Psychogenic pseudosyncope: Not always a diagnosis of exclusion.

BACKGROUND: Psychogenic pseudosyncope (PPS) frequently mimics syncope. The aim of this study was to assess the prevalence and clinical features of PPS and its relationship to vasovagal syncope (VVS). METHODS: We examined retrospectively the medical records of 1,401 consecutive patients referred to a syncope unit. We identified patients who had the final diagnosis of PPS. In these patients, we retrieved the initial diagnosis made during their first visit and the subsequent tests performed leading to the final diagnosis. RESULTS: Fourteen (1.0%) patients (mean age 35 ± 14; 11 females) were diagnosed as having PPS: seven had a diagnosis of PPS alone and seven had both VVS and PPS. High frequency of attacks (53 ± 35 attacks during the previous year), prolonged loss of consciousness (minutes to > 1 hour), and a history of psychiatric disorders characterized PPS patients. Tilt test reproduced a PPS attack in the presence of normal blood pressure and heart rate in seven patients (50%), and induced VVS in another three patients who had the final diagnosis of both PPS and VVS. In two patients, one or more events occurred during the clinic visits and were directly witnessed by the clinic personnel. CONCLUSIONS: We have shown that 1% of referrals to a syncope unit have the final diagnosis of PPS and that up to 50% of cases presented with a different initial diagnosis, namely VVS. Our findings suggest that causality between syncope and psychiatric disorders is likely bidirectional. The presence of a multidisciplinary team is important to address this often unrecognized relationship.

Clinical Characteristics and Outcome of Patients with Situational Syncope Compared to Patients with Vasovagal Syncope.

BACKGROUNDS: The purpose of the study was to assess the clinical outcome of patients with situational syncope (SS) compared to patients with vasovagal syncope (VVS). METHODS: We assessed the prevalence, patients' characteristics, and outcome of consecutive patients with SS and VVS who presented to the Faint and Fall Clinic (University of Wisconsin) between January 2013 and December 2015. RESULTS: SS was found in 55/1,401 (4.0%) syncope patients with follow-up data available in 47 patients: defecation (n = 16), micturition (n = 15), cough (n = 10), swallow (n = 3), laughter (n = 1), sneeze (n = 1), and cough plus laughter (n = 1). Over the same time period, 252/1,401 patients (18%) were diagnosed with VVS with follow-up data available in 171 patients. Compared with VVS patients, SS patients were older, more likely to be male, had a higher prevalence of hypertension, had an absence of prodromes, and experienced more injuries at the time of syncope (P = 0.01 for all). During a mean follow-up duration of 15.4 ± 9.1 months, syncope recurred in 5/47 (10.6%) patients with SS and 16/171 (9.4%) patients with VVS. The recurrence rates at 1 year and 2 years were 20% (95% SE ± 13) and 40% (95% SE ± 20) for the SS group, and 23% (95% SE ± 13) and 43% (95% SE ± 20) for the VVS group (P = 0.6). No patient died. CONCLUSIONS: We have shown in a large cohort of consecutive patients with syncope that SS is a relatively infrequent form of reflex syncope with different clinical characteristics but similar recurrence rate to VVS.

Long-Term Outcome of Patients with Bifascicular Block and Unexplained Syncope Following Cardiac Pacing.

BACKGROUND: According to the ACC/AHA/HRS guidelines, cardiac pacing is reasonable in patients with bifascicular block (BF-B) and syncope when other causes have been excluded. The purpose of this study was to assess the long-term outcome of patients with BF-B and unexplained syncope following cardiac pacing. METHODS AND RESULTS: Between 2009 and 2015, we identified 43 consecutive patients (mean age of 78 ± 12 years, 64% males) who presented with syncope and BF-B and had received a pacemaker (PM). During a mean follow-up period of 31 ± 21 months, syncope recurred in seven patients (16%): 7% (95% standard error [SE] ± 3%) at 1 year and 18% (95% SE ± 7%) at 5 years. At univariable analysis, the only predictor of syncope recurrence was empiric pacing (P = 0.03). There were no syncope recurrences in the 12 patients who received a PM following a positive electrophysiological study (EPS) and the five patients with documentation of paroxysmal atrioventricular block (AVB) during cardiac monitoring (insertable loop recorder [ILR]), (EPS/ILR Group, n = 17) compared to seven of 26 (27%) patients who received empiric pacing (Empiric Group, n = 26; P = 0.02). Progression to high-degree AVB was documented during follow-up in 16 (37%) patients: nine of 17 (53%) patients in the EPS/ILR Group and seven of 26 (27%) patients in the Empiric Group (P = 0.11). There were no injuries reported during ILR monitoring. CONCLUSIONS: We have shown that syncope recurs not infrequently in patients with BF-B who received pacing for syncope. Nearly one in four patients who had empiric pacing suffered syncope recurrence compared to no recurrences in patients who received a PM following a positive EPS or documentation of transient AVB.

The pathophysiologic mechanisms associated with hypotensive susceptibility.

INTRODUCTION: Patients with vasovagal syncope (VVS) and positive tilt table test (TTT) were not found to benefit from pacing in the ISSUE-3 trial despite the presence of spontaneous asystole during monitoring. "Hypotensive susceptibility" unmasked by TTT was reported as a possible explanation. The purpose of this study was to assess the pathophysiologic mechanisms associated with hypotensive susceptibility. METHODS: 366 consecutive patients with the diagnosis of VVS who also had TTT were identified. Baroreflex gain (BRG) in addition to blood pressure (BP) and heart rate (HR) responses during the first 20 min of TTT were analyzed and compared between patients with positive TTT (n = 275, 75 %) and negative TTT (n = 91, 25 %). RESULTS: The mean BRG was similar between the groups (12.5 ± 6.3 versus 12.4 ± 6.3 ms/mmHg, p = 0.72); however, an age-dependent decrease was noted (17.6 ± 4.8, 15.0 ± 6.0, 10.6 ± 4.2, 10.3 ± 6.4 and 9.9 ± 8.5 ms/mmHg for patients <21, 21-40, 41-60, 61-80 and >80 years old, respectively; p < 0.001). In addition, we saw a main effect of age on the type of response with a greater prevalence of a vasodepressor response in older subjects (p < 0.001). During the first 20 min of TTT, BP was similar in patients with tilt-positive VVS when compared with patients with tilt-negative VVS; however, HR was significantly lower. CONCLUSION: BRG is similar in tilt-positive VVS patients when compared with tilt-negative VVS patients. An age-dependent decrease in BRG was noted with a higher prevalence of a vasodepressor response seen in older patients. The clinical significance of the blunted HR response in tilt-positive VVS remains to be determined.

"Vasovagal" response during ventricular fibrillation: incidence and implications.

BACKGROUND: The purpose of this study was to assess the relationship between changes in sinus node cycle length (SNCL) during ventricular fibrillation (VF) and the peripheral changes in blood pressure (BP) and sympathetic nerve activity (SNA) in human subjects. We hypothesized that patients with no SNCL shortening during VF have a vasovagal-like response with a greater decrease in BP and SNA when compared to patients with SNCL shortening. METHODS: SNCL, BP, and SNA recordings were attempted in 24 patients undergoing the implantation of a dual-chamber implantable defibrillator. Changes were measured during the first 5 seconds of VF and compared with the 5 seconds prior to VF induction. RESULTS: SNCL shortened during VF in nine patients (mean%∆SNCL = -12 ± 8%) and remained unchanged or lengthened in seven patients (mean%∆SNCL = 7 ± 7%). Eight patients had ventriculoatrial (VA) conduction prohibiting assessment of SNCL changes. In patients with SNCL shortening, the %∆MBP (mean BP) was -47 ± 6% compared to -58 ± 8% in patients with no SNCL shortening (P < 0.01). In patients with VA conduction, the %∆MBP was -54 ± 3%. SNA recordings were successfully obtained in four patients. When compared to baseline, SNA increased by 34 ± 30% in two patients with SNCL shortening, decreased by 25% in one patient with SNCL lengthening, and by 90% in the fourth patient with VA conduction. CONCLUSIONS: We have shown that patients with no SNCL shortening have a significantly greater decrease in MBP during VF when compared to patients with SNCL shortening. The underlying mechanism appears to be reflex mediated with a vasovagal-like response in patients with no SNCL shortening.

Mechanisms of sinus node cycle length changes during ventricular fibrillation.

OBJECTIVE: We have previously shown that up to one-third of patients develop no change or an increase in sinus node cycle length (SNCL) during ventricular fibrillation (VF). The purpose of the present study was to investigate the mechanism of SNCL changes during VF in a swine model. We hypothesized that changes in SNCL during VF are vagally-mediated. METHODS: In 33 anesthetized pigs DC current was used to induce VF for 10 s followed by defibrillation. SNCL changes were assessed during VF and compared to baseline. Animals that had ventriculo-atrial conduction during VF were excluded. Post-defibrillation, the pigs were randomized to receive atropine, propranolol, atropine + propranolol or placebo followed by repeat VF induction and measurement of SNCL changes. RESULTS: Ventriculo-atrial conduction was present in 14 pigs prohibiting SNCL measurements. In the remaining 19 animals, 10 demonstrated SNCL shortening (S-Group) and 9 demonstrated non-shortening (NS-Group). Atropine decreased the absolute change in SNCL from 51.2 to 26.6 ms (n = 6; p = 0.03). It attenuated the SNCL shortening previously observed in the S-Group (-99.2 ms versus -47.9 ms, p = 0.04) and reversed the SNCL prolongation initially observed in the NS-Group (27.1 ms versus -6.5 ms, p = 0.13). Similarly, atropine + propranolol decreased the absolute change in SNCL from 33.3 to 12.2 ms (n = 4; p = 0.05). No significant changes were noted with propranolol or placebo. INTERPRETATION: The SNCL changes during VF appear to be vagally-mediated. The clinical implications vis-à-vis defibrillation threshold and future device programming await future studies.

Standardized care pathway versus conventional approach in the management of patients presenting with faint at the University of Utah.

BACKGROUND: Despite the availability of guidelines, the evaluation of patients with faint continues to be inconsistent. The purpose of this study was to test the hypothesis that utilization of a new standardized-care pathway (Faint-Algorithm) reduces hospital admissions and improves diagnostic yield when compared to the conventional approach in the evaluation of patients with faint. METHODS: We reviewed the data of 154 consecutive patients presenting with faint to the Faint and Fall Clinic at the University of Utah (standardized group) and 100 patients previously evaluated for faint using the conventional approach (conventional group). RESULTS: Using a standardized approach, only 4% of patients were admitted when compared to 20% in the conventional group (P < 0.001). The rate of diagnosis at initial evaluation was similar between the groups; however, at 45 days, it was greater in the standardized group when compared to the conventional group (57% vs 45% in the total population, P = 0.09; 57% vs 39% in the outpatient subgroups, P = 0.02). The number of tests or consultations associated with additional charges was significantly lower in the standardized group when compared to the conventional group (1.9 ± 1.0 vs 2.6 ± 1.2, P = 0.001). CONCLUSIONS: The use of a standardized approach in the evaluation of patients with faint decreased the number of hospital admissions and increased the rate of diagnosis at 45 days. This was achieved with less utilization of costly tests and consultations.

Restoring sinus rhythm results in blood pressure reduction in patients with persistent atrial fibrillation and a history of hypertension.

INTRODUCTION: The long-term effects of atrial fibrillation (AF) on blood pressure (BP) in patients with hypertension (HTN) remain unclear. We hypothesized that restoration of normal sinus rhythm (NSR) results in a decrease in BP despite the expected increase in cardiac output. METHODS AND RESULTS: Twenty-four-hour BP measurements were obtained during AF, and on Day 1 and Day 30 post-successful cardioversion in 18 patients with AF and HTN (cardioversion group), and another 22 patients with AF and HTN with no immediate plans for cardioversion (control group). Except for the duration of AF, the clinical characteristics and use of medications were similar between the groups. In the cardioversion group, a significant decrease in diastolic blood pressure (DBP) and mean blood pressure (MBP) were noted on Day 1 post-cardioversion with no significant change in systolic blood pressure (SBP): 117/74/88 ± 13/9/9 mmHg during AF and 116/70/85 ± 13/9/10 mmHg during Day 1 post-cardioversion (P = 0.68; <0.01 and 0.04 for SBP, DBP, and MBP, respectively). In the 13 subjects who remained in NSR at Day 30, DBP and MBP decreased further on Day 30 when compared to Day 1 with no significant change in SBP: 118/76/90 ± 13/7/8 mmHg during AF; 119/72/88 ± 12/8/9 mmHg during Day 1; and 118/69/86 ± 10/8/7 mmHg during Day 30 post-cardioversion (P = 0.97; <0.001 and 0.03 for SBP, DBP, and MBP, respectively). In the control group, no significant changes in BP were noted. CONCLUSION: Restoring NSR in patients with AF and HTN resulted in a sustained decrease in DBP and MBP. To our knowledge, this is the first study to show that maintenance of NSR improves BP control in patients with AF and HTN.

Atrial bigeminy results in decreased left ventricular function: an insight into the mechanism of PVC-induced cardiomyopathy.

BACKGROUND: Premature ventricular complexes have been recently recognized as a reversible cause of cardiomyopathy. The purpose of this study was to determine if premature complexes independent of "dyssynchrony" resulted in increased left ventricular (LV) dimensions and decreased LV function. METHODS: Ten mongrel dogs underwent the implantation of a pacemaker and were randomized to a control group (n = 5) or a paced group (n = 5). In the paced group, the pacemaker was connected to two endocardial atrial leads, one inserted into the atrial port and the other one into the ventricular port with an atrioventricular delay adjusted to ensure the presence of coupled pacing simulating atrial bigeminy with conducted beats in the absence of aberrancy. Echocardiographic parameters of LV size (LV end-diastolic diameter [LV-EDD], LV end-systolic diameter [LV-ESD]), and LV ejection fraction (LVEF) were measured at baseline and after 4 weeks of monitoring (control group) or pacing (paced group). RESULTS: In the control group, LV size decreased with no significant changes in LVEF: 55% at baseline versus 70% at 4 weeks (P = 0.23). In the paced group, LV-EDD decreased with no significant change in LV-ESD. Unlike the control group, LVEF decreased significantly from 69 ± 9% at baseline to 32 ± 22% after 4 weeks of pacing (P = 0.05). CONCLUSION: We have shown that 4 weeks of coupled pacing simulating atrial bigeminy significantly reduced LV function. Our findings suggest that premature complexes independent of ventricular dyssynchrony might lead to the development of cardiomyopathy.

Atrial fibrillation: an independent risk factor for nonaccidental falls in older patients.

BACKGROUND: Nonaccidental falls are often the result of a combination of factors including cardiovascular disorders such as orthostatic hypotension and unspecified cardiac arrhythmias. The objective of this study was to determine if there is an association between atrial fibrillation (AF) and nonaccidental falls. METHODS: We reviewed the records of 442 consecutive patients >65 years old who presented to the Emergency Department at the University of Utah Medical Center with a complaint of fall. RESULTS: Two-hundred eleven patients presented with nonaccidental fall, 231 patients with accidental fall. Patients with nonaccidental fall were more likely to be older, have a history of hypertension and neurological disorders, and taking five or more medications when compared to patients with accidental fall. Despite a similar prevalence of sinus rhythm at presentation, the prevalence of a history of AF was significantly higher in patients with nonaccidental fall compared to patients with accidental fall (26% vs 15%; P = 0.003). After adjusting for clinically and statistically significant predictors with a multivariate logistic regression analysis, AF, neurological disorders, and age ≤81 years were independent predictors of nonaccidental fall. In patients ≤81 years old (median age), the risk of nonaccidental falls was 2.5 times greater in patients with a history of AF when compared to those without a history of AF (odds ratio = 2.53 [confidence interval 95% 1.3-5], P = 0.007). CONCLUSION: AF is an independent risk factor for nonaccidental falls. Our results emphasize the need to screen for AF in patients presenting with nonaccidental fall.

Safety, Pharmacokinetic, and Pharmacodynamic Study of a Sublingual Formula for the Treatment of Vasovagal Syncope.

BACKGROUND: Vasovagal syncope is a common cause of syncope which, if recurrent, can have multiple negative consequences such as injury and occupational disability. Various medications can be used to decrease the recurrence of vasovagal syncope but there are no drugs that can be used by patients to interrupt a perceived vasovagal episode. METHODS: A phase I study was performed to evaluate the tolerability and safety of a gel formulation containing capsaicin (1 mg), phenylephrine HCL (PE) and caffeine citrate (200 mg) (CPC) in normal adult volunteers. Secondary objectives were to characterize the pharmacokinetics (PK) of the CPC formulation and the highest dose of PE needed to achieve a target increase in systolic BP of at least 40 mmHg. After receiving the first dose, a second dose of the CPC mixture was administered at 2 h. Suboptimal changes in systolic blood pressure (SBP) were noted at PE doses of 0.6, 1.2, and 1.8 mg, therefore a second cohort was studied at PE doses of 10, 20, and 30 mg. Blood samples were collected in rapid sequence and were assayed for all three drugs. RESULTS: A total of 17 subjects received the drug with no serious adverse effects reported. All doses were well tolerated, although the capsaicin content usually caused expected temporary oral and gastric discomfort. One subject did not complete the study because of a vasovagal reaction that was associated with the frequent blood sampling. There was a 5-25 min lag in the appearance of measurable blood concentrations of capsaicin and phenylephrine. Most subjects had baseline caffeine concentrations from dietary use, with a gradual increase noted after 15 min consistent with GI absorption. Although the intended criterion of a 40 mmHg increase in SBP was not reached, a clinically significant increase in BP for at least 15 min was noted in the six subjects who received the highest dose of PE (30 mg), with a gradual decline over the next 2 h. CONCLUSION: The ternary mixture of capsaicin, phenylephrine, and caffeine was well tolerated when administered as two sublingual/oral doses over a 2-h period.

Sinus Tachycardia: a Multidisciplinary Expert Focused Review.

Sinus tachycardia (ST) is ubiquitous, but its presence outside of normal physiological triggers in otherwise healthy individuals remains a commonly encountered phenomenon in medical practice. In many cases, ST can be readily explained by a current medical condition that precipitates an increase in the sinus rate, but ST at rest without physiological triggers may also represent a spectrum of normal. In other cases, ST may not have an easily explainable cause but may represent serious underlying pathology and can be associated with intolerable symptoms. The classification of ST, consideration of possible etiologies, as well as the decisions of when and how to intervene can be difficult. ST can be classified as secondary to a specific, usually treatable, medical condition (eg, pulmonary embolism, anemia, infection, or hyperthyroidism) or be related to several incompletely defined conditions (eg, inappropriate ST, postural tachycardia syndrome, mast cell disorder, or post-COVID syndrome). While cardiologists and cardiac electrophysiologists often evaluate patients with symptoms associated with persistent or paroxysmal ST, an optimal approach remains uncertain. Due to the many possible conditions associated with ST, and an overlap in medical specialists who see these patients, the inclusion of experts in different fields is essential for a more comprehensive understanding. This article is unique in that it was composed by international experts in Neurology, Psychology, Autonomic Medicine, Allergy and Immunology, Exercise Physiology, Pulmonology and Critical Care Medicine, Endocrinology, Cardiology, and Cardiac Electrophysiology in the hope that it will facilitate a more complete understanding and thereby result in the better care of patients with ST.

Irregular ventricular activation results in QT prolongation and increased QT dispersion: a new insight into the mechanism of AF-induced ventricular arrhythmogenesis.

INTRODUCTION: Atrial fibrillation (AF) has been shown to be associated with increased risk of ventricular arrhythmias. We have previously shown reverse electrical remodeling of the ventricles following successful restoration of sinus rhythm in patients with persistent AF. The purpose of this study was to assess the relative role of irregular ventricular activation in mediating the previously observed changes. METHODS AND RESULTS: Twenty-two patients referred for an invasive electrophysiologic study were randomized to 30 minutes of regular or irregular atrioventricular (AV) sequential pacing at 100 beats per minute (bpm) with a programmed AV interval of 100 ms. Irregular pacing was triggered from prerecorded digital signal with a mean rate of 100 bpm, and a standard deviation of 150 ms (25% of the mean rate). In the regular pacing group, QT and QTc decreased from 448 ± 102 ms and 453 ± 105 ms to 428 ± 109 ms and 442 ± 104 ms, respectively (P < 0.001 for QT interval and P < 0.001 for QTc interval). There was no significant change in QT dispersion. In the irregular pacing group, QT and QTc increased from 477 ± 104 ms and 486 ± 78 ms to 489 ± 106 ms and 500 ± 106 ms (P < 0.01 for QT interval and P = 0.03 for QTc interval). In addition, there was a significant increase in QT dispersion from 50 ± 22 ms to 66 ± 22 ms (P = 0.001). Since the rate and pacing sites were similar between the groups, we attribute the repolarization changes in the irregular pacing group to the irregular activation of the ventricles. CONCLUSION: The detrimental effects of irregular pacing go beyond the hemodynamic changes and include electrical remodeling that favors an arrhythmogenic substrate.

Syncope in the emergency department: comparison of standardized admission criteria with clinical practice.

AIMS: Syncope is a major health care problem that accounts for many emergency department (ED) and hospital admissions. This study was conducted to investigate the short-term risk of serious events in patients presenting to the ED with syncope and to compare guideline-based admission criteria with those adopted in clinical practice. METHODS AND RESULTS: A single-centre retrospective analysis was performed on ED visits between January and June 2009. We used the ICD-9 code 780.2 for syncope as the primary diagnosis. The prevalence of serious events within 7 days of the index presentation was evaluated. In addition, admissions and discharges were classified as being appropriate or inappropriate based on standardized guideline-based criteria integrated in a new Faint-Algorithm developed at the University of Utah. Two hundred and fifty-four ED visits met the inclusion criteria. One hundred and thirty-six patients were discharged home and the remaining 118 were admitted. The prevalence of serious events in the discharged and admission groups were 5 and 10, respectively, (P= NS). According to the Faint-Algorithm, the number of inappropriate discharges and admissions were 8 out of 136 and 69 out of 118, respectively. Using the Faint-Algorithm, only 57 patients instead of 118 patients should have been admitted resulting in a 52% reduction in admission rate. Furthermore, in the remaining 197 patients who should have been discharged, the prevalence of serious events was not significantly different than that observed in the 136 patients who were actually discharged (3% vs. 4%). CONCLUSION: There are significant numbers of inappropriate discharges and admissions in patients presenting with syncope. The standardized guideline-based criteria integrated in the new Faint-Algorithm provide promise but require further prospective evaluation.

The prevalence and cost of the faint and fall problem in the state of Utah.

BACKGROUND: Understanding the frequency and economic impact of faint and fall is a prerequisite for the creation of cost-effective diagnostic approaches. METHODS: We evaluated the total number of patients presenting with faint or fall to the University of Utah Health Care System between November 1, 2008, and October 31, 2009. Using these data, we estimated the prevalence and total cost of the faint and fall problem in the state of Utah. RESULTS: A total of 1,936 and 6,043 patients presented with faint and fall resulting in a total number of visits equal to 2,701 and 8,163, respectively. The yearly prevalence of faints was 9.5 patients (13.2 visits) per 1,000 inhabitants and the yearly prevalence of falls was 29.8 patients (40.2 visits) per 1,000 inhabitants. The prevalence of faints and falls progressively increased with age, reaching the values of 40 and 115 per 1,000 inhabitants in subjects aged >80 years. In both patient populations, two-thirds of visits were outpatient evaluations. While the cardiovascular service was involved in the outpatient evaluation of faint visits in 24% of the cases, <1% of outpatient fall visits resulted in a cardiovascular consultation. The average payments received per faint and fall patient evaluations were $2,517 and $3,200, respectively, resulting in an estimated yearly cost equal to $90,901,958 and $351,959,040, respectively. CONCLUSION: This study highlights the magnitude of the faint and fall problem in the state of Utah. Our results provide all stakeholders with a frame of reference for the creation of cost-effective diagnostic approaches.

An animal model for ectopy-induced cardiomyopathy.

BACKGROUND: Ectopy-induced cardiomyopathy is an increasingly recognized cause of reversible left ventricular (LV) dysfunction. The underlying mechanisms remain unknown. Our goal was to create an animal model for ectopy-induced cardiomyopathy. METHODS: Eleven mongrel dogs underwent the implantation of a dual-chamber pacemaker. Four dogs served as the control group and seven as the paced group. In the paced group, the pacemaker was connected to two endocardial right ventricular leads, one inserted into the atrial port and the other one into the ventricular port with an atrioventricular delay adjusted to ensure the presence of coupled pacing simulating ventricular bigeminy. Echocardiographic measurements of LV size (LV end-diastolic diameter [LV-EDD], LV end-systolic diameter [LV-ESD]), LV ejection fraction (LVEF), and mitral regurgitation (MR) were obtained at baseline and after 4 weeks of monitoring or pacing in all dogs except one who had lead dislodgement. RESULTS: In the control group (n = 4), no significant changes in LV dimensions or function were noted. In the paced group (n = 6), LV-EDD and LV-ESD increased from 3.58 ± 0.65 cm and 2.47 ± 0.55 cm to 4.15 ± 0.59 cm and 3.21 ± 0.47 cm, respectively (P < 0.01). In addition, LVEF decreased from 60 ± 7% to 46 ± 9% (P < 0.05). No changes in MR were noted. CONCLUSION: We have shown that coupled pacing simulating ventricular bigeminy was feasible and resulted in increased LV dimensions and decreased LV function. By controlling the percentage of pacing, the coupling interval and the location of the pacing lead, this new model will allow the assessment of the relative roles of these variables in the development of ectopy-induced cardiomyopathy.

Evaluation of patients with "faint" in an American teaching hospital: a dire need for a standardized approach.

BACKGROUND: Fainting is a major healthcare problem with significant morbidity, mortality, and healthcare cost. We sought to assess the appropriateness of current clinical practice when compared to a guideline-based algorithm. METHODS: The records of 100 consecutive patients who presented with faint and were referred to the University of Utah for further evaluation by specialists were reviewed. We analyzed the clinical characteristics, tests performed, diagnosis made, and number of admissions. In addition, we applied a guideline-based algorithm to assess the appropriateness of these evaluations. RESULTS: The mean age was 49 ± 21 years with 57% being female. One-third presented with their first event. Structural heart disease was present in 22% of the cases. Twelve (36%) of 32 admissions were inappropriate. There was an underutilization of orthostatic testing, carotid sinus massage, and implantable loop recorder and overutilization of imaging studies and neurologic consultation. Specifically, active standing and tilt-table testing were performed in only 24% and 7% of the cases, respectively, none of the patients had carotid sinus massage despite 26% of them being ≥65 years old, and only 3% of the patients received an implantable loop recorder. With the current practice, a final diagnosis was made in 45 cases with 17 (38%) of the 45 final diagnoses not being sufficiently supported by the completeness of the evaluation. CONCLUSION: With the current practice at a major university hospital, the cause of faint was unexplained in a high number of cases. Our findings highlight the need for a standardized approach to patients presenting with faint.

Oscillatory vagal maneuvers produce ventricular entrainment in patients with atrial fibrillation.

BACKGROUND: Atrial fibrillation (AF) is the most common sustained dysrhythmia and appears to be an independent predictor of sudden cardiac death. The irregular ventricular rhythm contains both linear and non-linear patterns; however, it remains unclear whether vagally mediated effects are present within these patterns. OBJECTIVE: We sought to determine if (1) power spectral analysis of heart rate can detect changes in vagal activity in patients with AF and (2) if the vagus modulates ventricular response during AF. METHODS: Time and frequency domain parameters of heart rate variability (HRV) were calculated during forced vagal oscillations at 0.125 and 0.25 Hz imposed by neck suction and deep breathing in five AF patients. RESULTS: There was a significant increase in SDRRI during deep breathing/neck suction combined compared to baseline (p=0.01) and deep breathing (p=0.03). Neck suction significantly increased SDRRI compared to baseline (p=0.03). Deep breathing/neck suction significantly increased spectral power compared to baseline (p=0.02) and deep breathing (p=0.03). Neck suction significantly increased spectral power compared to baseline (p=0.03). Deep breathing did not significantly increase HRV compared to baseline (p>0.20). In addition, SDRRI and spectral power were significantly correlated during deep breathing (r=0.91, p=0.03) and deep breathing/neck suction combined (r=0.92, p=0.02). INTERPRETATION: These data suggest that (1) power spectral analysis can detect vagal influences on heart rate in AF patients, and (2) oscillatory vagal maneuvers produce ventricular entrainment during AF.