Quantitative methods for group bibliotherapy research: a pilot study

Background: Bibliotherapy is under-theorized and under-tested: its purposes and implementations vary widely, and the idea that 'reading is good for you' is often more assumed than demonstrated. One obstacle to developing robust empirical and theoretical foundations for bibliotherapy is the continued absence of analytical methods capable of providing sensitive yet replicable insights into complex textual material. This pilot study offers a proof-of-concept for new quantitative methods including VAD (valence-arousal-dominance) modelling of emotional variance and doc2vec modelling of linguistic similarity. Methods: VAD and doc2vec modelling were used to analyse transcripts of reading-group discussions plus the literary texts being discussed, from two reading groups each meeting weekly for six weeks (including 9 participants [5 researchers (3 authors, 2 collaborators), 4 others] in Group 1, and 8 participants [2 authors, 6 others] in Group 2). Results: We found that text-discussion similarity was inversely correlated with emotional volatility in the group discussions (arousal: r = -0.25; p = ns; dominance: r = 0.21; p = ns; valence: r = -0.28; p = ns), and that enjoyment or otherwise of the texts and the discussion was less significant than other factors in shaping the perceived significance and potential benefits of participation. That is, texts with unpleasant or disturbing content that strongly shaped subsequent discussions of these texts were still able to sponsor 'healthy' discussions of this content, as evidenced by the combination of low arousal plus high dominance despite low valence in the emotional qualities of the discussion. Conclusions: Our methods and findings offer for the field of bibliotherapy research both new possibilities for hypotheses to test, and viable ways of testing them. In particular, the use of natural language processing methods and word norm data offer valuable complements to intuitive human judgement and self-report when assessing the impact of literary materials.

169. The Resurgence of Candida auris in California during the Novel Coronavirus (COVID-19) Pandemic, May 2020–May 2021

Background

In February 2019, California (CA) experienced its first C. auris outbreak in Orange County (OC). The CA Department of Public Health (CDPH) and OC with the Centers for Disease Control and Prevention (CDC), mounted a successful containment response; by November 2019, cases were limited to low-level spread in OC long-term acute care hospitals (LTACH).

In May 2020, C. auris cases began to surge in OC, followed by extensive spread in six other southern CA local health jurisdictions (LHJ). CDPH with LHJ and CDC, initiated an aggressive, interjurisdictional containment response.

Methods

We carried out response and preventive point prevalence surveys (PPS), onsite infection prevention and control (IPC) assessments, and in-service trainings at outbreak and interconnected hospitals and skilled nursing facilities in six LHJ. Other regional activities included: epidemiologic investigation, contact and discharge tracking and screening; increasing laboratory testing capacity; screening patients admitted to and from LTACH; statewide healthcare facility (HCF) education and outreach; sending regional outbreak HCF lists to all HCF; and biweekly state-LHJ coordination calls. The Antibiotic Resistance (AR) Lab Network supported testing.

Results

From May 2020—May 2021, we conducted screening at 226 HCF, and identified 1192 cases at 93 HCF, mostly through screening (n=1109, 93%) and at LTACH (n=906, 76%); we identified 113 (10%) cases at ACH, including 35 (31%) in COVID-19-burdened units. Cases peaked in August 2020 (n=93) and February 2021 (n=191) and have since declined, with C. auris resurgence mirroring COVID-19 incidence.

We conducted 98 onsite IPC assessments, and identified multiple, improper IPC practices which had been implemented in response to COVID-19, including double-gloving and -gowning, extended use of gowns and gloves outside patient rooms, and cohorting according to COVID-19 status only.

Figure 1. C. auris and COVID-19 Cases in California through May 2021, and C. auris Cases by Local Health Jurisdiction (LHJ) May 2020–May 2021

Table 1. By Facility Type: Colonization Testing May 2020–May 2021, and Total Case Counts before and from May 2020

Table 2. COVID-19-related Infection Control Practices Affecting C. auris Spread, and Associated Public Health Recommendations

Conclusion

The C. auris resurgence in CA was likely a result of COVID-19-related practices and conditions. An aggressive, coordinated, interjurisdictional C. auris containment response, including proactive prevention activities at HCF interconnected with outbreak HCF, can help mitigate spread of C. auris and potentially other novel AR pathogens.

Disclosures

All Authors: No reported disclosures

802. Corynebacterium striatum Outbreak Among Ventilated COVID-19 Patients in an Acute Care Hospital – California, 2021

Background

Corynebacterium striatum (CS), a common human commensal colonizing the skin and nasopharynx, has been associated with nosocomial infections in immunocompromised and chronically ill patients. During the winter 2020-2021 COVID-19 surge, a 420-bed California hospital reported a marked increase in CS respiratory cultures among ventilated COVID-19 patients. We conducted a public health investigation to assess and mitigate nosocomial transmission and contributing infection prevention and control (IPC) practices.

Methods

A case was defined as a patient with CS in respiratory cultures from January 1, 2020 - February 28, 2021. We reviewed clinical characteristics on a subset of cases in 2021 and IPC practices in affected hospital locations. CS respiratory isolates collected on different dates and locations were assessed for relatedness by whole genome sequencing (WGS) on MiSeq.

Results

Eighty-three cases were identified, including 75 among COVID-19 patients (Figure 1). Among 62 patients identified in 2021, all were ventilated; 58 also had COVID-19, including 4 cases identified on point prevalence survey (PPS). The median time from admission to CS culture was 19 days (range, 0-60). Patients were critically ill; often it was unclear whether CS cultures represented colonization or infection. During the COVID-19 surge, two hospital wings (7W and 7S) were converted to negative-pressure COVID-19 units. Staff donned and doffed personal protective equipment in anterooms outside the units; extended use of gowns was practiced, and lapses in glove changes and hand hygiene (HH) between patients likely occurred. In response to the CS outbreak, patients were placed in Contact precautions and cohorted. Staff were re-educated on IPC for COVID-19 patients. Gowns were changed between CS patients. Subsequent PPS were negative. Two CS clusters were identified by WGS: cluster 1 (5 cases) in unit 7W, and cluster 2 (2 cases) in unit 7S (Figure 2).

Figure 1. Corynebacterium striatum Respiratory Cultures January 2020-February 2021

Conclusion

A surge in patients, extended use of gowns and lapses in core IPC practices including HH and environmental cleaning and disinfection during the winter 2020-2021 COVID-19 surge likely contributed to this CS outbreak. WGS provides supportive evidence for nosocomial CS transmission among critically ill COVID-19 patients.

Disclosures

All Authors: No reported disclosures

Post-Acute Sequelae of SARS-CoV-2 Infection Among Adults Aged ≥18 Years - Long Beach, California, April 1-December 10, 2020

Post-acute sequelae of COVID-19, also known as "long COVID," is used to describe the long-term symptoms that might be experienced weeks to months after primary infection with SARS-CoV-2, the virus that causes COVID-19. Among persons with a previous COVID-19 diagnosis, estimates of the prevalence of sequelae range from 5% among nonhospitalized persons to 80% among hospitalized persons (1,2). Studies have analyzed the aftereffects of COVID-19, but few have assessed the demographic characteristics associated with long COVID (3,4). Health disparities resulting from pervasive structural and socioeconomic barriers in the U.S. health care system might contribute to differences in these effects and might continue to exacerbate existing inequities (5). To identify trends in post-acute sequelae, the Long Beach Department of Health and Human Services (LBDHHS) interviewed a random sample of 366 persons aged ≥18 years who received a positive SARS-CoV-2 test result during April 1-December 10, 2020. One third of the persons interviewed reported having at least one symptom 2 months after their positive test result, with higher odds of sequelae among persons aged 40-54 years, females, and those with preexisting conditions. Black or African American (Black) participants had higher odds of reporting dyspnea and myalgia/arthralgia compared with other racial/ethnic groups. Persons who were aged ≥40 years, female, Black, or who reported known preexisting conditions also reported higher numbers of distinct sequelae. As the number of recovered COVID-19 patients increases, monitoring the prevalence of post-acute sequelae among larger cohorts in diverse populations will be necessary to understand and manage this condition. Identification of groups disproportionately affected by post-acute COVID-19 sequelae can help develop efforts to prioritize preventions and treatment strategies, including vaccination of groups at higher risk for these long-term sequelae, and access to testing and care for post-acute sequelae.

Sensitivity of multiple life stages of 2 freshwater mussel species (Unionidae) to various pesticides detected in Ontario (Canada) surface waters

Freshwater mussels contribute important ecological functions to aquatic systems. The water filtered by mussel assemblages can improve water quality, and the mixing of sediments by burrowing mussels can improve oxygen content and release nutrients. However, nearly 70% of North American freshwater mussel species are listed as either endangered, threatened, or in decline. In Ontario, 28 species are in decline or in need of protection. Even though freshwater mussels have a heightened sensitivity to some contaminants, few studies have investigated the risks that various pesticide classes pose to one freshwater mussel species or among life stages. Lampsilis siliquoidea and Villosa iris were the focus of the present study, with the latter currently listed as of "special concern" in Canada. A potential risk to the recovery of freshwater mussel species is the presence and persistence of pesticides in Ontario surface waters. Acute (48 h) toxicity tests were performed with V. iris glochidia to determine the effect on viability (surrogate for survival) following exposure to 4 fungicides (azoxystrobin, boscalid, metalaxyl, and myclobutanil), 3 neonicotinoids (clothianidin, imidacloprid, and thiamethoxam), 2 carbamates (carbaryl and malathion), 1 organophosphate (chlorpyrifos), and 1 butenolide (flupyradifurone). Juvenile and adult L. siliquoidea were also exposed to azoxystrobin, clothianidin, imidacloprid (juvenile only), and carbaryl (adult only). Our study found in general that all life stages were insensitive to the pesticides tested, with median effect and lethal concentrations >161 µg/L. The pesticides tested likely represent a minimal risk (hazard quotients <5.4 × 10^-3 ) to freshwater mussel viability and survival in acute (48 h) and subchronic (28 d) exposures, respectively, in Ontario streams where pesticide concentrations were considerably lower than those tested in the present study. Environ Toxicol Chem 2018;37:2871-2880. © 2018 SETAC.

There Is No Performance, There Is Just This Moment: The Role of Mindfulness Instruction in Promoting Health and Well-Being Among Students at a Highly-Ranked University in the United States

Mindfulness-based stress reduction (MBSR) has been shown to improve health outcomes across populations. We explored the feasibility, acceptability, and initial effects of a pilot MBSR program at a highly-ranked university in the United States. We conducted 23 in-depth interviews with 13 students. Interviews explored stressors and coping mechanisms, experiences with MBSR, and its reported impact and potential future use. Interviews were analyzed using thematic content and narrative analyses. Results indicated that students are exposed to a very high level of constant stress related to the sheer amount of work and activities that they have and the pervasive surrounding university culture of perfectionism. MBSR offered an opportunity to step back and gain perspective on issues of balance and priorities and provided concrete techniques to counter the effects of stressors. We conclude that MBSR and mindfulness programs may contribute to more supportive university learning environments and greater health and well-being among students.

THE PHYSIOLOGICAL RESPONSE OF THE CIRCULATORY SYSTEM TO EXPERIMENTAL ALTERATIONS : I. THE EFFECT OF INTRACARDIAC FISTULAE

An abnormal communication, experimentally produced between the right and left ventricles, causes a deflection of part of the blood stream into the shorter pulmonary circuit. Proceeding pari passu with the increase in volume flow of blood through this shorter circuit, there occurs a gradual enlargement of the heart limited to that part of the circulatory system through which the deflected blood passes; namely, the left ventricle, the right ventricle, the pulmonary artery, and the left auricle. There is also a demonstrable hypertrophy of the right and left ventricles, which presumably is the result of the increased effort necessary to propel forward an increased volume flow of blood, since it cannot be attributed to an increased peripheral resistance. Immediately after the production of the defect, the right auricle and aorta become smaller than usual, conforming in size to the decreased volume flow of blood through them. As full compensation for the deflected flow occurs by an increase in total blood volume, they return to their normal size. If full compensation has not occurred they remain smaller than normal (Dog X 11). The changes incident to the establishment of an opening in the septum are entirely dependent upon the size of the defect, and hence, upon the extent of the volume of blood deflected into the shorter circuit. Commensurate with the volume of blood deflected, there is a fall in general blood pressure. If the animal survives the immediate fall in blood pressure, certain compensatory adjustments occur which reestablish a more normal blood pressure: (a) an immediate increase in pulse rate; (b) a gradual increase in total blood mass. The increase in blood volume is directly commensurate with the size of the defect. The pulse returns to a normal rate when complete compensation through an increase in blood volume has been attained. It is suggested that the enlargement of the heart seen clinically in so called "idiopathic hypertrophy," "essential hypertension," and also in certain cases of cardiorenal disease, may be due to an increase in total blood mass following some interference with the mechanism for its control. The seat of this impairment in blood volume control may be: (a) in a chemical alteration in the blood; (b) in a diseased function of the kidneys which may be responsible for a decreased elimination, or for a change in the chemical composition of the blood; or (c) in an abnormal stimulation of the organs producing the cellular elements of the blood.

THE PHYSIOLOGICAL RESPONSE OF THE CIRCULATORY SYSTEM TO EXPERIMENTAL ALTERATIONS : II. THE EFFECT OF VARIATIONS IN TOTAL BLOOD VOLUME

The pericardium presents a limiting or constricting action to acute dilatation of the heart. The diastolic pressure tends to approach the systolic pressure in a circulatory system distended with blood. The limiting action of the pericardium may be responsible for the small differences in the size of the heart noted by Meek and Eyster in their studies on the effect of plethora. The views concerning the function of the pericardium are divergent. That it may restrict the heart in cases of acute dilatation is shown in the above experiments. If the tension upon the pericardium be exerted over a prolonged period of time, as occurs in cases of pericardial effusion, the pericardium readily enlarges. If, however, the intrapericardial pressure should at any time equal the pressure in the venæ cavæ, blood would no longer enter the heart and the condition would become fatal. In recovery experiments, pericardiectomy was followed by no demonstrable effect upon the general health of the dog, upon the response to exercise, or upon the size of the heart (6).

Advanced applications of 3-dimensional echocardiography

Over the last few decades, advancements in ultrasound, electronic and computing technologies have permitted current second generation 3-dimensional (3D) echocardiography to display on-line 3D rendered images of the heart. Since various studies demonstrated its superiority over 2-dimensional echocardiography, there is growing enthusiasm to embrace this new 3D echocardiographic technology. With its increasing widespread clinical availability, 3D echocardiography is getting closer to routine clinical use. However, as with any new emerging technologies, clinical applications of 3D echocardiography should be based on current evidence. This review will focus on the evidence from clinical studies that form the scientific basis for the advanced applications of 3D echocardiography, from cardiac chamber volume assessments, left ventricular dyssynchrony assessments, quantifications of valvular abnormalities, to the role of 3D echocardiography during cardiac interventions.

Simultaneous bilateral compared with unilateral percutaneous nephrolithotomy

OBJECTIVE

To compare simultaneous bilateral percutaneous nephrolithotomy (SBPCNL) and unilateral PCNL in separate sessions in patients with bilateral renal stones for several variables before and after surgery.

PATIENTS AND METHODS

The results from SBPCNL carried out at two centres in different countries on 198 patients (aged 1.25-70 years) were compared with those from 300 patients undergoing unilateral PCNL in separate sessions. At one centre where extracorporeal shockwave lithotripsy (ESWL) was available SBPCNL was used for stones where at least two sessions of ESWL would have been required on each side. Other associated procedures were also used wherever required.

RESULTS

The stones were cleared bilaterally in one session of SBPCNL in 190 patients; in eight, fragments of < 3 mm remained but were not clinically significant. A second session was required in six patients on one side only. Variables assessed before and after treatment (e.g. hospital stay, analgesia requirements and complications) were not significantly different between SBPCNL and PCNL. The mean (range) total operative duration for SBPCNL was 46 (20-100) min and the hospital stay 4.3 (3-8) days.

CONCLUSION

From this experience, SBPCNL is a cost-effective and beneficial solution for selected patients, with clear advantages over separate unilateral PCNL in patients with bilateral stones.

Percutaneous suprapubic cystolithotripsy for pediatric bladder stones in a developing country

OBJECTIVE

To evaluate our experience with percutaneous suprapubic cystolithotripsy (PCCL) in Yemeni children with endemic urinary bladder stones.

PATIENTS AND METHODS

Between January 1993 and December 1998, 117 children underwent percutaneous suprapubic lithotripsy in Arabia Felix Modern Hospital, Sana'a Republic of Yemen. The patients' ages ranged from 8 months to 14 years (average 3.7 years). Ninety patients (77%) were under 5 years old; 20 patients (16%) were between 6 and 10 years old, and 7 patients (6%) were between 11 and 14 years old. There were 116 boys and 1 girl. The stone size ranged from 0.7 to 4 (average 2.3) cm. Five patients had coexisting urinary bilharziasis and another 5 patients had coexisting renal stone. In 10 patients, the stone was in the urethra. The procedure was done under general anesthesia. Dilation of the tract was made under fluoroscopy. The instrument was an adult 26-french nephroscope, the same as that used for percutaneous nephrolithotripsy. Ultrasound disintegration was needed for stones of > 1 cm. A suprapubic catheter was left for 24 h, and a urethral catheter was kept for 48 h.

RESULTS

All patients became stone free. The average operating time was 15 (5-50) min. The average hospital stay was 2.7 (2-5) days. No severe intra- or postoperative complication was observed. The nucleus and/or the main component of the stones were ammonium acid urate in 109 patients (93%).

CONCLUSION

Based on our experience we can conclude that percutaneous suprapubic lithotripsy is a safe and effective method for the treatment of bladder stones in children. It reduces morbidity and hospital stay and thus the cost of treatment. Our series proves the nutritional etiology of endemic pediatric bladder stones. To our knowledge, this is the largest series reported on percutaneous suprapubic management of endemic bladder stones in children.

Percutaneous nephropexy

OBJECTIVE

The authors present a 12-year (1986-98) study of a new procedure called percutaneous nephropexy (PCNP). This procedure was performed on 51 renal ptosis patients at two urological departments (in Pakistan and Hungary) with satisfactory results. The idea for PCNP was adapted from the observation that after drain insertion following nephrostomy a scar is quite sufficient to hold the kidney in place. That idea was used to fix the kidney at the required level.

MATERIAL AND METHODS

Thirteen patients complained of a palpable mobile mass in the abdomen while others suffered from pain in their affected flank with recurrent attacks of urinary tract infection. On ultrasonic examination the kidney was found to be lower than the normal position. This observation was confirmed by a standing intravenous urography (IVU) examination that also showed a tortuous ureter. Nine patients also had a stone in the affected kidney. The operation involved puncture and dilatation of a channel through the lower calyx.

RESULTS

Control IVU examination was performed after wound healing and was repeated 2 months after the operation, followed by consecutive ultrasonic examinations. Standing X-ray films obtained after contrast material injection showed the kidney to be at a higher level with a straight ureter. Forty-five patients (88.2%) recovered completely.

CONCLUSION

In the authors' opinion PCNP is a good alternative to open nephropexy operations in renal ptosis cases, particularly when laparoscopic surgery facilities are not available. Although PCNP was developed in circumstances in which the availability of equipment was restricted, in terms of benefits it is comparable with laparoscopic nephropexy.

Laparoscopically assisted percutaneous transperitoneal nephrolithotomy in pelvic dystopic kidneys: experience in 15 successful cases

The stone-holding pelvic dystopic kidneys of 15 patients were treated with laparoscopically assisted percutaneous transperitoneal nephrolithotomy. With patients in the Trendelenburg position under laparoscopic control, the bowels were dislodged with forceps until the kidney became visible. Under simultaneous laparoscopic and fluoroscopic control, the nephrostomy track was created on the antegrade route using telescopic metal dilators and a rigid nephroscope. Percutaneous nephrolithotomy was carried out in the usual manner. All the stones could be removed successfully. The only minor complication was a delayed urine leakage through the abdominal drain in a patient with a double J stent. Severe complications did not occur. The average operating time was 55 (40-85) minutes; the average hospital stay was 4.8 (4-11) days. On the basis of the authors' experience and a literature review of cases of failed shock wave lithotripsy-which is quite frequently unsuccessful in these cases-and cases of large, dense stones, this method appears to be the simplest and most suitable minimally invasive treatment of the stone-holding pelvic dystopic kidney.

Validation of low-dose dobutamine magnetic resonance imaging for assessment of myocardial viability after infarction by serial imaging

Cine magnetic resonance imaging with low-dose dobutamine stimulation allows prediction of viability after infarction with an accuracy of 80%. In akinetic segments, however, viability tends to be underestimated.

Laparoscopic management of ureteral perforation during ureterolithotripsy

The author presents a case of successful laparoscopic repair of a ureteral perforation happening during ureterolithotripsy (URS). The perforation of the mid-ureter was managed by a retroperitoneal approach: the stone from the retroperitoneum was removed, a double-J stent was inserted up to the kidney, the perforation opening was sutured, and the retroperitoneum was drained. The patient healed without any complication. Similar management of a ureteral perforation has not been found in the literature.

Endopyelotomy: experience with 320 cases

We were the first to initiate endopyelotomy in Hungary (in 1986) and in Yemen and Pakistan (in 1993). Through the end of 1995, 320 cases of ureteropelvic junction (UPJ) stenosis have been operated upon. The procedure was performed under local anesthesia in adult patients and general anesthesia in children. The minimum age of the patient was 4 years, while the oldest patient was 80 years of age. The UPJ was incised longitudinally at the posterolateral aspect until the perinephric fat was seen, and a drain of 8F to 12F was inserted transrenally into the ureter through a nephroscope. Patients soon left the hospital and were able to start working in 5 days (average). The drain was removed after 6 weeks. During the follow-up period, ultrasonic examination was performed each 3 months. The success rate (mean of three centers) came out to be 87%. Open pyeloplasty was performed in cases where the symptoms of pyelectasia were persisting and caused complaints and stenosis was present even after 6 months. In our opinion, endopyelotomy should be the procedure of first choice for UPJ stenosis, because it is less troublesome for the patient than open pyeloplasty, and the results are real encouraging.

Endoscopic clip-knot suturing technique: preliminary report of application in retroperitoneal ureterolithotomies

A newly developed laparoscopic knot-substituting technique is presented and applied in cases of retroperitoneal laparoscopic ureterolithotomies. The authors substituted the difficult laparoscopic knotting techniques with the technique of using one or two clips to hold the sutures tight, which shortens and simplifies the endoscopic suturing. This technique is a great advantage, mainly in cases of major reconstructive laparoscopic operations. The technique and advantages of retroperitoneoscopy are discussed as well.

[Percutaneous nephropexy]

We present a new, minimally invasive method for the treatment of nephroptosis. We are suggesting the more spreaded use of this method after the good results we found during the long term observation of our 40 patients with percutaneous nephropexy.

Laparoscopically controlled and assisted percutaneous transperitoneal nephrolithotomy in a pelvic dystopic kidney

Two renal pelvic stones were removed percutaneously from a pelvic dystopic kidney using a transabdominal, transperitoneal approach. The puncture was made antegrade and controlled partly fluoroscopically and partly laparoscopically. Where the kidney was covered by bowels, these were displaced with forceps inserted through another laparoscopic trocar. The dilation and stone removal were performed traditionally. As the kidney was just behind the uterus, the authors considered extracorporeal lithotripsy contraindicated in this case, so the only minimally invasive resolution was percutaneous nephrolithotomy, which could be performed only with the aid of laparoscopy.

[Endoscopic removal of urinary calculi in children]

In 55 children less than 14 years old urinary calculi have been removed endoscopically. In larger stones the ultrasonic lithotripsy has been used. Due to our experience and a review of the literature it was found that the majority of urinary calculi in children could be removed endoscopically. The open operation should be used in exceptional cases. Problems, results and complications of the endoscopic approach are described in detail.

[Endoscopic removal of urinary calculi in children]

The authors present their experience with the endoscopic kidney stone removal in pediatric patients. They treated 55 children under 14 with this method. If the stone was large they used ultrasonic disintegration. On the basis of their own experience and the technical literature they assert that most of the pediatric kidney stones are removable in this way and there is no reason for the existence of open surgery only in exceptional cases. They detail the difficulties of the performance, their results and complications. On the basis of these they emphasize that the aversion from the endoscopic kidney stone removal in pediatric patients--if someone has the necessary skill--is causeless.

[Percutaneous ultrasound lithotripsy of staghorn calculi]

It is reported on the percutaneous litholapaxy of 3 staghorn calculi. Since November 1984 1100 percutaneous nephrolitholapaxies were performed, 106 cases of them were staghorn calculi.

[Single-row wire suture of the sigmoid in Goodwin operations]

In Goodwin operations the authors have closed the intestinal wound resulting from longitudinal sigmoidotomy using a single-row uninterrupted transverse suture with atraumatic monofile steel wire. This suture technique has proved to be safe. No complications which might be associated with it have been observed.

Abnormal arteriovenous communications. Great variability of effects with particular reference to delayed development of cardiac failure

Clinical experiences and experimental studies provide evidence that an abnormal communication between the arterial and venous systems introduces into the circulation two circuits of flowing blood, one characterized by high arterial pressure and high peripheral resistance, and a second system bypassing part of the first, thus introducing a shorter circuit back to the heart, characterized by low pressure and low resistance, each supplied with flowing blood from the same central source, the heart. This shorter circuit acts solely as a parasitic circuit engrafted upon the normal circulation, serving no useful purpose, but capable of producing serious deleterious effects, depending upon the volume of blood diverted from the normal circulation into the shorter or parasitic circuit.

Intimately dependent upon this diversion of differing volumes of blood into the shorter circuit is the great diversity in the effects of a peripheral fistula upon the heart: the complete absence of cardiac dilatation in some cases; the rapid development of cardiac dilatation and cardiac failure within 2½ months as exemplified in Mason's case; and the long delay of 57 years in the development of cardiac failure as observed by Dorney.

Due to the high pressure in the normal circuit and the low resistance in the fistula circuit, there is a constant tendency for blood to be diverted or sequestered, as it were, in the fistulous or parasitic circuit, the factors determining the volume of blood so diverted being the size of the fistula and the distensibility of its rim or border, this, in turn, being dependent upon the character of the fibrous tissue deposited around the fistula in the course of healing. Firm, rigid, and excessive scarring permits only a small volume of blood to be sequestered in the fistula circuit, dilating only mildly the components of the parasitic circuit, whereas an elastic and distensible fistulous border permits progressive expansion of the fistulous opening with a progressive increase in the volume of blood sequestered in the fistula circuit, causing progressive dilatation of all components of this circuit including the four chambers of the heart, the aorta and artery proximal to the fistula, the fistula itself, the proximal vein, the vena cava, and the pulmonary vascular bed.

All gradations in distensibility of the fistula may occur, and hence all gradations in cardiac dilatation will occur. Also, all gradations in the rapidity of fistulous expansion may occur and, therefore, all gradations in rapidity of cardiac dilatation will occur.

This concept of a progressive expansion of a fistula of slow or rapid development permitting more and more blood to be shunted or sequestered in a shorter parasitic circuit at very rapid or very slow rates of increase provides the long-sought explanation of the rapid or long-delayed development of cardiac dilatation and failure in the presence of a peripheral fistula.

It is suggested that the same explanation is applicable to the effects of all abnormal arteriovenous communications, including intracardiac shunts and even some hemangiomata, since all are subject to the same hydrodynamic law that flowing blood like flowing water seeks the path of least resistance.

The Medical and Surgical Treatment of Hypertension

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Roentgenologic Kymographic Studies of the Heart in the Presence of an Arteriovenous Fistula and their Interpretation

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