diagnosed in 2009. The examiner similarly pointed to numerous instances as early as February 2010 and as late as October 2017 in which the Veteran had complained of chest pains, irregular heartbeat, and palpitations only for subsequent echocardiograms and assessments to be normal. Upon physical examination, the examiner found that the Veteran’s heart rate, rhythm, and sounds were all normal. Based on this medical evidence, the examiner opined that the tachyarrhythmia was unrelated to service on a direct basis, particularly in light of the absence of documentation that the Veteran was having similar problems while in service or within one year of separation. As to the claim of secondary service connection, the October 2017 VA examiner opined that it was less likely than not that an arrhythmia was caused or aggravated by a service-connected duodenal ulcer or the medications used to treat it. The examiner reasoned that a review of the medical literature found no medical evidence suggesting that an arrhythmia could be caused or aggravated by a duodenal ulcer. Indeed, the October 2017 VA examiner noted and agreed with the prior September 2015 VA examination findings that the medical evidence did not support a finding that a duodenal ulcer could cause or aggravate tachyarrhythmias. To that end, the September 2015 VA examiner reviewed, summarized, and pointed out the lack of support for that contention in each of the medical publications the Veteran had submitted into evidence, including those submissions regarding the possible long-term effects of using PPIs to treat such ulcers. As the September 2015 VA examiner explained, however, such an arrhythmia developed in just 1 percent of those takings PPIs and there was no medical evidence suggesting that the Veteran fell into this category. The examiner also emphasized that other risk factors for developing tachyarrhythmias, such as the Veteran’s history of caffeine use and smoking, were more likely to have caused the disorder. Both the September 2015 and the October 2017 medical opinions weigh against the claim. Moreover, there is no contrary medical opinion of record. Though the Veteran claims to have sought medical treatment concerning a CV disorder from private medical practitioners at various times, no evidence of such treatment is of record. VA sent multiple requests to each of the three facilities he identified. The facilities responded either that no record exists of his having been a patient, or that no records of his treatment are available, as those records had been purged after seven years of inactivity. Consequently, the RO found that any further attempts to obtain those private records would be futile. In support of the claim, the Veteran submitted evidence suggesting a link between peptic ulcer disease and tachycardia. He also submitted a medical article discussing increased incidents of arrhythmias noted among patients who use PPIs to treat gastrointestinal symptomatology, including ulcers. He has also provided lay statements that he was prescribed PPIs by VA clinicians for at least 18 years, and that prior to that prescription, he took over-the-counter PPIs to treat his symptoms. A medical article or treatise can provide important support, when combined with a medical professional’s opinion, if that secondary evidence discusses generic relationships with a degree of certainty. Mattern v. West, 12 Vet. App. 222, 228 (1999); see also Sacks v. West, 11 Vet. App. 314 (1998). In this case, however, the Veteran has not provided such an opinion from a medical professional in support of his claim, and the medical literature he submitted can be considered no more than speculative in nature regarding the etiology of his tachyarrhythmia. See Obert v. Brown, 5 Vet. App. 30, 33 (1993); Tirpak v. Derwinski, 2 Vet. App. 609, 611 (1992). To the contrary, the September 2015 VA examination discussed the articles and found that they were not probative to the Veteran’s situation. Here, the only competent medical opinions of record weigh against finding that a link exists between the Veteran’s arrhythmia and a service-connected duodenal ulcer. Specifically, in the October 2017 VA examiner’s report addressing that claim, the examiner confirmed that the Veteran was diagnosed with a supraventricular arrhythmia. Nevertheless, the examiner opined that it was less likely than not the CV disorder was caused or aggravated by a service-connected duodenal ulcer or the PPIs with which it is treated. While the Veteran believes that his supraventricular arrhythmia is proximately due to, the result of, or aggravated beyond its natural progression by a service-connected duodenal ulcer or medications used to treat it, as a lay person, he is not competent to provide an adequate nexus opinion on these issues. The issues are medically complex, requiring a professional level of familiarity with medical pathology and the requisite knowledge and skills to interpret related medical diagnostic tests. The issues are thus beyond his competence as a lay person, as evidence is lacking that he has the medical qualifications and training to make such determinations. Consequently, more probative weight is afforded to the October 2017 and September 2015 VA examiners’ opinions, which weigh heavily against this claim of secondary service connection. Accordingly, the medical evidence does not support service connection for a CV disorder as secondary to the Veteran’s service-connected duodenal ulcer. Secondary Service Connection for Residuals of a Stroke This issue was never directly raised by the Veteran but rather was raised as part of a JMR that found a relationship between a cardiovascular disorder (arrhythmia) and a cerebrovascular disorder (stroke). Turning to the medical evidence, the first element of secondary service connection – a current disability – is met. In March 2010, the Veteran reported to VA clinicians that he had experienced symptoms indicative of a possible stroke in February 2010 after taking prescribed sildenafil medication and having low blood pressure. He was diagnosed with a small remote infarction in the anterior medial occipital lobe on the right side, which was later assessed as a history of a right occipital stroke. Though the stroke residuals were found to be stable on medication and many of his symptoms resolved by May 2010, residual visual deficits were diagnosed as left eye superior quadrantanopia. That residual condition continued to manifest symptoms such as ocular migraines, zigzag lines blocking his field of vision, light sensitivity, and other vision changes. VA clinicians performed diagnostic tests, including an MRI of the brain, to evaluate whether the symptoms were attributable to the earlier stroke. Age-related changes of the brain parenchyma with a stroke in the form of a remote infarction in the anterior medial occipital lobe of the right side was determined to be the likely explanation for those symptoms, as no other findings would explain his visual deficits. The Veteran also reported during a November 2017 VA examination that he sometimes experienced episodes of forgetfulness when driving. Accordingly, the evidence supports a current disorder. To the extent that the appeal is based on secondary service connection between stroke residuals and a CV disorder, as noted a current diagnosis of residuals of a stroke have been shown. Therefore, the first element of secondary service connection has been met. However, to the extent that secondary service connection is based on tachyarrhythmia, the second element of secondary service connection is not met as the Board has denied the appeal for a CV disorder. As such, any claimed secondary link between the residuals of a stroke and supraventricular arrhythmia is not supported by the medical evidence as a CV disorder is not service-connected. To the extent that the appeal is based on secondary service connection between stroke residuals and a duodenal ulcer, again the first element is met as the Veteran has been diagnosed with residuals of a stroke. As to the second element of secondary service connection, the Veteran has been service-connected for a duodenal ulcer for many years. Therefore, the second element of secondary service connection is met. Turning to the third element of secondary service connection – a link between the service-connected duodenal ulcer and the stroke residuals – the requisite nexus is not supported by the medical evidence. In particular, the Veteran contends that his duodenal ulcer may be linked to his stroke in two respects. First, he claims that peptic ulcer disease attributable to that ulcer or its treatment with PPIs could have caused tachycardia and blood pressure fluctuations, in turn, contributing to cause or aggravate the ensuing stroke. Second, he alleges that a helicobacter pylori bacterium associated with the ulcer may have increased his risk of a stroke. In this case, the competent medical opinions of record weigh heavily against a finding that a relationship exists between the Veteran’s stroke and residual disabilities and his service-connected duodenal ulcer. Specifically, a November 2017 VA examiner opined that it was less likely than not the stroke residuals were caused or aggravated by a service-connected duodenal ulcer or the PPIs with which it was being treated. The November 2017 VA examiner’s opinion as to the etiology of the Veteran’s stroke is highly probative because it is based on an accurate medical history and provides an explanation containing clear conclusions and supporting data. That opinion was based on a review of the medical records, medical literature, and the examiner’s clinical experience, including an in-person examination. Based on this medical evidence, the VA examiner identified multiple factors increasing the Veteran’s risk of a stroke, such as age, gender, and a history of nonservice-connected hypertension. The examiner also pointed to the use of sildenafil at the time of onset as likely linked to the stroke. In particular, the November 2017 VA examiner opined that the medical literature weighed against a relationship, whether based on causation, or on aggravation, between a duodenal ulcer or PPIs and the Veteran’s residuals of a stroke. Specifically, the examiner pointed out that the medical evidence the Veteran had submitted, including articles suggesting a link between ulcers and strokes, was belied by his own account of his medical history reported during the examination. The Veteran had reported having previously been infected with a strain of helicobacter pylori bacteria, but had stated – and his medical records showed – that the infection had been treated appropriately and not recurred. Consequently, evidence allegedly linking infection with that bacterium to strokes was of less probative value. The examiner reasoned that the Veteran had experienced a single isolated episode of a stroke while taking sildenafil. That medication had been discontinued, after which the examiner found no objective evidence of recurrence of the stroke, or of aggravation or further onset of stroke residuals. This finding, the examiner noted, was supported by his medical history and objective examinations and studies. In addition, the November 2017 examiner found it significant, in light of the Veteran’s risk factors for a stroke, that he was now taking three different medications for stroke prevention, including medication to control his blood pressure but was still prescribed PPIs. The medical evidence referenced in the examiner’s well-reasoned opinion thus supports a finding that the stroke was not due to a service-connected duodenal ulcer or the medication used to treat it. Pertinently, no contrary medical opinion is of record. In support of the appeal, the Veteran submitted several articles. As noted above, medical publications can serve as important support, if combined with the opinion of a medical professional, where those publications discuss generic relationships with a degree of certainty. But here, the Veteran has not obtained such an opinion from a medical professional supporting his claim, and the materials he submitted can be considered no more than speculative in nature as to the etiology of his stroke. To the contrary, the examiner reviewed the articles and found no relationship. While the Veteran believes the residuals of a stroke were caused or aggravated by his service-connected duodenal ulcer, including the PPIs used to treat it, he is not competent to provide a nexus opinion regarding that issue. The issue is medically complex, as it requires knowledge of neurological pathology and interpretation of complicated medical diagnostic tests. Therefore, it is outside his competence in this case because the record does not show that he has the requisite medical training or credentials to make such determinations. Consequently, more probative weight is afforded to the November 2017 VA examiner’s opinion, which weighs heavily against the claim of secondary service connection. Accordingly, the evidence does not support service connection for residuals of a stroke as secondary to the service-connected duodenal ulcer. Presumptive Service Connection Due to Chronicity/Continuity Turning to presumptive service connection, the Veteran contends that his arrhythmia is a chronic condition that first manifested, albeit undiagnosed, in 1971, within one year of his separation from service. Specifically, he claims to have begun at that time to experience symptoms that he attributed to a manifestation of the current arrhythmias. These included episodes of rapid heartbeat, heart flutters, palpitations, and a pounding chest sensation. He also contends, and his wife in a supporting statement attests, that he has experienced a continuity of that symptomatology since its onset. Pursuant to 38 C.F.R. §§ 3.307/3.309, qualifying chronic diseases include, for example, such CV disorders as cardiomegaly, cardiomyopathy, and coronary heart disease. See 38 C.F.R. § 3.309(a). Importantly, it is the manifestation of a particular qualifying chronic disease, not the onset of potentially related symptoms, that must be shown to have occurred in the requisite timeframe. To show that one of the listed chronic diseases had its onset in or within one year of separation from service, therefore, a combination of manifestations sufficient to identify the disease entity is required. Further, sufficient observation to establish chronicity at the time must be shown. If, however, chronicity of a qualifying condition in service has not been established by medical evidence of sufficient manifestation in or within a year of separation from service, then a continuity of symptomatology must be shown to have occurred after service. Id. § 3.303(b); see Walker v. Shinseki, 708 F.3d 1331 (Fed. Cir. 2013). But even this theory of entitlement to service connection for a condition based on a continuity of symptomatology can be applied only to those disorders explicitly recognized as chronic diseases by VA and listed in 38 C.F.R. § 3.309(a). To the extent that the Veteran contends that service connection is warranted for arrhythmias on a presumptive basis due to chronicity/continuity of symptomatology, cardiac arrhythmias generally, and forms of supraventricular tachycardia specifically – including the Veteran’s current diagnosis – are not listed as chronic diseases under 38 C.F.R. § 3.309(a). Therefore, a diagnosis of arrhythmias is not one of the enumerated disorders entitled to a presumption of service connection based on chronicity/continuity of symptomatology, regardless of the timeliness of onset in or following service. Therefore, even if undiagnosed manifestations of a cardiac arrhythmia were shown within one year of service or symptoms were shown to be chronic following service, presumptive service connection is not warranted as arrhythmias are not on the list of diseases referenced in 38 C.F.R. §§ 3.307/3.309. Therefore, presumptive service connection based on chronicity/continuity of symptomatology is not warranted. Further, chronicity and continuity of symptomatology was, in fact, not shown. For example, during a March 1970 examination in service, the Veteran’s heart and vascular system were found to be normal. In August 1970 separation examination, he denied an existing or history of shortness of breath, chest pain, heart palpitations, or high blood pressure. The results of that examination likewise were normal functioning of the CV and vascular system, with no reported symptoms of any form of cardiac arrhythmia. In November 1996, decades after the Veteran separated from service, the Veteran underwent a private echocardiogram but the cardiologist did not identify any arrhythmias or any symptoms associated with arrhythmias. No existing CV disorder was diagnosed or reported at that time. Accordingly, chronicity/continuity of symptomatology related to arrhythmias has not been shown. To the extent that the Veteran contends that service connection is warranted for residuals of a stroke on a presumptive basis due to chronicity/continuity of symptomatology, the medical evidence does not support the claim. The STRs do not reflect findings or complaints of a stroke, or treatment for residuals of a stroke in service. In fact, he reported no existing or history of neurologic disorders, nor were any identified, during the March 1970 or August 1970 physical examinations in service. Likewise, a December 1971 VA examiner found that his neurological status was normal. The Veteran has not since reported in the context of this claim that he experienced a stroke in service. Rather, the medical records show that he has consistently reported that the onset of his symptoms of a stroke began nearly 40 years after his separation from service. Moreover, there is no medical evidence of record before 2010 that a stroke had occurred or that he had the residual effects of one. Thus, the medical evidence does not support a finding of the onset of a stroke in service or within a year of separation from service. Similarly, the Veteran does not contend and the medical evidence does not show continuity of symptomatology of residual effects of a stroke has occurred since his discharge from service. Accordingly, the medical evidence weighs against his claim of presumptive service connection for chronic residuals of a stroke. Service Connection Based on Herbicide Exposure To the extent that the Veteran contends that service connection is warranted for a CV disorder or residuals of a stroke due to herbicide exposure, the evidence does not support the appeal. The term “herbicide agent” means a chemical in an herbicide, including Agent Orange, used in support of the United States and allied operations in the Republic of Vietnam during the Vietnam era. 38 C.F.R. § 3.307(a)(6)(i). In contrast, commercial herbicides do not fall under the regulations governing presumptive exposure to herbicide agents. This distinction matters because certain diseases associated with exposure to herbicide agents will be presumed to have been incurred in service even though there is no evidence of that disease during service. 38 U.S.C. § 1116(a); 38 C.F.R. §§ 3.307(a)(6), 3.309(e). Where in-service exposure to an herbicide agent is shown, therefore, with few limitations, later manifestations of any listed disease will be deemed service connected. 38 C.F.R. §§ 3.307(a)(6)(ii), 3.309(e). To show a disease is service connected based on an in-service exposure to a commercial herbicide, however, requires additional proof that the disease is linked to exposure. For veterans with certain qualifying service, moreover, exposure to herbicide agents itself is presumed. See 38 U.S.C. § 1116; 38 C.F.R. § 3.309(e). As mentioned, for example, veterans who served in the Republic of Vietnam during the relevant time period are presumed to have been exposed to herbicide agents, unless there is affirmative evidence of non-exposure. 38 C.F.R. § 3.307(a)(6)(iii). The Veteran’s service personnel records (SPRs) do not show service at any location or any time frame in which a presumption of exposure to herbicide agents applies. For example, the MPRs do not reflect any foreign or sea service. Rather, he was trained for active duty at Fort Knox, Kentucky and was stationed at Fort Ord for the entire duration of his active service. The Veteran’s DD-214 also indicates that he did not serve aboard an aircraft known to have been used to spray herbicide agents, or otherwise serve in a capacity presumptively associated with exposure. Accordingly, the evidence does not support service connection for a CV disorder or a stroke based on presumed in-service exposure to herbicide agents. The Veteran contends that he was repeatedly exposed to herbicide agents at two locations on base while stationed at Fort Ord between June 1969 and October 1970. First, he alleges that his duties included loading and unloading trucks that, he contends, transported five-gallon cans of Agent Orange to and from a supply room. Second, he alleges that he handled brittle, solidified pieces of Agent Orange found near a mock-up of a Vietnamese village that, he claims, had been sprayed with it. A threshold question in addressing these claims is whether sufficient evidence is of record to substantiate the Veteran’s accounts that Agent Orange was transported, stored, and used at Fort Ord during his period of active duty. The RO investigated this and, in May 2017, issued a formal finding of a lack of information to corroborate his claims of direct exposure to herbicide agents at Fort Ord. Specifically, a Department of Defense (DoD) list notes the locations outside of Vietnam and Korea where Agent Orange was used, tested, or stored. It contains no references to use of Agent Orange for routine base activities, such as weed killing. DoD attested that military bases exclusively utilized commercial herbicides for these activities. Consequently, the Veteran must show that the chemicals to which he was exposed actually contained Agent Orange, not commercial herbicides. In this case, competent, credible evidence indicates that those chemicals were, at most, commercial herbicides, not herbicide agents. Indeed, DoD has not identified Fort Ord as a location where Agent Orange was used, tested, stored, or transported. According to DoD, there was no need to use Agent Orange at Fort Ord, as no combat operations occurred there during the years it was in use in Vietnam, from 1962 to 1971, covering the Veteran’s entire period of active service. For example, as to his claim of exposure to a brittle, solidified chemical that had been sprayed on base, DoD has confirmed that Agent Orange was never used on mock-ups of Vietnamese villages in the United States. This is highly probative evidence undermining the claim that the spray residue he handled contained Agent Orange. In addition, Fort Ord was not on the Agent Orange supply line, which went directly from storage in Mississippi to Vietnam via merchant ships. Moreover, DoD attested that Agent Orange was not shipped in five-gallon cans. It was instead transported in drums, each holding fifty-five gallons. This is highly probative evidence that any five-gallon cans the Veteran encountered at Fort Ord did not contain Agent Orange. In contrast to the above evidence, the Veteran’s personal accounts of repeated direct exposures to chemicals in service do not substantiate the bare contentions that five-gallon cans he transported or spray residue he handled actually contained Agent Orange. For example, he submitted into evidence a 2009 article concerning potential health hazards of waste found at Fort Ord. But that article mentions Agent Orange merely as an example of a well-known compound containing dioxin. The article does not assert that Agent Orange was itself ever used or present, or has since been found, at Fort Ord. Moreover, no evidence suggests that the Veteran was told of, learned during the performance of his duties about, or had the knowledge and expertise to determine on his own the identity of those chemicals or to distinguish Agent Orange from commercial herbicides. Indeed, the only related evidence is that he admittedly had handled solidified spray residue without any idea or warning that it was harmful. Thus, his admittedly limited experience with such chemicals is insufficient to show competence to accurately identify them. For these reasons, the evidence weighs against a finding the Veteran was directly exposed to herbicide agents in service. As such, direct causation has not been shown. See Combee, 34 F.3d at 1042; Brock v. Brown, 10 Vet. App. 155, 162-64 (1997). Accordingly, service connection of a CV disorder and stroke residuals is not warranted on the basis of exposure to herbicide agents. The Board has also considered the Veteran’s lay statements, and his wife’s supporting statement, that his arrhythmias and residuals of a stroke are chronic disorders linked to service, are related to exposure to herbicide agents in service, or were caused or aggravated by his service-connected duodenal ulcer or the PPIs prescribed to treat it. He is competent to report symptoms and his wife is competent to report her observations because this requires only personal knowledge as it comes to them through their senses. But they are not competent as a lay persons to opine as to the etiology of his current disorders due to the medical complexity of the matters involved. Such competent evidence has been provided by the service records, clinical evidence, and examinations obtained and associated with the claims file. Here, greater probative weight is afforded to the clinical findings than to the Veteran’s (and his wife’s) lay statements. In light of the above, the preponderance of the evidence is against the claims of service connection and there is no doubt to be otherwise resolved. As such, the appeals are denied. Finally, the Veteran has not raised any other issues, nor have any other issues been reasonably raised by the record for the Board’s consideration. See Doucette v. Shulkin, 28 Vet. App. 366, 369-70 (2017) (confirming that the Board is not required to address issues unless they are specifically raised by a claimant or reasonably raised by the evidence of record). L. HOWELL Veterans Law Judge Board of Veterans’ Appeals Attorney for the Board Associate Counsel Edward P. Vrtis The Board’s decision in this case is binding only with respect to the instant matter decided. This decision is not precedential and does not establish VA policies or interpretations of general applicability. 38 C.F.R. § 20.1303.